SURGICAL TECHNIQUE
Treatment of Swan Neck Deformity in Cerebral Palsy Erik J. Carlson, MD, Michelle Gerwin Carlson, MD
Surgical Technique
Swan neck deformity in patients with cerebral palsy can result from hand intrinsic muscle spasticity or overpull of the digital extensors. After accurate identification of the etiology of the deformity, surgical treatment is directed at correcting the underlying muscle imbalance. Intrinsic lengthening can be used to treat intrinsic muscle spasticity, whereas central slip tenotomy is employed when digital extensor overpull is the deforming force. Accurate diagnosis and application of the proper surgical technique are essential when treating swan neck deformity in patients with cerebral palsy. (J Hand Surg Am. 2014;39(4):768e772. Copyright Ó 2014 by the American Society for Surgery of the Hand. All rights reserved.) Key words Cerebral palsy, swan neck deformity, intrinsic tightness, extensor tendons.
S
characterized by hyperextension of the proximal interphalangeal (PIP) joint and extensor lag of the distal interpahalageal joint (DIP). In cerebral palsy (CP), this deformity has 2 etiologies resulting in slightly different presentations: (1) hand intrinsic muscle spasticity or (2) overpull of the extrinsic digital extensors. Both of these etiologies cause stretching of the PIP volar plate over time, allowing for PIP hyperextension and subsequent DIP flexion. Treatment should be directed to the cause of the deformity, which makes identification of the etiology essential. The 2 variants of swan neck deformity can be differentiated based on the position of the metacarpophalangeal (MCP) joints during digital extension. Patients with intrinsic muscle spasticity will present with MCP joint flexion and PIP hyperextension upon active digital extension, because the WAN NECK DEFORMITY IS
From the Division of Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, NY. Received for publication January 16, 2014; accepted in revised form January 24, 2014. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article. Corresponding author: Michelle Gerwin Carlson, MD, Division of Hand and Upper Extremity Surgery, Hospital for Special Surgery, 523 East 72nd Street, New York, NY 10021; e-mail: [email protected]. 0363-5023/14/3904-0029$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2014.01.039
768
r
Ó 2014 ASSH
r
Published by Elsevier, Inc. All rights reserved.
intrinsics lie volar to the center of rotation of the MCP joint and dorsal at the PIP joint. The Bunnell test will confirm intrinsic spasticity. With the wrist in flexion to relax possible tight digital flexors, passive PIP flexion is first measured with the MCP flexed and subsequently with the MCP extended. Patients with intrinsic tightness will exhibit more passive PIP flexion with the MCP flexed. Patients presenting with swan neck deformity and full MCP extension upon active digital extension have deformity resulting from overpull of the extensor digiti communis (Fig. 1). These patients have flexor carpi ulnaris spasticity, weak wrist extensors, and resultant wrist flexion deformity. Over the years, as they attempt to extend their fingers and wrist, they overpull the digital extensors to augment wrist extension, and over time stretch the volar plates of the PIP joints, allowing for hyperextension. The Bunnell test is negative in these patients. SURGICAL ANATOMY The extensor mechanism is a complex confluence of the extrinsic digital extensors and the intrinsics of the hand. These tendons work in concert to allow independent extension of the MCP and PIP joints. The extrinsic digital extensors originate at the lateral epicondyle of the distal humerus and travel in the dorsal compartment of the forearm, crossing the wrist
SURGICAL TECHNIQUE FOR SWAN NECK DEFORMITY
769
INDICATIONS Treatment of swan neck deformity should be considered if the deformity is functionally limiting. In severe cases, patients are unable to flex the PIP joints actively from the hyperextended position. In milder cases, patients have annoying clicking and catching when trying to actively flex the PIP joints out of full extension. Often, the swan neck deformity is also of aesthetic concern to the patient. Preoperatively, the surgeon can demonstrate the clinical effects of reducing PIP hyperextension by extension blocking figure-of-8 splints at the PIP joint. In addition, an ulnar nerve block can demonstrate the correction of MCP joint contracture expected by intrinsic lengthening alone. We address swan neck deformity in CP patients only when active PIP hyperextension is greater than or equal to 20 . For deformities resulting from hand intrinsic spasticity, we perform intrinsic fractional lengthening. For deformities caused by overpull of the digital extensors, we perform central slip tenotomy. Other procedures for the treatment of swan neck deformity in patients with CP have been reported. Swanson1 described a sublimis tenodesis, using a slip of the sublimis tendon for PIP joint tenodesis. Tonkin et al2 and Van Heest and House3 reported using lateral band translocation from the dorsally subluxated position to a volar position in patients with CP and swan neck deformity.
