Case Study
Lateral-hip pain in footballers is usually blamed on bursitis a contusion injury, yet an apparently innocuous diving save can generate the shearing forces that create a Morel-Lavallée lesion, a closed de-gloving injury that is easily overlooked in the pitch-side setting.
Clinical History
The athlete is a 19-year-old semi-professional goalkeeper. He has no significant medical history and takes no medication.
During a wet-turf evening training session he dived low to his left to block a shot. His left greater trochanter struck the ground first and his hip slid roughly two metres, subjecting the lateral soft tissues to a tangential shear force. He felt a brief sting, finished training, and awoke the next morning with only dull ache (VAS 2/10).
On day 5 he awoke to a palpable, fluctuant mass at the bruise site and experienced sharp discomfort when lying on his left side. He was able to jog and cycle with slight discomfort and presented to clinic on day 5 following this injury.
Physical Examination
Gait: Normal cadence and stride length; no antalgic pattern.
Visual Inspection: Dome-shaped, fluctuant swelling measuring approximately 9 × 5 cm over the left greater trochanter, surrounded by purple-to-yellow ecchymosis; no muscle atrophy elsewhere.
Skin Mobility: Overlying skin glides freely over the deep fascia, demonstrating marked hyper-motility.
Range of Motion / Functional Tasks: Full, pain-free hip flexion, extension. Discomfort limiting abduction, adduction, and internal-external rotation on both sides. Trunk rotation only elicits a mild “stretching” sensation in the region of the swelling. Side-lying on the left hip is not tolerated within seconds because of focal pressure on the lesion.
Palpation Findings: Compressible, non-pulsatile, pocket with a tender superior rim; surrounding tissues non-tender.
Neurological Exam: Diminished light-touch sensation in the anterolateral thigh consistent with lateral femoral cutaneous nerve. Motor power and distal pulses are normal, and Slump test is negative.
Imaging and Investigations
Point-of-care ultrasound (POCUS)
In clinic ultrasound revealed an anechoic collection between subcutaneous fat and the fascia lata. The lesion is compressible under gentle probe pressure, and colour Doppler showed no internal flow
Patel M, Morel-Lavallée lesion. Case study, Radiopaedia.org (Accessed on 18 May 2025) https://doi.org/10.53347/rID-43138
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MRI
MRI demonstrated A left upper anterolateral thigh thick-walled lentiform STIR bright collection between superficial and deep fascia, with thin hypointense pseudocapsule, no solid nodules or marrow change
ElBeialy M, Morel-Lavallée lesion. Case study, Radiopaedia.org (Accessed on 18 May 2025) https://doi.org/10.53347/rID-23743
Reproduced under Creative Commons Attribution-Noncommercial-NoDerivs 3.0 License
Differential Diagnosis
Greater-Trochanteric Bursitis
Greater-trochanteric bursitis usually develops insidiously rather than acutely after blunt trauma. Patients often describe lateral-hip pain that worsens when lying on the affected side at night. Swelling, if present, is modest and sits deep to the gluteus medius tendon. Ultrasound typically shows a thin-walled, anechoic or mildly hypoechoic fluid distension of the bursa with trace vascularity on Doppler.
In our goalkeeper the swelling lay superficial to fascia lata, the overlying skin was hyper-mobile, and POCUS demonstrated a compressible mass many times larger than the bursa’s normal dimensions. These features, combined with the history of a shearing dive rather than cumulative friction, favoured a Morel-Lavallée lesion over bursitis.
Intramuscular or Expanding Haematoma
Direct blows or anticoagulation can produce intramuscular haematomas. Such lesions reside within muscle bellies and feel firm rather than fluctuant. MRI typically shows heterogeneous signal intensity with a peripheral low-signal haemosiderin rim that thickens over time. Chronic expanding haematomas may display a “mosaic” internal pattern of blood degradation products.
Our athlete’s MRI localised the fluid between the subcutaneous tissue and fascia, not within the gluteal or vastus musculature, and ultrasound confirmed complete compressibility, not in keeping with an intramuscular haematoma.
Fat Necrosis / Post-Traumatic Pseudolipoma
Fat necrosis presents months after blunt trauma as a firm, often painless nodule. Imaging reveals T1-hyperintense fat signal with or without a thin fibrous capsule, but there is little or no free fluid. These lesions are non-compressible and do not fluctuate under pressure.
Because our patient presented within a week of injury with a fluid-filled, compressible swelling and no internal fat signal on MRI, fat necrosis was considered unlikely. Early timing, fluid composition and rapid change in size all pointed instead toward a haemolymphatic collection characteristic of an acute Morel-Lavallée lesion.
Sarcoma
Soft-tissue sarcomas, including myxoid or necrotic variants, can mimic cystic lesions. They usually enlarge gradually and may remain painless until late. MRI often demonstrates solid nodular components, irregular enhancing septa, and internal vascularity on contrast studies or Doppler ultrasound.
In this case Doppler showed no vascular flow within the lesion, and MRI lacked any solid or enhancing tissue. The clear traumatic onset, rapid appearance of fluid, and responsive collapse on probe pressure also argued strongly against malignancy. Nonetheless, persistent masses with atypical imaging would warrant referral for biopsy, and clinicians should maintain vigilance.
