ARTHROSCOPIC EVALUATION OF THE LATERAL COMPARTMENT OF KNEES WITH GRADE-3 POSTEROLATERAL KNEE COMPLEX INJURIES

The purpose of this study was to evaluate prospectively the arthroscop ic findings in the lateral compartment of knees with posterolateral kn ee complex injuries, to help identify individual injured anatomic stru ctures, and to assist in the clinical identification of these injuries . Thirty of 33 consecutive knees noted to have grade 3 posterolateral knee complex injuries on preoperative evaluations and examinations und er anesthesia underwent arthroscopic evaluation concurrently with open reconstruction. The arthroscopic evaluation revealed a significant nu mber of pathologic changes in the lateral compartment that may have go ne undetected if only an open reconstruction had been performed. Tears were identified arthroscopically in 25 (83%) of the anteroinferior, 2 2 (73%) of the posterosuperior, and 14 (47%) of the posteroinferior po pliteomeniscal fascicles. Injuries to the coronary ligament (80%) and meniscotibial portion of the midthird lateral capsular ligament (73%) were also frequently seen. Other structures injured included the menis cofemoral portion of the posterior capsule (37%), the ligament of Wris berg (33%), and the meniscofemoral portion of the midthird lateral cap sular ligament (10%). Ten avulsions (33%) of the popliteal tendon orig in off the femur were also identified. identification of these injured components greatly facilitated open reconstruction of injuries to the posterolateral complex of the knee. All 30 knees were noted to have g reater than 1 cm of lateral joint laxity with application of a varus s tress, When an unexpected amount of lateral joint laxity is seen arthr oscopically (a ''drive-through'' sign) in a patient with suspected lig amentous instability, one should consider a diagnosis of posterolatera l knee complex injury.