FIGURE 1: Preoperative patient with swan neck deformity of the index and middle fingers, resulting from overpull of the extrinsic extensors.
through their respective dorsal wrist compartments: the extensor indicis proprius and extensor digitorum communis in the fourth dorsal compartment and the extensor digiti quinti in the fifth dorsal compartment. They traverse the dorsum of the hand and enter the extensor hood at the MCP joint. The sagittal bands center the extensor tendon over the dorsum of the MCP joint. Over the proximal phalanx, the extensor mechanism divides into a single central slip and 2 lateral slips. The lateral slips continue distally, where they are joined by the lateral band contribution from the interossei and lumbricals at the level of the distal proximal phalanx. After crossing the PIP joint, the conjoined lateral bands (lateral slip plus lateral bands) join at the dorsum of the middle phalanx to form the terminal tendon, which crosses the DIP joint and inserts onto the distal phalanx. The central slip continues distally across the PIP joint after dividing from the lateral slips, and inserts onto the base of the middle phalanx. The 4 dorsal interossei are bipennate muscles that originate from the metacarpal shafts of all digits. The dorsal interossei insert onto the ulnar aspect of the middle and ring fingers and the radial aspect of the index and middle fingers. Their deep heads insert onto the lateral band and become the lateral tendon while the superficial heads insert onto the proximal phalanx. The 3 volar interossei originate from the ulnar aspect of the second metacarpal shaft and the radial aspect of the fourth and fifth metacarpal shaft. They insert into the ulnar lateral band of the second digit and the radial lateral band of the ring and little fingers. The interossei travel volar to the center of rotation of the MCP joint and are the primary intrinsic flexors of the MCP joint. All of the interossei are innervated by the deep motor branch of the ulnar nerve. J Hand Surg Am.
CONTRAINDICATIONS Patients with fixed MCP joint contracture not relieved by ulnar nerve block may not benefit from intrinsic release. Arthrodesis may be more appropriate in this clinical scenario. Intrinsic release should not be performed in patients with weak finger flexion. These patients may rely solely on their intrinsics to effectively flex the MCP joints. Patients must be able to actively flex the PIP joint with the joint placed in a neutral position with r
Vol. 39, April 2014
Surgical Technique
The lumbricals originate on the tendon of the flexor digitorum profundus and insert onto the oblique fibers and the radial lateral bands of each digit except the thumb. They are primarily extensors of the interphalangeal joints, and less so, flexors of the MCP joints. The lumbricals to the index and middle fingers are bipennate and are innervated by the median nerve; those to the ring and little fingers are unipennate and innervated by the deep motor branch of the ulnar nerve.
770
SURGICAL TECHNIQUE FOR SWAN NECK DEFORMITY
Surgical Technique
FIGURE 2: Intrinsic lengthening surgical technique: After fractional lengthening of the lumbrical, the interossei compartment is opened and 2 tenotomies are performed at the muscle tendon junction of the palmar and dorsal interossei.
an extension block figure-of-8 splint. Patients who cannot do so because of flexor weakness have a high likelihood of recurrence of the deformity after central slip tenotomy. A balancing flexor force is necessary for success. SURGICAL TECHNIQUE Intrinsic lengthening Intrinsic lengthening is performed similar to the technique described by Matsuo et al.4 After regional anesthesia, we perform a single transverse incision in the palm at the level of the distal palmar crease when all digits require release. In cases that necessitate only release of select digits, the incision can be shortened. After incision, subcutaneous flaps are created proximally and distally to allow for exposure of the intermetacarpal area. The common neurovascular bundles are identified and retracted either radially or ulnarly to allow for exposure of the lumbricals and interossei (Fig. 2). The lumbricals are addressed first and a single fractional lengthening with tenotomy of the tendinous portion of the muscle tendon junction is performed. The interossei compartment is opened longitudinally and the palmar interossei are identified first, and a fractional lengthening is performed with 2 tenotomies in the musculotendinous junction. A fractional lengthening is then performed similarly for the dorsal interossei with 2 tenotomies. After all tenotomies have been performed, gentle Bunnell testing of PIP flexion of the fingers should be J Hand Surg Am.
