There are a variety of pathologic entities that cause knee pain after total knee arthroplasty (TKA). Posterolateral knee pain, with or without mechanical symptoms such as snapping, is commonly attributed to impingement of the popliteus tendon on the lateral condylar component or an osteophyte in the popliteal sulcus. The diagnosis may be suspected clinically, but ultrasound (US)-guided injection may be requested for confirmation.
Geannette et al. (2018) state in their case study that ultrasound may be effective in the discovery and confirmation of clinically suspected symptomatic osteophyte formation affecting the popliteus tendon after TKA and for guiding anesthetic and steroid injection into the popliteus tendon sheath as a diagnostic and potentially therapeutic treatment.