[Resection of navicular bone for severe midfoot deformity in children].

PURPOSE OF THE STUDY

The navicular bone lies at the apex of the deformity in severe talipes planovalgus with forefoot abductus, in the residual cavus of congenital talipes equinovarus, in certain cases of congenital convexity, and in certain types of neurological equinovarus. Resection of the navicular bone can be proposed to correct certain deformities.

MATERIAL AND METHODS

This series included 15 feet operated on in 13 children from 1980 to 2003. The deformity to be corrected was a residual cavus after surgery for congenital talipes equinovarus (five feet), plantar and medial dislocation of the navicular bone on an acquired equinovarus in non-walking children (three feet), planovalgus with major forefoot abductus in non-walking children (four feet). Among the 13 children in this series, five did not walk (seven feet) and underwent surgery because of skin wounds caused by protrusion of the head of the talus and serious mechanical problems (shoes, ortheses). Mean age at operation was 8.5 years (range 2-16 years). The surgical procedure was part of an overall strategy combining use of ortheses, physiotherapy, and medical management. For congenital equinovarus with residual cavus, naviculectomy was performed after the usual technique for equinovarus when the navicular bone was dislocated above the medial tarsal and prevented reduction of the cavus. After extraperiosteal release, resection of the navicular bone enabled correction of the cavus. The lateral column had to be shortened in order to avoid adductus subsequent to medial-lateral length discrepancy. The same surgical technique was used for acquired equinovarus except that the navicular bone was displaced medially and above the talus. The lateral column had to be shortened. Standard procedures were applied for congenital convex feet before naviculectomy when there was major forefoot abductus after medial tarsal release and tendon lengthenings. The lateral column was not shortened since it was already too short. For planovalgus with forefoot abductus, naviculectomy was combined with release of the calcaneocuboid joint. Fibular tendons were lengthened.

RESULTS

Mean follow-up was two years five months (range 5 months-12 years 6 months). For the talipes equinovarus feet, the Méary Toméno angle was 24.4 degrees on average preoperatively and 5 degrees at last follow-up, giving a mean gain of 19.4 degrees . For congenital convex feet, the M5-lateral calcaneal border angle was 29.7 degrees on average preoperatively and 11.7 degrees at last follow-up for a mean gain of 18 degrees . For the planovalgus feet with forefoot abductus, the M5-lateral calcaneal border angle was 32.7 degrees on average preoperatively and 12.2 degrees at last follow-up, for a gain of 20.5 degrees on average; the mean Méary Toméno angle was -30 degrees preoperatively and -3 degrees at last follow-up, for a mean gain of 27 degrees .

CONCLUSION

For carefully selected patients, naviculectomy performed in combination with other procedures can provide appropriate correction of severe midfoot deformities in children.