FIGURE 3: Central slip tenotomy surgical technique. A A central slip tenotomy is made 1 cm proximal to the PIP joint. B Diagrammatic location of the tenotomy.
conducted to ensure that the intrinsics are no longer tight in MCP extension. Care should be taken not to overlengthen the fractional lengthening by flexing the PIP joints past 70 with MCP joints extended. The wound is irrigated and closure is usually performed with a subcuticular absorbable suture. r
Vol. 39, April 2014
SURGICAL TECHNIQUE FOR SWAN NECK DEFORMITY
771
in the office, active flexion and extension is begun. An oval-8 splint limiting extension to 10 short of full extension is worn for another 4 weeks. After 8 weeks, splinting is not normally required (Fig. 4).
Central slip tenotomy Central slip tenotomy is performed similar to that originally described by Fowler5 for treatment and reported by us before in the treatment of CP patients.6 After adequate regional anesthesia, we perform a transverse incision 1 cm proximal to the PIP joint of the affected digit. The extensor mechanism is identified with contribution from the 2 lateral bands and the central slip at this level. The demarcation between the 2 lateral bands and the central slip is noted and a forceps is used to pull up on the central slip, helping to separate it from the lateral bands. The central slip is then sharply transected, with care to transect the entire central slip, just to the edge of the lateral bands (Fig. 3). After transection, retraction of the central slip usually leads to a more obvious demarcation between the central slip and the lateral bands. The wound is irrigated and closure is performed with subcuticular suture. The PIP joint is transfixed in 10 flexion with a 0.9-mm (0.035-in) or 1.4-mm (0.045-in) Kirschner wire, depending on the size of the digit.
PEARLS AND PITFALLS In treating swan neck deformity in patients with CP, correct recognition of the etiology of the deformity is imperative for successful treatment. Failure of the surgeon to differentiate between intrinsic spasticity and extensor digiti communis overpull will lead to treatment failure. Intrinsic lengthening Pearl: The digits that need intrinsic release should be carefully selected. Often, not all digits will need release. For instance, the intrinsics of only the middle and ring fingers can be addressed, leaving the index and little finger intact if they do not have deformity.
POSTOPERATIVE CARE After intrinsic lengthening, a soft dressing is applied for 7 to 10 days to allow for skin healing. The tails of the absorbable sutures are removed at this time and thin adhesive strips are applied. Patients are encouraged to perform early range-of-motion exercises with or without hand therapy assistance as soon as possible after surgery. In the postoperative period, if patients are having difficulty with MCP extension, a palm-based splint with the MCP joints in extension and the PIP joints free can be used for stretching. After central slip tenotomy, the PIP joint is splinted and pinned for 4 weeks. After removal of the pins J Hand Surg Am.
Pitfall: Do not overlengthen the interossei, and try to avoid lengthening the first dorsal interosseous to the index finger because it will weaken pinch. Central slip tenotomy Pearl: Using a forceps to grasp and pull up on the central portion of the central slip can help the surgeon correctly identify the demarcation between the central slip and lateral bands at the level of the central slip tenotomy. Pitfall: Transection should be performed of the central slip only, not of the lateral bands. r
Vol. 39, April 2014
Surgical Technique
FIGURE 4: A, B Postoperative correction of swan neck deformity after central slip tenotomy of the index and long finger in the patient from Figure 1.
