Comparison of routine computed tomography and plain X-ray imaging for malleolar fractures—How much do we miss?

•Previous ankle fracture is a risk factor for early ankle osteoarthrosis.•X-ray evaluation alone of malleolar fractures does not give a full insight into all posttraumatic pathologies.•Overlooked and not addressed pathologies might be one of the reasons for early osteoarthrosis in ankle fracture patients.•A routine CT scan completes a full diagnosis within malleolar fractures, and treatment of those might prevent OA. Most patients with ankle arthrosis have a history of ankle fracture. Evaluation of malleolar fractures solely on X-ray may be insufficient to identify many pathologies that potentially contribute to ankle arthrosis, with a consequent poor prognosis. We investigated the pathologies that may be overlooked in malleolar fractures evaluated solely on plain X-ray. During 2012–2019, 65,479 patients attended our Emergency Department, of which 6508 complained of an ankle joint problem. X-rays indicated a fracture in 454 of these patients. Patients with isolated, simple fracture of the lateral or medial malleolus, or talus, or a history of surgery to this area were excluded; finally, 67 patients were enrolled (31 males, 36 females; mean age: 51,2 years (range: 9–83 years). Patients underwent X-ray imaging of both ankles in anterio-posterior, lateral, and Mortise views, as well as CT scans. Three independent observers with varied experience in diagnostic imaging (orthopaedic resident, experienced orthopaedic surgeon, and musculoskeletal radiologist) evaluated X-ray images blinded to CT scans. Their diagnoses were subsequently compared with CT findings. Modeling results indicated that about 40% [95% CI: 32%, 50%] of pathologies may be overlooked based on X-ray evaluation, regardless of evaluator experience. The most frequently overlooked injuries were: Tillaux fracture, Pillon fracture, loose bodies and syndesmosis injury. All of that missed pathologies required dedicated treatment and could be easily missed with standard surgical approach. Evaluation of malleolar fractures by X-ray only inevitably results in overlooking of many pathologies, despite the clinician’s experience. Routine CT scan can help to improve the accuracy of diagnosis, and thereby reduce the risk of ankle osteoarthrosis.