Medium to Long-Term Results of Non-anatomic Spring Ligament Reconstruction Using an Allograft Tendon in Progressive Collapsing Foot Deformity with Severe Abduction Deformity

Abstract

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Spring ligament reconstruction (SLR) has been proposed as an adjunct to other reconstructive procedures to potentially avoid talonavicular joint fusion in progressive collapsing foot deformity (PCFD) with severe abduction deformity. However, most clinical reports present short-term follow-up data and include only a small number of patients. Recent cadaveric studies have demonstrated that the spring ligament maintains medial tibiotalar stability by forming a large confluent (tibiospring) ligament with the superficial deltoid ligament. Therefore, the purpose of this study was to investigate the medium to long-term results of our nonanatomic tibiospring ligament complex reconstruction using allograft tendon, as an adjunct to other reconstructive procedures in PCFD with severe abduction deformity. This study to our knowledge represents the largest number of patients and the longest follow-up to date. Methods: This study retrospectively reviewed prospectively collected data of 26 patients (27 feet, mean age of 61.4 years) who underwent SLR with allograft tendon as part of PCFD reconstruction. The mean follow-up of the cohort was 8 years (range, 5- 13.4). The SLR was performed when bony correction with lateral column lengthening (LCL) achieved at least 50% of abduction correction but failed to provide adequate abduction correction under intraoperative fluoroscopy. The tendon graft was positioned from the inferior navicular to the medial malleolus via bone tunnels and screw posts (Figure 1). Radiographic evaluation consisted of five parameters including talonavicular coverage angle (TNC), with the maintenance of correction being evaluated by comparing parameters from the early postoperative period (mean: 11.6 months, range, 8-17) to final follow-up. Foot and Ankle Outcome Score (FAOS) and patient satisfaction questionnaires were collected at final follow-up. Conversion to talonavicular or subtalar fusion was considered as a failure. Results: Final radiographs demonstrated successful abduction correction, with the mean TNC improving from 43.7 degrees preoperatively to 14.1 degrees postoperatively (P < .0001). All other radiographic parameters improved significantly and exhibited maintenance of the correction (Table 1). All FAOS subscales showed significant improvement. Responses to the satisfaction questionnaire were received from all except one patient, of whom 88.5% (23/26) were satisfied with the results, 96.2% (25/26) would undergo the surgery again, and 88.5% (23/26) would recommend the surgery. Eight feet (29.6%) required painful hardware removal and one (3.7%) developed non-union of the LCL osteotomy. No patient required conversion to talonavicular or subtalar fusion. Conclusion: This study demonstrates favorable medium- to long-term outcomes, as well as maintenance of the correction, following a nonanatomic tibiospring ligament complex reconstruction using allograft tendon augmentation in addition to other corrective procedures for the surgical treatment of PCFD with severe abduction deformity. As there is growing evidence of the potential for excessive foot stiffness following LCL, a remaining question is whether it is reasonable to use SLR to reduce the amount of LCL needed, as long as the bony procedure achieves at least 50% of the required abduction correction, as described in the current study.