Diagnostic ultrasound and ultrasound-guided injections for peri-articular pain after knee replacement

Objective The purpose of this technical report is to review the sonographic spectrum of abnormalities accounting for peri-articular pain after knee replacement surgery, as well as to demonstrate the clinical utility of ultrasound in the diagnosis and treatment of this subset of patients. Materials and methods Utilizing an imaging report database, we performed a search for ultrasound examinations performed by a single radiologist for knee pain after knee arthroplasty at our institution over a 10-year period. The search yielded 63 patients, whom we have categorized by causative pathology, with representative diagnostic and procedural ultrasound images selected for inclusion. Results Our search yielded multiple causes of peri-articular knee pain after arthroplasty, including medial and lateral retinacular impingement and scarring, iliotibial band or conjoined tendon irritation, popliteus tendon impingement, medial collateral ligament impingement, pes anserine bursitis, and scarring of Hoffa’s fat pad. Conclusion While knee arthroplasty is an often-successful procedure, it can be complicated by post-operative peri-articular knee pain. Ultrasound provides a valuable tool for the diagnosis of painful peri-articular knee pathology, as it allows for both static and dynamic evaluation, as well as direct correlation with patient symptoms, and is not confounded by the metal components. In addition to its diagnostic utility, ultrasound can also guide diagnostic and/or therapeutic injections of anesthetic and corticosteroid. Given these advantages, ultrasound is an important tool in managing the painful post-arthroplasty knee.