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Resection of the Fifth Metatarsal Base in the Severe Rigid Cavovarus Foot Raheel Shariff, Mark S. Myerson and Ezequiel Palmanovich Foot Ankle Int 2014 35: 558 originally published online 7 April 2014 DOI: 10.1177/1071100714531225 The online version of this article can be found at: http://fai.sagepub.com/content/35/6/558
Published by: http://www.sagepublications.com
On behalf of:
American Orthopaedic Foot & Ankle Society
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research-article2014
FAIXXX10.1177/1071100714531225Foot & Ankle InternationalShariff et al
Article
Resection of the Fifth Metatarsal Base in the Severe Rigid Cavovarus Foot
Foot & Ankle International® 2014, Vol. 35(6) 558–565 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100714531225 fai.sagepub.com
Raheel Shariff, FRCS1, Mark S. Myerson, MD1, and Ezequiel Palmanovich, MD1
Abstract Background: Cavovarus deformity associated with neuromuscular imbalance is a challenging pathology. Most of these deformities lead to pressure symptoms at the lateral border of the foot. This leads to pain, callosity, and commonly fracture of the fifth metatarsal base. This study reports the outcome of a cohort of patients who underwent an adjunctive procedure of resection of the fifth metatarsal, either partial or complete, in conjunction with cavovarus foot reconstruction to offload the lateral border of the foot. Methods: This was a retrospective study looking at the clinical and radiographic outcome of patients with an underlying neuromuscular problem with a cavovarus foot who underwent a resection of the fifth metatarsal. This was used as an adjunctive procedure during reconstruction for lateral foot pressure overload symptoms. Case notes and radiographs were reviewed. The distance on weight-bearing radiographs from the inferior most part of the bony prominence on the lateral border of the foot to the floor was measured and compared between pre- and postoperatively. Eighteen patients met the inclusion criteria. Mean age was 55 years. Mean follow-up was 32 months. Results: Fourteen patients had a partial base of fifth metatarsal resection, and 4 had a complete fifth ray resection. Radiographic measurements showed a statistically significant improvement in the distance from the inferior most part of the bony prominence on the lateral border of the foot to the floor between pre- and postoperative radiographs. Sixteen patients reported a significant improvement in their symptoms, 2 had some persistent lateral overload symptoms. Conclusion: The technique described in this study has not been reported previously for this indication. We believe it is a good adjunctive procedure in cavovarus foot reconstruction for patients suffering from lateral pressure overload. We describe strict guidelines and indications for this procedure. Level of Evidence: Level IV, case series. Keywords: cavovarus foot, lateral pressure overload, fifth metatarsal resection, Charcot–Marie–Tooth In 1886, Charcot, Marie, and Tooth independently described families with specific conditions of progressive muscular atrophy beginning in the feet and legs.3 Pes cavus due to progressive neuromuscular disease is a challenging management problem.1 Approximately 80% of cavovarus foot deformities can be attributed to a neurologic disorder. The most common cause is Charcot–Marie–Tooth (CMT) disease.9 The cavovarus deformity leads to pain and callus formation under the metatarsal heads, foot fatigue, difficulty wearing normal shoes, lateral ankle instability and tripping.3 In the more severe forms, the patients present with marked callosity under the base of the fifth metatarsal due to abnormal loading of the lateral border of the foot. Even though CMT is a sensory neuropathy, many patients still have sensation and the deformity can be painful. Historically the cavovarus foot has been a difficult deformity to correct with poor long-term results, noting recurrence of deformity irrespective of whether a combination of bony or soft tissue
procedures is employed.9,10 If there is excessive stress over the fifth metatarsal, correction of the hindfoot is essential. The overload of the fifth metatarsal can be a particularly difficult problem. Various options can be employed in treating it. In a majority of cases a plantigrade foot can be achieved with a combination of bony and soft tissue procedures. These usually involve a triple arthrodesis with derotation through the Chopart joints, biplanar wedge resections/ calcaneal osteotomy. This is augmented with tibialis posterior tendon transfers or peroneus longus transfers to the lateral side of the foot. In some severe cases however, once the above-mentioned procedures are done, the fifth metatarsal 1
Institute for Foot and Ankle Reconstruction at Mercy, Baltimore, MD, USA Corresponding Author: Raheel Shariff, FRCS, Institute for Foot and Ankle Reconstruction at Mercy, 301 St. Paul Place, Baltimore, MD 21202, USA. Email: [email protected]
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Shariff et al continues to remain prominent. This is usually confirmed with intraoperative flouroscopy where the fifth ray remains inferiorly placed relative to the plane of the cuboid, in spite of trying to rotate the foot through the osteotomy site or dorsally translating it to ease the plantar pressure. For this cohort, we present a novel concept of resection of the fifth metatarsal base to offload the foot and alleviate symptoms. The objective of this study was to review the outcome of the fifth metatarsal base resection as an adjunctive procedure in the reconstruction for severe symptomatic rigid cavovarus foot deformities secondary to neuromuscular problems, causing persistent lateral plantar foot overload and pressure symptoms. This technique has not been described for the above-mentioned indication. We also present guidelines and indications for this technique.
Methods This was a retrospective study. We examined 18 patients who underwent fifth metatarsal base resection along with foot reconstruction for a rigid symptomatic cavus foot between 2003 and 2013. Local hospital board institutional review board approval was obtained. Demographic data were collected. No patients were lost to follow-up.
Table 1. Patient Demographics. Total number of patients Mean age Mean follow-up Male to female ratio Laterality (left to right ratio)
18 55 years (range 32-73) 32 months (range 8-58 months) 13:5 12:6
excluded. Between 2003 and 2013, 18 patients fulfilled the inclusion criteria for the study. Table 1 lists the demographic details of the patient cohort. Table 2 highlights individual patient characteristics. The patients charts were evaluated. All patients underwent a clinical examination by 1 of the authors. Preoperatively the patients underwent a Coleman block test. The hindfoot failed to correct in all. However, the Coleman block test was not really necessary in the majority of these patients since the hindfoot was absolutely rigid in varus and the transverse tarsal joint similarly rigid. Pre- and postoperative weight-bearing X-rays were assessed to determine the distance from the inferior most aspect of the lateral border of the foot to the floor. This was the radiographic measure used to determine how much improvement in lateral foot overload was achieved following the resection.
