Does Deltoid Ligament Repair Reduce Complications and Improve Functional Outcomes Measured by PROMIS Scores Following Ankle Fracture Surgery?

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: The deltoid ligament provides crucial stability and support to the ankle joint, especially against valgus stress. 20-58% of ankle fractures occur with concomitant deltoid ruptures. The role of deltoid repair (DR) in ankle fracture surgery remains controversial, as mixed data exist on to what extent DR improves patient-reported outcomes and reduces complication rates. This study aims to determine whether DR reduces complications and improves outcomes measured by Patient Reported Outcomes Measurement Information System (PROMIS) computerized adaptive tests (CATs) of physical function (PF) and pain interference (PI). We hypothesized that DR would reduce complications and improve PROMIS scores. Methods: This was a retrospective study of 782 patients at a single institution who underwent ankle fracture surgery between January 2016-December 2021. Two fellowship-trained foot and ankle orthopaedic surgeons independently reviewed all radiographs and assessed reduction quality and complications at final follow-up. Multiple extremity injuries, open fractures, and pilon variants were excluded. Deltoid ligament rupture was radiographically identified by injury films, defined as a ≥2mm difference between the superior clear space and the medial clear space, or stress positive with same criteria. 345 patients with deltoid ruptures were sent PROMIS CATs. 265 patients with minimum one-year follow-up were analyzed for complications. 112 patients who completed CATs were analyzed for PROMIS. A subgroup analysis with only the 83/112 isolated fibular fractures was also conducted. Wilcoxon rank-sum test compared PROMIS between groups. Linear regression modeled DR effect on PROMIS adjusted for relevant covariates and propensity scores. Results: 50/265 (18.9%) underwent DR. Radiographic complication incidence among 215 patients (81.1%) without repair (DNR) was 14.42%: 7 (3.26%) degenerative joint disease, 3 (1.40%) ankle joint malreduction, 4 (1.86%) syndesmotic malreduction, and 8 (3.72%) malleolar malunion. DR had no radiographic complications. Among patients who completed CATs (n=112), DR (n=21) had non-significantly higher mean PF (54.31±9.83 vs. 52.79±10.42, P=.71) and non-significantly lower mean PI (47.21±7.82 vs. 48.53±8.37, P=.59). Adjusted regression models estimated 1.89-point increase in PF and 1.67 decrease in PI for DR vs. DNR. When adjusted for propensity scores, DR had PF 2.17 higher and PI 1.73 lower vs. DNR. Among isolated fibular fractures, DR had PF 2.28 higher and PI 1.04 lower and PF 2.32 higher and PI 0.96 lower when adjusting for propensity scores. Conclusion: DR reduces complications, notably syndesmotic malreduction and degenerative joint disease, following ankle fracture surgery regardless of fracture subtype, likely due to improved ankle joint stability and alignment. While this study was underpowered to detect small effect sizes in PROMIS, modest improvements in functional outcomes suggest DR may improve patient-reported outcomes. Future studies with larger samples are ultimately needed to determine definitively whether repair improves outcomes as measured by PROMIS.