[Subtalar arthrodesis for sequelae of calcaneal fractures. Apropos of 57 cases].

PURPOSE OF THE STUDY: 57 subtalar arthrodesis for sequelae of calcaneal fractures were reviewed with a minimum follow up of 6 years 11 months.

MATERIAL AND METHODS: Bone resection and interposition of bone grafts, stabilized by screws were used in 36 cases. Iliac crest grafts were used in 20 cases, cryopreserved grafts 15 times and local graft taken on the anterior tibial epiphysis once. No surgery was performed on the mid foot.

RESULTS: Results were evaluated using the grading system described by Mestdagh with 33 good global results, 18 fair results and 6 poor results for a total of only 58 per cent of good global results. Of the 57 cases reviewed, 18 remained painful with a limited range of motion for inversion and eversion of the foot. In 18 patients monopodal weight-bearing was unstable. Residual oedema persisted in 5 patients. 16 patients continued to limp and 3 required the use of a crutch. 7 valgus and 3 varus deviations of the hindfoot were noted at follow up with poor tolerance of the varus when compared to exaggerated valgus. Podoscopic examination revealed increase anterior pressure zones responsible for metatarsalgia which was relieved by corrective shoe inserts in 10 patients. Radiographic evidence of fusion could be demonstrated in 55 cases. There was little or no repercussion on the tibio-talar joint. In the Chopart joint we noted 4 cases of osteoarthritis; there were 6 lesions in the talo-navicular joint and no repercussion in Lisfranc's joint. 16 complications of varying severity were noted with 2 nonunions following use of cryopreserved grafts.

DISCUSSION: Subtalar arthrodesis for sequelae of traumatic lesion in the hindfoot gives good results in 2 cases out of 3. In our series, 26 per cent of the patients showed degenerative changes in the mid foot unlike the series published by Kempf. As Meary and Mestdagh noted, we found that residual varus or valgus deformity > 10 degrees was poorly tolerated as well as modifications > 20-30 degrees in the vertical ratio between the talus and the calcaneum in the horizontal plane.

CONCLUSION: Subtalar arthrodesis is a useful technique giving good results in 2 out of 3 cases of traumatic sequelae in the hindfoot. Triple arthrodesis does not seem indicated when the talus and the calcaneus can be realigned before fusion. Talo-navicular arthrodesis, though more easily realized, requires blocking a normal joint in order to immobilize a painful joint.