Plain Radiograph Alignment Features Associated With Medial Malleolar Stress Fractures in Athletes: A Matched Case-Control Study.

Background: Medial malleolar stress fractures (MMSFs) are difficult to detect early because of subtle or absent findings on plain radiographs, which often delays diagnosis and return to play. Identifying measurable radiographic alignment patterns may assist in raising early clinical suspicion, particularly in settings where advanced imaging such as computed tomography (CT) or magnetic resonance imaging (MRI) is not readily available.This study aimed to investigate the radiographic features of MMSFs in athletes by comparing specific ankle alignment angles on plain radiographs. Methods: A retrospective observational study was conducted. Athletes diagnosed with MMSFs were matched 1:1 with control athletes based on age, sex, and the laterality of the affected ankle. Radiographic measurements included the tibial anterior surface (TAS), tibial medial malleolus (TMM), tibial bimalleolar (TBM), and tibial lateral surface (TLS) angles. Results: The MMSFs group included 23 athletes (19 men, 4 women), and the control group included 23 athletes (20 men, 3 women). The TAS angle was significantly smaller in the MMSF group compared with controls (86.3 ± 2.1 degrees vs 89.3 ± 1.6 degrees, P < .01). Receiver operating characteristic curve analysis yielded an area under the curve of 0.86 (95% CI 0.75-0.96), with an optimal TAS angle cutoff value of 87.8 degrees showing 73.9% sensitivity and 91.7% specificity. No significant differences were observed for the TMM (P = .09), TBM (P = .14), or TLS angle (P = .84). Conclusion: These findings suggest that smaller TAS angles may be a radiographic feature associated with increased susceptibility to MMSFs in athletes and could support clinical suspicion during early evaluation. Level of Evidence: Level III, case-control study.