772
SURGICAL TECHNIQUE FOR SWAN NECK DEFORMITY
Surgical Technique
COMPLICATIONS Intrinsic lengthening The intrinsics contribute to the power of MCP flexion. Lengthening of these muscles may weaken grip, especially in patients with weak extrinsic flexion and weak grasp preoperatively. Intrinsic lengthening should be used with caution in these patients.
joint flexion indicates intrinsic muscle tightness, whereas MCP extension indicates overpull of the central slip. Correct diagnosis of the etiology of deformity is imperative. We recommend intrinsic lengthening for patients with hand intrinsic muscle tightness and central slip tenotomy for those with overpull of the digital extrinsic extensors.
Central slip tenotomy Central slip tenotomy (see Video 1, available on the Journal’s Web site at www.jhandsurg.org) usually results in a neutrally positioned digit, but may result in an extensor lag up to 20 . However, patients are usually happier with this outcome than the swan neck deformity because they do not have “catching” of the PIP joints, and they look more normal aesthetically. In conclusion, swan neck deformity in patients with CP results from PIP joint hyperextension with volar plate laxity and DIP flexion. It is caused by intrinsic muscle tightness or overpull of the digital extrinsic extensor tendons. With active digital extension, MCP
REFERENCES
J Hand Surg Am.
1. Swanson AB. Treatment of the swan-neck deformity in the cerebral palsied hand. Clin Orthop. 1966;48:167e171. 2. Tonkin MA, Hughes J, Smith KL. Lateral band translocation for swanneck deformity. J Hand Surg Am. 1992;17(2):260e267. 3. Van Heest AE, House JH. Lateral band rerouting in the treatment of swan neck deformities due to cerebral palsy. Tech Hand Up Extrem Surg. 1997;1(3):189e194. 4. Matsuo T, Matsuo A, Hajime T, Fukumoto S, Chen W, Iwamoto Y. Release of flexors and intrinsic muscles for finger spasticity in cerebral palsy. Clin Orthop Relat Res 2001;(384):162e168. 5. Harris C. The Fowler operation for Mallet-Finger. J Bone Joint Surg. 1966;48A:613. 6. Carlson MG, Gallagher K, Spirtos M. Surgical treatment of swan-neck deformity in hemiplegic cerebral palsy. J Hand Surg Am. 2007;32(9): 1418e1422.
r
Vol. 39, April 2014
Treatment of Swan Neck Deformity in Cerebral Palsy Erik J. Carlson, MD, Michelle Gerwin Carlson, MD
Surgical Technique
Swan neck deformity in patients with cerebral palsy can result from hand intrinsic muscle spasticity or overpull of the digital extensors. After accurate identification of the etiology of the deformity, surgical treatment is directed at correcting the underlying muscle imbalance. Intrinsic lengthening can be used to treat intrinsic muscle spasticity, whereas central slip tenotomy is employed when digital extensor overpull is the deforming force. Accurate diagnosis and application of the proper surgical technique are essential when treating swan neck deformity in patients with cerebral palsy. (J Hand Surg Am. 2014;39(4):768e772. Copyright Ó 2014 by the American Society for Surgery of the Hand. All rights reserved.) Key words Cerebral palsy, swan neck deformity, intrinsic tightness, extensor tendons.
S
characterized by hyperextension of the proximal interphalangeal (PIP) joint and extensor lag of the distal interpahalageal joint (DIP). In cerebral palsy (CP), this deformity has 2 etiologies resulting in slightly different presentations: (1) hand intrinsic muscle spasticity or (2) overpull of the extrinsic digital extensors. Both of these etiologies cause stretching of the PIP volar plate over time, allowing for PIP hyperextension and subsequent DIP flexion. Treatment should be directed to the cause of the deformity, which makes identification of the etiology essential. The 2 variants of swan neck deformity can be differentiated based on the position of the metacarpophalangeal (MCP) joints during digital extension. Patients with intrinsic muscle spasticity will present with MCP joint flexion and PIP hyperextension upon active digital extension, because the WAN NECK DEFORMITY IS
From the Division of Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, NY. Received for publication January 16, 2014; accepted in revised form January 24, 2014. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article. Corresponding author: Michelle Gerwin Carlson, MD, Division of Hand and Upper Extremity Surgery, Hospital for Special Surgery, 523 East 72nd Street, New York, NY 10021; e-mail: [email protected]. 0363-5023/14/3904-0029$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2014.01.039
768
r
Ó 2014 ASSH
r
Published by Elsevier, Inc. All rights reserved.
