There are few literature reports on anteromedial tibial plateau fracture with PLC injury, especially those with concomitant PCL injury. In 1981, Moore  was apparently the first to find that anteromedial tibial plateau fractures may lead to posterolateral instability of the knee. In 2001, Chiba et al.  reported 12 patients with compression fractures of the anteromedial tibial plateau combined with PLC injuries. In 7 of these patients, the fractures and the PLC injuries were combined with PCL injuries. The authors of this study concluded that small compression fractures (less than 25% of the anteroposterior length of the medial tibial plateau) strongly suggested concomitant PCL injury. In 2003, Bennet et al.  again proposed that there may be a correlation between tibial plateau fracture and PLC injury, as they found anterior medial tibial plateau fractures in 6 of 16 MRI images of knees with PLC injuries. In 2009, Yoo et al.  reported a case of compression fracture of the medial tibial plateau and medial femoral condyle with the injuries to PCL and PLC. Regrettably, the therapeutic schedule was not described in this report. Two subsequent studies reported 4 cases of the anteromedial tibial plateau fractures with PLC injuries and described positive effects of reduction and internal fixation of tibial plateau fracture combined with PLC reconstruction in single-stage surgery [15, 16]. However, arthroscopic techniques were not used in these cases. In 2021, Sundararajan et al.  reported single-stage surgery for these injuries with ARIF of a tibial rim fracture with PLC repair and PCL reconstruction, but the efficacy of the patient’s postoperative recovery was not described.
Up to now, the injury mechanism of this combined injury has been described as follows: under the action of forces of hyperextension and varus rotation, the medial femoral condyle and the anteromedial tibial plateau collide with each other, resulting in the fracture of the latter [7, 8, 14,15,16]. Simultaneously, the PLC is injured and the posterolateral joint space is widened. If the PCL is ruptured in this possess, the tibia will suffer a posterior translation, and the range of impact on the tibial plateau will become smaller, which means that the corresponding size of fragments may be reduced [7, 16]. However, this injury mechanism does not account for every case. In some literatures and in our cases, there have been large tibial plateau fractures, that are more than 25% of anteroposterior length of the medial tibial plateau, co-occurred with PCL and PLC injuries [7, 17]. This atypical presentation may be related to the intensity of the trauma. Moreover, when the knee joint is subjected to a large rotational stress, the position of contact between the femoral condyle and the tibial plateau may be more medial, resulting in a larger contact area in the anterior and posterior diameter of the tibia thus and a larger fragment.
Noteworthy, it has been reported that the rate of clinical missed diagnosis of the “diagonal” lesion can reach 78.6% (11 /14). Such an error can ultimately lead to knee instability and severe varus deformity of the lower extremity . Consequently, for this combined injury, it is important to avoid missed diagnosis or misdiagnosis in the initial examinations of the patients. The PLC and PCL injuries should be suspected when the anteromedial tibial plateau fracture is found on X-ray, especially when combined with avulsion fractures of the fibula head (“arcuate sign”) . The injury mechanism must be clarified when recording the patient’s medical history. Furthermore, we should be vigilant against posterolateral skin ecchymosis of the knee, because this ecchymosis was found in many of our cases (7/9). In physical examination, we should pay great attention to the signs of PCL and PLC injuries, such as the dial test, the varus stress test, the posterior drawer test and the Lachman test. When it is difficult to complete the above physical examination due to patient pain or swelling, physical examination is performed under anesthesia. Finally, the importance of the role of MRI in the diagnosis has been repeatedly mentioned [8, 15, 16]. MRI images of the knee joint are effective tools for the identification of PLC injury and other intra-articular injuries, such as PCL injury and meniscus injury.
The treatment of tibial plateau fractures in concomitant ligamentous injuries has been little considered so far. Previous studies have suggested that posterolateral tibial plateau fractures in the setting of an ACL rupture indicated the damage of the lateral meniscus and other structures of the knee , and were associated with decreased postoperative outcomes after ACL reconstruction . However, the management of the bony concomitant injuries in ligamentous damage is still unclear, especially anteromedial tibial plateau fracture with PLC injury. For the treatment options, almost all clinicians choose to complete the repair or reconstruction of all injured structures in a single-stage treatment [15,16,17]. There has also been a study that proposed the reduction and internal fixation of tibial plateau fracture and PLC repair in one-stage surgery, and PCL reconstruction was completed in two-stage surgery . In our opinion, it is necessary to complete the repair and reconstruction of all structures in single-stage surgery. Owing to the functional outcomes upon surgical treatment of PLC injury in the acute phase were better than those in the later phase . In addition, the simultaneous PCL and PLC injuries will seriously exacerbate the posterolateral instability of the knee joint. Isolated PCL reconstruction would not restore the normal stability of the knee joint, and the PCL reconstruction graft will be at a higher risk of failure . The failure of PCL reconstruction is often related to the ineffective treatment of PLC injury . Therefore, we recommend the single-stage surgery for PCL and PLC injuries. If all primary PLC structures are injured, an anatomic PLC reconstruction is the preferred technique . Fanelli et al.  described 3 types of PLC injuries: A, B and C. In this classification scheme, type C PLC injuries mean the injuries to all the primary PLC structures. In accordance with this principle, we performed the anatomical PLC reconstruction in type C PLC injuries, type B PLC injuries combined with LCL laxity, and irreducible avulsion fractures of the fibular head. In addition, we used the anatomical PLC reconstruction that includes fibular and tibial double tunnels. And the partial iliotibial bundle was transposed into the tibial tunnel, reducing the use of a free tendon and shortening the operation time. At the same time, anteromedial tibial plateau fractures should also be treated with reduction and internal fixation, because a recent study has demonstrated that the failure of initial surgery in patients with the “diagonal” lesion is not only due to missed diagnosis of PLC injury, but also due to incomplete reduction of the tibial plateau fracture . Compared with open reduction internal fixation, the ARIF technique has been proven to lead to faster postoperative recovery and better clinical outcomes in the treatment of tibial fractures . Moreover, the severe knee injuries are at higher risk of infection, and the ARIF technique can reduce the rates of surgical site infections . Therefore, we finally chose ARIF technique to treat anteromedial tibial plateau fracture.
The advantage of the arthroscopic-assisted technique in the treatment of the combined injury is that it can detect and deal with intra-articular injuries, including the injuries to the PCL, meniscus, cartilage, and joint capsule. Furthermore, it makes it possible to deal with all injured structures in single-stage surgery, and the tibial plateau fracture can be reduced under direct visualization. However, for inexperienced surgeons, this technique may prolong the operation time. There are some limitations in this study. The small sample size is the main limitation of this study. It has to be emphasized that this combined injury is a relatively rare disease. In addition, a control group of other surgical techniques is missing. Multicenter clinical studies and studies with larger cohorts are needed in the future to confirm the effectiveness of this surgical technique.
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