Contribution of First-Tarsometatarsal Joint Fusion to Deformity Correction in the Treatment of Adult-Acquired Flatfoot Deformity

Abstract

Background: Severe adult-acquired flatfoot deformity (AAFD) is often associated with painful medial column collapse at the naviculocuneiform (NC) joint. However, many surgeons surgically correct the deformity without directly addressing this joint. The purpose of this study was to examine the role of first-tarsometatarsal (TMT) fusion combined with subtalar fusion in correcting deformity at the NC joint. Methods: We retrospectively analyzed 40 patients (41 feet) who underwent first-TMT and subtalar (ST) fusion as part of a flatfoot reconstructive procedure. We assessed 6 radiographic parameters both preoperatively and at a minimum of 6 months postoperatively, including talonavicular (TN) coverage angle, lateral talo–first metatarsal angle, lateral talocalcaneal angle, calcaneal pitch, hindfoot moment arm, and a newly defined navicular-cuneiform incongruency angle (NCIA). Patient-Reported Outcomes Measurement Information System (PROMIS) clinical outcomes were assessed preoperatively and at a minimum 1-year follow-up. Results: The NCIA demonstrated excellent interobserver reliability, with no significant change between pre- and postoperative measurements. All other radiographic parameters, except calcaneal pitch, demonstrated statistically significant improvement postoperatively ( P < .01). Overall, patients had statistically significant improvement in all PROMIS domains ( P < .01), except for depression. Worsening NC deformity was not associated with worse patient-reported outcomes. Conclusions: Our data suggest that when addressing painful collapse of the medial arch in patients with AAFD, fusion of the first-TMT joint in combination with other procedures leads to acceptable radiographic and clinical outcomes. There was no change in deformity at the NC joint in our patient cohort at short-term follow-up, and patients achieved significant improvement in multiple PROMIS domains. Although TMT fusion had no effect on NC deformity, residual or worsening NC deformity did not significantly affect clinical outcomes. In addition, the NCIA was found to be a reliable radiographic parameter to assess NC deformity in the presence of talonavicular and/or first-TMT fusion. Level of Evidence: Level III, retrospective comparative study.