The Journal of Foot & Ankle Surgery xxx (2014) 1–9
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Case Reports and Series
Surgical Treatment Guidelines for Digital Deformity Associated with Intrinsic Muscle Spasticity (Intrinsic Plus Foot) in Adults with Cerebral Palsy Troy J. Boffeli, DPM, FACFAS 1, Rachel C. Collier, DPM, AACFAS 2 1 2
Director, Foot and Ankle Surgical Residency Program, Regions Hospital/HealthPartners Institute for Education and Research, St. Paul, MN Staff Surgeon, Foot and Ankle Surgical Residency Program, Regions Hospital/HealthPartners Institute for Education and Research, St. Paul, MN
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 4
Intrinsic plus foot deformity has primarily been associated with cerebral palsy and involves spastic contracture of the intrinsic musculature with resultant toe deformities. Digital deformity is caused by a dynamic imbalance between the intrinsic muscles in the foot and extrinsic muscles in the lower leg. Spastic contracture of the toes frequently involves curling under of the lesser digits or contracture of the hallux into valgus or plantar flexion deformity. Patients often present with associated pressure ulcers, deformed toenails, shoe or brace fitting challenges, and pain with ambulation or transfers. Four different patterns of intrinsic plus foot deformity have been observed by the authors that likely relate to the different patterns of muscle involvement. Case examples are provided of the 4 patterns of intrinsic plus foot deformity observed, including global intrinsic plus lesser toe deformity, isolated intrinsic plus lesser toe deformity, intrinsic plus hallux valgus deformity, and intrinsic plus hallux flexus deformity. These case examples are presented to demonstrate each type of deformity and our approach for surgical management according to the contracture pattern. The surgical approach has typically involved tenotomy, capsulotomy, or isolated joint fusion. The main goals of surgical treatment are to relieve pain and reduce pressure points through digital realignment in an effort to decrease the risk of pressure sores and allow more effective bracing to ultimately improve the patient’s mobility. Ó 2014 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: hammertoe minimally invasive spastic deformity hallux valgus intrinsic plus foot deformity
Cerebral palsy (CP) is a nonprogressive neurologic disorder that involves abnormal control of motor function (1–3). Deformities of the lower extremity in patients with CP are secondary to muscle imbalance (1,4). Adults with CP have often undergone operative and nonoperative treatment of hip, knee, and ankle contracture during childhood and adolescence in an effort to maintain ambulatory status. Toe contracture will typically become clinically relevant later in life when the deformity has become rigid or severe. In a case series of 200 children with CP, O’Connell (4) identified 93% with a dynamic or fixed deformity of the foot and ankle. The most frequent deformity was equinovalgus (4). As a child progresses through adolescence and into adulthood, the dynamic imbalance between the intrinsic and extrinsic muscles of the foot can progress to a rigid and fixed deformity of digits that were previously flexible (1,4,5). Adult patients with
Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Rachel C. Collier, DPM, AACFAS, Foot and Ankle Surgical Residency Program, Regions Hospital/HealthPartners Institute for Education and Research, 640 Jackson Street, St. Paul, MN 55101. E-mail address: [email protected] (R.C. Collier).
CP frequently present with severe and rigid contracture of the toes, similar to what Peimer (6) described in the fingers as intrinsic plus hand contracture, which involves metacarpal phalangeal joint flexion and proximal interphalangeal joint extension or hyperextension. Spastic contracture of the toes frequently involves curling under of the lesser digits or contracture of the hallux into a valgus or plantar flexion deformity. Patients will often present with associated pressure ulcers, deformed toenails, and shoe and/or brace fitting challenges and pain with ambulation or transfers. Intrinsic plus foot deformity can also be caused by other conditions associated with muscle imbalance, including spastic neurologic disorders, rheumatoid disease, trauma, and ischemia (6,7). Adults with CP may not have access to the dedicated medical resources afforded to children with CP and therefore might seek treatment from general medical practitioners who may not fully appreciate the neuromuscular etiology of intrinsic plus foot deformity. It is important to differentiate digital deformity caused by spasticity from the more traditional forms of biomechanically induced hammertoes, hallux valgus, and hallux limitus because the effective treatment options, including surgery, differ according to the etiology of the deformity.
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The intrinsic muscles of the foot provide a stabilizing function through the metatarsophalangeal joints (MPJs) and interphalangeal joints (IPJs). A delicate balance exists between the intrinsic muscles of the foot and the extrinsic muscles of the leg. Muscle imbalance can result in biomechanically induced digital deformity and intrinsic plus foot deformity; however, the underlying mechanism of imbalance is quite different. Traditional hammertoe contracture is generally caused when the extrinsic muscles gains a mechanical advantage over the intrinsic muscles. This leads to extension at the MPJs and flexion at the IPJs (8). Traditional hallux valgus deformity involves lateral deviation of the great toe, which changes the pull of the adductor hallucis and flexor hallucis brevis (FHB) muscles into deforming forces (9). In contrast, the muscle imbalance in the intrinsic plus foot deformity is caused by spasticity and not biomechanical imbalance. The pattern of digital deformity is highly dependent on which intrinsic muscles have been affected by spasticity. For instance, spasticity of the lumbricales and interosseous muscles results in plantar contracture at the lesser MPJs and extension at the IPJs (Fig. 1). Spasticity of the adductor hallucis will result in hallux valgus, but spasticity of the FHB will result in hallux flexus through the first MPJ (Fig. 2). It is common that a patient with CP has combined spastic contracture of both the extrinsic and the intrinsic muscles, which can result in equinovarus contracture of the ankle and intrinsic plus deformity of the toes. This is more likely in patients who have not undergone posterior medial release of the ankle during childhood, have not responded to medical treatment of spasticity, or are minimally ambulatory owing to severe bilateral lower extremity contracture. The lack of regular weightbearing stretch allows progressive or recurrent contracture through the foot and ankle. Patients with intrinsic plus foot deformity typically present with pain or sores associated with wearing braces or shoes. The clinical picture resembles that of a traditional hammertoe, bunion, or hallux limitus condition to the casual observer, with callused lesions, redness, bursitis, and ulcerations around the prominent joints or, perhaps, a dorsal bump, similar to that with hallux limitus. Recognizing the underlying neuromuscular involvement is essential to successful treatment. A gait examination and weightbearing radiographs will often be helpful to fully appreciate the spastic nature of the intrinsic plus deformity because standing will stimulate spasticity and provide a better view of the digital position when the patient is walking. Practitioners might be inclined to not perform the gait examination or weightbearing imaging studies for patients with CP who struggle with ambulation; however, these tests will be helpful in fully appreciating the extent of digital deformity in the spastic state. Four patterns of intrinsic plus foot contracture have been observed by the authors, including global intrinsic plus lesser toe deformity, isolated intrinsic plus lesser toe deformity, intrinsic plus hallux valgus deformity, and intrinsic plus hallux flexus deformity. The isolated lesser toe deformity seems to primarily affect the second toe. It is common for a patient to have a combination of deformity patterns, especially intrinsic plus hallux valgus deformity plus an underlapping intrinsic plus second toe contracture. The published studies of the hand have described various treatment options for intrinsic plus hand deformity, which have typically involved lengthening of the intrinsic muscle unit in the lesser fingers (7,10,11). The goal of surgical treatment of spasticity affecting the fingers is to restore finger function. The goal of surgical treatment of toe contracture is to straighten the toes to allow comfort with transfers, walking, and wearing braces and shoes. Surgical treatment of intrinsic plus foot contracture may, therefore, require a different approach than that used for hand surgery or traditional hammertoe and hallux valgus surgery. Focus has been lacking in published studies regarding surgical treatment of the various digital contractures associated with spasticity, leaving the surgeon without clear guidelines for treatment. The present case series
Fig. 1. Intrinsic plus foot deformity involving the lesser toes. Spasticity of the plantar intrinsic muscles of the lesser toes results in plantar contracture at the metatarsophalangeal joints and extension at the interphalangeal joints. This can affect 1 or more of the lesser toes and is distinctly different from the traditional hammertoe contracture caused by biomechanical imbalance in which the extrinsic musculature gains a mechanical advantage over the intrinsic musculature, leading to extension at the metatarsophalangeal joints and flexion at the interphalangeal joints. This photograph demonstrates intrinsic plus lesser toe contracture primarily affecting the second toe. Weightbearing stimulates spasticity, driving the tip of the affected toes into the ground and leading to pain at the tip of the toe, toenail problems, pressure sores, and difficulty with bracing and shoes.
provides clinical examples of 4 patients with intrinsic plus foot contracture, including the patient selection criteria for surgical management, procedure selection, surgical technique, and postoperative care protocols. Details regarding procedure selection according to the involved muscle contracture and goals for functional outcome in each type of intrinsic plus foot deformity are provided in the Table.
