Terminology is important in orthopaedics. When teaching, for instance, we stress the need for trainees to be able to articulate what a radiograph is showing using descriptive terms and classification systems.
Over the years, “multiligamentous knee injury” (MLKI) and “knee dislocation” have increasingly been used interchangeably within the orthopaedic vernacular, in part because of the high energy required to sustain such injuries, but also because of the potentially devastating complications that can be associated with both.
Kahan et al. sought to better characterize these injuries and their associated complications in a study now reported JBJS. They retrospectively evaluated cases treated at their Level-I trauma center between 2001 and 2020.
A total of 123 patients with MLKI were included in the analysis: 45 patients with and 78 patients without a documented knee dislocation. MLKI was defined as disruption of at least 2 of the following: the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. Cruciate ligament injuries and isolated injuries of the superficial medial collateral ligament were not included unless there was disruption of the posteromedial corner, semimembranosus, or medial patellofemoral ligament, indicating a more extensive medial-sided injury.
The investigators found that medial-sided injuries were more common in the dislocation group (53% vs 30%; p = 0.009), and the dislocation group had higher rates of peroneal nerve injury (38% vs 14%; p = 0.004) and vascular injury (18% vs 4%; p = 0.018). Of the 11 total patients with a vascular injury, 8 (73%) were in the dislocation group; 10 of the 11 underwent a vascular surgical procedure.
Not all cases of MLKI are a result of a knee dislocation, and in this adequately powered study, there were differences in the injury pattern and associated injuries between those with and without true dislocation. It is important to note that, although higher rates of neurovascular injury were seen in the dislocation group, such events also occurred in the group without dislocation, so a high index of suspicion must be maintained with these complex injuries. As the authors suggest, it may be better to consider cases of knee dislocation a subset of MLKI with the potential for increased neurovascular compromise.
Matthew R. Schmitz, MD
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