Inclusion Criteria To be included in this study, patients had to fulfill all the criteria mentioned below. These criteria also form the indication guidelines for this adjunctive procedure. a. Patients with an underlying neuromuscular imbalance contributing to a rigid cavus or cavovarus foot deformity, with lateral foot overload indicated preoperatively by prominence of the fifth metatarsal base, pain, and callosity b. Intraoperative persistent prominence of the fifth metatarsal base, which failed to correct following a cavus foot reconstruction having undergone either a triple arthrodesis or midfoot/hindfoot osteotomies with tendon transfers If the above-mentioned procedures failed to correct the lateral border overload, indicated intraoperatively by palpation of a bony prominence and confirmed fluoroscopically by the presence of an inferiorly placed fifth metatarsal in relation to the plane of the cuboid in the lateral projection, these patients were suitable for a resection of the fifth metatarsal base.
Exclusion Criteria All patients who had a prior history of osteomyelitis or an infected ulcer due to the lateral pressure overload were
Preoperative Radiographic Measurement This measured the distance from the inferior most aspect of the base of the fifth metatarsal to the floor.
Postoperative Radiographic Measurement This measured the distance from the inferior most aspect of the remaining fifth metatarsal following resection (in the case of a partial resection, which was what was done in the majority of the cases) or the inferior most bony prominence after a complete fifth ray resection, which happened to be the base of the fourth ray (in patients where a complete fifth ray resection had been done) to the floor. Although the measurements for those who underwent a base of fifth resection are not exactly comparable with those of the group who underwent a complete fifth ray resection, we found this was the best possible radiographic measure available, based on the available radiographic landmarks. We also looked at a way of identifying radiographically that the cavovarus deformity had been adequately corrected to a more plantigrade foot position, by the other procedures such as the triple arthrodesis or osteotomies. We looked at the pre- and postop sagittal radiographs of the foot. We measured the height of medial cuneiform, by drawing a line from the superior edge to the inferior most edge of the cuneiform. This line was drawn such that it was perpendicular to the weight-bearing surface (line A in the Figure 1). We then similarly measured the height of the base of the fourth
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Table 2. Individual patient operative characteristics. No
Fifth MTT Age Side Diagnosis resection
Triple arthrodesis
1 2 3 4 5 6 7
37 56 46 47 50 73 70
L L L R L L L
CMT CMT CMT CMT CMT CMT CMT
Partial Partial Partial Partial Partial Complete Partial
8 9 10 11 12 13 14 15 16 17 18
71 58 56 48 32 66 63 50 54 38 41
R L R L R L L L R L R
CMT CMT CMT CMT CMT CMT CMT CMT CMT CMT CMT
Partial Partial Partial Pantalar Complete Complete Revision triple Partial Partial Partial Complete TTC Partial Partial
Pantalar
PTT transfer
TMT fusion
Lengthening
Achilles length
Plantar fascia release
First MTT osteotomy
Lateral calc osteo
FDL transfer TA transfer
Lengthening
CMT, Charcot–Marie–Tooth disease; FDL, flexor digitorum longus; MTT, metatarsal; PTT, posterior tibial tendon; TA, tendoachilles; TMT, tarsometatarsal.
Operative Technique
Figure 1. The plantigrade foot ratio, A/B.
metatarsal, taking into account only the height of this metatarsal that was not overlapped by the medial cuneiform (line B in the Figure 1). The ratio of A/B was measured. A similar ratio was calculated for the postoperative radiograph. If the postop ratio was greater than the preoperative ratio, this meant that the measurement B was less postoperatively compared to preoperatively. This indicated that the metatarsal cascade had improved. Then adequate correction was deemed to have taken place, as this indicated that the foot was derotated and plantigrade. We called this the plantigrade measurement ratio.
The incision used for the calcaneal osteotomy, peroneal tendons or triple arthrodesis was extended distally along the dorsal aspect of the metatarsal base. After blunt dissection the bony prominence of the base of the fifth metatarsal was resected with a saw. First, the severity and apex of the deformity were determined. This was done by identifying whether the entire fifth metatarsal was rotated under the fourth and also where the apex of the deformity was located. If it was limited to the base only and not much rotation of the entire metatarsal was present, then only the base was excised. If the entire metatarsal was rotated and the apex was more distal to the base in the shaft then the entire metatarsal was resected. The saw cut was made distal to the apex, obliquely in 2 planes, such that the starting point of the osteotomy was dorsal and slightly lateral (Figure 2). Following this, the overlying skin was palpated to determine any residual bony prominences that needed further debridement after the initial resection.5 We routinely sacrificed the peroneus brevis as it was nonfunctional. We believe transferring the tendon would not have been beneficial. The plantar fascia was not routinely released. Figures 2 to 4 demonstrate the operative technique.
Results All the patients were diagnosed with CMT disease in the study cohort. All of them had neuropathy to a varying extent, but formal nerve conduction studies were not performed. Before surgery, all patients complained of pain over the lateral border of the foot, painful callosities, or a
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Figure 5. Stress fracture over the fifth metatarsal. Figure 2. Resection initially performed with a saw.
Figure 6. Bony procedures performed during the cavovarus foot reconstruction. Figure 3. Completion of resection with an osteotome.