Case Report Patient 1 Patient 1 depicts a typical case of global intrinsic plus lesser toe deformity involving a 30-year-old male with CP. His main complaint
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Fig. 2. Intrinsic plus foot deformity involving the first ray. Spastic contracture of the intrinsic muscles of the foot can lead to deformity of the first ray in patients with cerebral palsy. Spastic contracture of the adductor hallucis or flexor hallucis brevis can cause progressive and eventually rigid first ray deformity. The pattern of deformity is highly dependent on which intrinsic muscles have been affected by the spasticity. (A) For instance, intrinsic plus hallux valgus deformity is thought to be caused by spasticity of the adductor hallucis. (B) Alternatively, intrinsic plus hallux flexus deformity is likely caused by spasticity of the flexor hallucis brevis, which results in plantar flexion contracture of the first metatarsophalangeal joint, with secondary elevation of the first metatarsal. Hyperextension of the interphalangeal joint will be seen if the patient is ambulatory (B).
was significant pain on the dorsum of the second toe when walking, standing, wearing his ankle-foot orthoses (AFOs), and wearing shoes. The dorsal skin was intact; however, irritation was noted around the dystrophic second toenail and second proximal IPJ. Weightbearing and the gait examination when barefoot was difficult and painful for the patient but necessary to fully appreciate the extent of the deformity and spasticity. Examination of the second through fifth toes in the non-weightbearing position demonstrated plantar flexion contracture of the MPJs and extension of the IPJs (Fig. 3). The weightbearing examination demonstrated severe spasticity of the intrinsic musculature, causing severe plantar contracture and displacement through the lesser MPJs, creating the “upside-down” toe position characteristic of lesser toe intrinsic muscle spasticity. The patient basically walked on the dorsal surface of the lesser toes, which resulted in pressure around the toenails and IPJs. It was obvious that traditional hammertoe procedures would not effectively address this unique digital condition. The surgical treatment of patient 1, with global lesser toe intrinsic plus deformity, involved soft tissue release at the plantar aspect of each lesser MPJ. A plantar approach is preferred because intrinsic muscle contracture plantarly displaces the involved tendons, joint capsule, and ligament structures. These are difficult to reach using a traditional dorsal MPJ incision. The incision options also include a multiple longitudinal plantar incision, which is challenging, considering the close proximity of the incisions for multiple adjacent lesser MPJs. A minimal incision percutaneous approach is a consideration for flexor tenotomy; however, complete release of the intrinsic musculature and plantar MPJ capsule will be difficult without an open procedure. Our preferred method has been 1 transverse curvilinear
plantar incision that allows access to each of the lesser MPJs for full release of the contracted tissue. A longitudinal plantar incision is more appropriate for a deformity involving 1 isolated lesser toe contracture. The transverse curvilinear incision is performed at the level of MPJs 2 to 5 (Fig. 4). The transverse portion of the incision involves the skin and subcutaneous fat. The use of deep dissection is then isolated to each individual MPJ to avoid injury to the neurovascular structures. The MPJ anatomy is altered with intrinsic plus foot deformity in that the proximal phalanx, flexor tendons, intrinsic muscle tendons, periarticular ligaments, and plantar capsules are plantarly displaced, allowing relatively easy access for release. The toes are also plantarly displaced, along with the plantar fat pad. A curved hemostat is used to isolate the medial and lateral aspects of each joint, allowing the use of deep retractors to protect the intermetatarsal neurovascular structures (Fig. 5A). Individual MPJ exposure and release is performed in a sequential manner for
Table Treatment algorithm for intrinsic plus foot deformity Intrinsic plus foot deformity type
Surgical Treatment Options
Global intrinsic plus lesser toe deformity
Transverse plantar incision with capsulotomy and tenotomy of MPJs 2 to 5 Longitudinal plantar incision for MPJ capsulotomy and tenotomy First MPJ fusion
Isolated intrinsic plus lesser toe deformity Intrinsic plus hallux valgus deformity Intrinsic plus hallux flexus deformity
First MPJ fusion
Abbreviation: MPJ, metatarsophalangeal joint.
Patient Examples 1
2, 3
Figure Examples 3 to 7
1, 8, 10, 13
2
2A, 8, 10
3
2B, 12, 14
Fig. 3. Patient 1 depicts global intrinsic plus lesser toe deformity in a 30-year-old male with cerebral palsy (CP). The spasticity of the intrinsic musculature leads to this characteristic “upside-down” toe position. (A) Flexion contracture of the lesser metatarsophalangeal joints with extension of the interphalangeal joints of toes 2 through 5 was noted. Weightbearing stimulates spasticity, which accentuates the digital deformity, causing pain and pressure around the toenails and tips of the toes. (B) Patient 1 also had plantar contracture of the hallux (interphalangeal joint), indicating concomitant spasticity of the flexor hallucis longus muscle. It is common for patients with cerebral palsy to present with extrinsic muscle contracture deformity combined with intrinsic plus contracture deformity, making a careful clinical examination an important part of preoperative planning.
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incision at the mid-proximal phalanx level. Immediate improvement of digital positioning was noted (Fig. 5C). Immediate ambulation in a below the knee walker was allowed until he was ready to wear the AFOs at 2 weeks postoperatively. Immediate weightbearing will provide the desired stretch to the affected joints in an effort to maximize the correction. Ambulation in a surgical shoe would be allowed, although most patients will require AFO support of the ankle for ambulation. The plantar incisions were well healed at 2 weeks postoperatively, and the digital correction was well maintained (Fig. 6). The patient had transitioned to regular shoes and the use of his AFOs and had returned to seated work at 2 weeks postoperatively. He had well-healed plantar incisions without any identified postoperative complications and excellent digital alignment at the 10-month postoperative visit. The patient was very happy with the function, alignment, and appearance of his toes and no longer experienced pain or discomfort. Clinical photographs at 10 months postoperatively demonstrated that the toes had remained fairly rectus, although not in perfect alignment (Fig. 7). Patient 2
Fig. 4. Single transverse plantar incision for release of deformity in patient 1. A single plantar transverse incision has been our preferred approach for surgical correction of global intrinsic plus lesser toe deformity, because it allows direct access to the second through fifth metatarsophalangeal joints. The global intrinsic plus lesser toe deformity will plantarly displace the joint capsule, ligaments, and tendon structures, which can be easily visualized using the plantar approach and are difficult to access using multiple dorsal incisions.
digits 2 through 5. The transverse tenotomy and capsulotomy procedure is performed just proximal to the base of the proximal phalanx, which is plantarly displaced. The tendon sheath of the flexor tendons is encountered first, releasing both the long and the short flexor tendons. A medial, central, and lateral transverse MPJ capsulotomy is then performed. Intrinsic muscle tenotomy is accomplished on both sides of the joint with the capsulotomy, because the dorsal and plantar interossei and lumbricals will be plantarly displaced owing to the contracture deformity. The toe is then forced into hyperextension to further stretch the remaining soft tissue contractures. It is fairly easy to appreciate the occurrence of the complete release and the lack of continued deforming forces (Fig. 5B). The same procedure is then performed on the remaining lesser digits (Fig. 5C). Patient 1 also had spastic contracture of the flexor hallucis longus tendon, causing plantar contracture of the first toe through the IPJ. He did not exhibit spasticity of the FHB; therefore, treatment involved simple flexor hallucis longus tenotomy through a separate transverse
Patient 2 was a 53-year-old male with CP who had presented with a combination of isolated intrinsic plus lesser toe deformity and intrinsic plus hallux valgus deformity on the right foot. His chief complaint was pain at the tip of the second toe (Fig. 8). Previous surgical intervention had involved Achilles tendon lengthening and plantar fascia release during childhood. He remained active with the use of custom orthotics and a modified shoe to compensate for a significant limb length discrepancy on the right foot. The physical examination identified extreme nonreducible hallux valgus that was accentuated when standing. The second toe exhibited plantar flexion at the MPJ and the typical “upside-down” digital deformity associated with intrinsic plus foot deformity. He essentially walked on the second toenail, but no open sores or infection were present. The remaining lesser toes were contracted in a more typical claw toe fashion, which likely represented a component of flexor digitorum longus spasticity. The operative approach for this condition is different from that for traditional hallux valgus and second hammertoe surgery. Successful straightening of the second toe required concomitant correction of the hallux valgus deformity owing to the overlap. Surgical repair of neurogenic hallux valgus associated with spasticity typically requires first MPJ fusion if long-term correction of the digital deformity is to be expected. Locking plate fixation and 6 weeks of non-weightbearing protection were incorporated to minimize the additional stress that the altered gait from CP might cause. A percutaneous pin was used to maintain the IPJ correction after the flexor hallucis longus tenotomy. The second MPJ contracture deformity was addressed with a combination of dorsal and plantar incisions. This would traditionally be addressed using a longitudinal plantar incision at the level of the second MPJ, although patient 2 exhibited a deep crease in the local skin associated with chronic digital malalignment and the lack of MPJ purchase. A percutaneous plantar MPJ incision was therefore combined with a dorsal approach to access the necessary structures for release. The dorsal approach also facilitated pin fixation of the MPJ, which is difficult using the plantar approach. Percutaneous plantar proximal IPJ incisions were used for the traditional long and short flexor tenotomy of digits 3 through 5. The 2-week postoperative clinical photographs demonstrated intact incisions with improved digital alignment (Fig. 9). The external pins were removed at 6 weeks postoperatively, at which point he transitioned to weightbearing, as tolerated, in a walking boot. The pre- and postoperative anteroposterior radiographs
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Fig. 5. Open lesser metatarsophalangeal joint release for deformity in patient 1. After the initial incision, deep dissection was limited to each specific lesser metatarsophalangeal joint in an effort to minimize neurovascular compromise. Blunt dissection was advanced to the level of the flexor tendon sheath. The medial and lateral aspects of the joint complex were isolated, allowing deep retractors to protect the neurovascular structures (A). A transverse tenotomy was performed of the flexor digitorum longus and brevus at the base of the proximal phalanx, and a metatarsophalangeal joint capsulotomy was performed. The intrinsic muscle contracture and plantar displacement of the proximal phalanx allowed easy access to cut the dorsal and plantar interossei, lumbricals, and collateral ligaments when performing the capsulotomy. The toe was forced into hyperextension to further stretch the remaining soft tissue contractures. (B) Photograph demonstrating the substantial improvement in the second, third, and fourth toe alignment compared with the untreated fifth toe. (C) Photograph demonstrating the release of the first through fifth toes, including flexor hallucis longus tenotomy for hallux interphalangeal joint contracture.
