The "Diagonal" Lesion: A New Type of Combined Injury Pattern Involving the Impingement Fracture of Anteromedial Tibial Plateau and the Injury of Posterior Cruciate Ligament and Posterolateral Corner.

The purpose of this study was to investigate the incidence and clinical characteristics of the "diagonal" lesion. A total of 273 consecutive patients with combined posterolateral corner (PLC) and posterior cruciate ligament (PCL) injuries were retrospectively analyzed. All preoperative knee joint evaluations were reviewed including the computed tomography, the anteroposterior (AP) view, the lateral view, the full-length long-standing AP view, and the physical examination results with the patient under anesthesia. Twenty-six patients (9.5%) were verified as having the "diagonal" lesions. The anteromedial impingement fractures could be categorized into small (small fracture group, n = 7) and large (large fracture group, n = 19). The PCL injuries were classified into grade 2 (n = 22) and grade 3 (n = 4). The PLC injuries could be classified into type A (n = 3), type B (n = 8), and type C (n = 15) according to the Fanelli's classification system. Notably, there were 20 chronic cases. Among them, 14 (70%) had varus deformities. The proportion of patients with varus deformity in the large fracture group was significantly higher than that of the small fracture group (p = 0.026). In this study, the incidence of the "diagonal" lesions was 9.5%. Patients who had larger fracture size tended to develop subsequent varus deformity of the lower extremity. It was important for us to recognize the PCL/PLC injuries and to fully reduce the large bony fracture during the initial treatment of the "diagonal" lesions to prevent the residual instability and varus deformity. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.