intrinsics lie volar to the center of rotation of the MCP joint and dorsal at the PIP joint. The Bunnell test will confirm intrinsic spasticity. With the wrist in flexion to relax possible tight digital flexors, passive PIP flexion is first measured with the MCP flexed and subsequently with the MCP extended. Patients with intrinsic tightness will exhibit more passive PIP flexion with the MCP flexed. Patients presenting with swan neck deformity and full MCP extension upon active digital extension have deformity resulting from overpull of the extensor digiti communis (Fig. 1). These patients have flexor carpi ulnaris spasticity, weak wrist extensors, and resultant wrist flexion deformity. Over the years, as they attempt to extend their fingers and wrist, they overpull the digital extensors to augment wrist extension, and over time stretch the volar plates of the PIP joints, allowing for hyperextension. The Bunnell test is negative in these patients. SURGICAL ANATOMY The extensor mechanism is a complex confluence of the extrinsic digital extensors and the intrinsics of the hand. These tendons work in concert to allow independent extension of the MCP and PIP joints. The extrinsic digital extensors originate at the lateral epicondyle of the distal humerus and travel in the dorsal compartment of the forearm, crossing the wrist
SURGICAL TECHNIQUE FOR SWAN NECK DEFORMITY
769
INDICATIONS Treatment of swan neck deformity should be considered if the deformity is functionally limiting. In severe cases, patients are unable to flex the PIP joints actively from the hyperextended position. In milder cases, patients have annoying clicking and catching when trying to actively flex the PIP joints out of full extension. Often, the swan neck deformity is also of aesthetic concern to the patient. Preoperatively, the surgeon can demonstrate the clinical effects of reducing PIP hyperextension by extension blocking figure-of-8 splints at the PIP joint. In addition, an ulnar nerve block can demonstrate the correction of MCP joint contracture expected by intrinsic lengthening alone. We address swan neck deformity in CP patients only when active PIP hyperextension is greater than or equal to 20 . For deformities resulting from hand intrinsic spasticity, we perform intrinsic fractional lengthening. For deformities caused by overpull of the digital extensors, we perform central slip tenotomy. Other procedures for the treatment of swan neck deformity in patients with CP have been reported. Swanson1 described a sublimis tenodesis, using a slip of the sublimis tendon for PIP joint tenodesis. Tonkin et al2 and Van Heest and House3 reported using lateral band translocation from the dorsally subluxated position to a volar position in patients with CP and swan neck deformity.
FIGURE 1: Preoperative patient with swan neck deformity of the index and middle fingers, resulting from overpull of the extrinsic extensors.
through their respective dorsal wrist compartments: the extensor indicis proprius and extensor digitorum communis in the fourth dorsal compartment and the extensor digiti quinti in the fifth dorsal compartment. They traverse the dorsum of the hand and enter the extensor hood at the MCP joint. The sagittal bands center the extensor tendon over the dorsum of the MCP joint. Over the proximal phalanx, the extensor mechanism divides into a single central slip and 2 lateral slips. The lateral slips continue distally, where they are joined by the lateral band contribution from the interossei and lumbricals at the level of the distal proximal phalanx. After crossing the PIP joint, the conjoined lateral bands (lateral slip plus lateral bands) join at the dorsum of the middle phalanx to form the terminal tendon, which crosses the DIP joint and inserts onto the distal phalanx. The central slip continues distally across the PIP joint after dividing from the lateral slips, and inserts onto the base of the middle phalanx. The 4 dorsal interossei are bipennate muscles that originate from the metacarpal shafts of all digits. The dorsal interossei insert onto the ulnar aspect of the middle and ring fingers and the radial aspect of the index and middle fingers. Their deep heads insert onto the lateral band and become the lateral tendon while the superficial heads insert onto the proximal phalanx. The 3 volar interossei originate from the ulnar aspect of the second metacarpal shaft and the radial aspect of the fourth and fifth metacarpal shaft. They insert into the ulnar lateral band of the second digit and the radial lateral band of the ring and little fingers. The interossei travel volar to the center of rotation of the MCP joint and are the primary intrinsic flexors of the MCP joint. All of the interossei are innervated by the deep motor branch of the ulnar nerve. J Hand Surg Am.
