Ligamentous injuries of the knee.docx

Introduction Acute knee ligament injuries: common in sports & RTA. Knee stability depends on joint capsule, intra- & extra- articular ligaments & muscles rather than on bony structures. Knee ligaments are: ACL PCL MCL LCL Popliteal ligaments Meniscofemoral ligament Transverse ligament...

Introduction Acute knee ligament injuries: common in sports & RTA. Knee stability depends on joint capsule, intra- & extra- articular ligaments & muscles rather than on bony structures. Knee ligaments are: ACL PCL MCL LCL Popliteal ligaments Meniscofemoral ligament Transverse ligament Mechanism of injury The resulting injury depends on the type of the force applied to the knee as follow: Valgus force → MCL tear. Valgus + rotation→ MCL+ ACL tear. Valgus + rotation + weight bearing→ MCL + ACL + medial meniscus tear. Varus force→ LCL tear. Varus + rotation→ LCL + ACL tear. Dashboard injury → PCL tear. Clinical features History of twisting injury→ immediate painful doughy swelling (hemarthrosis), while in meniscus injury the swelling is late & fluctuant (synovial effusion). Look for a site of maximum tenderness, bruises & abrasion. Tests for ligament tear: Partial tear is painful with no abnormal movement, if in doubt→ stress view. Complete tear → painless abnormal movement. If the knee opens with valgus or varus stress in 30° flexion → only collateral tear. If open in extension→ capsule + collateral + cruciate tear. Anteroposterior stability: posterior sag → PCL tear. anterior drawer test→ ACL. Lachman test→ ACL. ACL injuries are common and acutely present with large hemarthrosis and pain; the Lachman test (anterior drawer at 20 degrees of flexion) is the most valid test for diagnosing ACL tears. Aspiration of hemarthrosis and injection of lidocaine may assist in diagnosis painfully swollen knee injuries. Anterior drawer test: With the knee in 90 flexion, the foot is anchored by the examiner sitting on it then, using both hands, the upper end of the tibia is grasped firmly and rocked backwards and forwards to see if there is any anteroposterior glide. Posterior sag sign: Place the patient supine, hip at 45 degrees, and knee at 90 degrees. View the knee from the lateral position. Posterior translation of the tibia in relation to the femur indicates a PCL injury. Imaging X -ray: may show an avulsion fracture e.g., ACL may avulse tibial spine. MRI: To differentiate partial from complete tear. Arthroscopy: is not indicated in acute complete tear. Treatment Partial tear: aspirate hemarthrosis→ with 6 weeks functional brace or crepe bandage with early exercise. Complete tear: MCL or LCL tear: 6 weeks cast-brace → then exercise. ACL or PCL tear: 6 weeks cast-brace→ then exercise; later if instability persists → ligament reconstruction. Combined collateral + ACL or PCL: 6 weeks cast-brace → then exercise→ later reconstruction. Avulsion injuries should be surgically treated earlier rather than later.