Abstract
Morel-Lavallée lesions (MLLs) are rare closed soft tissue degloving injuries caused by shear forces that separate subcutaneous tissue from the underlying fascia. Chronic MLLs can lead to persistent functional impairment and aesthetic deformities. Standardized treatment approaches are limited, particularly for long-standing lesions without overlying skin necrosis. We report the case of a 42-year-old female patient with a chronic MLL on the left thigh, >2 years after a traffic accident. She experienced discomfort, abnormal soft tissue mobility, and noticeable thigh asymmetry. MRI revealed a persistent subcutaneous cleft without hematoma or seroma. A water jet-assisted lipoaspiration (WAL) procedure was performed to create multiple subcutaneous tunnels, promoting scar formation and tissue adhesion to stabilize the mobile tissue. The postoperative course was uneventful, and the patient reported significant improvement in both function and appearance. Follow-up MRI demonstrated complete obliteration of the subcutaneous cavity. A second WAL procedure was performed because of residual asymmetry, again with favorable results. This case highlights the potential of WAL to induce scar formation and eliminate pathological dead space, restoring soft tissue stability. The patient experienced complete symptom resolution and improved contour symmetry. WAL may serve as a promising minimally invasive treatment for chronic MLLs. It allows functional restoration and satisfactory cosmetic outcomes while avoiding extensive surgical revision. Level of Evidence: 4 (Therapeutic).