Figure 4. Resected base of fifth metatarsal. Note the callosity on the plantar aspect due to lateral pressure overload.
bony prominence that worsened their gait. None of the patients were noted to have plantar pain. In 4 cases stress
fracture of the fifth metatarsal had been diagnosed preoperatively. All 4 had fixation attempted with a single intramedullary compression screw. Three of these failed to unite, while 1 progressed to satisfactory union. However, all of them including the 1 that united remained symptomatic with pain and overload. Their symptoms successfully resolved following the resection. Figure 5 is an example of a fifth metatarsal stress fracture that occurred due to lateral foot overload. During the primary surgery for correction of the cavus foot, bony and soft tissue procedures were performed. All these patients had a rigid deformity. The bony procedures included tarsometatarsal (TMT) fusion (3 cases), first metatarsal osteotomy (7 cases), sliding calcaneal osteotomy (8 cases), triple arthrodesis (7 cases), and pantalar fusion (2 cases). Of the 3 patients who underwent a TMT arthrodesis, 2 had an isolated first TMT arthrodesis and 1 had the first and second TMT joints fused as part of their correction. Figure 6 elucidates the bony procedures that were performed in these 15 patients. Soft tissue procedures included tibialis posterior tendon transfer or lengthening (10 cases), plantar fascia release (6
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Foot & Ankle International 35(6) base resection as opposed to a complete resection. In both these patients the pain was associated with slight rotation of the hindfoot and not insufficient resection of the base of the fifth, as the entire base of the fifth metatarsal had been resected in them. They were successfully managed with orthotic modifications, and no further operative intervention was undertaken in them. All patients reported a subjective improvement and a decrease in symptoms of lateral foot border overload at final follow-up. They all had a plantigrade foot at final follow-up.
Discussion Figure 7. Soft tissue procedures performed during the cavovarus foot reconstruction.
cases), tibialis anterior or FDL transfer (3 cases), and Achilles lengthening (1 case) (see Figure 7). In 14 cases a base of the fifth metatarsal resection was performed to reduce the bony pressure. In 4 cases the entire metatarsal was resected. Figure 8 is an example of a partial resection with improvement in lateral overload symptoms. Figure 9 is an example of a complete fifth metatarsal resection. The radiographic measurements used to assess distance from the floor to inferolateral border of the foot showed the mean preop measurement to be 1.4 mm and postoperative measurement 11.3 mm (2.4-31.8 mm). This difference was found to be statistically significant. Figure 10 highlights the measurements explained above. The mean preoperative plantigrade foot ratio as described above was 1.96. The mean postoperative ratio was 3.6 (P < .05) and showed that the cavovarus deformity had been well corrected with the other procedure performed.
Complications Both the patients who underwent a pantalar arthrodesis had complications. One of them developed osteomyelitis of the calcaneus with lateral wound dehiscence. This was treated with debridement, removal of hardware, IV antibiotics, and VAC dressings. The lateral wound was subsequently covered with a Gracilis free flap. This patient continued to have suppressive antibiotic therapy for low-grade osteomyelitis control at final follow-up. The other patient with a pantalar arthrodesis had a distal tibial fracture just proximal to the blade plate following a fall, 3 weeks following his reconstructive surgery. This was treated conservatively in a non-weight-bearing cast and went on to successful union 11 weeks later. Two patients complained of mild persistent lateral foot pain. Both these patients had undergone a fifth metatarsal
Operative intervention for reconstruction of painful cavus foot requires meticulous preoperative planning for a combination of bony and soft tissue procedures. A cavovarus foot is a progressive deformity in the presence of muscle imbalance.11 Distinguishing between fixed and flexible components of the deformity is an essential step in the decision-making process. Soft tissue procedures can be used to eliminate deforming forces and balance the foot, but osteotomies and arthrodesis frequently are necessary to correct alignment and alleviate symptoms.1 Isolated triple arthrodesis in the setting of neuromuscular imbalance particularly in CMT disease has not been very successful.7,10 Long-term results in a study by Whetmore et al showed 7% excellent results and 47% poor results, with the remainder being fair to good. This was because of a recurrence of a cavovarus deformity. To prevent recurrence, a combination of soft tissue balancing along with the triple arthrodesis has been advocated in the form of tendon transfers.5 The aim of operative correction is to realign the foot into a more plantigrade position. In the semirigid foot, a stepwise approach beginning at the hindfoot and progressively working up toward the forefoot should be employed. Although several different procedures are used, commonly these involve a calcaneal osteotomy, tibialis posterior tendon transfer, peroneus longus release or transfer, plantar fascia release, and TMT fusions or first metatarsal dorsiflexion osteotomy as demonstrated in our series. In the rigid deformity, a plantigrade foot is achieved by rotating the foot through the Chopart joints while performing a triple arthrodesis. Tendon transfers are also an integral part of correction of the rigid deformity to eliminate the deforming forces. However once this is done, if the fifth metatarsal continues to remain prominent, the dilemma arises with regard to what the next step in the operative algorithm should be. We feel that in these cases a resection of the base of the fifth metatarsal is an extremely useful adjunctive procedure to offload the pressure from the lateral border of the foot. The idea for this procedure first emerged when the senior author treated a patient over 20 years ago, for a cavovarus
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Figure 8. X-ray showing the pre- and postoperative results, after partial fifth ray resection. Note the improvement in metatarsal cascade and lack of lateral foot overload in the postoperative X-ray.
Figure 9. (a) Preoperative cavus foot with lateral pressure overload. Note the inferiorly located fifth ray in relation to the plane of the cuboid. (b) Postoperative X-ray of the same patient after complete fifth ray resection.
