First described in 1853 [1], the Morel-Lavallée lesion is a closed, post-traumatic, soft tissue degloving injury [1–3], characterized by an accumulation of blood, lymph, and other breakdown products between the subcutaneous tissue and underlying fascia [4] (Fig. 1). It is due to shearing stress with disruption of perforating blood vessels and the creation of potential spaces. Morel-Lavallée is most commonly associated with pelvic and acetabular fractures, but it may also occur at various locations [4]; the lesion has been reported occurring over the flank, buttock, lumbar spine, scapula, knee, and elsewhere.
Fig. 1.
Morel-Lavallée lesion. Morel-Lavallée lesion is a post-traumatic injury characterized by an accumulation of fluid (arrows) between subcutaneous tissue and underlying fascia
Clinical presentation of the lesion is pain, swelling, and stiffness at the site of injury. Upon examination, there is an area of tissue swelling that is soft to palpation [4]. Radiological investigations, especially ultrasound imaging and magnetic resonance imaging, are highly valued in the traumatic pathology of soft tissue [5] and so for the diagnosis of this condition [6]. The sonographic appearance is characterized by acute lesions that tend to be heterogeneous and lobular, with irregular margins. The chronic lesions are anechoic with well-defined margins, separating the subcutaneous tissue from the underlying fascia [7, 8]. Additionally, the magnetic resonance imaging appearance depends on the age and amount of blood, fat, and lymph [9].
The differential diagnosis is with muscle and soft tissue hematomas and with bursitis [10], more rarely with neoplasms. There is a lack of consensus regarding the management of these lesions, including non-operative therapies and operative techniques [11–13].
An 18-year-old male presented with left medial knee pain and swelling, 26 days following an injury occurred while playing soccer. Clinical examination showed a fluctuant swelling on the medial aspect of the right knee, without any surrounding cutaneous laceration or edema.
Ultrasound of the medial aspect of the right knee, using a linear transducer at 18 MHz (Fig. 1), showed a longitudinal homogenous fluid lesion, located between the subcutaneous tissue and muscle (Morel-Lavallée lesion) (Fig. 2). Magnetic resonance imaging of the lesion (Fig. 3) confirmed, on the medial aspect of the right knee, the presence of a homogenous collection of fluid, between the subcutaneous tissue and the underlying muscle. A conservative approach to treatment was preferred. After 3 months of simple resting of the knee, no significant effusion could be appreciated on sonographic examination. The patient is currently asymptomatic.
Fig. 2.
Morel-Lavallée lesion. Extended field-of-view sonograms a, b shows a fusiform homogeneous anechoic fluid collection (arrows) with smooth margins, located between subcutaneous tissue and muscle
Fig. 3.
Morel-Lavallée lesion. Axial and sagittal proton density fat suppressed images confirm the presence of fluid collection (arrows) with smooth margins, located between subcutaneous tissue and muscle
Morel-Lavallée lesions [1] are rare but should be suspected in high inertia trauma of the knee, commonly developing secondarily to blunt trauma separation of subcutaneous tissue from the underlying fascia.
The diagnosis remains primarily a clinical diagnosis [2], but there is a wide range of differential diagnoses, including hematomas, abscesses, bursitis, fat necrosis, and neoplasms; particularly, the clinical presentation of a post-traumatic hematoma and an acute Morel-Lavallée lesion are similar.
Ultrasound and MRI must be used to confirm the diagnosis [2, 4] and for the differential diagnosis. The sonographic and magnetic resonance imaging characteristics of Morel-Lavallée lesions are variable: lesions less than 1 month of age tend to be heterogeneous and irregularly marginated. When they evolve, they became more regularly marginated and homogeneous, but only the anatomic features are typical: a fluid lesion, located between subcutaneous tissue and muscle [6, 8].
The Morel-Lavallée lesion has a specific anatomic location and pathophysiological process that make it more prone to complications and chronicity. No clear best management is known, but the options can be narrowed based on location, age, and size of the lesion [2].
