1054 - Acute knee swelling in a tennis player

Thursday, February 22, 2024

5:00 PM – 6:30 PM EDT

Presenting Author(s)

NG

Nadejda Godoroja, BS

Medical Student
California Northstate University College of Medicine
Sacramento, California, United States

Co-Author(s)

BM

Bahaar Kaur Muhar, MS

Medical Student
California Northstate University College of Medicine
San Jose, California, United States

Co-Author(s)

AM

Anton Matveev, MD, MBS, RMSK

attending physician
Center for Sports and Regenerative Orthopedics
Alexandria, Virginia, United States

Case Diagnosis: Tophaceous gout of the patellar tendon

Case Description: A 47-year-old man presented with left anterior knee pain, stiffness, and swelling for 2 weeks. He described it as throbbing, rated at 8/10. He is a tennis player but denies any sport-related injury episode. Examination revealed a left knee effusion with tenderness at joint lines, worst at the distal patellar tendon insertion. Knee flexion was limited to 30 degrees. Gait was antalgic with limited weight-bearing on the left. Ultrasound of the left anterior knee revealed suprapatellar recess effusion with saddle-bagging and a double contour sign at the distal femoral cartilage. There was tophaceous gout at the distal patellar tendon with Power Doppler signal. Ultrasound-guided knee aspiration yielded 50 mL of synovial straw-colored fluid. Patient was started on colchicine and allopurinol. A referral to rheumatologist was provided. At follow-up, the patient’s pain was 1/10, gait normalized, and he returned to playing tennis.

Discussions: Acute-onset knee pain and swelling is common in middle-age athletes. The differential commonly includes traumatic or overuse injuries. Both an intra-articular and patellar tendon related pathology was suspected in our patient. Less commonly, gout may affect the tendons around the knee, along with the joint. The popliteus and patellar tendons are the most commonly involved at the knee. Ultrasound examination of the knee was critical in making a diagnosis due to characteristic appearance of tophi within the patellar tendon and double contour sign of the femoral cartilage. There are some key features to distinguish tophaceous gout from calcifications commonly seen in chronic patellar tendinosis. Urate deposits are more spherical, numerous, and less likely to cast an acoustic shadow. They are commonly associated with tendon swelling, hypoechogenicity, and interposed fluid between the deposits.

Conclusions: A broad differential, sound clinical suspicion, and distinctive sonographic features were crucial in our patient diagnosis.