showed the dramatic improvement in the first and second digital alignment (Fig. 10A and B). The pre- and postoperative lateral radiographs demonstrated desirable first digital alignment and union
at 10 weeks after surgery (Fig. 10C and D). The 10-week postoperative clinical photographs demonstrated complete healing and excellent digital alignment (Fig. 11). Long-term follow-up of 3 years for orthotics and modified shoes have revealed no subsequent problems or recurrent deformity. Patient 3
Fig. 6. (A and B) Postoperative photographs of patient 1 with global intrinsic plus lesser toe deformity. The near normal toe alignment can be seen 2 weeks after release of the intrinsic plus foot deformity of toes 2 through 5 by way of a plantar transverse incision. The incision was well healed despite immediate weightbearing. The patient was able to return to shoes and extremity bracing, normal activities, and seated work after this initial postoperative visit.
Patient 3 was a 49-year-old male with spastic quadriplegic CP who had a combination of isolated intrinsic plus lesser toe deformity and intrinsic plus hallux flexus deformity bilaterally. The patient presented with concerns of recurrent ulceration and pain at the dorsum of the third toe bilaterally. The third toes exhibited plantar flexion at the MPJ with the typical “upside-down” digital deformity associated with intrinsic plus foot deformity. The patient was not ambulatory yet experienced pressure on the third toes when sitting in a power wheelchair or wearing shoes. Compression stockings also accentuated the curling under of the third toes, causing added discomfort and pressure. The physical examination identified bilateral dorsal bunion deformity associated with intrinsic plus hallux flexus deformity, although no skin breakdown or history of pain associated with the first toes was present. Lateral radiographs demonstrated the intrinsic plus hallux flexus with secondary elevation of the first metatarsal (Fig. 12). Consideration was given to the most appropriate surgical plan for this patient. The patient was not ambulatory and did not use his limbs for transfers. A longitudinal plantar approach for third MPJ release would have been reasonable; however, the lack of daily weightbearing stretch could have resulted in recurrent deformity. The tightness of the plantar skin and longstanding joint contracture in nonambulatory patients results in slight uncertainty regarding the effectiveness of the soft tissue release. Amputation of both third toes was performed, because this approach best matched the patient’s desire for complete pain relief with prompt recovery. Hallux flexus would normally be treated with first MPJ fusion. The first ray
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Fig. 7. (A–C) Long-term postoperative clinical photographs of patient 1 with global intrinsic plus lesser toe deformity. The 10-month follow-up examination revealed acceptable toe alignment without recurrent deformity and a barely visible transverse scar. The patient remained pain free and had no postoperative complications. He no longer required an ankle-foot orthotic for ambulation but continued to use a walker because of knee and hip contractures.
deformity was asymptomatic; therefore, no treatment was necessary. The incisions had healed within 2 weeks, and the patient did not require additional postoperative care. The initial postoperative
radiographs demonstrated bilateral amputation at the level of the third MPJs (Fig. 13). No recurrence of ulceration or deformity occurred during the follow-up of 3.5 years.
Fig. 8. Patient 2 demonstrates a combination of isolated intrinsic plus lesser toe deformity and intrinsic plus hallux valgus deformity. He was a 53-year-old male with cerebral palsy. This is a common deformity combination, with implications for ideal procedure selection. This patient was ambulatory with the use of bracing, and his main source of pain was pressure on the tip of the second toe when standing or walking on the right foot. Note the plantar soft tissue crease, which is common in intrinsic plus deformity, and is thought to be associated with a lack of purchase of the metatarsal head in this area. Plantar and proximal retraction of the second toe will elevate the second metatarsal head, similar to first ray elevatus.
Fig. 9. (A and B) Photographs at 2-weeks postoperatively of patient 2 demonstrating healed incisions and percutaneous pins with well-maintained alignment of the toes. Treatment of intrinsic plus hallux valgus deformity involved fusion of the first metatarsophalangeal joint to prevent recurrence, given the spastic nature of the deformity. A percutaneous pin was used, in addition to locking plate fixation, to maintain interphalangeal joint correction. Treatment of the isolated intrinsic plus lesser toe deformity involved soft tissue release of the plantar contracture. A longitudinal plantar incision would have provided ideal exposure for isolated joint release, although this approach is not very amenable to second toe pin fixation. Patient 2 also had a deep plantar crease, further complicating the plantar incision options. An open dorsal second metatarsophalangeal joint approach was therefore combined with percutaneous plantar release. Note that the plantar skin in the digital sulcus can be compromised by single-stage release of a longstanding digital deformity. Percutaneous flexor tenotomy was also performed on toes 1, 3, 4, and 5.
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Fig. 10. Preoperative and 10-week postoperative radiographs of patient 2. (A) Preoperative and (B) postoperative weightbearing anteroposterior radiographs demonstrated dramatic improvement of the first and second digital alignment. (C) Preoperative and (D) postoperative lateral radiographs show desirable first digital alignment and union 10 weeks after surgery.
Discussion The present case series describes 4 patterns of intrinsic plus foot deformities that have been observed by the authors (Table). Different patterns of digital involvement are thought to be the result of variable involvement of intrinsic muscle spasticity. The direction of spastic contracture at each of the involved joints gives the surgeon an
indication of the structures that need to be released or negated through tenotomy, capsulotomy, or fusion. Intrinsic plus lesser digital deformity is likely to be associated with spasticity of the intrinsic muscles with severe plantar flexion through the MPJs yet extension of the IPJs. The proximal phalanx will be plantar flexed and will eventually retract proximally on the head of the metatarsal. Usually, some degree of flexor contracture will be present, including the long flexor
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Fig. 11. (A and B) Clinical photographs at 10 weeks postoperatively of patient 2 demonstrating well-healed incisions and maintenance of digital realignment. Long-term followup has demonstrated no recurrence of deformity, ulceration, or pain.
tendon, which can be secondary in longstanding digital deformity. The MPJ ligaments and plantar capsule will eventually become contracted, leading to a fixed deformity. Each of these structures can be released through plantar exposure in an effort to realign the involved toes to the neutral position. Immediate weightbearing postoperatively will produce tension and stretch to the affected joints,
Fig. 12. Case 3 demonstrates combined isolated intrinsic plus lesser toe deformity and intrinsic plus hallux flexus deformity in a 49-year-old male with spastic quadriplegic cerebral palsy with bilateral symmetric foot deformity. The third toe deformity involved metatarsophalangeal joint spastic contracture with the typical “upside down” toe appearance. His greatest concern was pain and recurrent ulcerations of the third toe associated with the use of compression stockings, bracing, shoes, and sitting in a power wheelchair. (A) Left and (B) right lateral radiographs best demonstrated hallux flexus deformity, which was asymptomatic owing to his nonambulatory status.