Conflict of interest
All authors confirm that they have no conflict of interest to disclose.
Ethical standard
All human and animal studies have been approved by the appropriate ethics committee and have therefore been performed in accordance with the ethical standards laid down in the Helsinki Declaration of 1975 and its late amendments.
References
- 1.Morel-Lavallée M (1863) Decollements traumatiques de la peau et des couches sousjacentes. Arch Gen Med 1:20–38, 172–200, 300–332
- 2.Turner CJ, Van Lancker H. A prepatellar Morel-Lavallée lesion in a pedestrian vs automobile collision. Am J Emerg Med. 2014;32(1):109. doi: 10.1016/j.ajem.2013.08.023. [DOI] [PubMed] [Google Scholar]
- 3.Bianchi S, Martinoli C. Ultrasound of the musculoskeletal system. Berlin: Springer; 2007. pp. 677–678. [Google Scholar]
- 4.Goodman BS, Smith MT, Mallempati S, Nuthakki P. A comparison of ultrasound and magnetic resonance imaging findings of a Morel-Lavallée lesion of the knee. PM R. 2013;5(1):70–73. doi: 10.1016/j.pmrj.2012.08.001. [DOI] [PubMed] [Google Scholar]
- 5.Draghi F, Bianchi S, Gervasio A, Fachinetti C, Gaignot C, De Gautard R. L’ecografia nella valutazione della patologia traumatica del polso e della mano. J Ultrasound. 2006;9(3):218–226. [Google Scholar]
- 6.van Gennip S, van Bokhoven SC, van den Eede E. Pain at the knee: the Morel-Lavallée lesion, a case series. Clin J Sport Med. 2012;22(2):163–166. doi: 10.1097/JSM.0b013e318246ee33. [DOI] [PubMed] [Google Scholar]
- 7.Robinson P, Farrant JM, Bourke G, Merchant W, McKie S, Horgan KJ. Ultrasound and MRI findings in appendicular and truncal fat necrosis. Skeletal Radiol. 2008;37(3):217–224. doi: 10.1007/s00256-007-0417-0. [DOI] [PubMed] [Google Scholar]
- 8.Neal C, Jacobson JA, Brandon C, Kalume-Brigido M, Morag Y, Girish G. Sonography of Morel-Lavallee lesions. J Ultrasound Med. 2008;27(7):1077–1081. doi: 10.7863/jum.2008.27.7.1077. [DOI] [PubMed] [Google Scholar]
- 9.Borrero CG, Maxwell N, Kavanagh E. MRI findings of prepatellar Morel-Lavallée effusions. Skeletal Radiol. 2008;37(5):451–455. doi: 10.1007/s00256-008-0450-7. [DOI] [PubMed] [Google Scholar]
- 10.Draghi F, Danesino GM, Coscia D, Precerutti M, Pagani C. Overload syndromes of the knee in adolescents: sonographic findings. J Ultrasound. 2008;11(4):151–157. doi: 10.1016/j.jus.2008.09.001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Nair AV, Nazar P, Sekhar R, Ramachandran P, Moorthy S. Morel-Lavallée lesion: a closed degloving injury that requires real attention. Indian J Radiol Imaging. 2014;24(3):288–290. doi: 10.4103/0971-3026.137053. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Nickerson TP, Zielinski MD, Jenkins DH, Schiller HJ. The Mayo clinic experience with Morel-Lavallée lesions: establishment of a practice management guideline. J Trauma Acute Care Surg. 2014;76(2):493–497. doi: 10.1097/TA.0000000000000111. [DOI] [PubMed] [Google Scholar]
- 13.Draghi F, Robotti G, Jacob D, Bianchi S. Interventional musculoskeletal ultrasonography: precautions and contraindications. J Ultrasound. 2010;13(3):126–133. doi: 10.1016/j.jus.2010.09.004. [DOI] [PMC free article] [PubMed] [Google Scholar]