Predictors of Spring Ligament Degeneration and Outcomes of Reconstruction during Correction of Adult Acquired Flatfoot Deformity

CATEGORY: Hindfoot; Midfoot/Forefoot INTRODUCTION/PURPOSE: It is currently unclear how injury to the spring ligament (SL) affects the preoperative presentation of adult acquired flatfoot deformity (AAFD). The purposes of this study were to retrospectively identify shared factors that could be used to preoperatively predict SL damage in patients undergoing AAFD correction as well as compare outcomes of patients undergoing SL reconstruction to those not undergoing reconstruction during AAFD correction. METHODS: All patients undergoing operative correction of grade 2B AAFD secondary to tibialis posterior tendon dysfunction by a single fellowship-trained foot and ankle orthopaedic surgeon from 2011 to 2017 were reviewed. Operative reports were reviewed for the surgeon’s evaluation of the competency of the SL and to determine whether SL reconstruction was performed. Patient charts were reviewed for demographic information, preoperative Visual Analog Scale (VAS) pain level, and their Foot and Ankle Ability Measure (FAAM) Activities of Daily Living (ADL) and -Sports subscales. Preoperative radiographic parameters were assessed by a surgeon blinded to the intraoperative findings. Patient outcomes of VAS pain, FAAM-ADL, and FAAM-Sports were collected at a minimum of 24 months postoperatively. Multiple logistic regression analysis was performed to determine significant independent predictors of spring ligament tears. RESULTS: The study included 115 feet undergoing corrective reconstruction, with 47 feet having a spring ligament tear (40.9%). Patients with tears were significantly older (p<0.001), with higher preoperative reported pain (p=0.01), and lower preoperative FAAM-ADL (p=0.04) and -Sports (p=0.006) scores than those without SL tears. Patients with a SLT demonstrated significant differences in AP talo-1st MT angle (p=.003), talonavicular uncoverage percentage (p<0.001), talonavicular angle (p=0.017), and Meary`s talo-1st MT angle (p=0.001). Based on multiple logistical regression analysis (odds ratio [95% confidence interval]), patient age (1.10 [1.03, 1.18]; p=0.003), talonavicular uncoverage percentage (1.35 [1.13, 1.60]; p<0.001), and talonavicular angle (0.82 [0.71, 0.96]; p=0.0133) were independently predictive of ligament degeneration. Patients undergoing SL reconstruction did not differ significantly in functional score improvements compared to those without reconstruction. CONCLUSION: Our findings suggest that a SLT is associated with more advanced flexible pes planovalgus, measured both by radiographic parameters as well as its impact on patient function. Increasing patient age, increasing talonavicular uncoverage percentage, and decreasing talonavicular angle are all independently associated with increased likelihood of patients with AAFD having a SLT. AAFD correction with concomitant SL reconstruction does not appear to influence absolute or changes in patient pain and function.