Deltoid-Spring Ligament Reconstruction in Adult Acquired Flatfoot Deformity With Medial Peritalar Instability

Background: A spring ligament tear is commonly present in advanced stages of adult acquired flatfoot deformity (AAFD). Previous anatomic studies have demonstrated that the superficial deltoid ligament blends with the superomedial spring ligament, forming the tibiocalcaneonavicular ligament (TCNL). Adding allograft TCNL reconstruction to osseous correction has been suggested to augment medial peritalar stability in advanced AAFD with large spring ligament tears. We aimed to investigate the clinical and radiographic outcomes of TCNL reconstruction for flexible AAFD with medial peritalar instability. Methods: Fourteen feet in 12 patients who underwent osseous and TCNL reconstructions for advanced AAFD (stage IIB with large spring ligament tears or stage IV) were recruited for the study. The mean postoperative follow-up was 24 (range, 12-33) months. Pre- and postoperative clinical outcomes were assessed by the Foot and Ankle Ability Measure (FAAM), SF-36, and Patient-Reported Outcomes Measurement Information System (PROMIS). Correction of forefoot abduction and the sagittal arch were measured from pre- and postoperative weightbearing radiographs. Results: The FAAM Activities of Daily Living improved from 69.3 to 90.1 (P = .001). The SF-36 Physical Function (PF) and Pain subscales both improved significantly (39.4 to 87.8 and 44.6 to 93.1, respectively, P < .001 for each). The PROMIS PF improved from 38.2 to 46.8 (P = .002) and the PROMIS Pain Interference (PI) from 62.6 to 50.1 (P = .003). Radiographic measures showed an improved anterior-posterior (AP) talo-first metatarsal angle of 24.7 to 11.8 degrees (P < .001) and talonavicular coverage angle of 47.4 to 23.1 degrees (P < .01). An improved Meary's angle of 29.7 to 12.5 degrees (P < .001) and a calcaneal pitch angle of 11.7 to 16.9 degrees (P = .14) were noted in the lateral view. Conclusion: Considering the anatomic characteristics of the deltoid-spring ligament complex, TCNL reconstruction may play a significant role in maintaining peritalar stability when performed with osseous correction. Deltoid-spring ligament (TCNL) reconstruction is a viable surgical option for those with advanced stage AAFD with medial peritalar instability that leads to improved functional and radiographic outcomes.