Multi-ligamentous knee injuries primarily occur during high-velocity traumas, such as skiing or car accidents. The knee often dislocates, damaging multiple ligaments and, potentially, local neurovascular structures. The knee may reduce in the field or require surgery to be put back into place. The early emphasis of care is a complete and thorough evaluation by a multi-disciplinary team at the receiving hospital.
A thorough work-up begins at the trauma center with examination and extensive imaging to assess for vascular, nerve, bony and soft tissue injuries. When the patient is deemed stable, a more thorough ligamentous exam is conducted when it is safe and reasonable to do so.
Lachman Test: this clinical test is used to evaluate the integrity of the ACL. With the knee bent to 30 degrees of flexion, the femur is stabilized while the examiner applies an anterior directed force to the tibia. If the knee is ACL-deficient, the tibia will move forward in relation to the femur excessively.
Varus and Valgus Stress Test: this clinical test is used to evaluate the integrity of the lateral collateral ligament (LCL) and medial collateral ligament (MCL), respectively. The knee is held in 20 degrees of flexion and loaded in varus or valgus distally such that the LCL or MCL is placed on stretch. The examiner assesses the amount of opening/gapping at the lateral (varus) and medial (valgus) joint space. The test is repeated with the knee in full extension.
Pivot Shift Test: This clinical test is used to evaluate for an ACL rupture. It may be difficult to perform in clinic due to pain/muscular guarding; however, it may be performed in the operating room under anesthesia. With the patient lying on their back, the affected knee is fully extended with the tibia internally rotated. The examiner then applies a coupled valgus and internal rotation force while flexing the knee. An appreciable “clunk” is felt at approximately 30 degrees of knee flexion if the ACL is torn.
Posterior Drawer Test: This clinical test is used to assess the integrity of the PCL. With the knee flexed to 90 degrees and the foot stabilized, the tibia is translated back posteriorly. The tibia will translate posteriorly in relation to the femur in the setting of a PCL tear.
Dial Test: this clinical test is used to assess the integrity of the PLC, as well as to assess for a possible combined PCL tear. The patient begins in prone, and both knees are flexed to 30 degrees. The examiner cups the patient’s heels and places an external rotation force. The foot-thigh angle is measured and compared side-to-side. The knees are then flexed to 90 degrees and the test is repeated. An isolated PLC injury is consistent with > 10 degrees of external rotation in the injured knee at 30 degrees only. If there is more than 10 degrees of external rotation in the injured knee at 30 and 90 degrees, this finding is consistent with a combined PLC and PCL injury.
Once all trauma imaging has been complete and the patient is deemed stable, stress x-rays are performed to quantify the side to side differences in ligament laxity. These images are often performed after the initial hospital stay. Further, standard x-rays assess for an avulsion fracture of the fibula and for degenerative changes, while long leg standing x-rays evaluate alignment. MRI assesses both the integrity of the involved ligaments and tendons, as well as the articular cartilage.
Non-operative care includes rest, short-term immobilization, and physical therapy are often prescribed in the early setting. In some cases, early external fixation is performed to protect a concomitant vascular injury and/or vascular repair. Surgical indications are determined on an individual basis, and often involve a multi-disciplinary team. Rehabilitation begins immediately to reduce swelling, encourage quadriceps recruitment and to restore range of motion.