Fig. 13. Postoperative radiographs of patient 3 who had undergone bilateral third toe amputation for isolated intrinsic plus lesser toe deformity. Typical treatment of intrinsic plus lesser toe deformity involves plantar tenotomy and capsulotomy at the level of the metatarsophalangeal joint. However, patient 3 was nonambulatory and did not use his legs for transfers. He also had no pain or problems with the first ray deformity. Surgical treatment involved bilateral third toe amputation. The incisions were well healed at 2 weeks postoperatively, allowing prompt recovery without the risk of recurrent deformity. (A) Left and (B) right foot radiographs at the initial postoperative visit after bilateral third toe amputation.
which is desired to achieve and maintain maximum correction of the released structures. Intrinsic plus hallux valgus deformity and intrinsic plus hallux flexus deformity involve the first ray, which has unique intrinsic muscle anatomy compared with the lesser toes. Spasticity of the adductor hallucis creates a deformity that presents with similarities to those of severe hallux valgus deformity (Fig. 1A). The first toe may overlap or underlap the second toe, and interdigital pressure sores are common. Fusion of the first MPJ is our preferred treatment if surgery is required, because the traditional procedures for hallux valgus are likely to fail, considering the spastic nature of this condition. This approach is in agreement with the published data that have documented fusion of the first MPJ as the procedure of choice to prevent recurrence in spastic conditions (1,12). Spasticity of the FHB muscle creates hallux flexus deformity, with plantar flexion through the first MPJ. The IPJ of the hallux will typically be extended when standing, suggesting that the long flexor tendon is not a deforming force (Fig. 1B). This condition presents with similarities to those of hallux limitus in that the hallux has limited dorsiflexion and a dorsal lump will be noted over the first metatarsal head. The lump results from the retrograde force of the plantarly contracted proximal phalanx, which creates extreme elevation of the first metatarsal. At first glance, a practitioner might incorrectly assume that the plantar flexed position of the first toe is secondary to the elevated medial column. The first ray elevation will eventually become rigid, further confusing this “chicken or egg” scenario. It is our belief that the muscle spasticity of the FHB is the deforming force that ultimately results in intrinsic plus hallux flexus deformity. The weightbearing lateral radiograph will typically demonstrate this dorsal position of the first metatarsal head in relation to the proximal phalanx (Fig. 14). Surgical treatment of intrinsic plus hallux flexus
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Fig. 14. Weightbearing lateral radiograph demonstrating intrinsic plus hallux flexus deformity. Spasticity of the flexor hallucis brevis muscle creates intrinsic plus hallux flexus deformity with plantar flexion and proximal retraction of the proximal phalanx and sesamoids. The interphalangeal joint of the hallux will typically be extended when standing, suggesting that the flexor hallucis longus is not a deforming force. Retrograde force from the proximal phalanx is thought to elevate the first metatarsal head, creating a dorsal bunion, which can cause shoe irritation and dorsal ulceration. The lateral radiograph demonstrates the elevated first metatarsal head and dorsal bunion.
deformity would ideally involve first MPJ arthrodesis. This approach will provide stable positioning of the hallux and also facilitate plantar positioning of the elevated first metatarsal. Soft tissue release is possible for nonfusion candidates. The FHB muscle inserts through the sesamoid apparatus, and the sesamoids will typically be retracted in the proximal direction. Soft tissue release would ideally be proximal to the sesamoids. Fixed elevation of the medial column might necessitate osteotomy or fusion through the midfoot for improved alignment. Intrinsic plus hallux flexus deformity seems to be more associated with patients with CP who are wheelchair bound and therefore not ambulating enough to maintain the stretch on the hallux and medial column. Nonambulatory patients with intrinsic plus hallux flexus deformity could present with ulceration over the elevated first metatarsal head. The primary goal of surgical treatment of intrinsic plus foot deformity is to remove or negate the deforming forces and allow realignment of the involved digits. Our focus has been on tenotomy, capsulotomy, and joint fusion, with the intent to prevent recurrence of the deformity. However, as demonstrated in patient 3, sometimes digital amputation becomes the procedure of choice, in accordance with patient function and desired outcome. Upper and lower extremity deformity, contracture, and spasticity will often result in the need for the patient to bear weight during postoperative recovery. The unsteady gait associated with spasticity will frequently result in abnormal stress on the surgical site; therefore, major reconstructive procedures involving joint fusion and osteotomy should be avoided when possible. Many patients with intrinsic plus foot contracture have undergone numerous operations during childhood yet still require bilateral braces for ambulation. Children are lightweight and can be lifted by family members; however, this is not a practical postoperative method for adults. This makes bilateral foot surgery more challenging and suggests the potential benefit of ambulatory procedures. Patients with neuromuscular disorders are often not expecting perfect digital alignment and will be very pleased to
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simply have relief of pain and pressure sores. A lifetime of living with CP and numerous experiences with less than ideal surgical outcomes help set the stage for patient expectations with digital surgery. Nonetheless, fusion will sometimes be the better option and primarily affects intrinsic plus contracture deformity of the first toe. Rigid correction allows predictable and permanent positioning of the first MPJ, which will help the overall alignment of the lesser toes and foot in general. A medial to lateral lag screw, combined with dorsal locking plate fixation, will allow weightbearing during healing of first MPJ fusion for most patients. Patient 2 underwent non-weightbearing recovery, which was our standard first MPJ fusion protocol at that time. Patients with CP need an individual gait assessment to determine whether weightbearing can be tolerated immediately after fusion. The present case series had shortcomings primarily related to the retrospective nature of the involved cases. Our purpose was to describe 4 presentations of intrinsic plus foot deformity, although any pattern or combination is theoretically possible owing to the complex nature of the intrinsic muscle anatomy. These 4 patterns were presented with the surgical approaches we have used to address the pathologic anatomy in each type. Additional studies are needed to establish a classification system that will allow for a more predictable outcome using a higher level of evidence-based medicine and larger patient population sizes. The present case study has demonstrated the goals for surgical intervention in intrinsic plus foot deformity, which are, ultimately, to relieve the pain and reduce the pressure points through digital realignment in an effort to decrease the risk of pressure sores and allow more effective bracing for this unique patient population. References 1. Canale ST, Beaty JH. Cerebral palsy. In: Campbell’s Operative Orthopaedics, Mosby, Maryland Heights, MO, 2013, pp. 1202–1254. 2. Horstmann HM, Hosalkar H, Keenan MA. Orthopaedic issues in the musculoskeletal care of adults with cerebral palsy. Dev Med Child Neurol 51:99–105, 2009. 3. Renshaw TS, Green NE, Griffin PP, Root L. Cerebral palsy: orthopaedic management. J Bone Joint Surg Am 77-A:1590–1605, 1995. 4. O’Connell PA, D’Souza L, Dudeney SM, Stephens MM. Foot deformities in children with cerebral palsy. J Pediatr Orthop 18:743–747, 1998. 5. Davids JR. The foot and ankle in cerebral palsy. Orthop Clin North Am 41:579–593, 2010. 6. Peimer CA. Intrinsic muscle contractures. In: Chapman’s Orthopaedic Surgery, ed 3, pp. 1749–1763, edited by MW Chapman, Lippincott Williams & Wilkins, Philadelphia, 2001. 7. Paksima N, Besch BR. Intrinsic contractures of the hand. Hand Clin 28:81–86, 2012. 8. McGlamry ED, Jimenez AL, Green DR. Lesser ray deformities. In: McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery, pp. 253–338, edited by The Podiatry Institute, J Sutherland, D Alder, J Boberg, M Downey, A Nakra, L Rabjohn, LV Rabjohn, Lippincott Williams and Wilkins, Philadelphia, 2001. 9. Martin EM, Pontious J. Introduction and evaluation of hallux abducto valgus. In: McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery, pp. 481–491, edited by The Podiatry Institute, J Sutherland, D Alder, J Boberg, M Downey, A Nakra, L Rabjohn, LV Rabjohn, Lippincott Williams & Wilkins, Philadelphia, 2001. 10. Harris C, Riordan DC. Intrinsic contracture in the hand and its surgical treatment. J Bone Joint Surg Am 36-A:10–18, 1953. 11. Matsuo T, Matsuo A, Hajime T, Fukumoto S, Chem W, Iwamoto Y. Release of flexors and intrinsic muscles for finger spasticity in cerebral palsy. Clin Orthop Relat Res 384:162–168, 2001. 12. Bishay SNG, El-Sherbini MH, Lotfy AA, Abdel-Rahman HM, Iskandar HN, El-Sayed MM. Great toe metatarsophalangeal arthrodesis for hallux valgus deformity in ambulatory adolescents with spastic cerebral palsy. J Child Orthop 3:47–52, 2009.
