If varus, valgus, or axial forces are applied while knee hyperextending, anteromedial, anterolateral, or anterior bicondylar depression will occur, respectively. The typical manifestation found on X-rays is a reversed posterior slope. According to the “diagonal injury mechanism” [
20] (similar to our “push-pull mechanism”), such fractures are more likely to combine injuries of the posterolateral complex and/or posteromedial ligaments, even with fibular head fractures, ligamentous avulsion fractures, and posterior metaphyseal cortical tension rupture. More severely, popliteal artery may be injured (contusion or rupture), but it can be easily misdiagnosed because it is often hard to tell it from compartment syndrome. And peripheral blood supply, such as arteria dorsalis pedis and posterior tibial artery, is sometimes unreliable due to collateral circulation. For that matter, arteriography should be conducted even with slightly suspicion of artery injury. Conesa et al. [
21] reported a case of anteromedial tibial plateau fracture associated with posterolateral complex injury diagnosed by MRI, and the lateral collateral ligament as well as biceps tendon was repaired and supplemented with a peroneal tendon allograft which emphasizes the importance of MRI and repair of posterior structural damage. Unfortunately, many patients in our study did not have MRI checked preoperatively mainly due to overbooking and the absence of MRI machine in the emergency room. And of course, lack of experience and knowledge is also a possible reason for incomplete preoperative diagnosis. Gonzalez et al. [
22] compared HEBTP (hyperextension bicondylar tibial plateau fracture) patients (15 cases) with non-HEBTP patients (69 cases) and found that HEBTP patients have higher Short Musculoskeletal Function Assessments (SMFA) and pain scores, indicating worsen functional outcomes and a tendency of having associated soft tissue damage and developing posttraumatic osteoarthritis. Since hypertension tibial plateau fractures remain a huge clinical challenge for orthopedic surgeons and no consensus has been reached on the treatment of these fractures, more evidence-based clinical trials are needed in the future. Therefore, in our department, we tend to use spanning external fixators as early stage management due to the difficulties of dealing severe overdepressed fragments using internal fixation techniques.
Our research does have certain limitations. First, our study is retrospective so the injury mechanism is based on our analysis of fracture morphological characteristics and clinical experiences over hundreds of tibial plateau fractures. But we do have noticed that many patients cannot recall the exact injury mechanism or even have a false memory due to coma, anxiety, etc. So medical history collecting or telephone follow-ups may be unreliable. Secondly, comprehensive follow-up results are needed to better distinguish each pattern from the aspect of postoperative functional prognosis. Thirdly, not all of our patients had MRI checked before surgery so there may be some missed diagnosis of undisplaced fractures or ligament lesions, which means we probably have underestimated or misdiagnosed some severe injuries. Therefore, comprehensive follow-ups and further clinical trials need to be conducted to improve our classification system.