Knee Pain - Swimming in Dangerous Waters

Abstract

Title: Knee Pain - Swimming in Dangerous Waters Authors: Lauren Nadkarni, MD and Kate Quinn, DO (sponsored by Heather Gillespie, MD, MPH, FACSM) HISTORY: A 17-year-old male with a non-contributory past medical history developed acute pain in his left knee while swimming 3 days prior to presentation. He experienced a popping sensation with hyperextension of his knee while treading water and throwing a rope swing to his friends on the bank of a river. He had immediate swelling and felt pressure on the lateral and posterior parts of his knee, associated with sharp and stabbing pain when straightening his knee. His pain was worse with flexion beyond 90 degrees, straightening his leg, or walking, but was improved with rest and ice. He did not have any give-way or locking episodes. PHYSICAL EXAM: Office examination of his left knee was limited by guarding but demonstrated a very subtle posterior sag sign and a positive effusion. There were no overlying skin changes. His range of motion was 5 degrees of hyperextension to 110 degrees flexion actively his flexion increased to 120 degrees passively. He also had mild posterior lateral joint line tenderness, negative patellar testing, and positive posterior drawer and lateral flexion pinch testing. His anterior drawer testing was negative, although he did exhibit guarding. His contralateral knee, ipsilateral hip/ankle, and neurovascular exams were unremarkable. DIFFERENTIAL DIAGNOSIS: • PCL injury • ACL injury • Lateral meniscus injury • Posterior lateral corner injury • Patellar subluxation • Lateral tibial plateau contusion or fracture • Lateral femur contusion or fracture TESTS AND RESULTS: Left knee x-ray: • Normal anatomy with small effusion • No acute fracture Left knee MRI: • Isolated PCL rupture FINAL/WORKING DIAGNOSIS: • Isolated PCL rupture TREATMENT AND OUTCOMES: • Knee immobilizer for 3-4 weeks • Physical therapy with initial avoidance of hamstring activation for the first 4 weeks • Over the counter analgesics as needed • Return to sport progression