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Case Reports and Series
Surgical Treatment Guidelines for Digital Deformity Associated with Intrinsic Muscle Spasticity (Intrinsic Plus Foot) in Adults with Cerebral Palsy Troy J. Boffeli, DPM, FACFAS 1, Rachel C. Collier, DPM, AACFAS 2 1 2
Director, Foot and Ankle Surgical Residency Program, Regions Hospital/HealthPartners Institute for Education and Research, St. Paul, MN Staff Surgeon, Foot and Ankle Surgical Residency Program, Regions Hospital/HealthPartners Institute for Education and Research, St. Paul, MN
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 4
Intrinsic plus foot deformity has primarily been associated with cerebral palsy and involves spastic contracture of the intrinsic musculature with resultant toe deformities. Digital deformity is caused by a dynamic imbalance between the intrinsic muscles in the foot and extrinsic muscles in the lower leg. Spastic contracture of the toes frequently involves curling under of the lesser digits or contracture of the hallux into valgus or plantar flexion deformity. Patients often present with associated pressure ulcers, deformed toenails, shoe or brace fitting challenges, and pain with ambulation or transfers. Four different patterns of intrinsic plus foot deformity have been observed by the authors that likely relate to the different patterns of muscle involvement. Case examples are provided of the 4 patterns of intrinsic plus foot deformity observed, including global intrinsic plus lesser toe deformity, isolated intrinsic plus lesser toe deformity, intrinsic plus hallux valgus deformity, and intrinsic plus hallux flexus deformity. These case examples are presented to demonstrate each type of deformity and our approach for surgical management according to the contracture pattern. The surgical approach has typically involved tenotomy, capsulotomy, or isolated joint fusion. The main goals of surgical treatment are to relieve pain and reduce pressure points through digital realignment in an effort to decrease the risk of pressure sores and allow more effective bracing to ultimately improve the patient’s mobility. Ó 2014 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: hammertoe minimally invasive spastic deformity hallux valgus intrinsic plus foot deformity
Cerebral palsy (CP) is a nonprogressive neurologic disorder that involves abnormal control of motor function (1–3). Deformities of the lower extremity in patients with CP are secondary to muscle imbalance (1,4). Adults with CP have often undergone operative and nonoperative treatment of hip, knee, and ankle contracture during childhood and adolescence in an effort to maintain ambulatory status. Toe contracture will typically become clinically relevant later in life when the deformity has become rigid or severe. In a case series of 200 children with CP, O’Connell (4) identified 93% with a dynamic or fixed deformity of the foot and ankle. The most frequent deformity was equinovalgus (4). As a child progresses through adolescence and into adulthood, the dynamic imbalance between the intrinsic and extrinsic muscles of the foot can progress to a rigid and fixed deformity of digits that were previously flexible (1,4,5). Adult patients with
Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Rachel C. Collier, DPM, AACFAS, Foot and Ankle Surgical Residency Program, Regions Hospital/HealthPartners Institute for Education and Research, 640 Jackson Street, St. Paul, MN 55101. E-mail address: [email protected] (R.C. Collier).
CP frequently present with severe and rigid contracture of the toes, similar to what Peimer (6) described in the fingers as intrinsic plus hand contracture, which involves metacarpal phalangeal joint flexion and proximal interphalangeal joint extension or hyperextension. Spastic contracture of the toes frequently involves curling under of the lesser digits or contracture of the hallux into a valgus or plantar flexion deformity. Patients will often present with associated pressure ulcers, deformed toenails, and shoe and/or brace fitting challenges and pain with ambulation or transfers. Intrinsic plus foot deformity can also be caused by other conditions associated with muscle imbalance, including spastic neurologic disorders, rheumatoid disease, trauma, and ischemia (6,7). Adults with CP may not have access to the dedicated medical resources afforded to children with CP and therefore might seek treatment from general medical practitioners who may not fully appreciate the neuromuscular etiology of intrinsic plus foot deformity. It is important to differentiate digital deformity caused by spasticity from the more traditional forms of biomechanically induced hammertoes, hallux valgus, and hallux limitus because the effective treatment options, including surgery, differ according to the etiology of the deformity.
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The intrinsic muscles of the foot provide a stabilizing function through the metatarsophalangeal joints (MPJs) and interphalangeal joints (IPJs). A delicate balance exists between the intrinsic muscles of the foot and the extrinsic muscles of the leg. Muscle imbalance can result in biomechanically induced digital deformity and intrinsic plus foot deformity; however, the underlying mechanism of imbalance is quite different. Traditional hammertoe contracture is generally caused when the extrinsic muscles gains a mechanical advantage over the intrinsic muscles. This leads to extension at the MPJs and flexion at the IPJs (8). Traditional hallux valgus deformity involves lateral deviation of the great toe, which changes the pull of the adductor hallucis and flexor hallucis brevis (FHB) muscles into deforming forces (9). In contrast, the muscle imbalance in the intrinsic plus foot deformity is caused by spasticity and not biomechanical imbalance. The pattern of digital deformity is highly dependent on which intrinsic muscles have been affected by spasticity. For instance, spasticity of the lumbricales and interosseous muscles results in plantar contracture at the lesser MPJs and extension at the IPJs (Fig. 1). Spasticity of the adductor hallucis will result in hallux valgus, but spasticity of the FHB will result in hallux flexus through the first MPJ (Fig. 2). It is common that a patient with CP has combined spastic contracture of both the extrinsic and the intrinsic muscles, which can result in equinovarus contracture of the ankle and intrinsic plus deformity of the toes. This is more likely in patients who have not undergone posterior medial release of the ankle during childhood, have not responded to medical treatment of spasticity, or are minimally ambulatory owing to severe bilateral lower extremity contracture. The lack of regular weightbearing stretch allows progressive or recurrent contracture through the foot and ankle. Patients with intrinsic plus foot deformity typically present with pain or sores associated with wearing braces or shoes. The clinical picture resembles that of a traditional hammertoe, bunion, or hallux limitus condition to the casual observer, with callused lesions, redness, bursitis, and ulcerations around the prominent joints or, perhaps, a dorsal bump, similar to that with hallux limitus. Recognizing the underlying neuromuscular involvement is essential to successful treatment. A gait examination and weightbearing radiographs will often be helpful to fully appreciate the spastic nature of the intrinsic plus deformity because standing will stimulate spasticity and provide a better view of the digital position when the patient is walking. Practitioners might be inclined to not perform the gait examination or weightbearing imaging studies for patients with CP who struggle with ambulation; however, these tests will be helpful in fully appreciating the extent of digital deformity in the spastic state. Four patterns of intrinsic plus foot contracture have been observed by the authors, including global intrinsic plus lesser toe deformity, isolated intrinsic plus lesser toe deformity, intrinsic plus hallux valgus deformity, and intrinsic plus hallux flexus deformity. The isolated lesser toe deformity seems to primarily affect the second toe. It is common for a patient to have a combination of deformity patterns, especially intrinsic plus hallux valgus deformity plus an underlapping intrinsic plus second toe contracture. The published studies of the hand have described various treatment options for intrinsic plus hand deformity, which have typically involved lengthening of the intrinsic muscle unit in the lesser fingers (7,10,11). The goal of surgical treatment of spasticity affecting the fingers is to restore finger function. The goal of surgical treatment of toe contracture is to straighten the toes to allow comfort with transfers, walking, and wearing braces and shoes. Surgical treatment of intrinsic plus foot contracture may, therefore, require a different approach than that used for hand surgery or traditional hammertoe and hallux valgus surgery. Focus has been lacking in published studies regarding surgical treatment of the various digital contractures associated with spasticity, leaving the surgeon without clear guidelines for treatment. The present case series
Fig. 1. Intrinsic plus foot deformity involving the lesser toes. Spasticity of the plantar intrinsic muscles of the lesser toes results in plantar contracture at the metatarsophalangeal joints and extension at the interphalangeal joints. This can affect 1 or more of the lesser toes and is distinctly different from the traditional hammertoe contracture caused by biomechanical imbalance in which the extrinsic musculature gains a mechanical advantage over the intrinsic musculature, leading to extension at the metatarsophalangeal joints and flexion at the interphalangeal joints. This photograph demonstrates intrinsic plus lesser toe contracture primarily affecting the second toe. Weightbearing stimulates spasticity, driving the tip of the affected toes into the ground and leading to pain at the tip of the toe, toenail problems, pressure sores, and difficulty with bracing and shoes.
provides clinical examples of 4 patients with intrinsic plus foot contracture, including the patient selection criteria for surgical management, procedure selection, surgical technique, and postoperative care protocols. Details regarding procedure selection according to the involved muscle contracture and goals for functional outcome in each type of intrinsic plus foot deformity are provided in the Table.
