Optimal Surgical Strategies for Posterior Malleolar Ankle Fractures: A Morphology-Based Approach

Background Surgical fixation of posterior malleolar fractures (PMFs) has traditionally been guided by fragment size. Recent studies have proposed fragment morphology as a more effective determinant for optimal fixation. To determine the optimal strategy for PMFs, we conducted a radiographic review of our patients. Methods Between January 2016 and December 2019, all adult patients with ankle fractures who underwent surgical fixation at our institution were reviewed (n=648). The exclusion criteria included pilon fractures, tumors, or infections causing neuromuscular dysfunction, insufficient follow-up, bilateral involvement, and prior injuries. After applying these criteria, 110 eligible patients remained for the study. They were further categorized on the basis of treatment type (non-fixation, screw, and plating) and fracture classification system (Haraguchi, Lauge-Hansen, and Weber classifications). The fracture fragment involvement was further classified as large (>25% of the articular surface) or small (<25%). The outcomes were evaluated via the modified Kellgren-Lawrence grade and the final malleolar step-off to assess osteoarthritis severity and fixation stability. Results Compared to non-fixation treatment, surgical intervention was associated with better outcomes in the Haraguchi type 1, supination-external rotation (SER), and pronation-external rotation (PER) groups. Additionally, surgical fixation using plates resulted in a lower step-off rate compared to screws. Notably, patients with small-fragment fractures who underwent surgical fixation exhibited outcomes comparable to or more favorable than those with larger fragments. These findings suggest that fracture morphology with size may have greater prognostic significance than fragment size alone. Conclusion This study on PMFs highlights that fracture morphology, rather than fragment size alone, should guide surgical decision-making for PMFs. Different PMF patterns call for personalized surgical strategies. Compared with screw fixation and non-fixation treatment, plate fixation yields superior outcomes, particularly in terms of joint space narrowing and stability. This study advocates for a morphology-based approach to managing PMFs, prioritizing plate fixation to achieve better results.