Figure 10. Measurements taken on weight-bearing radiographs.
foot complicated by osteomyelits of the fifth metatarsal with a neuropathic ulcer. This was successfully treated with a partial metatarsal base resection and debridement. That specific case is not included in this study and over the years the senior author has successfully employed this procedure for that indication. However this study looks at a more recent patient cohort in whom this procedure was employed for severe symptomatic rigid cavovarus foot deformities secondary to neuromuscular problems, causing persistent lateral foot overload and pressure symptoms. Hindfoot
correction is essential if there is excessive painful stress on the fifth metatarsal. Intractable pain, painful callosities or stress fracture are the most common complains. Complete fifth ray amputation has more recently been described for the cavovarus foot by Boffeli at al2 in the treatment of nonhealing neuropathic ulcers. They routinely performed a complete resection of the fifth metatarsal and transfer of the peroneus longus to the cuboid in a staged manner. This was done by debridement of the ulcer and treatment of osteomyelitis with antibiotic impregnated
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beads followed by the tendon transfer 2 weeks later. They claim that this staged protocol has not been described in the literature previously for this problem and suggest the longterm results were very gratifying, although the actual patient numbers and follow-up were not elaborated in this article. Our study has a different patient profile, in that we used a partial resection of the fifth metatarsal for deformity correction primarily and not for osteomyelits. The logical question that needs to be addressed is this: does the loss of the peroneus brevis cause any deficit when the base of the fifth metatarsal is resected? An interesting study by McCullough et al4 looked at the moment arms of the tendons about the ankle. Moment arms are geometric indicators of the contribution of individual muscles in a plane of movement and are vital for planning tendon transfers. They found that the peroneus brevis has the greatest moment in external rotation and its loss is best compensated for by a peroneus longus transfer to the peroneus brevis insertion site. Although previous studies in the podiatric literature have suggested that a transfer of the peroneus longus to the cuboid or lateral border of the foot is essential in preventing an adductovarus deformity due to overactivity of the tibialis posterior tendon after resection of the fifth metatarsal,6,8 we do not believe this is essential, as bony procedures in the form of triple arthrodesis are performed in conjunction and help maintain the position of the foot. In the case of correction of the cavovarus foot, the peronei are nonfunctional and as a result the peroneus brevis can be sacrificed without any loss in function perceived by the patient. The tibialis posterior tendon is also transferred or lengthened in the majority of cases and its deforming force is thereby negated. In our series we routinely sacrificed the peroneus brevis, when we resected the fifth metatarsal base by an oblique saw cut and we did not identify any complications or loss of correction/function. We do not know if loss of the fifth metatarsal following a partial or complete resection affects the biomechanics of the foot. Does the fourth ray become unstable, and if so is weight-bearing affected? These are questions worth posing. Our patients all had a plantigrade foot with subjective improvement in walking, although a drawback of our study is that we did not have any objective scoring systems or pedobarographic studies postoperatively. This procedure can also be done after a pantalar or a tibiotalocalcaneal arthrodesis. Its use in this patient cohort is even more beneficial as the foot is more rigid than following a triple arthrodesis and no compensatory rotation exists that may offload the lateral border of the foot if the fifth metatarsal is left unresected. We have performed this procedure as a last step to gain correction in the operative algorithm. Caution should be used in utilizing this as an isolated procedure to correct deformity. Specifically attention should be paid in patients where the fifth metatarsal is rotated under the fourth. In these patients much more extensive procedures need to be
performed in addition to the resection. The senior author has had experience with 2 patients who had undergone prior (multiple) hindfoot procedures where the base of fifth metatarsal was associated with ulceration. In these 2 cases isolated excision of the fifth was performed. These 2 patients were not included in this study since we do not have access to their information, as they were performed at a different institution. Although it would be tempting to compare this cohort to a group of patients who underwent cavovarus foot correction without a fifth metatarsal resection and see how they fared, this is not possible because the resection was not performed as the first part of the reconstruction, but as the very last step in the operative reconstruction algorithm when nothing else was possible to correct the lateral based prominence. Therefore, there is no point to comparing these patients with others once the osteotomies and/or arthrodesis has been done as correction of the lateral based prominence may have already occurred. After the resection, improvement in patient symptoms was observed. Recurrence of symptoms was observed in only 2 patients (11%). No further intervention was performed to our patients with the objective to reduce pressure over the lateral aspect of the foot.
Conclusion The cavovarus foot is a usually a progressive neuropathic disease. Operative treatment must include bony and soft tissue procedures to improve pain, deformity, and avoid recurrence. Resection of the fifth metatarsal base was a useful adjunctive procedure in the cavovarus foot reconstruction for severe symptomatic rigid deformities secondary to neuromuscular problems resulting in persistent lateral foot overload and pressure symptoms. To the best of our knowledge this technique has not been described in the literature for the above-mentioned indication. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
References 1. Alexander I, Johnson K. Assessment and management of pes cavus in Charcot–Marie–Tooth disease. Clin Orthop Relat Res. 1989;(246):273-281. 2. Boffeli TJ, Abben KW. Complete fifth ray amputation with peroneal tendon transfer–a staged surgical protocol. J Foot Ankle Surg. 2012;51(5):696-701.
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Shariff et al 3. Mann R, Missirian J. Pathophysiology of Charcot–Marie– Tooth disease. Clin Orthop Relat Res. 1988;(234):221-228. 4. McCullough MB, Ringleb SI, Arai K, Kitaoka HB, Kaufman KR. Moment arms of the ankle throughout the range of motion in three planes. Foot Ankle Int. 2011;32(3):300-306. 5. Myerson M. Reconstructive Foot and Ankle Surgery: Management of Complications. 2nd ed. Philadelphia, PA: Elsevier; 2010. 6. Schoenhaus J, Jay RM, Schoenhaus H. Transfer of the peroneus brevis tendon after resection of the fifth metatarsal base. J Am Podiatr Med Assoc. 2004;94:594-603. 7. Raikin SM. Failure of triple arthrodesis. Foot Ankle Clin. 2002;7(1):121-133.
8. Roper RB, Altman MI. Fifth metatarsal excision with peroneus brevis transfer. J Am Podiatr Med Assoc. 1985;75: 607-610. 9. Ward CM, Dolan LA, Bennett DL, Morcuende JA, Cooper RR. Long-term results of reconstruction for treatment of a flexible cavovarus foot in Charcot–Marie–Tooth disease. J Bone Joint Surg Am. 2008;90(12):2631-2642. 10. Whetmore RS, Drennan JC. Long-term results of triple arthrodesis in Charcot–Marie–Tooth disease. J Bone Joint Surg Am. 1989;71(3):417. 11. Younger AS, Hansen ST Jr. Adult cavovarus foot. J Am Acad Orthop Surg. 2005;13(5):302-315.