Case Report Patient 1 Patient 1 depicts a typical case of global intrinsic plus lesser toe deformity involving a 30-year-old male with CP. His main complaint
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Fig. 2. Intrinsic plus foot deformity involving the first ray. Spastic contracture of the intrinsic muscles of the foot can lead to deformity of the first ray in patients with cerebral palsy. Spastic contracture of the adductor hallucis or flexor hallucis brevis can cause progressive and eventually rigid first ray deformity. The pattern of deformity is highly dependent on which intrinsic muscles have been affected by the spasticity. (A) For instance, intrinsic plus hallux valgus deformity is thought to be caused by spasticity of the adductor hallucis. (B) Alternatively, intrinsic plus hallux flexus deformity is likely caused by spasticity of the flexor hallucis brevis, which results in plantar flexion contracture of the first metatarsophalangeal joint, with secondary elevation of the first metatarsal. Hyperextension of the interphalangeal joint will be seen if the patient is ambulatory (B).
was significant pain on the dorsum of the second toe when walking, standing, wearing his ankle-foot orthoses (AFOs), and wearing shoes. The dorsal skin was intact; however, irritation was noted around the dystrophic second toenail and second proximal IPJ. Weightbearing and the gait examination when barefoot was difficult and painful for the patient but necessary to fully appreciate the extent of the deformity and spasticity. Examination of the second through fifth toes in the non-weightbearing position demonstrated plantar flexion contracture of the MPJs and extension of the IPJs (Fig. 3). The weightbearing examination demonstrated severe spasticity of the intrinsic musculature, causing severe plantar contracture and displacement through the lesser MPJs, creating the “upside-down” toe position characteristic of lesser toe intrinsic muscle spasticity. The patient basically walked on the dorsal surface of the lesser toes, which resulted in pressure around the toenails and IPJs. It was obvious that traditional hammertoe procedures would not effectively address this unique digital condition. The surgical treatment of patient 1, with global lesser toe intrinsic plus deformity, involved soft tissue release at the plantar aspect of each lesser MPJ. A plantar approach is preferred because intrinsic muscle contracture plantarly displaces the involved tendons, joint capsule, and ligament structures. These are difficult to reach using a traditional dorsal MPJ incision. The incision options also include a multiple longitudinal plantar incision, which is challenging, considering the close proximity of the incisions for multiple adjacent lesser MPJs. A minimal incision percutaneous approach is a consideration for flexor tenotomy; however, complete release of the intrinsic musculature and plantar MPJ capsule will be difficult without an open procedure. Our preferred method has been 1 transverse curvilinear
plantar incision that allows access to each of the lesser MPJs for full release of the contracted tissue. A longitudinal plantar incision is more appropriate for a deformity involving 1 isolated lesser toe contracture. The transverse curvilinear incision is performed at the level of MPJs 2 to 5 (Fig. 4). The transverse portion of the incision involves the skin and subcutaneous fat. The use of deep dissection is then isolated to each individual MPJ to avoid injury to the neurovascular structures. The MPJ anatomy is altered with intrinsic plus foot deformity in that the proximal phalanx, flexor tendons, intrinsic muscle tendons, periarticular ligaments, and plantar capsules are plantarly displaced, allowing relatively easy access for release. The toes are also plantarly displaced, along with the plantar fat pad. A curved hemostat is used to isolate the medial and lateral aspects of each joint, allowing the use of deep retractors to protect the intermetatarsal neurovascular structures (Fig. 5A). Individual MPJ exposure and release is performed in a sequential manner for
Table Treatment algorithm for intrinsic plus foot deformity Intrinsic plus foot deformity type
Surgical Treatment Options
Global intrinsic plus lesser toe deformity
Transverse plantar incision with capsulotomy and tenotomy of MPJs 2 to 5 Longitudinal plantar incision for MPJ capsulotomy and tenotomy First MPJ fusion
Isolated intrinsic plus lesser toe deformity Intrinsic plus hallux valgus deformity Intrinsic plus hallux flexus deformity
First MPJ fusion
Abbreviation: MPJ, metatarsophalangeal joint.
Patient Examples 1
2, 3
Figure Examples 3 to 7
1, 8, 10, 13
2
2A, 8, 10
3
2B, 12, 14
Fig. 3. Patient 1 depicts global intrinsic plus lesser toe deformity in a 30-year-old male with cerebral palsy (CP). The spasticity of the intrinsic musculature leads to this characteristic “upside-down” toe position. (A) Flexion contracture of the lesser metatarsophalangeal joints with extension of the interphalangeal joints of toes 2 through 5 was noted. Weightbearing stimulates spasticity, which accentuates the digital deformity, causing pain and pressure around the toenails and tips of the toes. (B) Patient 1 also had plantar contracture of the hallux (interphalangeal joint), indicating concomitant spasticity of the flexor hallucis longus muscle. It is common for patients with cerebral palsy to present with extrinsic muscle contracture deformity combined with intrinsic plus contracture deformity, making a careful clinical examination an important part of preoperative planning.
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incision at the mid-proximal phalanx level. Immediate improvement of digital positioning was noted (Fig. 5C). Immediate ambulation in a below the knee walker was allowed until he was ready to wear the AFOs at 2 weeks postoperatively. Immediate weightbearing will provide the desired stretch to the affected joints in an effort to maximize the correction. Ambulation in a surgical shoe would be allowed, although most patients will require AFO support of the ankle for ambulation. The plantar incisions were well healed at 2 weeks postoperatively, and the digital correction was well maintained (Fig. 6). The patient had transitioned to regular shoes and the use of his AFOs and had returned to seated work at 2 weeks postoperatively. He had well-healed plantar incisions without any identified postoperative complications and excellent digital alignment at the 10-month postoperative visit. The patient was very happy with the function, alignment, and appearance of his toes and no longer experienced pain or discomfort. Clinical photographs at 10 months postoperatively demonstrated that the toes had remained fairly rectus, although not in perfect alignment (Fig. 7). Patient 2
Fig. 4. Single transverse plantar incision for release of deformity in patient 1. A single plantar transverse incision has been our preferred approach for surgical correction of global intrinsic plus lesser toe deformity, because it allows direct access to the second through fifth metatarsophalangeal joints. The global intrinsic plus lesser toe deformity will plantarly displace the joint capsule, ligaments, and tendon structures, which can be easily visualized using the plantar approach and are difficult to access using multiple dorsal incisions.
digits 2 through 5. The transverse tenotomy and capsulotomy procedure is performed just proximal to the base of the proximal phalanx, which is plantarly displaced. The tendon sheath of the flexor tendons is encountered first, releasing both the long and the short flexor tendons. A medial, central, and lateral transverse MPJ capsulotomy is then performed. Intrinsic muscle tenotomy is accomplished on both sides of the joint with the capsulotomy, because the dorsal and plantar interossei and lumbricals will be plantarly displaced owing to the contracture deformity. The toe is then forced into hyperextension to further stretch the remaining soft tissue contractures. It is fairly easy to appreciate the occurrence of the complete release and the lack of continued deforming forces (Fig. 5B). The same procedure is then performed on the remaining lesser digits (Fig. 5C). Patient 1 also had spastic contracture of the flexor hallucis longus tendon, causing plantar contracture of the first toe through the IPJ. He did not exhibit spasticity of the FHB; therefore, treatment involved simple flexor hallucis longus tenotomy through a separate transverse
Patient 2 was a 53-year-old male with CP who had presented with a combination of isolated intrinsic plus lesser toe deformity and intrinsic plus hallux valgus deformity on the right foot. His chief complaint was pain at the tip of the second toe (Fig. 8). Previous surgical intervention had involved Achilles tendon lengthening and plantar fascia release during childhood. He remained active with the use of custom orthotics and a modified shoe to compensate for a significant limb length discrepancy on the right foot. The physical examination identified extreme nonreducible hallux valgus that was accentuated when standing. The second toe exhibited plantar flexion at the MPJ and the typical “upside-down” digital deformity associated with intrinsic plus foot deformity. He essentially walked on the second toenail, but no open sores or infection were present. The remaining lesser toes were contracted in a more typical claw toe fashion, which likely represented a component of flexor digitorum longus spasticity. The operative approach for this condition is different from that for traditional hallux valgus and second hammertoe surgery. Successful straightening of the second toe required concomitant correction of the hallux valgus deformity owing to the overlap. Surgical repair of neurogenic hallux valgus associated with spasticity typically requires first MPJ fusion if long-term correction of the digital deformity is to be expected. Locking plate fixation and 6 weeks of non-weightbearing protection were incorporated to minimize the additional stress that the altered gait from CP might cause. A percutaneous pin was used to maintain the IPJ correction after the flexor hallucis longus tenotomy. The second MPJ contracture deformity was addressed with a combination of dorsal and plantar incisions. This would traditionally be addressed using a longitudinal plantar incision at the level of the second MPJ, although patient 2 exhibited a deep crease in the local skin associated with chronic digital malalignment and the lack of MPJ purchase. A percutaneous plantar MPJ incision was therefore combined with a dorsal approach to access the necessary structures for release. The dorsal approach also facilitated pin fixation of the MPJ, which is difficult using the plantar approach. Percutaneous plantar proximal IPJ incisions were used for the traditional long and short flexor tenotomy of digits 3 through 5. The 2-week postoperative clinical photographs demonstrated intact incisions with improved digital alignment (Fig. 9). The external pins were removed at 6 weeks postoperatively, at which point he transitioned to weightbearing, as tolerated, in a walking boot. The pre- and postoperative anteroposterior radiographs
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Fig. 5. Open lesser metatarsophalangeal joint release for deformity in patient 1. After the initial incision, deep dissection was limited to each specific lesser metatarsophalangeal joint in an effort to minimize neurovascular compromise. Blunt dissection was advanced to the level of the flexor tendon sheath. The medial and lateral aspects of the joint complex were isolated, allowing deep retractors to protect the neurovascular structures (A). A transverse tenotomy was performed of the flexor digitorum longus and brevus at the base of the proximal phalanx, and a metatarsophalangeal joint capsulotomy was performed. The intrinsic muscle contracture and plantar displacement of the proximal phalanx allowed easy access to cut the dorsal and plantar interossei, lumbricals, and collateral ligaments when performing the capsulotomy. The toe was forced into hyperextension to further stretch the remaining soft tissue contractures. (B) Photograph demonstrating the substantial improvement in the second, third, and fourth toe alignment compared with the untreated fifth toe. (C) Photograph demonstrating the release of the first through fifth toes, including flexor hallucis longus tenotomy for hallux interphalangeal joint contracture.
