Comparing Functional Outcomes After Injury-Specific Fixation of Posterior Malleolar Fractures and Equivalent Ligamentous Injuries in Rotational Ankle Fractures

OBJECTIVES: To evaluate the effect of posterior bony versus ligamentous injury pattern on functional outcomes in operatively treated rotational ankle fractures. DESIGN: Retrospective cohort analysis of prospective registry. SETTING: Academic Level I trauma center. PATIENTS/PARTICIPANTS: Operatively treated supination external rotation IV and pronation external rotation IV ankle fractures. INTERVENTION: Lateral malleolus plate fixation with either posterior malleolus (PM) plate fixation or posterior inferior tibiofibular ligament (PITFL) repair. MAIN OUTCOME MEASUREMENTS: Foot and ankle outcome scores at minimum 12 months postoperatively. RESULTS: One hundred seventy-eight fractures were treated with injury-specific anatomic fixation of a PM fracture (n = 122) or torn PITFL (n = 56). The PM group was significantly older, contained more women, and had lower mean body mass index versus the PITFL group. There was a higher rate of medial malleolar fracture in the PM group; other fracture and baseline characteristics were similar between groups. Univariate and multivariable analysis revealed no difference in foot and ankle outcome scores for any of the 5 summary domains (symptoms, pain, activities of daily living, sports, or quality of life) at the time of most recent follow-up. The median length of follow-up was 16.3 and 12.8 months in the PM and PITFL groups, respectively. CONCLUSIONS: In our cohort of ankle fractures, we have demonstrated comparable outcomes in stage IV rotational ankle fractures with and without PM fractures, indicating that the presence of a PM fracture may not result in inferior outcomes compared with ligamentous equivalent injuries if these fractures are addressed in an injury-specific manner. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.