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Resection of the Fifth Metatarsal Base in the Severe Rigid Cavovarus Foot Raheel Shariff, Mark S. Myerson and Ezequiel Palmanovich Foot Ankle Int 2014 35: 558 originally published online 7 April 2014 DOI: 10.1177/1071100714531225 The online version of this article can be found at: http://fai.sagepub.com/content/35/6/558
Published by: http://www.sagepublications.com
On behalf of:
American Orthopaedic Foot & Ankle Society
Additional services and information for Foot & Ankle International can be found at: Email Alerts: http://fai.sagepub.com/cgi/alerts Subscriptions: http://fai.sagepub.com/subscriptions Reprints: http://www.sagepub.com/journalsReprints.nav Permissions: http://www.sagepub.com/journalsPermissions.nav
>> Version of Record - Jun 2, 2014 OnlineFirst Version of Record - Apr 7, 2014 What is This?
Downloaded from fai.sagepub.com at UNIVERSITE LAVAL on July 14, 2014
531225
research-article2014
FAIXXX10.1177/1071100714531225Foot & Ankle InternationalShariff et al
Article
Resection of the Fifth Metatarsal Base in the Severe Rigid Cavovarus Foot
Foot & Ankle International® 2014, Vol. 35(6) 558–565 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100714531225 fai.sagepub.com
Raheel Shariff, FRCS1, Mark S. Myerson, MD1, and Ezequiel Palmanovich, MD1
Abstract Background: Cavovarus deformity associated with neuromuscular imbalance is a challenging pathology. Most of these deformities lead to pressure symptoms at the lateral border of the foot. This leads to pain, callosity, and commonly fracture of the fifth metatarsal base. This study reports the outcome of a cohort of patients who underwent an adjunctive procedure of resection of the fifth metatarsal, either partial or complete, in conjunction with cavovarus foot reconstruction to offload the lateral border of the foot. Methods: This was a retrospective study looking at the clinical and radiographic outcome of patients with an underlying neuromuscular problem with a cavovarus foot who underwent a resection of the fifth metatarsal. This was used as an adjunctive procedure during reconstruction for lateral foot pressure overload symptoms. Case notes and radiographs were reviewed. The distance on weight-bearing radiographs from the inferior most part of the bony prominence on the lateral border of the foot to the floor was measured and compared between pre- and postoperatively. Eighteen patients met the inclusion criteria. Mean age was 55 years. Mean follow-up was 32 months. Results: Fourteen patients had a partial base of fifth metatarsal resection, and 4 had a complete fifth ray resection. Radiographic measurements showed a statistically significant improvement in the distance from the inferior most part of the bony prominence on the lateral border of the foot to the floor between pre- and postoperative radiographs. Sixteen patients reported a significant improvement in their symptoms, 2 had some persistent lateral overload symptoms. Conclusion: The technique described in this study has not been reported previously for this indication. We believe it is a good adjunctive procedure in cavovarus foot reconstruction for patients suffering from lateral pressure overload. We describe strict guidelines and indications for this procedure. Level of Evidence: Level IV, case series. Keywords: cavovarus foot, lateral pressure overload, fifth metatarsal resection, Charcot–Marie–Tooth In 1886, Charcot, Marie, and Tooth independently described families with specific conditions of progressive muscular atrophy beginning in the feet and legs.3 Pes cavus due to progressive neuromuscular disease is a challenging management problem.1 Approximately 80% of cavovarus foot deformities can be attributed to a neurologic disorder. The most common cause is Charcot–Marie–Tooth (CMT) disease.9 The cavovarus deformity leads to pain and callus formation under the metatarsal heads, foot fatigue, difficulty wearing normal shoes, lateral ankle instability and tripping.3 In the more severe forms, the patients present with marked callosity under the base of the fifth metatarsal due to abnormal loading of the lateral border of the foot. Even though CMT is a sensory neuropathy, many patients still have sensation and the deformity can be painful. Historically the cavovarus foot has been a difficult deformity to correct with poor long-term results, noting recurrence of deformity irrespective of whether a combination of bony or soft tissue
procedures is employed.9,10 If there is excessive stress over the fifth metatarsal, correction of the hindfoot is essential. The overload of the fifth metatarsal can be a particularly difficult problem. Various options can be employed in treating it. In a majority of cases a plantigrade foot can be achieved with a combination of bony and soft tissue procedures. These usually involve a triple arthrodesis with derotation through the Chopart joints, biplanar wedge resections/ calcaneal osteotomy. This is augmented with tibialis posterior tendon transfers or peroneus longus transfers to the lateral side of the foot. In some severe cases however, once the above-mentioned procedures are done, the fifth metatarsal 1
Institute for Foot and Ankle Reconstruction at Mercy, Baltimore, MD, USA Corresponding Author: Raheel Shariff, FRCS, Institute for Foot and Ankle Reconstruction at Mercy, 301 St. Paul Place, Baltimore, MD 21202, USA. Email: [email protected]
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Shariff et al continues to remain prominent. This is usually confirmed with intraoperative flouroscopy where the fifth ray remains inferiorly placed relative to the plane of the cuboid, in spite of trying to rotate the foot through the osteotomy site or dorsally translating it to ease the plantar pressure. For this cohort, we present a novel concept of resection of the fifth metatarsal base to offload the foot and alleviate symptoms. The objective of this study was to review the outcome of the fifth metatarsal base resection as an adjunctive procedure in the reconstruction for severe symptomatic rigid cavovarus foot deformities secondary to neuromuscular problems, causing persistent lateral plantar foot overload and pressure symptoms. This technique has not been described for the above-mentioned indication. We also present guidelines and indications for this technique.
Methods This was a retrospective study. We examined 18 patients who underwent fifth metatarsal base resection along with foot reconstruction for a rigid symptomatic cavus foot between 2003 and 2013. Local hospital board institutional review board approval was obtained. Demographic data were collected. No patients were lost to follow-up.
