Knee Injury - Dancer

Abstract

HISTORY: A 20 year old female dance instructor was performing split jump lunges when she developed acute onset of pain and swelling in the medial left knee while loading the leg in the posterior position. She reported feeling a tearing sensation and was unable to immediately weight bear. On presentation to the emergency room was partially weightbearing. Initial left knee radiographs were negative for acute fracture. She was given a soft knee sleeve, started ibuprofen 600mg TID, and initially used ice. She presented to outpatient sports medicine clinic 1 week later with persistent 7/10 pain and swelling in the medial knee. She denied locking or buckling of the knees. PHYSICAL EXAMINATION: Exam revealed mild-to-moderate effusion of the left knee and restricted range of motion due to pain (flexion to 100 degrees, extension to 10 degrees). There was tenderness to palpation over the medial joint line and pain with valgus stress testing. Anterior drawer with bilateral mild laxity but symmetric. McMurray’s was limited by guarding and restricted range of motion. Gait was antalgic with limited knee flexion on the left. Hip abduction strength 4-/5 bilaterally. DIFFERENTIAL DIAGNOSIS: 1. Medial meniscus tear 2. Medial collateral ligament injury 3. Anterior cruciate ligament injury 4. Patellar dislocation/subluxation 5. Osteochondral injury TESTS AND RESULTS: Left Knee X-ray: - No acute osseous findings - Suggestive of lateral patellar tilt and subluxation Left Knee MRI: - Sequela of prior transient lateral patellar dislocation and medial patellar retinaculum rupture - Osseous contusions of the medial patella and lateral femoral condyle - Shallow trochlear groove with minimal lateral patellar subluxation FINAL/WORKING DIAGNOSIS: Acute lateral patellar dislocation and medial patellar retinaculum rupture in setting of trochlear dysplasia TREATMENT AND OUTCOMES: 1. Left knee immobilizer started 1-week post-injury. 2. Isometric quadriceps strengthening exercises started 1-week post-injury. 3. Improved range of motion, swelling, and gait at 1 month follow up. 4. Started in physical therapy for knee range of motion, strengthening and stabilization exercises, hip abduction strengthening, and progression to return to dance/exercise. 5. Discussed orthopedic referral if no further improvement or recurrent dislocation.