Clinical study of femoral peel-off lesions in acute posterolateral corner injuries

Objective To determine the incidence of clinically common acute avulsions of the popliteus tendon (PT) and the lateral collateral ligament (LCL) of the femur (peel-off lesion) in knees with multiple injured ligaments.Methods A retrospective review of 48 acute grade 3 posterolateral corner (PLC) knee surgeries was conducted.All office evaluations were reviewed to determine the demographic data,tear description,preoperative MRI examination,physical examination under anesthesia,intraoperative arthroscopic findings and surgical techniques.Results In total,19 patients were surgically verified as having femoral peel-off lesions as a portion of a series of multiple pathologic findings.Tear patterns were typically categorized into 3 patterns:isolated PT tear (pattern 1,4 patients),combined PT and LCL tears (pattern 2,8 patients) and complex tears (associated intrasubstance and/or fibular-based injuries,pattern 3,7 patients).Seventeen of the 19 patients underwent preoperative MRI examination,which demonstrated conclusive signs of femoral insertion separation and discontinuity in 13 patients (76%) and inconclusive signs of femoral insertion separation.Examination under anesthesia (EUA) revealed that for the 4 patients with pattern 1 injuries,the tibial external rotation increases were all greater than 10°.For the 15 patients with pattern 2 and 3 injuries,the yarus instability was as follows:grade 3 in 8 patients,grade 2 in 2,grade 1 in 1,and negative in 4.External rotation increases were greater than 10° in 12 patients and less than 10° in 3.Seventeen of the 19 patients were inspected with an arthroscope prior to PLC surgery:of these patients,94% had acute avulsion findings and positive lateral gutter drive-through sign;8 patients were repaired with recess or reattachment procedures;6 patients were primarily reconstructed;4 patients were treated with combined repair and reconstruction;and 1 patient was left untreated for secondary reconstruction due to priority repair for concurrent patellar tendon rupture.Conclusion For adequate clinical identification,we recommend a comprehensive diagnostic protocol,including MRI,physical examination and arthroscopic inspection,to avoid underdiagnosis of the lesion in multiple-ligament injured knees.The lateral gutter arthroscopic evaluation is particularly sensitive for detecting the lesion. Key words: Arthroscopy; Knee injuries; Ligaments; Treatment outcome