Author: Matthew Waldrop, MD
Affiliation: University of Wisconsin-Madison, Department of Orthopedics and Rehabilitation
Co Author(s): Erin Hammer, MD, MPH
Senior Editor: Nicholas Moore, MD

Clinical Vignette: A 31-year-old female rugby player presented with 17 days of right knee pain following a direct blow to the medial knee while being tackled. She endorsed medial knee pain with associated swelling, as well as numbness and tingling localized to the injury location. She denied prior history of right knee injury. She had a history of left knee complete ACL rupture ten years ago status-post surgical reconstruction. She also had a Morel-Lavallee lesion near her left knee five years ago from a rugby injury that resolved with conservative management. Exam was notable for significant ecchymosis over the medial knee with a large area of fluctuance consistent with a possible fluid pocket, with no warmth or erythema present. She was tender to palpation over the right medial femoral condyle and medial patellar facet. She had no strength or range of motion deficits, no ligamentous laxity, and normal special tests. 170 mL of serous fluid was aspirated with ultrasound-guidance, followed by a corticosteroid injection. The lesion recurred three months after ther initial aspiration (about four months post-injury) and was re-aspirated yielding only 10 mL of serous fluid, followed by another corticosteroid injection. She attempted return-to-sport four months after the second aspiration (about eight months after injury), but the lesion recurred a subsequent time. This time following aspiration of 37 mL of serous fluid, a doxycycline sclerodesis was performed. Unfortunately, the lesion recurred two months later after the sclerodesis, and she ultimately underwent an open surgical resection of the lesion with short-term drain placement about one full year after the initial injury. Her post-operative course was uncomplicated, and she returned to rugby four months after surgery without recurrence of the Morel-Lavallee lesion. Given her history of bilateral Morel-Lavallee lesions, she is undergoing a workup for connective tissue disorders.

Type of Probe Used: 4-12 MHz linear array transducer.