showed the dramatic improvement in the first and second digital alignment (Fig. 10A and B). The pre- and postoperative lateral radiographs demonstrated desirable first digital alignment and union
at 10 weeks after surgery (Fig. 10C and D). The 10-week postoperative clinical photographs demonstrated complete healing and excellent digital alignment (Fig. 11). Long-term follow-up of 3 years for orthotics and modified shoes have revealed no subsequent problems or recurrent deformity. Patient 3
Fig. 6. (A and B) Postoperative photographs of patient 1 with global intrinsic plus lesser toe deformity. The near normal toe alignment can be seen 2 weeks after release of the intrinsic plus foot deformity of toes 2 through 5 by way of a plantar transverse incision. The incision was well healed despite immediate weightbearing. The patient was able to return to shoes and extremity bracing, normal activities, and seated work after this initial postoperative visit.
Patient 3 was a 49-year-old male with spastic quadriplegic CP who had a combination of isolated intrinsic plus lesser toe deformity and intrinsic plus hallux flexus deformity bilaterally. The patient presented with concerns of recurrent ulceration and pain at the dorsum of the third toe bilaterally. The third toes exhibited plantar flexion at the MPJ with the typical “upside-down” digital deformity associated with intrinsic plus foot deformity. The patient was not ambulatory yet experienced pressure on the third toes when sitting in a power wheelchair or wearing shoes. Compression stockings also accentuated the curling under of the third toes, causing added discomfort and pressure. The physical examination identified bilateral dorsal bunion deformity associated with intrinsic plus hallux flexus deformity, although no skin breakdown or history of pain associated with the first toes was present. Lateral radiographs demonstrated the intrinsic plus hallux flexus with secondary elevation of the first metatarsal (Fig. 12). Consideration was given to the most appropriate surgical plan for this patient. The patient was not ambulatory and did not use his limbs for transfers. A longitudinal plantar approach for third MPJ release would have been reasonable; however, the lack of daily weightbearing stretch could have resulted in recurrent deformity. The tightness of the plantar skin and longstanding joint contracture in nonambulatory patients results in slight uncertainty regarding the effectiveness of the soft tissue release. Amputation of both third toes was performed, because this approach best matched the patient’s desire for complete pain relief with prompt recovery. Hallux flexus would normally be treated with first MPJ fusion. The first ray
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Fig. 7. (A–C) Long-term postoperative clinical photographs of patient 1 with global intrinsic plus lesser toe deformity. The 10-month follow-up examination revealed acceptable toe alignment without recurrent deformity and a barely visible transverse scar. The patient remained pain free and had no postoperative complications. He no longer required an ankle-foot orthotic for ambulation but continued to use a walker because of knee and hip contractures.
deformity was asymptomatic; therefore, no treatment was necessary. The incisions had healed within 2 weeks, and the patient did not require additional postoperative care. The initial postoperative
radiographs demonstrated bilateral amputation at the level of the third MPJs (Fig. 13). No recurrence of ulceration or deformity occurred during the follow-up of 3.5 years.
Fig. 8. Patient 2 demonstrates a combination of isolated intrinsic plus lesser toe deformity and intrinsic plus hallux valgus deformity. He was a 53-year-old male with cerebral palsy. This is a common deformity combination, with implications for ideal procedure selection. This patient was ambulatory with the use of bracing, and his main source of pain was pressure on the tip of the second toe when standing or walking on the right foot. Note the plantar soft tissue crease, which is common in intrinsic plus deformity, and is thought to be associated with a lack of purchase of the metatarsal head in this area. Plantar and proximal retraction of the second toe will elevate the second metatarsal head, similar to first ray elevatus.
Fig. 9. (A and B) Photographs at 2-weeks postoperatively of patient 2 demonstrating healed incisions and percutaneous pins with well-maintained alignment of the toes. Treatment of intrinsic plus hallux valgus deformity involved fusion of the first metatarsophalangeal joint to prevent recurrence, given the spastic nature of the deformity. A percutaneous pin was used, in addition to locking plate fixation, to maintain interphalangeal joint correction. Treatment of the isolated intrinsic plus lesser toe deformity involved soft tissue release of the plantar contracture. A longitudinal plantar incision would have provided ideal exposure for isolated joint release, although this approach is not very amenable to second toe pin fixation. Patient 2 also had a deep plantar crease, further complicating the plantar incision options. An open dorsal second metatarsophalangeal joint approach was therefore combined with percutaneous plantar release. Note that the plantar skin in the digital sulcus can be compromised by single-stage release of a longstanding digital deformity. Percutaneous flexor tenotomy was also performed on toes 1, 3, 4, and 5.
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Fig. 10. Preoperative and 10-week postoperative radiographs of patient 2. (A) Preoperative and (B) postoperative weightbearing anteroposterior radiographs demonstrated dramatic improvement of the first and second digital alignment. (C) Preoperative and (D) postoperative lateral radiographs show desirable first digital alignment and union 10 weeks after surgery.
Discussion The present case series describes 4 patterns of intrinsic plus foot deformities that have been observed by the authors (Table). Different patterns of digital involvement are thought to be the result of variable involvement of intrinsic muscle spasticity. The direction of spastic contracture at each of the involved joints gives the surgeon an
indication of the structures that need to be released or negated through tenotomy, capsulotomy, or fusion. Intrinsic plus lesser digital deformity is likely to be associated with spasticity of the intrinsic muscles with severe plantar flexion through the MPJs yet extension of the IPJs. The proximal phalanx will be plantar flexed and will eventually retract proximally on the head of the metatarsal. Usually, some degree of flexor contracture will be present, including the long flexor
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Fig. 11. (A and B) Clinical photographs at 10 weeks postoperatively of patient 2 demonstrating well-healed incisions and maintenance of digital realignment. Long-term followup has demonstrated no recurrence of deformity, ulceration, or pain.
tendon, which can be secondary in longstanding digital deformity. The MPJ ligaments and plantar capsule will eventually become contracted, leading to a fixed deformity. Each of these structures can be released through plantar exposure in an effort to realign the involved toes to the neutral position. Immediate weightbearing postoperatively will produce tension and stretch to the affected joints,
Fig. 12. Case 3 demonstrates combined isolated intrinsic plus lesser toe deformity and intrinsic plus hallux flexus deformity in a 49-year-old male with spastic quadriplegic cerebral palsy with bilateral symmetric foot deformity. The third toe deformity involved metatarsophalangeal joint spastic contracture with the typical “upside down” toe appearance. His greatest concern was pain and recurrent ulcerations of the third toe associated with the use of compression stockings, bracing, shoes, and sitting in a power wheelchair. (A) Left and (B) right lateral radiographs best demonstrated hallux flexus deformity, which was asymptomatic owing to his nonambulatory status.
