Case Report Isolated Rupture and Repair of the Popliteus Tendon Geoffrey H. Westrich, M.D., Jo A. Hannafin, M.D., Ph.D., and Hollis G. Potter, M.D. Summary: The authors report the case of a 21-year-old woman who sustained a femoral avulsion of the popliteus tendon in a motor vehicle accident. The postero- lateral injury was suspected on physical examination and confirmed by magnetic resonance imaging and arthroscopic examination. The popliteus tendon was re- paired using two suture anchors. Mild clinical instability was present initially and resolved postoperatively. No residual pain, weakness, or posterolateral instability was noted. Key Words: Popliteus tendon-Popliteofibular ligament-Posterolat- era1corner-Magnetic resonance imaging-Arthroscopy-Knee. F ew cases of isolated rupture of the popliteus tendon have been reported in the literature.‘*2 Most com- monly, concomitant injury to the posterolateral liga- mentous complex occurs with acute or chronic lateral, posterior, or posterolateral laxity.‘,3-x In these complex injury patterns, disruption may include the complete arcuate ligament complex, the lateral collateral liga- ment, the anterior cruciate ligament, the posterior cru- ciate ligament, and the medial and lateral menisci. Iso- lated rupture of the popliteus tendon has been reported’%2,s; however, no surgical treatment was of- fered. We present a case of a popliteus tendon avulsion and a partial anterior cruciate ligament injury with sub- tle, but clinically detectable, preoperative posterolat- era1 instability. CASE REPORT The patient is a 21-year-old female college student who was involved in a single vehicle accident after falling asleep while driving. The automobile flipped multiple times, but the patient remained conscious From the Hospital for Special Surgery, New York, New York, U.S.A. Address correspondence and reprint requests to Geoffrey H. Wes- trich, M.D., The Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, U.S.A. 0 1995 by the Arthroscopy Association of North America 0749-8063/95/1105-1252$3.00/O without head trauma. The patient was hospitalized for 1 week with bruised ribs, a lung contusion, and bilat- eral knee pain. The patient had no previous history of knee injury and had been an active recreational athlete. Two weeks after the injury, the patient was exam- ined by the treating orthopaedist (J.H.). Initial exami- nation was significant for an antalgic gait without full extension of the left knee. Range of motion of the left hip was normal, while that of the left knee was 10” to 110”. Patellar tracking was normal. Varus/valgus stress testing was within normal limits at both 0” and 30”. The anterior crnciate ligament revealed mildly increased excursion without a good endpoint (Lachman IB), and the posterior cruciate ligament was stable. The patient had nondiagnostic medial and lateral joint line tender- ness. High-contrast, fat-suppressed magnetic reso- nance imaging (MRI) examination showed bony con- tusion of the mid tibia and anterior femur, as well as intrasubstance signal change within the anterior cruci- ate ligament, interpreted as a tear. The MRI also showed abnormal signal in the lateral collateral liga- ment and avulsion of the femoral insertion of the pop- liteus tendon (Fig 1). Two weeks later, examination under anesthesia demonstrated a full range of motion of the left knee with no instability to varus or valgus stress at 0” or 30” of knee flexion. A mild increase in excursion of the anterior cruciate ligament with a good endpoint (Lachman IA), a negative pivot shift, and mild evi- dence of posterolateral rotatory laxity (10” increase in 628 Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol II, No 5 (October), 1995: pp 628-632