(Kiosk 2) An Uncommon Cause of Chronic Knee Pain and Swelling After a Traumatic Patellar Fracture: A Case Report

Case Diagnosis: A 64-year-old female was found to have chronic prepatellar bursitis with retained blood products from a prior fall onto her knee with associated patellar fracture.

Case Description or Program Description: We present a patient with complaints of chronic right knee pain after a fall 6 months prior. At the time of injury, she was found to have a patellar fracture identified on x-ray. Following the initial injury endorsed persistent pain and periodic swelling which was worse towards the end of the day. She noted pain and swelling were exacerbated by increased activity, especially walking.

Setting: The patient was evaluated in an academic outpatient clinic.

Assessment/Results: On exam, the patient was found to have prepatellar swelling with tenderness to palpation on the anterior patella. Repeat x-ray and subsequent CT scan without contrast of right knee were obtained with no signs of fracture, arthritic changes, or effusion identified. MRI was unable to be obtained due to non-MRI compatible cochlear implant.

Diagnostic ultrasound was performed with the identification of chronic prepatellar bursitis with a homogenous isoechoic, well-circumscribed structure within the bursal space, thought to be a consolidation of blood products from prior trauma. Patient pending steroid injection of prepatellar bursa for evaluation of improvement of symptoms

Discussion (relevance): Hemorrhagic prepatellar bursitis can occur following trauma to the knee. This case represents an abnormal presentation of consolidation of blood products within the prepatellar bursa following trauma leading to pain. It additionally illustrates the limitations of X-ray and CT imaging in the correct diagnosis. Ultrasound can be used to better evaluate knee effusions for more accurate and quick diagnosis and care.

Conclusions: When evaluating effusions and chronic pain of the knee ultrasound should be considered for accurate diagnosis. In the setting of trauma to the knee, hemorrhagic prepatellar bursitis must be on the differential as this can be a rare consequence.