Rectus femoris muscle injury

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Rectus femoris muscle injuries are muscle injuries, which encompass contusions, strains, tears and avulsions of the rectus femoris muscle.

Epidemiology

Rectus femoris muscle injuries are a common injury in athletes, especially in football/soccer players . The rectus femoris muscle is most frequently affected in a quadriceps injury and the most common pattern are muscle strains .

Risk factors

Sports and activities involving a great amount of kicking, jumping and running are considered risk factors for developing a rectus femoris muscle injury and include :

  • football/soccer
  • American football
  • rugby
  • baseball
  • martial arts

Additional factors that increase the likelihood of developing a rectus femoris muscle injury include:

  • recent or remote injury
  • low muscle strength
  • muscle fatigue
  • inadequate warm-up
  • improper technique
Associations

Rectus femoris muscle injuries are associated with other quadriceps injuries and hamstring injuries .

Clinical presentation

In the event of acute strain, patients frequently present with a sharp pain of the anterior thigh associated with a functional deficit. Tenderness with palpation is a typical finding, which can usually be triggered by resisted muscle activity. Palpable defects might be found . Chronic strains might present with vague discomfort, thigh enlargement and variably associated strength deficit .

Complications

If left untreated rectus femoris muscle injury can lead to the following conditions :

Pathology

The rectus femoris muscle crosses two joints, plays an active part in knee extension and hip flexion and features a high proportion of fast-twitch (type II) muscle fibers and is characterized by a complex musculotendinous architecture, which is considered predisposing factors for strain injury . Muscle injury patterns include strains, contusions and lacerations.

Mechanism

Especially sprinting, jumping and kicking motions are associated with forceful eccentric contractions during counteraction of knee flexion and hip extension leading to the development of high forces across the muscle-tendon units, which can cause strain injury .

 With jumping, hip extension is counteracted during upward propulsion and knee flexion upon landing .

Location

Typical locations of rectus femoris muscle injuries include the origin of the direct and indirect head, the proximal myotendinous junction, the muscle belly, the muscle periphery with the fascia or myofascial unit and the distal myotendinous junction .

Subtypes

Rectus femoris muscle injuries can be classified based on type and location into the following :

Radiographic features

Most injuries of the rectus femoris muscle affect the myotendinous junction and are best evaluated with ultrasound or MRI.

Plain radiograph

Plain radiographs of the pelvis can be used as an initial examination especially in young patients to visualize anterior inferior iliac spine avulsions and to rule out other pathology . Besides, an avulsion injury of the indirect head of the femoris muscle at the superior acetabular ridge might be detected.

Ultrasound

The proximal tendons and the rectus femoris muscle can be nicely visualized on ultrasound. An anterior iliac spine avulsion injury can be visualized with a variably sized fragment separated from the pelvic bone by an anechoic fluid collection. The conjoined tendon and the direct head can be also depicted and easily assessed, evaluation of the indirect head is more difficult due to its depth .

Typical features of acute muscle injuries are ill-defined hyper or hypoechoic lesions with varying degrees of fibrillar discontinuity or disruption and can be graded accordingly .

Chronic proximal lesions might appear as hypoechoic tendon thickening and might show calcification or heterotopic ossification . Scar formation within the muscle displays an irregularly delineated hyperechoic appearance with focal retraction of the adjacent muscle fibers .

CT

CT can detect and characterize avulsion injuries. Additionally, it can be of used to depict large intramuscular hemorrhage. Due to radiation exposure and alternatives with better soft tissue discrimination properties as ultrasound and MRI, its value in the workup of muscle injuries is only limited.

MRI

Typical features of muscle injuries on MRI include fluid signal intensity tracking and surrounding the muscle fibers, myofascial, myotendinous or tendinous units of the rectus femoris muscle and/or discontinuities of the respective muscle components. Location, severity and extent of the muscle injury and extent of muscle retraction can be determined on MRI and even subtle tears can be detected with a suitable MRI protocol and proper knowledge of anatomy.

A further objective of MRI is to predict the time required for rehabilitation, recovery and return to sports especially in the athletes.

A magnetic resonance imaging grading scheme proposed for myotendinous injury:

  • grade 1: focal or diffuse high signal intensity or feathery muscle edema without fiber disruption
  • grade 2: partial tear of the myotendinous junction with the discontinuity of some fibers
  • grade 3: complete tear of the myotendinous junction with or without tendon retraction

The bull’s eye sign seen on axial images indicates a deep intramuscular degloving injury.

Another MR based classification is the British Athletics muscle injury classification, which also allows for subclassification according to the site.

Radiology report

The radiological report should include a description of the following:

  • location, type and extent of the lesion
  • injury grading if possible
  • the extent of tendon retraction
  • associated injuries

Treatment and prognosis

The vast majority of rectus femoris muscle including avulsion injuries are managed conservatively.

Conservative management includes activity modification with an initial period following the RICE (rest, ice, compression and limb elevation) principle followed up by a comprehensive rehabilitation and exercise regimen.

The initial resting period (usually 3-5 days) serves as a measure to prevent further progression of the injury and a more severe strain injury might require an initial use of crutches. Limb elevation and intermittent application of ice and compression are aiming to decrease blood flow and increased amounts of interstitial fluid accumulation. Ice application also serves pain control and can be supplemented by non-steroidal anti-inflammatory drugs (NSAIDs) in the initial period .

A rehabilitation protocol should comprise movement, walking, running exercises as well as stretching, strengthening, range of motion, endurance and agility training. Exercises should be initiated gradually and advanced continuously and should be conducted without increasing pain in the quadriceps .

Recovery will depend on the type and extent of the injury and might take from 2-3 weeks in case of a muscle contusion or myofascial injury up to 4 months or longer in displaced anterior iliac spine avulsion injuries .

Surgery is an alternative option in professional athletes with full-thickness tendon tears, two tendon head avulsions, patients with recurrent injuries or conservative treatment failure and can be done by surgical resection of the proximal tendon remnants followed by muscular suture repair .

To return to sports athletes should be pain-free and range of motion should be normal in the hip and knee. Strength should be near normal compared to the contralateral side .

History and etymology

A tear of the deep myotendinous junction of the indirect head of the rectus femoris muscle was first described by Hughes et al. in 1995 .

Differential diagnosis

Conditions which can mimic the presentation and/or the appearance of a rectus femoris muscle injury include:

See also