The "lateral gutter drive-through" sign: an arthroscopic indicator of acute femoral avulsion of the popliteus tendon in knee joints.

Acute avulsions of the popliteus tendon and the lateral collateral ligament of the femur (peel-off lesion) are common and can both be missed during preoperative assessment and later overlooked during surgery if not specifically sought out. Arthroscopic observation of the direct avulsion sign of the torn end of the popliteus tendon occurs less frequently in patients with acute and subacute injuries. This study describes an arthroscopic sign that detects these tears when they either involve only the popliteal tendon or include the lateral collateral ligament assessed from the lateral gutter of the joint. The "lateral gutter drive-through," visualized during diagnostic arthroscopy, is described as entering of the arthroscope into the posterolateral compartment through the interval between the popliteal tendon and the lateral femoral condyle. A positive sign indicates (1) the presence of femoral avulsion tears of the popliteal tendon or concomitant lateral collateral ligament, (2) the presence of repairable posterolateral corner tears, and (3) the enablement of mini-open surgery for the repair of these avulsion tears with a recess or reattachment procedure. In addition, arthroscopic evaluation of the lateral compartment and preoperative magnetic resonance imaging assessment are used to eliminate the multiple-level injuries of the popliteus tendon and lateral collateral ligament.