Importance of Medial Ligament Complex Tears Associated with Posterior Cruciate Ligament Avulsion Fractures

Posterior cruciate ligament avulsion fractures (PCLAFs) are infrequent injuries. Their management often presents challenges due to the potential for associated damage to surrounding soft-tissue structures within the knee. I could not find a systematic review of the literature specifically addressing the association between PCLAFs and medial ligament complex injuries. In the current study, Wang et al. utilized combined computed tomography (CT) and magnetic resonance imaging (MRI) to determine the incidence of Grade-III medial collateral ligament (MCL) injuries (involving both the superficial and the deep MCL ligament) associated with PCLAFs, which they called an “underrecognized” condition. The authors, who included 2 radiologists experienced in musculoskeletal imaging, conducted a well-designed retrospective study of 148 patients with PCLAF. They developed a standardized method to quantify the size of the PCL fracture fragment and assess associated injuries. The authors commented that clinicians may initially have difficulty diagnosing injuries to the medial ligament complex due to significant swelling or the patient guarding due to pain, which prevent proper evaluation. MCL tears were present in 28.4% of the cases studied, and posterior horn tears of the medial meniscus (MM) were associated with 66.7% of the MCL tears. On the basis of these findings, the authors concluded that one should suspect MCL injury when the anteroposterior diameter of the PCL avulsion fracture measures ≥50.2% of the tibial plateau anteroposterior diameter on combined CT and MRI studies. The objective of the study was to draw more attention to the associated soft-tissue injuries that occur with PCLAF, with the authors noting that previous studies have given more attention to posterior lateral ligament tears and limited attention to MCL and MM tears1. For example, the study by Noyes and Barber-Westin1 stated that, in combined injuries, posterolateral tears are usually associated with PCL tears. Also, they found that the most common probable causes of failure of PCL reconstruction surgery were associated with posterior lateral ligament deficiency. Injuries to the MCL were not mentioned as a major factor in PCL surgical failure. Despite the well-documented study by Wang et al., the reader is left without information on how significant the MCL and posterior horn MM tears were in the final clinical results of management of PCLAF because, as the authors acknowledge, they presented no clinical information concerning the patients’ preoperative or postoperative condition. However, the findings reveal that a substantial number of Grade-III MCL injuries and posterior MM tears occur with larger avulsion fragments, alerting the clinician to be aware of the medial complex injuries. The authors describe the MCL complex but do not present data concerning the incidence of posterior oblique ligament (POL) tears, which they acknowledge as a limitation of their study. The POL is an important structure that needs to be evaluated and repaired to obtain the best PCL reconstruction results, according to a cadaver study performed by Weimann et al.2. In that study, after sectioning of the PCL and medial complex structures, reconstruction of only the PCL could not prevent posterior tibial translation (PTT). However, additional reconstruction of the POL improved PTT at all flexion angles in comparison with reconstruction of the PCL only. Reconstruction of the MCL had no significant effect on PTT. Another concern about the current paper is that the authors rationalize the use of a supplementary CT scan by pointing out that MRI is not routinely available in the emergency department setting. However, it is still a question whether a CT scan should be used to obtain this information on fragment size since, as the authors acknowledge, it involves substantial radiation exposure and thus should not be performed unless necessary to obtain information on the fracture pattern for reconstruction. The authors questioned whether MCL injuries should be treated nonoperatively or operatively because the proper treatment of associated injuries of the MCL remains unclear. In 2025, a systematic review of the literature was published3. It was prompted by previous studies lacking comprehensive recommendations regarding the treatment of MCL and posterior MM tears when combined with PCL tears3. This review summarized the consensus of 90 worldwide experts, experienced clinicians in orthopaedics and sports medicine, who provided their opinions of PCL injuries after reviewing a literature search of PubMed, Cochrane Library, Embase, and Web of Science for articles up to October 17, 2024. The experts’ conclusions bring clarity to the issue of operative versus nonoperative treatment of associated injuries of the MCL as well as other associated soft tissue injuries. They concluded that only Grade-III MCL complex injuries require surgical correction when combined with PCL injuries, and that the main goal is to stabilize the medial side of the knee from varus/valgus laxity. Noyes and Barber-Westin proposed an algorithm for the management of acute PCL injuries with combined injury consisting of early repair of a Grade-III MCL, posterior medial corner, or meniscal tear1. In conclusion, the study by Wang et al. adds significant information to the literature concerning the diagnosis of PCLAF injuries. Their findings provide useful information for determining the severity of MCL injuries when the results of a clinical examination are questionable. Clinicians will now know that when the size of the posterior cruciate avulsion fracture is ≥50.2% of the anteroposterior diameter of the tibial plateau, there is a likelihood of MCL injury as well as a posterior horn MM tear.