Abscess / Cellulitis
An abscess presents with systemic signs such as fever, elevated inflammatory markers and local erythema. Ultrasound exhibits complex echogenic fluid with septations and marked peripheral hyperaemia, whereas cellulitis manifests as “cobblestoning” of subcutaneous fat and diffuse hypervascularity.
Our athlete remained afebrile, and the overlying skin retained broadly normal temperature and colour. Ultrasound revealed simple anechoic fluid without septations or vascular rim, effectively excluding infection and supporting a sterile post-traumatic seroma.
Anatomy of the Lateral Hip
A Morel-Lavallée lesion (MLL) is a closed de-gloving injury in which the skin-subcutaneous complex shears off the deep fascia, creating a dead-space that fills with blood, lymph and liquefied fat. Untreated, the acute seroma can progress to an organised or encapsulated haematoma.
The skin‐fat envelope over the lateral hip is separated from the deep fascia (fascia lata) by sub-cutaneous tissue. Sparse fibrous septa loosely tether this envelope to the fascia, making it susceptible to shear. Immediately deep to the fascia lie the iliotibial tract, tensor fasciae latae, and the gluteus medius/minimus tendons, all firmly anchored to the greater trochanter. Numerous vertically oriented perforating vessels and lymphatics traverse the fascia; when a tangential force peels the hypodermis away, these perforators tear and a potential space fills rapidly with haemolymphatic fluid.
Skalski M, Morel-Lavallée lesion (illustration). Case study, Radiopaedia.org (Accessed on 18 May 2025) https://doi.org/10.53347/rID-22762
Reproduced under Creative Commons Attribution-Noncommercial-NoDerivs 3.0 License
This anatomy explains the clinical paradox: side-lying pressure is exquisitely painful, yet active hip range is often full because the joint capsule and contractile tissues remain intact. Management principles mirror the anatomy. Evacuating the fluid obliterates the space; sustained compression forces the skin and fascia back into contact, encouraging re-adhesion of their opposing surfaces.
Management & Rehabilitation
Under ultrasound guidance 38 ml of serosanguinous fluid were aspirated from the pocket. The area was immediately wrapped in cohesive bandage and over-laid with a neoprene hip-protector short for 72 continuous hours.
From day 4 the bandage was exchanged for a discreet graduated-compression short, which the athlete wore for a further ten days while awake. Partial weight-bearing on two crutches was maintained for 48 hours. This regimen aimed to collapse the dead-space and minimise early re-accumulation.
Once local tenderness subsided, pain-free isometric hip abduction and adduction began and were advanced to concentric loading as tolerated. Stationary cycling at low resistance preserved cardiovascular fitness without imparting shear forces.
A follow-up scan on day 7 confirmed a dry potential space; eccentric hip-dominant drills were therefore introduced that afternoon and progressed to dynamic exercises at the start of week 2.
In week 3 the athlete completed a functional assessment and returned to play. A routine surveillance ultrasound in week 5 confirmed permanent cavity obliteration and was designed to capture the small proportion of late recurrences.
Why we chose aspiration
The collection volume measured less than 50 ml, and MRI confirmed the absence of a fibrous capsule. Evidence indicates that acute lesions under this threshold respond well to aspiration plus tight compression, achieving faster resolution and lower recurrence than early sclerodesis, particularly in young athletes whose fascial layers can still re-adhere rapidly.
Injury Recurrence
The greatest likelihood of re-accumulation occurs in the first two weeks. In the Mayo Clinic series of 87 lesions, aspiration volumes > 50 ml recurred in 83 % of cases, compared with 33 % when ≤ 50 ml was removed.1 A recent review places published recurrence rates between 0 % and 75 %, underscoring how lesion size, early capsule formation and compression adherence drive outcomes. 2 A smaller second peak can appear around week 5 as athletes re-introduce shear and impact; hence the scheduled surveillance scan at that point. Re-fills detected at week 5 usually resolve with a second aspiration and renewed compression, but persistent pockets may benefit from doxycycline sclerodesis, which limits recurrence. 3
Complication watch-list
Red-flags demanding escalation are rapid expansion of the mass, development of overlying cellulitis or erythema, and any new sensorimotor deficit.
Key Learning Points
- Consider a Morel-Lavallée lesion when a fluctuant mass emerges days after blunt shear injury to an osseous prominence.
- POCUS-guided aspiration with compression is first-line for acute lesions under 50 ml and without a capsule.
- Compression adherence, load progression and early detection of recurrence or infection are key to recovery
References
- Nickerson TP, Zielinski MD, Jenkins DH, Schiller HJ. The Mayo Clinic experience with Morel-Lavallée lesions: establishment of a practice-management guideline. Journal of Trauma and Acute Care Surgery. 2014;76(2):493-497. doi:10.1097/TA.0000000000000111
- Yang Y, Tang TT. The Morel-Lavallée lesion: review and update on diagnosis and management. Orthopaedic Surgery. 2023;15:2485-2491. doi:10.1111/os.13826.
- Bansal A, Bhatia N, Singh A, Singh AK. Doxycycline sclerodesis as a treatment option for persistent Morel-Lavallée lesions. Injury. 2013;44(1):66-69. doi:10.1016/j.injury.2011.11.024.
