VCOM Carolinas Research Day 2023

Clinical Case-Based Reports

Diagnosis and Treatment of Morel-Lavallée Lesion to the Lateral Knee with Point of Care Ultrasonography Kathryn Vess, MA, Jeff Cashman, DO, MS, Jacob Ringenberg, MD, Jordan Freeland, DO Via College of Osteopathic Medicine – Carolinas Campus, Spartanburg, SC

Abstract # CBR-2



MLL diagnosis is difficult due to the lack of distinguishing characteristics on exam. Many are not discovered until operative treatment is performed for other causes and discovered incidentally. Physical exam for injuries from a blunt force trauma, particularly with a shearing force, should look for fluctuant skin, skin hypermobility, ecchymosis, and decreased sensation over the injury. MLL are visible on MRI; however, if determined not to be necessary, then an ultrasound is diagnostic. On ultrasound the lesions can be identified by anechoic or hypoechoic spaces separated by fascial planes and other subcutaneous layers of tissue (fluid accumulation will not be located intra articularly). It is important to treat the lesion rapidly to prevent sequelae including further fluid accumulation, skin necrosis and breakdown, and infection. Lesions smaller than 400 mL of fluid by ultrasound measurements can be treated with compression dressing or percutaneously draining and sclerosing. Dextrose is cost effective, has low likelihood of adverse events, and readily available. Following treatment, continued compressive wrappings and prevention of re-injury are paramount. Recurrence is a common complication that occurs in up to 56% of non surgically treated MLL.

Morel-Lavallee lesions (MLL): collections of fluid that occur between different planes of subcutaneous tissue following blunt force or shearing trauma. Case: 14-year-old male with right lateral knee pain for 3 weeks. Forceful blow to right lateral knee. Physical exam showed a large fluctuance over the lateral right knee, ecchymosis, and decreased sensation. Point of care ultrasound showed a large hypoechoic space over the lateral knee consistent with MLL. Twenty-six milliliters of serosanguinous fluid were aspirated under ultrasound guidance and sclerosed with of 5 mL of 50% dextrose and 5 mL lidocaine 1%. The quick diagnosis and intervention helped prevent complications including pseudocyst formation, skin necrosis, and infection. MLL are uncommon and difficult to diagnose. This case is unique in its presentation of an isolated MLL in the lateral knee. Early diagnosis and intervention prevent further sequelae. History of Present Illness • 14-year-old male with right lateral knee pain and swelling for 3 weeks • Began after taking a blow to the area in a football game • Able to ambulate following injury without unsteadiness • Swelling, pain, and bruising increased over the next few weeks • Pain is worse with repeated trauma, relieved with Tylenol 325 mg q4-6 hours Physical Exam • General: ambulating with antalgic gait. • Skin: R lateral knee with large area of scattered bruising. • Musculoskeletal: R lateral knee with large area of fluctuance, approximately 8 inches by 3 inches. Tender to palpation along fluctuant lesion. Negative anterior and posterior drawer, negative Lachman, negative McMurray. No pain with varus or valgus stress. • Neurological Exam: Decreased sensation overlying lesion. DTR intact. Imaging • XR R knee negative for evidence of bony injury (Figure 1) • Point of Care Ultrasound of R knee showed a large hypoechoic mass in between distinct fascial planes on the lateral aspect of the right knee (Figure 2). Consistent with MLL. Report of Case

Figure 1: Knee XR

AP right knee, b) PA right knee, c) lateral view right knee, d) sunrise view right knee

Figure 2: Knee US

US imaging of the right lateral knee with a large hypoechoic space between subcutaneous layers of tissue.


INTERVENTION 26 mL of serosanguinous fluid aspirated from fascial planes of R lateral knee under ultrasound guidance. Sclerosing therapy with 5 mL of 50% dextrose and 5 mL lidocaine 1% Compressive wrappings Caution with return to play for 1 week Cultured aspirate with no growth at 5 days. Reassessment 1 week later with no evidence of reoccurrence on US or physical exam.

Dr. Melissa Heidari, Ph. D, and Dr. Lindsey Saleski, DO, MBA, for helping review this paper for publication. Acknowledgements


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