Posterolateral plating increases peroneal tendon thickness without affecting clinical outcomes: a ultrasonographic comparative study of 76 SER ankle fractures

To evaluate, using ultrasonography and the AOFAS (The American Orthopaedic Foot and Ankle Society) score, changes in the peroneal tendons of patients with ankle fractures resulting from a supination-external rotation (SER) mechanism treated with either lateral or posterolateral plate fixation. This retrospective observational study was conducted at a tertiary level III trauma center. Adult patients (> 18 years) with unilateral SER ankle fractures, a minimum follow-up of 1 year, no persistent symptoms, and fixation using a 1/3 tubular 3.5-mm locking plate (lateral or posterolateral) were included. Exclusion criteria comprised bilateral injuries, Weber A/C fractures, pathological fractures, previous ankle disorders, infection, postoperative pain, or functional limitations. The primary outcomes were peroneal tendon thickness on ultrasonography and functional performance assessed using the AOFAS Ankle-Hindfoot Scale. Outcomes were compared between fixation techniques. Seventy-six patients were included (65.8% aged 35–64 years, 60.5% women, 53.9% left-sided injuries). In most cases (71.1%), tendon thickness was greater on the operated side. Posterolateral plating demonstrated a higher frequency of positive tendon-thickness differences. Most differences measured 0–2 mm (56.6%), with a statistically significant difference between lateral and posterolateral fixation groups (p < 0.001). AOFAS scores were high in both groups, indicating satisfactory postoperative functional outcomes. A difference in peroneal tendon thickness between the operated and contralateral sides was observed in 89.5% of patients, and these differences were significantly greater after posterolateral plating. Although plate position directly influenced postoperative tendon thickness, no clinically relevant consequences were identified. Level III.