1060 - The Utility of Diagnostic Ultrasound - a Case of Medial Collateral Ligament Calcific Bursitis

Case Diagnosis:
Calcific MCL Bursitis

Case Description:
A 78-year-old female with history of osteoarthritis presented with three weeks of atraumatic left medial knee pain and swelling. She was initially diagnosed with pes anserine bursitis and did not have any relief with oral steroids or topical analgesics. Exam revealed medial joint line and pes anserinus tenderness, limited range of motion to 90 degrees of knee flexion, and a knee effusion. X-ray imaging showed medial joint space narrowing with subchondral sclerosis as well as ossification along the medial aspect of the left knee, possibly consistent with a remote medial collateral ligament (MCL) injury. Diagnostic ultrasound showed a well-circumscribed, hypoechoic, medial knee body with hyperechoic borders and no posterior acoustic shadow. This was located superior to the joint line and deep to the MCL, consistent with calcific MCL bursitis.

Discussions:
The MCL bursa is located within the superficial and deep portions of the MCL. Inflammation of the MCL bursa is quite rare but has been described as a source of knee pain for some patients. Calcific bursitis often arises in the setting of chronic bursitis or tendonitis leading to calcification of the bursa itself. This more frequently occurs in the shoulder, however, can also occur in other locations, such as the MCL bursa. Calcific bursitis is a diagnosis that historically has been made with x-ray or MRI. While x-ray may identify the presence of calcifications, bedside ultrasound can help clarify whether these are post-traumatic ligamentous or post-inflammatory bursal calcifications, as bursal pathology may be amenable to targeted injections.

Conclusions:
This is a case of calcific MCL bursitis diagnosed by ultrasound, showcasing the utility of diagnostic ultrasound in clinical practice.