Tests to assess ACL rupture
With the patient lying in the supine position, flex the knee 20° to 30° while the heel rests on the end of the exam table. Grasp the femur with the nondominant hand to prevent movement of the upper leg. Then, grasp the lower leg at the proximal tibia and apply a forward tug. This movement should produce a firm endpoint. If the endpoint is not firm or there is increased anterior translation of the tibia, the Lachman test is positive.
Anterior Drawer Test
With the patient lying the supine position, place the knee in 90° of flexion without rotation. Place both hands on the proximal tibia, and pull the upper part of the calf forward. An anterior drawer test is positive when the tibia moves anteriorly without an abrupt, hard endpoint.
Pivot Shift Test
hen the lower leg is stabilized in near full extension. With increasing flexion, a palpable springlike reduction should be observed. A positive pivot shift test usually produces a thud or jerk around 10° to 20° of flexion. During a positive exam, the force created by the examiner will cause the knee joint to slip, giving a positive visual for identifying rotational knee instability.
Conducting a thorough clinical examination, along with MRI, provides the most accurate noninvasive source of information for pathological findings of the ACL. The physical exam consists of inspection, palpation, and assessment of knee-joint function. Three functionality tests should be performed to determine the stability of the joint and ACL. These tests evaluate joint integrity and any degree of separation by applying stress in certain directions and assessing the endpoints. Intact ligaments produce an abrupt, firm end-feel, whereas sprained or torn ligaments have soft, indistinct endpoints