Table 1. Patient Demographics. Total number of patients Mean age Mean follow-up Male to female ratio Laterality (left to right ratio)
18 55 years (range 32-73) 32 months (range 8-58 months) 13:5 12:6
excluded. Between 2003 and 2013, 18 patients fulfilled the inclusion criteria for the study. Table 1 lists the demographic details of the patient cohort. Table 2 highlights individual patient characteristics. The patients charts were evaluated. All patients underwent a clinical examination by 1 of the authors. Preoperatively the patients underwent a Coleman block test. The hindfoot failed to correct in all. However, the Coleman block test was not really necessary in the majority of these patients since the hindfoot was absolutely rigid in varus and the transverse tarsal joint similarly rigid. Pre- and postoperative weight-bearing X-rays were assessed to determine the distance from the inferior most aspect of the lateral border of the foot to the floor. This was the radiographic measure used to determine how much improvement in lateral foot overload was achieved following the resection.
Inclusion Criteria To be included in this study, patients had to fulfill all the criteria mentioned below. These criteria also form the indication guidelines for this adjunctive procedure. a. Patients with an underlying neuromuscular imbalance contributing to a rigid cavus or cavovarus foot deformity, with lateral foot overload indicated preoperatively by prominence of the fifth metatarsal base, pain, and callosity b. Intraoperative persistent prominence of the fifth metatarsal base, which failed to correct following a cavus foot reconstruction having undergone either a triple arthrodesis or midfoot/hindfoot osteotomies with tendon transfers If the above-mentioned procedures failed to correct the lateral border overload, indicated intraoperatively by palpation of a bony prominence and confirmed fluoroscopically by the presence of an inferiorly placed fifth metatarsal in relation to the plane of the cuboid in the lateral projection, these patients were suitable for a resection of the fifth metatarsal base.
Exclusion Criteria All patients who had a prior history of osteomyelitis or an infected ulcer due to the lateral pressure overload were
Preoperative Radiographic Measurement This measured the distance from the inferior most aspect of the base of the fifth metatarsal to the floor.
Postoperative Radiographic Measurement This measured the distance from the inferior most aspect of the remaining fifth metatarsal following resection (in the case of a partial resection, which was what was done in the majority of the cases) or the inferior most bony prominence after a complete fifth ray resection, which happened to be the base of the fourth ray (in patients where a complete fifth ray resection had been done) to the floor. Although the measurements for those who underwent a base of fifth resection are not exactly comparable with those of the group who underwent a complete fifth ray resection, we found this was the best possible radiographic measure available, based on the available radiographic landmarks. We also looked at a way of identifying radiographically that the cavovarus deformity had been adequately corrected to a more plantigrade foot position, by the other procedures such as the triple arthrodesis or osteotomies. We looked at the pre- and postop sagittal radiographs of the foot. We measured the height of medial cuneiform, by drawing a line from the superior edge to the inferior most edge of the cuneiform. This line was drawn such that it was perpendicular to the weight-bearing surface (line A in the Figure 1). We then similarly measured the height of the base of the fourth
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Table 2. Individual patient operative characteristics. No
Fifth MTT Age Side Diagnosis resection
Triple arthrodesis
1 2 3 4 5 6 7
37 56 46 47 50 73 70
L L L R L L L
CMT CMT CMT CMT CMT CMT CMT
Partial Partial Partial Partial Partial Complete Partial
8 9 10 11 12 13 14 15 16 17 18
71 58 56 48 32 66 63 50 54 38 41
R L R L R L L L R L R
CMT CMT CMT CMT CMT CMT CMT CMT CMT CMT CMT
Partial Partial Partial Pantalar Complete Complete Revision triple Partial Partial Partial Complete TTC Partial Partial
Pantalar
PTT transfer
TMT fusion
Lengthening
Achilles length
Plantar fascia release
First MTT osteotomy
Lateral calc osteo
FDL transfer TA transfer
Lengthening
CMT, Charcot–Marie–Tooth disease; FDL, flexor digitorum longus; MTT, metatarsal; PTT, posterior tibial tendon; TA, tendoachilles; TMT, tarsometatarsal.
Operative Technique
Figure 1. The plantigrade foot ratio, A/B.
metatarsal, taking into account only the height of this metatarsal that was not overlapped by the medial cuneiform (line B in the Figure 1). The ratio of A/B was measured. A similar ratio was calculated for the postoperative radiograph. If the postop ratio was greater than the preoperative ratio, this meant that the measurement B was less postoperatively compared to preoperatively. This indicated that the metatarsal cascade had improved. Then adequate correction was deemed to have taken place, as this indicated that the foot was derotated and plantigrade. We called this the plantigrade measurement ratio.
The incision used for the calcaneal osteotomy, peroneal tendons or triple arthrodesis was extended distally along the dorsal aspect of the metatarsal base. After blunt dissection the bony prominence of the base of the fifth metatarsal was resected with a saw. First, the severity and apex of the deformity were determined. This was done by identifying whether the entire fifth metatarsal was rotated under the fourth and also where the apex of the deformity was located. If it was limited to the base only and not much rotation of the entire metatarsal was present, then only the base was excised. If the entire metatarsal was rotated and the apex was more distal to the base in the shaft then the entire metatarsal was resected. The saw cut was made distal to the apex, obliquely in 2 planes, such that the starting point of the osteotomy was dorsal and slightly lateral (Figure 2). Following this, the overlying skin was palpated to determine any residual bony prominences that needed further debridement after the initial resection.5 We routinely sacrificed the peroneus brevis as it was nonfunctional. We believe transferring the tendon would not have been beneficial. The plantar fascia was not routinely released. Figures 2 to 4 demonstrate the operative technique.
Results All the patients were diagnosed with CMT disease in the study cohort. All of them had neuropathy to a varying extent, but formal nerve conduction studies were not performed. Before surgery, all patients complained of pain over the lateral border of the foot, painful callosities, or a
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Figure 5. Stress fracture over the fifth metatarsal. Figure 2. Resection initially performed with a saw.
Figure 6. Bony procedures performed during the cavovarus foot reconstruction. Figure 3. Completion of resection with an osteotome.
