Updated: 5/24/2021

Morel-Lavallee Lesion

Review Topic
  • Summary
    • A Morel-Lavallee Lesion (MLL) is a closed traumatic soft tissue degloving injury characterized by separation of the dermis from the underlying fascia due to a shearing force. 
    • Diagnosis requires high a index of suspicion with presence of an area of ecchymosis, swelling, fluctuance and skin hypermobility in the polytrauma patient with underlying fractures.
    • Treatment is generally operative irrigation and debridement for most lesions given the proximity to planned surgical incisions and increased risk of infection.
  • Epidemiology
    • Incidence
      • present in up to 8% of acetabulum fractures
    • Anatomic location
      • most often along proximal lateral thigh, in the peritrochanteric region
      • to a lesser extent gluteal, lumbosacral, and abdominal areas
        • due to hypermobility of skin in these regions
    • Risk factors
      • high-energy, shearing trauma
  • Etiology
    • Pathophysiology
      • divided into 4 stages:
        • shearing forces to soft-tissue envelope lead to separation of the dermis from the underlying fascia
        • injured lymphatics and vasculature from the injured subdermal plexus produce
        • these components are then replaced by serosanguinous fluid as the lesion enlarges
        • finally, if left untreated during the acute stage, local inflammation leads to pseudocapsule formation and lesion maturation as the body attempts to sequester the space
      • bacterial colonization of the fluid occurs in up to 46% of lesions
    • Associated conditions
      • orthopaedic conditions
        • pelvic and acetabular fractures
        • proximal femur fractures
  • Anatomy
    • Anatomy of soft tissues (order of layers from superifical to deep)
      • epidermis
      • dermis
      • subcutaneous fat
        • MLL develops deep to subctuaneous fat and superfical to deep fascia
      • deep fascia
      • muscle
  • Presentation
    • History
      • there should be high clinical suspician for a MLL in a polytrauma patient with a high-energy mechanism
    • Symptoms
      • often minimally symptomatic or marginalized due to underlying distracting injuries or patient body habitus
        • up to 33% of lesions are missed at the time of index evaluation
      • chronic lesions may lead to cosmetic issues
    • Physical exam
      • inspection
        • ecchymosis, swelling, fluctuance and skin hypermobility
        • skin discoloration may not be apparent until several days later
      • neurovascular
        • key indicator is paresthesias of overlying skin
  • Imaging
    • Radiographs
      • indications
        • evaluate underlying proximal femur, acetabulum or pelvis fractures
      • findings
        • may show soft tissue swelling
    • CT
      • indications
        • CT of the area of interest often obtained due to high-energy nature of the injury, underlying fracture, or abdominal/pelvic injury
      • findings
        • used to measure size of lesion to determine management
        • soft tissue windows will show slice of fluid within fascial plane
    • Ultrasound
      • indications
        • can be used to localize lesion for percutaneous treatment
      • findings
        • hypoechoic space superficial to fascial layer
    • MRI
      • indications
        • generally not required for diagnosis but will best demonstrate extent of the lesion
      • findings
        • average size reported to be 30 x 12 cm
        • fluid-filled space is often identifiable on T1- and T2-weighted MRI sequences.
          • acute lesions are hypointense on T1-weighted images and hyperintense on T2-weighted sequences
          • subacute lesions are homogenously hyperintense on T1- and T2-weighted sequences, with a peripheral capsule that is hypointense on both T1- and T2-weighted sequences
  • Treatment
    • Nonoperative
      • compressive therapy
        • indications
          • small lesions (< than 50 cm3)
        • outcomes
          • resolutional of smaller lesions can be successful with compressive therapy but this requries high patient compliance
      • percutaneous drainage with drain placement
        • indications
          • small lesions (< than 50 cm3)
        • outcomes
          • considered inferior to open debridement given inability to perform an adequate debridement of necrotic tissue
    • Operative
      • Single-incision irrigation and debridement (I&D)
        • relative indications
          • large lesions (> 50 cm3) or persistent MLL having failed non-operative management
          • lesion is not in the way of surgical approach for fracture
        • outcomes
          • successful resolution of lesion in up to 75% of cases with single I&D
            • more than I&D may be required for very large lesions
      • Dual-incision I&D
        • relative indications
          • lesion overlies surgical approach for fracture management
          • MLL discovered intra-operatively during surgical approach
        • outcomes
          • lesions near a surgical approach have a higher rate of infection and may require serial I&Ds prior to definitive managment of underlying fracture
      • Open debridement with resection of the fibrous capsule
        • relative indication
          • chronic MLLs with pseudocyst formation
        • outcomes
          • mixed, often requires multiple surgeries for eradication
  • Techniques
    • Compressive therapy
      • technique
        • most common modalities are ace wraps, compression bandages, bike shorts (for proximal thigh lesions)
    • Percutaneous drainage with drain placement
      • technique
        • use ultrasound to localize lesion then make 1-2 cm incision overlying leison
        • insert a suction tip into the lesion to remove hemorrhagic fluid
        • irrigate with normal saline
    • Single incision I&D
      • approach
        • incision centered over MLL
      • technique
        • aggressive debridement of cavity performed with scrub brush, Cobb and/or other instruments
        • placement of a drain exiting away from lesion (consider using 15 Fr or larger drain)
          • recommend leaving drain until minimal output (< 20-30 cc/day)
        • primary closure of lesion versus delayed closure
          • controversial
          • depends on size of lesion
          • delayed closure would involve wound vaccum placement and repeat I&D and closure in 48-72 hours
    • Dual-incision I&D
      • approach
        • incision over most proximal aspect of lesion
        • counter incision over most distal aspect of lesion
      • technique
        • similar to single incision for rest of treatment EXCEPT
          • primary closure of most proximal incision during first I&D
          • delayed closure of distal incision with wound vacuum (VAC)
            • return in 48-72 hours for repeat I&D through distal incision and closure
  • Complications
    • Recurrence
      • incidence
        • most common complication
          • up to 56% in patients with non-operative managment and 15-20% in those with open debridements
      • risk factors
        • inadequate debridement, larger lesions
      • treatment
        • repeat I&D and placement of drain
        • use of VAC and secondary healing (requires delayed skin graft)
        • use of sclerotherapy with talc or other sclerosing compound
    • Pseudocyst formation
      • risk factors
        • chronic, untreated MLL
      • treatment
        • open debridement with resection of the fibrous capsule
    • Skin necrosis
      • risk factors
        • delay in treatment, loss of epidermal blood supply due to inciting event or several repeat I&Ds of large MLL lesions
      • treatment
        • skin grafting
    • Peri-operative infection
      • risk factors
        • presence of a MLL has been cited as an independent risk factor for postoperative surgical site infection following pelvic and acetabular surgery
  • Prognosis
    • MLL cited as an independent significant risk factor for postoperative surgical site infection following pelvic and acetabular surgery
    • Overall prognosis varies with lesion chronicity and size
      • improved prognosis with smaller, acute lesions and discontiguous with surgical incisions
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