tendon, and popliteofibular ligament Studies have reported that these structures work together to stabilize the knee by restraining varus, external rotation and combined posterior translation with external rotation to it. Bones The bones that make up the knee are the femur, patella, tibia, and fibula. In the posterolateral corner, the bony landmarks of the tibia, fibula and femur serve as the attachment sites of the ligaments and tendons that stabilize this portion of the knee. The patella plays no significant role in the posterolateral corner. The bony shape of the posterolateral knee, with the two convex opposing surfaces of the lateral femoral condyle and the lateral tibial plateau, makes this portion of the knee inherently unstable compared to the medial aspect. Thus, it has a much higher risk of not healing properly after injury than the medial aspect of the knee. Ligaments The fibular collateral ligament (FCL) connects the femur to the fibula. It attaches on the femur just proximal and posterior to the femoral lateral epicondyle and extends approximately 70 mm down the knee to attach to the fibular head. From 0° to 30° of knee flexion, the FCL is the main structure preventing varus opening of the knee joint. The popliteofibular ligament (PFL) connects the popliteus muscle at the musculotendinous junction to the posterior and medial portion of the fibular styloid. It has two divisions, anterior and posterior, and acts to stabilize the knee during external rotation. The mid-third lateral capsular ligament is made of a part of the lateral capsule as it thickens and extends along the femur, attaching just anterior to the popliteus attachment at the lateral epicondyle, and extends distally to the tibia attaching slightly posterior to Gerdy's tubercle and anterior to the popliteal hiatus. In addition, it has a capsular attachment at the lateral meniscus. It has two divisions, the meniscofemoral component and the meniscotibial component named for the areas they span, respectively. Studies suggest that the mid-third capsular ligament functions as a secondary varus stabilizer in the knee. Tendons and muscles The long and short heads of the biceps femoris each branch off into 5 attachment arms as they course distally in the knee. In the posterolateral corner, the long head has 3 important anatomic attachments. The direct arm attachment is on the posterolateral fibular styloid, the anterior arm lateral to the FCL and the lateral aponeurotic arm on the posterior and lateral