First tarsometatarsal joint medial subluxation after contemporary minimally invasive distal osteotomy for hallux valgus: A weight-bearing computed tomography assessment.

BACKGROUND: Minimally invasive (MIS) osteotomy for Hallux Valgus (HV) may alter the congruence of the first tarsometatarsal joint (1ST-TMT). This study evaluated postoperative 1ST-TMT subluxation and associated imaging factors. METHODS: This retrospective cohort included 63 patients undergoing MIS HV correction with ≥ 6 months of radiological follow-up. Imaging parameters included a novel C1 - M1 joint lateral distance to assess 1ST-TMT subluxation. Multivariable linear regression evaluated factors associated with postoperative subluxation and midshaft foot width. RESULTS: Interobserver reliability for the C1 - M1 joint lateral distance was excellent (r = 0.93). Mean C1 - M1 lateral distance increased from 0.26 to 1.33 mm (P<0.001), with a greater dorsal displacement (2.6 mm). Postoperative subluxation correlated with preoperative C1 - M1 lateral distance (P=0.022) and plantar gap (P = 0.008) and was associated with increased midshaft foot width (P=0.004). CONCLUSION: MIS HV correction was associated with consistent dorsal 1ST-TMT medial subluxation and increased midshaft foot width. Future studies are needed to determine the clinical relevance of these findings.