Fig. 13. Postoperative radiographs of patient 3 who had undergone bilateral third toe amputation for isolated intrinsic plus lesser toe deformity. Typical treatment of intrinsic plus lesser toe deformity involves plantar tenotomy and capsulotomy at the level of the metatarsophalangeal joint. However, patient 3 was nonambulatory and did not use his legs for transfers. He also had no pain or problems with the first ray deformity. Surgical treatment involved bilateral third toe amputation. The incisions were well healed at 2 weeks postoperatively, allowing prompt recovery without the risk of recurrent deformity. (A) Left and (B) right foot radiographs at the initial postoperative visit after bilateral third toe amputation.
which is desired to achieve and maintain maximum correction of the released structures. Intrinsic plus hallux valgus deformity and intrinsic plus hallux flexus deformity involve the first ray, which has unique intrinsic muscle anatomy compared with the lesser toes. Spasticity of the adductor hallucis creates a deformity that presents with similarities to those of severe hallux valgus deformity (Fig. 1A). The first toe may overlap or underlap the second toe, and interdigital pressure sores are common. Fusion of the first MPJ is our preferred treatment if surgery is required, because the traditional procedures for hallux valgus are likely to fail, considering the spastic nature of this condition. This approach is in agreement with the published data that have documented fusion of the first MPJ as the procedure of choice to prevent recurrence in spastic conditions (1,12). Spasticity of the FHB muscle creates hallux flexus deformity, with plantar flexion through the first MPJ. The IPJ of the hallux will typically be extended when standing, suggesting that the long flexor tendon is not a deforming force (Fig. 1B). This condition presents with similarities to those of hallux limitus in that the hallux has limited dorsiflexion and a dorsal lump will be noted over the first metatarsal head. The lump results from the retrograde force of the plantarly contracted proximal phalanx, which creates extreme elevation of the first metatarsal. At first glance, a practitioner might incorrectly assume that the plantar flexed position of the first toe is secondary to the elevated medial column. The first ray elevation will eventually become rigid, further confusing this “chicken or egg” scenario. It is our belief that the muscle spasticity of the FHB is the deforming force that ultimately results in intrinsic plus hallux flexus deformity. The weightbearing lateral radiograph will typically demonstrate this dorsal position of the first metatarsal head in relation to the proximal phalanx (Fig. 14). Surgical treatment of intrinsic plus hallux flexus
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Fig. 14. Weightbearing lateral radiograph demonstrating intrinsic plus hallux flexus deformity. Spasticity of the flexor hallucis brevis muscle creates intrinsic plus hallux flexus deformity with plantar flexion and proximal retraction of the proximal phalanx and sesamoids. The interphalangeal joint of the hallux will typically be extended when standing, suggesting that the flexor hallucis longus is not a deforming force. Retrograde force from the proximal phalanx is thought to elevate the first metatarsal head, creating a dorsal bunion, which can cause shoe irritation and dorsal ulceration. The lateral radiograph demonstrates the elevated first metatarsal head and dorsal bunion.
deformity would ideally involve first MPJ arthrodesis. This approach will provide stable positioning of the hallux and also facilitate plantar positioning of the elevated first metatarsal. Soft tissue release is possible for nonfusion candidates. The FHB muscle inserts through the sesamoid apparatus, and the sesamoids will typically be retracted in the proximal direction. Soft tissue release would ideally be proximal to the sesamoids. Fixed elevation of the medial column might necessitate osteotomy or fusion through the midfoot for improved alignment. Intrinsic plus hallux flexus deformity seems to be more associated with patients with CP who are wheelchair bound and therefore not ambulating enough to maintain the stretch on the hallux and medial column. Nonambulatory patients with intrinsic plus hallux flexus deformity could present with ulceration over the elevated first metatarsal head. The primary goal of surgical treatment of intrinsic plus foot deformity is to remove or negate the deforming forces and allow realignment of the involved digits. Our focus has been on tenotomy, capsulotomy, and joint fusion, with the intent to prevent recurrence of the deformity. However, as demonstrated in patient 3, sometimes digital amputation becomes the procedure of choice, in accordance with patient function and desired outcome. Upper and lower extremity deformity, contracture, and spasticity will often result in the need for the patient to bear weight during postoperative recovery. The unsteady gait associated with spasticity will frequently result in abnormal stress on the surgical site; therefore, major reconstructive procedures involving joint fusion and osteotomy should be avoided when possible. Many patients with intrinsic plus foot contracture have undergone numerous operations during childhood yet still require bilateral braces for ambulation. Children are lightweight and can be lifted by family members; however, this is not a practical postoperative method for adults. This makes bilateral foot surgery more challenging and suggests the potential benefit of ambulatory procedures. Patients with neuromuscular disorders are often not expecting perfect digital alignment and will be very pleased to
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simply have relief of pain and pressure sores. A lifetime of living with CP and numerous experiences with less than ideal surgical outcomes help set the stage for patient expectations with digital surgery. Nonetheless, fusion will sometimes be the better option and primarily affects intrinsic plus contracture deformity of the first toe. Rigid correction allows predictable and permanent positioning of the first MPJ, which will help the overall alignment of the lesser toes and foot in general. A medial to lateral lag screw, combined with dorsal locking plate fixation, will allow weightbearing during healing of first MPJ fusion for most patients. Patient 2 underwent non-weightbearing recovery, which was our standard first MPJ fusion protocol at that time. Patients with CP need an individual gait assessment to determine whether weightbearing can be tolerated immediately after fusion. The present case series had shortcomings primarily related to the retrospective nature of the involved cases. Our purpose was to describe 4 presentations of intrinsic plus foot deformity, although any pattern or combination is theoretically possible owing to the complex nature of the intrinsic muscle anatomy. These 4 patterns were presented with the surgical approaches we have used to address the pathologic anatomy in each type. Additional studies are needed to establish a classification system that will allow for a more predictable outcome using a higher level of evidence-based medicine and larger patient population sizes. The present case study has demonstrated the goals for surgical intervention in intrinsic plus foot deformity, which are, ultimately, to relieve the pain and reduce the pressure points through digital realignment in an effort to decrease the risk of pressure sores and allow more effective bracing for this unique patient population. References 1. Canale ST, Beaty JH. Cerebral palsy. In: Campbell’s Operative Orthopaedics, Mosby, Maryland Heights, MO, 2013, pp. 1202–1254. 2. Horstmann HM, Hosalkar H, Keenan MA. Orthopaedic issues in the musculoskeletal care of adults with cerebral palsy. Dev Med Child Neurol 51:99–105, 2009. 3. Renshaw TS, Green NE, Griffin PP, Root L. Cerebral palsy: orthopaedic management. J Bone Joint Surg Am 77-A:1590–1605, 1995. 4. O’Connell PA, D’Souza L, Dudeney SM, Stephens MM. Foot deformities in children with cerebral palsy. J Pediatr Orthop 18:743–747, 1998. 5. Davids JR. The foot and ankle in cerebral palsy. Orthop Clin North Am 41:579–593, 2010. 6. Peimer CA. Intrinsic muscle contractures. In: Chapman’s Orthopaedic Surgery, ed 3, pp. 1749–1763, edited by MW Chapman, Lippincott Williams & Wilkins, Philadelphia, 2001. 7. Paksima N, Besch BR. Intrinsic contractures of the hand. Hand Clin 28:81–86, 2012. 8. McGlamry ED, Jimenez AL, Green DR. Lesser ray deformities. In: McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery, pp. 253–338, edited by The Podiatry Institute, J Sutherland, D Alder, J Boberg, M Downey, A Nakra, L Rabjohn, LV Rabjohn, Lippincott Williams and Wilkins, Philadelphia, 2001. 9. Martin EM, Pontious J. Introduction and evaluation of hallux abducto valgus. In: McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery, pp. 481–491, edited by The Podiatry Institute, J Sutherland, D Alder, J Boberg, M Downey, A Nakra, L Rabjohn, LV Rabjohn, Lippincott Williams & Wilkins, Philadelphia, 2001. 10. Harris C, Riordan DC. Intrinsic contracture in the hand and its surgical treatment. J Bone Joint Surg Am 36-A:10–18, 1953. 11. Matsuo T, Matsuo A, Hajime T, Fukumoto S, Chem W, Iwamoto Y. Release of flexors and intrinsic muscles for finger spasticity in cerebral palsy. Clin Orthop Relat Res 384:162–168, 2001. 12. Bishay SNG, El-Sherbini MH, Lotfy AA, Abdel-Rahman HM, Iskandar HN, El-Sayed MM. Great toe metatarsophalangeal arthrodesis for hallux valgus deformity in ambulatory adolescents with spastic cerebral palsy. J Child Orthop 3:47–52, 2009.
