First-Tarsometatarsal Joint Alignment After First-Metatarsophalangeal Joint Arthrodesis for Hallux Valgus

Background: Instability of the first-tarsometatarsal (TMT) joint has been proposed as a cause of hallux valgus. Although there is literature demonstrating how first-TMT arthrodesis affects hallux valgus, there is little published on how correction of hallux valgus affects the first-TMT joint alignment. The purpose of this study was to determine if correction of hallux valgus impacts the first-TMT alignment and congruency. Improvement in alignment would provide evidence that hallux valgus contributes to first-TMT instability. Our hypothesis was that correcting hallux valgus angle (HVA) would have no effect on the first-TMT alignment and congruency.

Methods: Radiographs of patients who underwent first-MTP joint arthrodesis for hallux valgus were retrospectively reviewed. The HVA, 1-2 intermetatarsal angle (IMA), first metatarsal-medial cuneiform angle (1MCA), medial cuneiform-first metatarsal angle (MC1A), relative cuneiform slope (RCS), and distal medial cuneiform angle (DMCA) were measured and recorded for all patients preoperatively and postoperatively.

Results: Of the 76 feet that met inclusion criteria, radiographic improvements were noted in HVA (23.6 degrees, P < .0001), 1-2 IMA (6.2 degrees, P < .0001), 1MCA (6.4 degrees, P < .0001), MC1A (6.5 degrees, P < .0001), and RCS (3.3 degrees, P = .001) comparing preoperative and postoperative radiographs. There was no difference noted with DMCA measurements (0.5 degrees, P = .53).

Conclusion: Our findings indicate that the radiographic alignment and subluxation of the first-TMT joint will reduce with isolated treatment of the first-MTP joint. Evidence suggests that change in the HVA can affect radiographic alignment and subluxation of the first-TMT joint.

Level of evidence: Level IV, retrospective case series.