{"id":10091,"date":"2022-05-08T06:00:22","date_gmt":"2022-05-08T05:00:22","guid":{"rendered":"https:\/\/blogs.bmj.com\/bjsm\/?p=10091"},"modified":"2022-05-09T07:25:31","modified_gmt":"2022-05-09T06:25:31","slug":"morel-lavallee-lesions-diagnosis-and-practical-management-of-these-troublesome-injuries","status":"publish","type":"post","link":"https:\/\/blogs.bmj.com\/bjsm\/2022\/05\/08\/morel-lavallee-lesions-diagnosis-and-practical-management-of-these-troublesome-injuries\/","title":{"rendered":"Morel-Lavallee Lesions – Diagnosis and practical management of these troublesome injuries!"},"content":{"rendered":"

Part 1 of a 2-part blog series.<\/strong><\/p>\n

A road cyclist in his forties has to brake suddenly to avoid a collision when a car pulls out abruptly, throwing him over the bicycle handlebars. He decides to seek medical advice and is diagnosed with a Morel-Lavallee lesion.<\/p>\n

A Morel-Lavallee lesion (MLL) is a closed degloving injury that occurs where skin and superficial fascia get separated from the deep fascia, creating a potential space. This was first described by a French surgeon, Maurice Morel-Lavallee, in 1853, hence the eponymous name. (1)\u00a0\u00a0<\/sup><\/p>\n

Anatomy<\/strong><\/p>\n

The greater trochanter (lateral hip) is the most commonly affected region for a MLL to occur, owing to a combination of the superficial position of the femoral cortex, relative mobility of the subdermal soft tissues, and strength of the underlying tensor fascia lata. (1)<\/sup> MLL can also occur in the thigh, pelvis, knee, gluteal region, lumbosacral area, abdominal area, and calf\/ lower leg. (4)<\/sup>\u00a0<\/strong><\/p>\n

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Figure 1: Created with BioRender.com (8)<\/figcaption><\/figure>\n

Aetiology<\/strong><\/p>\n

The initial shearing insult between the fascial layers disrupts the soft-tissue envelope’s perforating vascular and lymphatic structures, resulting in a characteristic haemolymphatic fluid collection. Inflammatory and metabolic products within this fluid stimulate cellular permeability and further leakage from the vessels and lymphatics into the created space. (3)<\/sup> As time progress, a capsulated lesion develops, which is lined by a fibrous capsule. The lesion is filled with blood products, necrotic fatty tissue, debris, and fibrin. (2)<\/sup><\/p>\n

Lesion evolution is divided into four stages. (i) The dermis is separated from the underlying fascia in the first stage. (ii) Exsanguination from the lymphatics and vasculature from the injured subdermal plexus subsequently produces a fluid collection mixture of blood, lymph, and fatty debris. (iii) Over time, these components become replaced by serosanguinous fluid as the lesion enlarges. (iv) If left untreated during the acute stage, local inflammation leads to the fourth stage of pseudocapsule formation and lesion maturation as the body attempts to sequester the fluid-filled space.<\/p>\n

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Figure 2: Illustrations depicting a cross-section of tissue from the skin to bone demonstrating the effect of a Morel-Lavallee lesion (MLL). (9)<\/figcaption><\/figure>\n

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A:<\/strong>\u00a0Normal layers of skin, tissue and bone.<\/p>\n

B:<\/strong>\u00a0Shear forces lead to the separation of superficial and deep fascial layers.<\/p>\n

C:\u00a0<\/strong>Fluid extravasation from injured vasculature leads to a haemolyphatic collection within the created space. (3)<\/sup><\/p>\n

Patient journey<\/strong><\/p>\n

As a result of the collision, the cyclist sustained an impact on his left lateral hip. Some pain is observed at the time, but otherwise, there are no immediate concerns about an acute injury. No other significant injuries were reported. After 5 days, there is increasing tenderness over the lateral aspect of the left hip with a considerable swelling that the cyclist can self-palpate.<\/p>\n

Upon clinical examination, there is a complete and pain-free range of motion of the affected hip. With closer inspection, there is a visible swelling over the lateral hip in the greater trochanter region, and a soft cystic-like swelling accompanies this on palpation. Additionally, the overlying skin has moderate bruising, which extends a short distance distally from the swelling. Finally, there is moderate tenderness over the greater trochanter.<\/p>\n

A diagnostic musculoskeletal ultrasound scan is performed. An anechoic (dark) lesion is identified on both longitudinal and transverse ultrasound imaging\u2014the dimensions of the lesion measure several centimetres in craniocaudal length and width. The lesion is deep to the subcutaneous fat and above the underlying muscle later- there is compressibility with probe pressure. No doppler activity is seen within the fluid collection, and there are no sinister features to suggest a malignant space-occupying lesion. No bony abnormality of the greater trochanter is seen. A diagnosis of Morel-Lavallee lesion is made.<\/p>\n

Diagnosis<\/strong><\/span><\/p>\n

History and Examination<\/strong><\/p>\n