CONTRAINDICATIONS Patients with fixed MCP joint contracture not relieved by ulnar nerve block may not benefit from intrinsic release. Arthrodesis may be more appropriate in this clinical scenario. Intrinsic release should not be performed in patients with weak finger flexion. These patients may rely solely on their intrinsics to effectively flex the MCP joints. Patients must be able to actively flex the PIP joint with the joint placed in a neutral position with r
Vol. 39, April 2014
Surgical Technique
The lumbricals originate on the tendon of the flexor digitorum profundus and insert onto the oblique fibers and the radial lateral bands of each digit except the thumb. They are primarily extensors of the interphalangeal joints, and less so, flexors of the MCP joints. The lumbricals to the index and middle fingers are bipennate and are innervated by the median nerve; those to the ring and little fingers are unipennate and innervated by the deep motor branch of the ulnar nerve.
770
SURGICAL TECHNIQUE FOR SWAN NECK DEFORMITY
Surgical Technique
FIGURE 2: Intrinsic lengthening surgical technique: After fractional lengthening of the lumbrical, the interossei compartment is opened and 2 tenotomies are performed at the muscle tendon junction of the palmar and dorsal interossei.
an extension block figure-of-8 splint. Patients who cannot do so because of flexor weakness have a high likelihood of recurrence of the deformity after central slip tenotomy. A balancing flexor force is necessary for success. SURGICAL TECHNIQUE Intrinsic lengthening Intrinsic lengthening is performed similar to the technique described by Matsuo et al.4 After regional anesthesia, we perform a single transverse incision in the palm at the level of the distal palmar crease when all digits require release. In cases that necessitate only release of select digits, the incision can be shortened. After incision, subcutaneous flaps are created proximally and distally to allow for exposure of the intermetacarpal area. The common neurovascular bundles are identified and retracted either radially or ulnarly to allow for exposure of the lumbricals and interossei (Fig. 2). The lumbricals are addressed first and a single fractional lengthening with tenotomy of the tendinous portion of the muscle tendon junction is performed. The interossei compartment is opened longitudinally and the palmar interossei are identified first, and a fractional lengthening is performed with 2 tenotomies in the musculotendinous junction. A fractional lengthening is then performed similarly for the dorsal interossei with 2 tenotomies. After all tenotomies have been performed, gentle Bunnell testing of PIP flexion of the fingers should be J Hand Surg Am.
FIGURE 3: Central slip tenotomy surgical technique. A A central slip tenotomy is made 1 cm proximal to the PIP joint. B Diagrammatic location of the tenotomy.
conducted to ensure that the intrinsics are no longer tight in MCP extension. Care should be taken not to overlengthen the fractional lengthening by flexing the PIP joints past 70 with MCP joints extended. The wound is irrigated and closure is usually performed with a subcuticular absorbable suture. r
Vol. 39, April 2014
SURGICAL TECHNIQUE FOR SWAN NECK DEFORMITY
771
in the office, active flexion and extension is begun. An oval-8 splint limiting extension to 10 short of full extension is worn for another 4 weeks. After 8 weeks, splinting is not normally required (Fig. 4).
Central slip tenotomy Central slip tenotomy is performed similar to that originally described by Fowler5 for treatment and reported by us before in the treatment of CP patients.6 After adequate regional anesthesia, we perform a transverse incision 1 cm proximal to the PIP joint of the affected digit. The extensor mechanism is identified with contribution from the 2 lateral bands and the central slip at this level. The demarcation between the 2 lateral bands and the central slip is noted and a forceps is used to pull up on the central slip, helping to separate it from the lateral bands. The central slip is then sharply transected, with care to transect the entire central slip, just to the edge of the lateral bands (Fig. 3). After transection, retraction of the central slip usually leads to a more obvious demarcation between the central slip and the lateral bands. The wound is irrigated and closure is performed with subcuticular suture. The PIP joint is transfixed in 10 flexion with a 0.9-mm (0.035-in) or 1.4-mm (0.045-in) Kirschner wire, depending on the size of the digit.
