Background: Previous studies indicate that isolated posterior cruciate ligament injuries demonstrate magnetic resonance imaging (MRI) and clinical evidence of healing when treated nonoperatively; however, the authors are unaware of any other study that has looked at whether initial MRI can predict posterior cruciate ligament stability at the time of surgery in patients with knee dislocation.
Hypothesis: An MRI grading system will predict laxity on posterior drawer testing at the time of surgery in patients with knee dislocations.
Study Design: Cohort study (prognosis); Level of evidence, 2.
Methods: Forty-two consecutive patients with knee dislocation or multiple-ligament knee injury evaluated by MRI were included in the study. An assignment of grade 0 (intact), grade I (injured/fibers intact), grade II (partial tearing of ligament), or grade III (complete tear) was made after each reading on 2 separate occasions by 3 surgeons. Posterior laxity of the knee was graded by the magnitude of excursion on the posterior drawer test by the senior author at the time of surgery. Interobserver and intraobserver reliability of the MRI grading scheme expressed by the kappa statistic , as well as the predictive value of MRI grade in determining stability of the posterior cruciate ligament at the time of surgery, was assessed.
Results: The posterior cruciate ligament injury grading scheme tested demonstrated moderate to substantial intraobserver agreement ( = 0.66, = 0.53, and = 0.52, respectively, for all raters). Interobserver reliability demonstrated only moderate agreement ( = 0.49). If the grading scheme was changed to group both grades 0 and I (intact) and grades II and III (disrupted), intraobserver reliability demonstrated substantial to almost perfect agreement ( = 0.83, = 0.80, and = 0.75), and interobserver reliability demonstrated substantial agreement ( = 0.70). If the posterior cruciate ligament was classified as intact (grade 0 [intact] or grade I [injured]) on initial MRI, the injured knee was judged clinically stable (tibia anterior to or flush with the femoral condyles on posterior drawer testing) at the time of surgery 98.5% (95% confidence interval, 93%-100%) of the time. When the posterior cruciate ligament was classified as disrupted (grade II [partial tear] or grade III [complete tear]), the injured knee was judged unstable (tibia posterior to the femoral condyles on posterior drawer testing) 57.5% (95% confidence interval, 40%-73%) of the time.
Conclusion: The presented system of grading posterior cruciate ligament injury in patients with knee dislocation on initial MRI demonstrates moderate to substantial interobserver and intraobserver reliability that increases if the grading scheme is modified. An initial MRI scan read as grade I may predict stability to posterior drawer at the time of surgery. Even with MRI evidence of disruption in the posterior cruciate ligament (grade II and grade III injuries), posterior cruciate ligament reconstruction may not be clinically indicated at the time of reconstruction and/or repair of other associated injuries.
Background: Bone bruises on magnetic resonance imaging (MRI) are common in patients with acute knee ligament injuries and have been well described for injuries involving the anterior and posterior cruciate ligaments and the medial collateral ligament. These have not yet been described in detail for posterolateral corner injuries.
Hypothesis: Acute grade III posterolateral corner (PLC) injuries are often accompanied by bone bruises located in the medial compartment.
Study Design: Case series; Level of evidence, 4.
Methods: One hundred two patients with acute grade III PLC knee injuries and MRI scans within 6 weeks of injury were prospectively identified. Images were reviewed for the location of bone bruises, which were defined as areas with high signal intensity adjacent to the joint surface on fat-suppressed, T2-weighted sequences.
Results: Overall, 83 patients had at least 1 bone bruise and 56 patients had a bone bruise of the anteromedial femoral condyle. Tibial plateau fractures were found in 19 knees, with 12 in the anteromedial quadrant. Isolated PLC injuries were found in 28 patients; of this group, 18 had at least 1 bone bruise with 17 located in the anteromedial femoral condyle. Seventy-four patients sustained a combined ligamentous injury; 65 of these had at least 1 bone bruise on MRI and 39 had a bone bruise on the anteromedial femoral condyle. In patients with a combined injury to the PLC and anterior cruciate ligament (38), anteromedial femoral condyle bruises were seen in 19 patients and posteromedial tibial plateau bruises in 11.
Conclusion: Medial compartment bone bruises, most commonly of the anteromedial femoral condyle, were frequently found in patients with both acute isolated and combined PLC injuries. Thus, the presence of an anteromedial femoral condyle bone bruise should increase the level of suspicion of a concurrent PLC knee injury. In addition, we believe that the presence of a posteromedial tibial plateau bone bruise may be a secondary sign of a potential combined PLC injury in the setting of anterior cruciate ligament tear.
Background: The cause of osteochondritis dissecans (OCD) is unknown, but mechanical factors seem to play a role.
Purpose: To identify a relationship between localization of OCD and mechanical axis of the leg.
Study Design: Case series; Level of evidence, 4.
Methods: Using bilateral full-leg standing radiographs, we analyzed the position of the mechanical axis of the leg in a group of 93 adolescent and adult patients (103 knees) with OCD of the medial or lateral femoral condyle.
Results: The location of OCD and the position of the mechanical axis in the same knee compartment was significantly correlated for both knees with medial (P < .001) as well as lateral (P < .012) compartment OCD. In the medial OCD group, the mean mechanical axis was located in the medial knee compartment (28% medial ± 2.8%; range, 100% medial to 14% lateral) with a statistically insignificant medial shift with respect to the unaffected side. In lateral OCD, the mean mechanical axis was located laterally (13% lateral ± 3.9%; range, 13% medial to 60% lateral) with a significant shift from the medial into the lateral knee compartment when comparing unaffected with affected knees. No significant difference was observed between adolescents with open growth plates compared with adults with closed growth plates (P > .05).
Conclusion: We found an association between medial condyle OCD and varus axis and between lateral condyle OCD and valgus axis. This evokes higher loading of the affected than of the unaffected knee compartment, and therefore, axial alignment may be a cofactor in OCD of the femoral condyles.
