A rare cause of post-traumatic low back pain: Lumbar Morel-Lavallée lesion in a collegiate athlete — A case report

Morel-Lavallée lesions (MLLs) are closed traumatic degloving injuries caused by separation of the subcutaneous tissue from the underlying fascia. Although most commonly described around the greater trochanter and pelvis, lumbar MLLs are rare and may be overlooked in patients presenting with post-traumatic low back pain. We report a 23-year-old collegiate rugby player who developed severe axial low back pain after being lifted and driven onto his back during a game. Initial computed tomography demonstrated no fracture or traumatic malalignment. Persistent severe pain and focal fluctuant swelling over the lumbar spine prompted magnetic resonance imaging five days after injury, which demonstrated a superficial fluid collection between the dorsal subcutaneous fat and lumbar fascia at L4, consistent with an MLL. The patient was referred for consideration of ultrasound-guided aspiration and treated with continuous compression. Interval ultrasound demonstrated only a minimal residual collection without drainable fluid, and aspiration was deferred. His symptoms progressively improved and completely resolved within four weeks. This case highlights lumbar MLL as an uncommon cause of severe post-traumatic low back pain despite reassuring osseous imaging. Early recognition and appropriate soft-tissue imaging can guide management, help avoid unnecessary invasive treatment, and allow selected small acute lesions to resolve successfully with conservative care.