PEARLS AND PITFALLS In treating swan neck deformity in patients with CP, correct recognition of the etiology of the deformity is imperative for successful treatment. Failure of the surgeon to differentiate between intrinsic spasticity and extensor digiti communis overpull will lead to treatment failure. Intrinsic lengthening Pearl: The digits that need intrinsic release should be carefully selected. Often, not all digits will need release. For instance, the intrinsics of only the middle and ring fingers can be addressed, leaving the index and little finger intact if they do not have deformity.
POSTOPERATIVE CARE After intrinsic lengthening, a soft dressing is applied for 7 to 10 days to allow for skin healing. The tails of the absorbable sutures are removed at this time and thin adhesive strips are applied. Patients are encouraged to perform early range-of-motion exercises with or without hand therapy assistance as soon as possible after surgery. In the postoperative period, if patients are having difficulty with MCP extension, a palm-based splint with the MCP joints in extension and the PIP joints free can be used for stretching. After central slip tenotomy, the PIP joint is splinted and pinned for 4 weeks. After removal of the pins J Hand Surg Am.
Pitfall: Do not overlengthen the interossei, and try to avoid lengthening the first dorsal interosseous to the index finger because it will weaken pinch. Central slip tenotomy Pearl: Using a forceps to grasp and pull up on the central portion of the central slip can help the surgeon correctly identify the demarcation between the central slip and lateral bands at the level of the central slip tenotomy. Pitfall: Transection should be performed of the central slip only, not of the lateral bands. r
Vol. 39, April 2014
Surgical Technique
FIGURE 4: A, B Postoperative correction of swan neck deformity after central slip tenotomy of the index and long finger in the patient from Figure 1.
772
SURGICAL TECHNIQUE FOR SWAN NECK DEFORMITY
Surgical Technique
COMPLICATIONS Intrinsic lengthening The intrinsics contribute to the power of MCP flexion. Lengthening of these muscles may weaken grip, especially in patients with weak extrinsic flexion and weak grasp preoperatively. Intrinsic lengthening should be used with caution in these patients.
joint flexion indicates intrinsic muscle tightness, whereas MCP extension indicates overpull of the central slip. Correct diagnosis of the etiology of deformity is imperative. We recommend intrinsic lengthening for patients with hand intrinsic muscle tightness and central slip tenotomy for those with overpull of the digital extrinsic extensors.
Central slip tenotomy Central slip tenotomy (see Video 1, available on the Journal’s Web site at www.jhandsurg.org) usually results in a neutrally positioned digit, but may result in an extensor lag up to 20 . However, patients are usually happier with this outcome than the swan neck deformity because they do not have “catching” of the PIP joints, and they look more normal aesthetically. In conclusion, swan neck deformity in patients with CP results from PIP joint hyperextension with volar plate laxity and DIP flexion. It is caused by intrinsic muscle tightness or overpull of the digital extrinsic extensor tendons. With active digital extension, MCP
REFERENCES
J Hand Surg Am.
1. Swanson AB. Treatment of the swan-neck deformity in the cerebral palsied hand. Clin Orthop. 1966;48:167e171. 2. Tonkin MA, Hughes J, Smith KL. Lateral band translocation for swanneck deformity. J Hand Surg Am. 1992;17(2):260e267. 3. Van Heest AE, House JH. Lateral band rerouting in the treatment of swan neck deformities due to cerebral palsy. Tech Hand Up Extrem Surg. 1997;1(3):189e194. 4. Matsuo T, Matsuo A, Hajime T, Fukumoto S, Chen W, Iwamoto Y. Release of flexors and intrinsic muscles for finger spasticity in cerebral palsy. Clin Orthop Relat Res 2001;(384):162e168. 5. Harris C. The Fowler operation for Mallet-Finger. J Bone Joint Surg. 1966;48A:613. 6. Carlson MG, Gallagher K, Spirtos M. Surgical treatment of swan-neck deformity in hemiplegic cerebral palsy. J Hand Surg Am. 2007;32(9): 1418e1422.
r
Vol. 39, April 2014
