[Modified Evans osteotomy for the operative treatment of acquired pes planovalgus]

Restoration of the longitudinal arch of the foot and reorientation of the hindfoot for painful decompensating flatfoot (pes planovalgus) due to posterior tibial tendon dysfunction.

Passively correctable, painful pes planovalgus of various etiologies such as stage II flatfoot as graded by Johnson & Strom mostly due to degeneration of the posterior tibial tendon in stage II-III as described by Jahss.

Fixed pes planovalgus, osteoporosis of the calcaneus, advanced degenerative arthritis of the subtalar, talonavicular or calcaneocuboid joints.

Transverse osteotomy of the anterior process of the calcaneus approximately 1.5 cm proximal of and parallel to the calcaneocuboid joint. Lengthening of the lateral column using the sandwich technique by the interposition of one to two autologous, tricortical bone grafts, which are structured to straighten the hindfoot and to move it toward neutral position. If the technique is performed correctly, the talus and the calcaneus are in alignment. When the talar head is externally rotated and the calcaneus is moved toward varus, this results in axial alignment of the abducted forefoot and straightening of the collapsed longitudinal arch of the foot.

Between June 1995 and March 2003, 21 patients with stage II painful pes planovalgus as described by Johnson & Strom underwent a modified Evans osteotomy. In one case an arthrodesis of the first tarsometatarsal joint was carried out, and in four cases a lengthening of the gastrocnemius muscle according to Strayer. A replacement of the insufficient posterior tibial tendon was not necessary in any of the cases. With respect to complications one wound edge necrosis and one nonunion were seen. 15 patients (eleven women, four men, average age 54 years) were followed up for an average of 48 months (12-81 months) postoperatively. The Maryland Foot Score improved significantly from 49.6 points preoperatively to 87.8 points postoperatively (p < 0.01). In the cases of one-sided deformity the foot axes in the weight-bearing radiographs were corrected to being close to the physiologic values of the opposite side.