Figure 4. Resected base of fifth metatarsal. Note the callosity on the plantar aspect due to lateral pressure overload.
bony prominence that worsened their gait. None of the patients were noted to have plantar pain. In 4 cases stress
fracture of the fifth metatarsal had been diagnosed preoperatively. All 4 had fixation attempted with a single intramedullary compression screw. Three of these failed to unite, while 1 progressed to satisfactory union. However, all of them including the 1 that united remained symptomatic with pain and overload. Their symptoms successfully resolved following the resection. Figure 5 is an example of a fifth metatarsal stress fracture that occurred due to lateral foot overload. During the primary surgery for correction of the cavus foot, bony and soft tissue procedures were performed. All these patients had a rigid deformity. The bony procedures included tarsometatarsal (TMT) fusion (3 cases), first metatarsal osteotomy (7 cases), sliding calcaneal osteotomy (8 cases), triple arthrodesis (7 cases), and pantalar fusion (2 cases). Of the 3 patients who underwent a TMT arthrodesis, 2 had an isolated first TMT arthrodesis and 1 had the first and second TMT joints fused as part of their correction. Figure 6 elucidates the bony procedures that were performed in these 15 patients. Soft tissue procedures included tibialis posterior tendon transfer or lengthening (10 cases), plantar fascia release (6
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Foot & Ankle International 35(6) base resection as opposed to a complete resection. In both these patients the pain was associated with slight rotation of the hindfoot and not insufficient resection of the base of the fifth, as the entire base of the fifth metatarsal had been resected in them. They were successfully managed with orthotic modifications, and no further operative intervention was undertaken in them. All patients reported a subjective improvement and a decrease in symptoms of lateral foot border overload at final follow-up. They all had a plantigrade foot at final follow-up.
Discussion Figure 7. Soft tissue procedures performed during the cavovarus foot reconstruction.
cases), tibialis anterior or FDL transfer (3 cases), and Achilles lengthening (1 case) (see Figure 7). In 14 cases a base of the fifth metatarsal resection was performed to reduce the bony pressure. In 4 cases the entire metatarsal was resected. Figure 8 is an example of a partial resection with improvement in lateral overload symptoms. Figure 9 is an example of a complete fifth metatarsal resection. The radiographic measurements used to assess distance from the floor to inferolateral border of the foot showed the mean preop measurement to be 1.4 mm and postoperative measurement 11.3 mm (2.4-31.8 mm). This difference was found to be statistically significant. Figure 10 highlights the measurements explained above. The mean preoperative plantigrade foot ratio as described above was 1.96. The mean postoperative ratio was 3.6 (P < .05) and showed that the cavovarus deformity had been well corrected with the other procedure performed.
Complications Both the patients who underwent a pantalar arthrodesis had complications. One of them developed osteomyelitis of the calcaneus with lateral wound dehiscence. This was treated with debridement, removal of hardware, IV antibiotics, and VAC dressings. The lateral wound was subsequently covered with a Gracilis free flap. This patient continued to have suppressive antibiotic therapy for low-grade osteomyelitis control at final follow-up. The other patient with a pantalar arthrodesis had a distal tibial fracture just proximal to the blade plate following a fall, 3 weeks following his reconstructive surgery. This was treated conservatively in a non-weight-bearing cast and went on to successful union 11 weeks later. Two patients complained of mild persistent lateral foot pain. Both these patients had undergone a fifth metatarsal
Operative intervention for reconstruction of painful cavus foot requires meticulous preoperative planning for a combination of bony and soft tissue procedures. A cavovarus foot is a progressive deformity in the presence of muscle imbalance.11 Distinguishing between fixed and flexible components of the deformity is an essential step in the decision-making process. Soft tissue procedures can be used to eliminate deforming forces and balance the foot, but osteotomies and arthrodesis frequently are necessary to correct alignment and alleviate symptoms.1 Isolated triple arthrodesis in the setting of neuromuscular imbalance particularly in CMT disease has not been very successful.7,10 Long-term results in a study by Whetmore et al showed 7% excellent results and 47% poor results, with the remainder being fair to good. This was because of a recurrence of a cavovarus deformity. To prevent recurrence, a combination of soft tissue balancing along with the triple arthrodesis has been advocated in the form of tendon transfers.5 The aim of operative correction is to realign the foot into a more plantigrade position. In the semirigid foot, a stepwise approach beginning at the hindfoot and progressively working up toward the forefoot should be employed. Although several different procedures are used, commonly these involve a calcaneal osteotomy, tibialis posterior tendon transfer, peroneus longus release or transfer, plantar fascia release, and TMT fusions or first metatarsal dorsiflexion osteotomy as demonstrated in our series. In the rigid deformity, a plantigrade foot is achieved by rotating the foot through the Chopart joints while performing a triple arthrodesis. Tendon transfers are also an integral part of correction of the rigid deformity to eliminate the deforming forces. However once this is done, if the fifth metatarsal continues to remain prominent, the dilemma arises with regard to what the next step in the operative algorithm should be. We feel that in these cases a resection of the base of the fifth metatarsal is an extremely useful adjunctive procedure to offload the pressure from the lateral border of the foot. The idea for this procedure first emerged when the senior author treated a patient over 20 years ago, for a cavovarus
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Figure 8. X-ray showing the pre- and postoperative results, after partial fifth ray resection. Note the improvement in metatarsal cascade and lack of lateral foot overload in the postoperative X-ray.
Figure 9. (a) Preoperative cavus foot with lateral pressure overload. Note the inferiorly located fifth ray in relation to the plane of the cuboid. (b) Postoperative X-ray of the same patient after complete fifth ray resection.
