Plantarflexion opening wedge medial cuneiform osteotomy for correction of fixed forefoot varus associated with flatfoot deformity.

BACKGROUND:
Flatfoot presents as a wide spectrum of foot deformities that include varying degrees of hindfoot valgus, forefoot abduction, and forefoot varus. Medial displacement calcaneal osteotomy, lateral column lengthening, and subtalar fusion can correct heel valgus, but may not adequately correct the fixed forefoot varus component. The purpose of this study was to determine the effectiveness of plantarflexion opening wedge medial cuneiform (Cotton) osteotomy in the correction of forefoot varus.

METHODS:
Sixteen feet (15 patients) had plantarflexion opening wedge medial cuneiform osteotomies to correct forefoot varus associated with flatfoot deformities from several etiologies, including congenital flatfoot (six feet, average age 37 years), tarsal coalition (five feet, average age 15 years), overcorrected clubfoot deformity (two feet, ages 17 years and 18 years), skewfoot (one foot, age 15 years), chronic posterior tibial tendon insufficiency (one foot, 41 years), and rheumatoid arthritis (one foot, age 56 years).

RESULTS:
Standing radiographs showed an average improvement in the anterior-posterior talo-first metatarsal angle of 7 degrees (9 degrees preoperative, 2 degrees postoperative). The talonavicular coverage angle improved an average of 15 degrees (20 degrees preoperative, 5 degrees postoperative). The lateral talo-first metatarsal angle improved an average of 14 degrees (-13 degrees preoperative, 1 degree postoperative). Correcting for radiographic magnification, the distance from the mid-medial cuneiform to the floor on the lateral radiograph averaged 40 mm preoperatively and 47 mm postoperatively (average improvement 7 mm). All patients at followup described mild to no pain with ambulation. There were no nonunions or malunions.

CONCLUSIONS:
Opening wedge medial cuneiform osteotomy is an important adjunctive procedure to correct the forefoot varus component of a flatfoot deformity. Advantages of this technique in comparison to first tarsometatarsal arthrodesis include predictable union, preservation of first ray mobility, and the ability to easily vary the amount of correction. Because of the variety of hindfoot procedures done in these patients, the degree of hindfoot correction contributed by the cuneiform osteotomy alone could not be determined. We have had excellent results without major complications using this technique.