Temporary Kirschner wire fixation of the first metatarsophalangeal joint before osteotomy for hallux valgus

Introduction: Numerous operative procedures have been described for correction of hallux valgus, including distal step-cut osteotomy such as the Mitchell osteotomy. However, overcorrection can occur due to technical problems with the initial metatarsal osteotomy. Here, we describe a modified Mitchell osteotomy with a novel method, the temporary Kirschner wire fixation of the first metatarsophalangeal joint (TeKFiM) method (Tonogai method), that can be used before osteotomy for hallux valgus to avoid incongruency and overcorrection. Operative technique: A skin incision and Y-shaped capsulotomy are performed and the medial exostosis is excised. Lateral capsule release is done if the first metatarsophalangeal (MTP) joint cannot be reduced manually. Next, a Kirschner wire (K-wire) is inserted subcutaneously through the medial side of the first proximal phalanx to the lateral side of the first metatarsal to preserve the correct congruency of the first MTP joint during surgery. To correct pronation of the distal fragment, step-off transverse cuts are made in the distal fragment, as described by Mitchell, reaching one-second to two-thirds of the transverse diameter of the neck from the plantar medial side. After the osteotomies are completed, the lateral spike of the proximal fragment is flattened. The distal fragment is displaced laterally and slightly plantarward, and the pronation deformity of the distal fragment is corrected by inserting a K-wire to act as a joystick. The osteotomy site is stabilized using two Herbert-type screws. After removal of the K-wire, the operation is completed by closing the medial capsule of the first MTP joint and the skin. A plantar cast is applied for 2 weeks, followed by a special heel brace for 4-6 weeks. Sutures are removed 2 weeks after surgery. Patients are allowed to start weightbearing gradually as tolerated from 2 weeks after surgery. Discussion: After osteotomy, it is difficult to maintain the correct congruency of the first MTP joint due to instability of the distal fragment. The TeKFiM method (Tonogai method) reliably maintains this congruency during surgery. Also, by using a K-wire as a joystick to fix the joint in correct congruency, the first toe is rotated and pronation is corrected by supinating the distal fragment. The K-wire also serves as a landmark for determining how far the distal fragment is shifted plantarward. Conclusions: We have developed a modified Mitchell osteotomy with the novel TeKFiM method (Tonogai method) before osteotomy for hallux valgus to avoid incongruency and overcorrection. This method also provides a landmark to correct pmnation and plantarward shifting.