LIGAMENT INJURIES
Anterior cruciate ligament The anterior cruciate ligament (ACL) is a primary stabilizer of the knee. Approximately 60% of knee ligament injuries include the ACL, and occurs nine times more in women than men (Cimino, 2010). The most commonly reported mechanism of injury is twisting of the body with a planted foot, producing an audible “pop.” It may occur with or without deceleration of the body in motion and produces a sudden onset of pain and instability of the knee. Tears of the ACL are frequently accompanied by medial collateral ligament (MCL) tears and meniscus tears in an injury referred to as “the unhappy triad” (Cimino et al., 2010). Diagnosis of ACL tears include subjective history of mechanism of injury as described above. Objective examination includes performance of Lachman’s test, which holds a sensitivity value of 60% to 100%, (mean 84%; Decary, 2017). Other objective tests specific to the ACL are the anterior drawer test (mean sensitivity 62%), and pivot- shift test (mean sensitivity also 62%; Makhmalbaf, 2013). The use of MRI is the gold standard in identifying ACL tears, with 95% specificity as confirmed by an arthroscopic procedure. After identification of an ACL tear, initial management often includes immediate referral to physical therapy to address inflammation and of motion impairments. The decision must then be made by the patient and physician to manage the injury conservatively (often with physical therapy alone), or to surgically reconstruct the ACL. The decision to reconstruct the ACL is most often made when the patient anticipates continuing physical activities in which rapid acceleration and deceleration are required. Surgery may also be recommended for patients who experience recurrent episodes of the injured knee giving way, as well as patients with impaired collateral ligaments or meniscus damage. Postoperative rehabilitation will vary by surgeon. Many protocols require the patient to begin physical therapy within 3 to 5 days of surgery. The patient often presents with significant amounts of pain, with a brace and crutches with weight-bearing status orders created by the physician and enforced by the physical therapist. Early achievement of terminal knee extension is critical. Perhaps the most debilitating complication of ACL reconstruction is arthrofibrosis with knee flexion contracture due to lack of early and consistent knee extension stretching. Low load, long-duration stretching and patella mobilization is recommended to achieve early knee terminal extension. Muscular activation of the knee extensors is also important. This may be achieved by using neuromuscular electric stimulation (NMES), or electromyographic (EMG) biofeedback. Systematic review of the literature favors the use of NMES for patients post-ACL reconstruction, with improved muscle scores by approximately 6 weeks post-op (Kim et al., 2010). Interestingly, the ACL graft is most often at its weakest at 6 weeks post-op. Special considerations and patient education should be made at that time to prevent graft rupture. Patients should be gradually progressed through the physician-determined rehabilitation protocol, with dynamic activities introduced generally around 6 months post-op. For athletes, a return to sport training often takes 1 year. Posterior cruciate ligament The posterior cruciate ligament (PCL) serves as stabilizing ligament to prevent excessive posterior translation of the tibia on the femur. Complete tear of this ligament is far less common than in the ACL, constituting 3.5% to 20% of knee ligament tear injuries (Peterson, 2017). The reported mechanism of injury is often falling on a flexed
knee or a motor vehicle accident in which the knee struck the dashboard. The posterior drawer test assesses the intact nature of the PCL. Posterior translation during the test indicates impairment to the PCL. Many athletes return to sports with a PCL-deficient knee and isolated PCL reconstruction is rare. Physical therapy treatment for PCL tears depends on primary treatment. Conservative care generally calls for immediate physical therapy, whereas post-op care is dictated by the operating surgeon. The immediate goal for non-operative PCL tears is to reduce pain and inflammation and restore range of motion, similar to ACL rehabilitation. Early progression of weight bearing and quadriceps strengthening is pertinent to ensure stability of the tibia on The MCL is the prime static stabilizer of the medial side of the knee joint, and is important for providing support against valgus stress, rotational forces, and anterior translational forces on the tibia (Andrews, 2017). The medial collateral ligament is also the most injured ligament of the knee. Injury is generally sustained in the athletic population as a result of valgus contact with or without tibial external rotation. The capacity of the medial collateral ligament to heal has been demonstrated, however it is noted that complete ruptures heal less consistently and may result in persistent instability of the knee joint (Logan, 2016). Signs and symptoms of MCL injury include a history of the above-described mechanism of injury, coupled with a positive valgus test with the knee tested in 30° of flexion to isolate the MCL. Additionally, reported knee joint line pain and pain with resisted knee flexion suggest an MCL tear. Following a valgus test with the knee flexed to 30°, the test should be repeated in 0° of flexion (full extension). An increase in medial joint space during this valgus test indicates additional posterior oblique ligament injury, and possible PCL or ACL involvement (Logan, 2016). Standard radiograph films may be ordered when there is high suspicion of an MCL tear due to the possibility of bony avulsion with tearing, as the presence of these or osteochondral fragment will significantly change the treatment plan. Furthermore, medial tibial plateau fractures can result from valgus force to the knee, and can imitate medial joint instability on physical exams. Stress views may help rule out physeal damage in skeletally immature patients. the femur (Peterson, 2017). Medial collateral ligament Tears of the MCL are classified into three grades. Grades I and II are partial tears and most often medically managed conservatively with physical therapy, and most athletic patients with MCL tears across all grades can return to their pre-injury performance level without surgical intervention (Andrews, 2017). However, if the MCL is compromised in combination with other ligaments in the knee, especially the ACL, then surgical intervention may be warranted (Logan 2016). The emphasis for rehabilitation of Grades I and II tears is protecting the knee from excessive valgus forces and loading. Early rehabilitation and ROM exercises with progressive strength training is advised (Andrews, 2017). Graded exposure to balance and proprioceptive activities is also pertinent. Grade III rupture of the MCL ligament in isolation can be treated either conservatively or surgically. Rehabilitation will depend on the course of treatment taken, and will include promotion of range of motion, lower-extremity progressive resistive strengthening, proprioceptive training, and
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