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Lateral Collateral Ligament
Introduction
Research regarding the posterolateral corner (PLC) of the knee has significantly improved our understanding of the anatomy and biomechanics it encompasses, yielding vital information regarding the three major stabilizing structures of the PLC: the fibular (lateral) collateral ligament (FCL), the popliteus tendon (PLT), and the popliteofibular ligament (PFL) (shown in Fig. 18.1 ). This greater understanding has allowed for a substantial advancement in the treatment options available for injury to the PLC, and the subsequent patient outcomes that result. Because of the youth of such treatment protocols, there are a substantial number of complications that can occur during any phase of treatment that may compromise patients’ ability to recover from such injuries.
Complications in treating PLC injuries vary from misdiagnosis during the preoperative stage to intraoperative issues dependent on the selected surgical procedure and postoperative issues in rehabilitation following surgery. Several anatomy, biomechanics, and clinical outcomes studies in the literature have detailed solutions to avoid such complications so that outcomes for these injuries may be improved.
Preoperative Issues
Preoperative issues involving PLC injuries mainly stem from misdiagnosis in which PLC injuries are overlooked and subsequently unaddressed at the time of treatment for differing injuries. PLC injuries most frequently occur in concomitance with anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injuries, with isolated injuries only occurring in 28% of all PLC injuries. Failure of detecting and subsequently treating a PLC injury in conditions of multiligamentous surgical management has been shown to compromise concurrent cruciate ligament reconstruction procedures, resulting in failure of the cruciate ligament reconstruction graft stemming from the failure to restore native biomechanics to the knee. , , Additionally, reports of degenerative changes, persistent instability, and poor functional outcomes commonly occur upon nonoperative treatment of grade III PLC injuries. ,
Diagnosis Failure
To test for the various possible injuries to the PLC, a study by LaPrade et al. found that, based on varus stress radiographs, isolated FCL injuries increased the lateral compartment opening by approximately 2.7 mm, whereas a complete PLC injury (Grade III) led to 4.0 mm of increased gapping, and a combined PLC and ACL injury further increased gapping to 5.3 mm relative to the intact state. If stress radiographs are inconclusive for a diagnosis, MRI further provides a validated means for effectively identifying posterolateral complex knee injuries. , If detection of the PLC is overlooked or clouded by edema/swelling in imaging, associated lesions may suggest referral for a more in-depth recheck of the PLC structures and/or confirmation during an examination under anesthesia.
Association With Bone Bruises
In a study by Geeslin et al., patients with grade III PLC injuries, either isolated or combined, commonly displayed bone bruises of the medial compartment. The most commonly associated bone bruise with isolated PLC injuries was of the anteromedial femoral condyle, and of these patients, one in five additionally displayed an anteromedial tibial plateau fracture. In nearly all of the patients with a multiligamentous injury involving the PLC, ACL, and PCL, posteromedial tibial plateau bone bruises were found, indicating that this bone bruise location has a strong association with PLC injuries involving ACL and PCL, and may provide a supplementary method for detection of PLC injuries.
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