Patellar Clunk Syndrome Following Posterior Stabilized Total Knee Replacement: Report of Two Cases

Patellar clunk syndrome (PCS) occasionally occurs after posterior stabilized total knee replacement (PS-TKR), and is characterized by a painful palpable audible clunk of the patella when the knee moves from flexion to extension. It has been classically attributed to the formation of fibrous nodule at the junction of the proximal pole of the patella and the undersurface of the distal quadriceps tendon. However, various intra-articular peripatellar proliferative fibrous formations have also been reported with a wide spectrum of symptoms, ranging from crepitation to frank patellar clunk. Treatment of the syndrome remains essentially surgical, and usually consists of resection of the fibrous nodules. This paper reports two cases of PCS and aims at bringing attention to this entity in terms of pathogenesis, clinical diagnosis, and treatment, through a review of the literature.