Primary Endpoint Analysis for a Prospective Multicenter Study Assessing Radiographic Recurrence and Patient Outcomes Following Triplanar Tarsometatarsal Arthrodesis with Early Weightbearing

Abstract

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: The majority of hallux valgus (HV) corrections have been historically performed via a two-dimensional, transverse plane-focused approach, which has demonstrated high long-term recurrence rates. Recent research demonstrates that 87% of HV deformities are three-dimensional with abnormal frontal-plane rotation of the metatarsal, which cannot be completely addressed with a two-dimensional metatarsal osteotomy alone. While correction at the 1st tarsometatarsal (TMT) joint may provide the optimal surgical approach for 3D anatomic restoration at the apex of the deformity, 1st TMT fusion historically entails an extended period of non-weightbearing. This study evaluated the clinical, radiographic, and patient-reported outcomes in patients undergoing instrumented triplanar 1st TMT arthrodesis (TMTA) with a biplanar plating system and protected near- immediate weightbearing. Methods: A prospective multicenter study that will continue for 60 months post-operatively. Patients 14-58 years old with symptomatic HV (intermetatarsal and HV angles between 10-22° and 16-40°, respectively) and no prior HV surgery on the operative foot were eligible for this study. Patients were treated with an instrumented TMTA procedure using a biplanar plating system with protected early weightbearing. The primary endpoint of this study is radiographic recurrence of HV deformity at 24 months for subjects with successful correction (defined as IMA < 9°, HVA < 15° and TSP ≤ 3 at 6 weeks post-procedure). Recurrence is defined by any two of the three conditions: IMA of ≥12°, HVA ≥20° and TSP ≥4. Secondary outcomes (return to weightbearing and activities, pain measured by visual analog scale (VAS), Manchester-Oxford Foot Questionnaire (MOxFQ), and Patient Reported Outcomes Measurement Information System (PROMIS)) were evaluated post-operatively. Two independent fellowship trained musculoskeletal radiologists reviewed all radiographic data. Results: 173 patients underwent TMTA with mean age of 41.0 (range:14-58) years; 92% females. Median (range) time-to-follow-up is 25 (1.5-49.2) months. Eighteen (10.4%) patients have discontinued. Mean (SD) days to protected weightbearing in CAM boot and return to full work were 8.4 (7.4) and 57.9 (46.2), respectively. At 24 months post-procedure, 99.3% (134/135) of patients were recurrence-free. Statistically significant improvements from baseline in HVA, IMA, and TSP (Table 1), VAS score, MOxFQ and PROMIS domains were observed as early as 6 weeks post-operatively and maintained over time. In 143 patients, mean (95% CI) 24-month improvements were VAS: 3.9 (3.5, 4.2); Walking/Standing (MOxFQ): 39.2 (34.9, 43.4); Physical Function (PROMIS): 9.7 (8.3, 11.2). Nineteen (11.0%) patients experienced hardware complications yet maintained radiographic correction. Conclusion: The results of this study’s primary and secondary endpoints provide supporting evidence that TMTA with biplanar plating is successful in correcting the 3D hallux valgus deformity with early return to weightbearing and low recurrence while demonstrating favorable clinical and patient-reported outcomes. Patients exhibited meaningful pain reduction after surgery and were able to return to full, unrestricted work and activities in less than two months, on average. Statistically significant improvements in patients’ health-related quality-of-life were observed through 36 months, post-operatively. Patients will continue to be followed for up to 60 months with additional evaluations for complications, recurrence, and patient satisfaction.