Association between Postoperative Medial: Middle Intercuneiform Joint Gapping and Recurrence Rates in Hallux Valgus

Abstract

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Hallux valgus (HV) is a triplanar deformity of the first metatarsal, which may extend beyond the first ray. Compared with normal feet, previous studies have found that HV patients have an increase in hypermobility of the joints along the medial column and at the medial – middle (MM) intercuneiform joint. Despite increased instability at the MM intercuneiform joint, no study has investigated its clinical significance. The primary purpose of this study was to determine if postoperative widening of the MM intercuneiform joint was associated with recurrence in HV patients who undergo a first tarsometatarsal fusion (modified Lapidus procedure). A secondary purpose was to investigate whether other HV imaging parameters were associated with a widening of the MM intercuneiform joint. Methods: This study included 52 consecutive HV patients who underwent a modified Lapidus procedure and had preoperative and at least 5-month postoperative weightbearing CT (WBCT) scans. Preoperative and postoperative measurements of HV deformity, including the intermetatarsal angle and hallux valgus angle (HVA) on plain radiographs and triplanar pronation angle and sesamoid station from WBCTs, were performed as previously described. MM intercuneiform distance was measured on the coronal multiplanar reconstructed WBCT scans after reorienting the axial and sagittal planes such that the coronal cuts were orthogonal to the intercuneiform joint (Figure 1A). Recurrence of the HV deformity was defined as a postoperative HVA ≥ 20°. Paired t-tests were used to compare preoperative and postoperative imaging parameters, and Mann-Whitney U tests were used to compare measurements between patients with and without HV recurrence. Pearson correlation coefficients were used to explore associations between preoperative and postoperative measurements and the change in MM intercuneiform distance. Results: Nine of 52 patients (17.3%) had recurrence of their HV deformity. For the entire cohort, the mean preoperative and postoperative MM intercuneiform distances were 0.73 mm (standard deviation (SD) 0.3) and 1.08 mm (SD 0.5), respectively. In patients with and without HV recurrence, the mean widening at the MM intercuneiform joint was 0.69 mm (95% confidence interval (CI) 0.52-0.86) and 0.27 mm (95% CI 0.17-0.38, P< 0.001), respectively. Patients with recurrence had significantly greater widening of the MM intercuneiform joint than patients without recurrence (P=0.001, Figure 1B and Table 1). While no preoperative imaging parameters were associated with a change in the MM intercuneiform distance, increasing postoperative sesamoid position (r=0.32, P=0.022) and HVA (r=0.28, P=0.046) were correlated with a greater change MM intercuneiform joint gapping. Conclusion: In patients undergoing a modified Lapidus procedure for correction of their HV deformity, postoperative widening of the MM intercuneiform joint was associated with recurrence of the HV deformity. As understanding of the HV deformity continues to evolve, our study suggests that there is a complex interplay between deformity at the hallux metatarsophalangeal (MP) joint, reduction of the metatarsosesamoid joint complex, and the instability at the tarsometatarsal and intercuneiform joints. This may guide surgical correction as surgeons may need to address both intercuneiform instability and correction at the hallux MP joint in order to decrease HV recurrence rates.