Dynamic Ultrasound Assessment for Diagnosis of Pseudo-Patellar Clunk Syndrome: A Case Report.

Patellar clunk syndrome (PCS) is a complication of total knee arthroplasty (TKA) leading to audible and palpable clunking of the patellofemoral joint as the knee is extended out of deep flexion. While historically a clinical diagnosis, some cases require further workup and imaging. Here, we demonstrated the utility of dynamic ultrasound assessment for a patient with clunking after TKA and identified a variant of PCS that is not well described in the literature. Therefore, this case provides considerations for the workup of post-TKA knee clunking while illustrating unique findings that may contribute to a more challenging diagnosis.