Figure 10. Measurements taken on weight-bearing radiographs.
foot complicated by osteomyelits of the fifth metatarsal with a neuropathic ulcer. This was successfully treated with a partial metatarsal base resection and debridement. That specific case is not included in this study and over the years the senior author has successfully employed this procedure for that indication. However this study looks at a more recent patient cohort in whom this procedure was employed for severe symptomatic rigid cavovarus foot deformities secondary to neuromuscular problems, causing persistent lateral foot overload and pressure symptoms. Hindfoot
correction is essential if there is excessive painful stress on the fifth metatarsal. Intractable pain, painful callosities or stress fracture are the most common complains. Complete fifth ray amputation has more recently been described for the cavovarus foot by Boffeli at al2 in the treatment of nonhealing neuropathic ulcers. They routinely performed a complete resection of the fifth metatarsal and transfer of the peroneus longus to the cuboid in a staged manner. This was done by debridement of the ulcer and treatment of osteomyelitis with antibiotic impregnated
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beads followed by the tendon transfer 2 weeks later. They claim that this staged protocol has not been described in the literature previously for this problem and suggest the longterm results were very gratifying, although the actual patient numbers and follow-up were not elaborated in this article. Our study has a different patient profile, in that we used a partial resection of the fifth metatarsal for deformity correction primarily and not for osteomyelits. The logical question that needs to be addressed is this: does the loss of the peroneus brevis cause any deficit when the base of the fifth metatarsal is resected? An interesting study by McCullough et al4 looked at the moment arms of the tendons about the ankle. Moment arms are geometric indicators of the contribution of individual muscles in a plane of movement and are vital for planning tendon transfers. They found that the peroneus brevis has the greatest moment in external rotation and its loss is best compensated for by a peroneus longus transfer to the peroneus brevis insertion site. Although previous studies in the podiatric literature have suggested that a transfer of the peroneus longus to the cuboid or lateral border of the foot is essential in preventing an adductovarus deformity due to overactivity of the tibialis posterior tendon after resection of the fifth metatarsal,6,8 we do not believe this is essential, as bony procedures in the form of triple arthrodesis are performed in conjunction and help maintain the position of the foot. In the case of correction of the cavovarus foot, the peronei are nonfunctional and as a result the peroneus brevis can be sacrificed without any loss in function perceived by the patient. The tibialis posterior tendon is also transferred or lengthened in the majority of cases and its deforming force is thereby negated. In our series we routinely sacrificed the peroneus brevis, when we resected the fifth metatarsal base by an oblique saw cut and we did not identify any complications or loss of correction/function. We do not know if loss of the fifth metatarsal following a partial or complete resection affects the biomechanics of the foot. Does the fourth ray become unstable, and if so is weight-bearing affected? These are questions worth posing. Our patients all had a plantigrade foot with subjective improvement in walking, although a drawback of our study is that we did not have any objective scoring systems or pedobarographic studies postoperatively. This procedure can also be done after a pantalar or a tibiotalocalcaneal arthrodesis. Its use in this patient cohort is even more beneficial as the foot is more rigid than following a triple arthrodesis and no compensatory rotation exists that may offload the lateral border of the foot if the fifth metatarsal is left unresected. We have performed this procedure as a last step to gain correction in the operative algorithm. Caution should be used in utilizing this as an isolated procedure to correct deformity. Specifically attention should be paid in patients where the fifth metatarsal is rotated under the fourth. In these patients much more extensive procedures need to be
performed in addition to the resection. The senior author has had experience with 2 patients who had undergone prior (multiple) hindfoot procedures where the base of fifth metatarsal was associated with ulceration. In these 2 cases isolated excision of the fifth was performed. These 2 patients were not included in this study since we do not have access to their information, as they were performed at a different institution. Although it would be tempting to compare this cohort to a group of patients who underwent cavovarus foot correction without a fifth metatarsal resection and see how they fared, this is not possible because the resection was not performed as the first part of the reconstruction, but as the very last step in the operative reconstruction algorithm when nothing else was possible to correct the lateral based prominence. Therefore, there is no point to comparing these patients with others once the osteotomies and/or arthrodesis has been done as correction of the lateral based prominence may have already occurred. After the resection, improvement in patient symptoms was observed. Recurrence of symptoms was observed in only 2 patients (11%). No further intervention was performed to our patients with the objective to reduce pressure over the lateral aspect of the foot.
Conclusion The cavovarus foot is a usually a progressive neuropathic disease. Operative treatment must include bony and soft tissue procedures to improve pain, deformity, and avoid recurrence. Resection of the fifth metatarsal base was a useful adjunctive procedure in the cavovarus foot reconstruction for severe symptomatic rigid deformities secondary to neuromuscular problems resulting in persistent lateral foot overload and pressure symptoms. To the best of our knowledge this technique has not been described in the literature for the above-mentioned indication. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
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Shariff et al 3. Mann R, Missirian J. Pathophysiology of Charcot–Marie– Tooth disease. Clin Orthop Relat Res. 1988;(234):221-228. 4. McCullough MB, Ringleb SI, Arai K, Kitaoka HB, Kaufman KR. Moment arms of the ankle throughout the range of motion in three planes. Foot Ankle Int. 2011;32(3):300-306. 5. Myerson M. Reconstructive Foot and Ankle Surgery: Management of Complications. 2nd ed. Philadelphia, PA: Elsevier; 2010. 6. Schoenhaus J, Jay RM, Schoenhaus H. Transfer of the peroneus brevis tendon after resection of the fifth metatarsal base. J Am Podiatr Med Assoc. 2004;94:594-603. 7. Raikin SM. Failure of triple arthrodesis. Foot Ankle Clin. 2002;7(1):121-133.
8. Roper RB, Altman MI. Fifth metatarsal excision with peroneus brevis transfer. J Am Podiatr Med Assoc. 1985;75: 607-610. 9. Ward CM, Dolan LA, Bennett DL, Morcuende JA, Cooper RR. Long-term results of reconstruction for treatment of a flexible cavovarus foot in Charcot–Marie–Tooth disease. J Bone Joint Surg Am. 2008;90(12):2631-2642. 10. Whetmore RS, Drennan JC. Long-term results of triple arthrodesis in Charcot–Marie–Tooth disease. J Bone Joint Surg Am. 1989;71(3):417. 11. Younger AS, Hansen ST Jr. Adult cavovarus foot. J Am Acad Orthop Surg. 2005;13(5):302-315.
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