FURTHER EXPERIENCE WITH EXTRA-ARTICULAR ARTHRODESIS OF THE SUBTALAR JOINT

Abstract

In the original presentation of this operation, it was stated that the correction of the paralytic flat-foot evolved into a problem of obtaining several major objectives. The calcaneus must be replaced beneath the talus and must be maintained in a normal relation to it. The talus must be brought out of equinus deformity. Muscle balance should be restored by muscle transplantation in order to avoid recurrence. The deforming everting power of the peroneal muscles should be removed, and active inversion and dorsiflexion should be restored to the talonaviscular area. Since it is desirable to correct the deformity in a child before it becomes fixed, the operative technique should not interfere with the growth of the foot. After a review of the fifty-two patients who had been operated upon, it was apparent that adherence to these fundamental principles will give satisfactory results in the management of the paralytic flat-foot. Failures have been due to inadequate replacement of the calcaneus beneath the talus, failure to correct the equinus deformity of the foot, inadequate correction of the muscle imbalance, and overcorrection of the deformity with a resultant talipes varus. As a result of the experiences we have had during the past nine years with this method, it can be stated that extra-articular fusion of the subtalar joint, with bone grafts placed in the sinus tarsi, can be performed quite easily and can provide adequate correction of paralytic flat-foot. In order to prevent recurrence in severely deformed feet, it is necessary to correct the equinus deformity of the foot and to restore support to the talonaviscular area. This procedure is well adapted to use in the young child in the age group four to eight years in whom the deformity is progressing rapidly. The procedure can also be used as an alternate procedure to triple arthrodesis for the correction of valgus deformities in older patients. In feet that are of adult architecture and which display severe deformity, it will probably he impossible to restore the normal relationship of the calcaneous beneath the talus without resection of the subtalar joint. Therefore, a triple arthrodesis will be necessary. In the patients in this series, solid fusion was obtained in all in whom authogenous bone had been used. The one instance of absorption occurred in a patient in whom homogenous bone had been used. The height of the foot is restored by this procedure, and growth is maintained. Fusion of the subtalar joint with autogenous bone grafts placed in the sinus tarsi is principally an extra-articular arthrodesis which does not interfere with the growth of the foot. If this procedure is carried out in combination with tendon transplantation to equalize muscle strength about the foot, a satisfactory correction of the deformity can be obtained. The insertion of the grafts in the sinus tarsi is a simple mechanical problem, and, if they are properly placed under slight compression, solid fusion and strong fixation of the subtalar joint should be obtained. Inadequate correction, insecure placement of the grafts, or overcorrection of the deformity will give poor results. This procedure is well adapted to the problem of paralytic flat-foot, but the same principles can be applied to the correction of the congenital planovalgus foot in which the talus is in marked equinus and to talipes valgus observed in cerebral palsy.