Intramuscular degloving injury
An intramuscular degloving injury is a term referred to a circumferential intermuscular dissociation of inner and outer muscular components with or without retraction. It has been described in the rectus femoris muscle.
Terminology
An intramuscular degloving injury has been also described as bull’s eye lesion and lesion with a ‘muscle-within-a-muscle’ appearance.
Epidemiology
Intramuscular degloving injuries apparently account for about 9% of rectus femoris muscle injuries .
Risk factors
Factors that increase the likelihood of developing an intramuscular degloving injury include:
- kicking motions
- recent or remote injury
- low muscle strength
- muscle fatigue
- inadequate warm-up
- improper technique
Associations
Intramuscular degloving injuries can be associated with other types of muscular injuries of the same or different muscles or muscle hematoma.
Clinical presentation
Symptoms are quite variable and patients can present with thigh pain and/or hip pain, discomfort thigh enlargement with variably associated strength deficit.
Complications
If left untreated an intramuscular degloving injury probably leads to re-injury and focal or diffuse muscle atrophy with fatty replacement.
Pathology
Mechanism
Especially kicking has been described as a mechanism leading to a degloving injury of the rectus femoris muscle, sprinting and forced quadriceps extension are other mechanisms.
Location
This type of tear has been described in a setting of a rectus femoris muscle injury, where the peripheral fibers of the inner indirect head (bipennate muscle) are separated from the overlying direct head (unipennate muscle).
Radiographic features
Plain radiograph
Plain radiographs might show soft tissue swelling.
Ultrasound
On ultrasound, an intramuscular degloving injury has been described to show a muscle-within-a-muscle appearance showing an area of mixed echogenicity surrounding the inner indirect head of the rectus femoris muscle with the transducer in the axial plane.
MRI
An intramuscular degloving injury can be visualized on fat-saturated T2 weighted or intermediate weighted MRI images.
The inner part of the bipennate indirect head of the muscle is usually surrounded by fluid dividing it from the outer muscle fibers of the unipennate direct head and might be retracted proximally.
Radiology report
The radiological report should include a description of the following:
- the location and extent of the injury
- the extent of muscular retraction of the dissociated indirect head
Treatment and prognosis
Similar than other rectus femoris muscle including avulsion injuries can be managed conservatively.
Conservative management includes activity modification with an initial resting period, cryotherapy, nonsteroidal anti-inflammatory drugs (NSAIDs) followed by an active and comprehensive rehabilitation protocol with physical therapy early motion and light running exercises, over strengthening exercises, endurance and agility training. The rehabilitation protocol can comprise different stages to facilitate and improve return to activity .
Recovery of this type of injury partially depends on the extent of tendon retraction and has been reported to take 5-6 weeks on average.
History and etymology
Hughes et al in 1995 first described a tear of the deep myotendinous junction of the indirect head of the rectus femoris muscle on MRI and spoke of a ‘bull’s eye lesion’, Bianchi et al. and Balius et al. described the condition on ultrasound as a ‘muscle-within-a-muscle’ appearance. Kassarjian et al. used the term ‘intramuscular degloving injury’.
See also
