Synovial Folds Impingement After Unicondylar Knee Arthroplasty.

Soft tissue impingement after total knee arthroplasty has been reported; however, complications after unicondylar knee arthroplasty (UKA) have rarely been reported. We report a rare case of synovial fold impingement that occurred after UKA and caused severe pain with clicking during knee flexion and extension. Diagnostic arthroscopy was performed 3 weeks after UKA and found that a hypertrophied and congested synovial fold in the medial compartment impinged on the femoral component during knee flexion and extension. After excising the synovial fold, the patient's symptoms improved.  is a complication that should be considered when patients complain of severe pain with clicking in the knee after UKA.