Quadriceps Muscle Strain

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Definition/Description

A quadriceps muscle strain is an acute tearing injury of the quadriceps. This injury is usually due to an acute stretch of the muscle, often at the same time of a forceful contraction or repetitive functional overloading. The quadriceps, which consists of four parts, can be overloaded by repeated eccentric muscle contractions of the knee extensor mechanism.
Acute strain injuries of the quadriceps commonly occur in athletic competitions such as soccer, rugby, and football. These sports regularly require sudden forceful eccentric contraction of the quadriceps during regulation of knee flexion and hip extension. Higher forces across the muscle–tendon units with eccentric contraction can lead to strain injury. Excessive passive stretching or activation of a maximally stretched muscle can also cause strains. Of the quadriceps muscles, the rectus femoris is most frequently strained. Several factors predispose this muscle and others to more frequent strain injury. These include muscles crossing two joints, those with a high percentage of Type II fibers, and muscles with complex musculotendinous architecture. Muscle fatigue has also been shown to play a role in acute muscle injury.

Clinically Relevant Anatomy

The Quadriceps femoris is a hip flexor and a knee extensor. It is located in the anterior compartment of the thigh. This muscle is composed of 4 sub components:

• Rectus femoris
• Vastus lateralis
• Vastus medialis
• Vastus intermedius

The Rectus femoris is the only part of the muscle participating in both flexion of the hip and extension of the knee.  The other 3 parts are only involved in the extension of the knee. The rectus femoris is the most superficial part of the quadriceps and it crosses both the hip and knee joints, thus also making it more susceptible to stretch-induced strain injuries.  The most common sites of strains are the muscle tendon junction just above the knee (both distal and proximal but most frequently at the distal muscle-tendon) and in the muscle itself.

Epidemiology/ Etiology

There are 4 types of skeletal muscle injuries: muscle strain,muscle contusion, muscle cramp and muscle soreness.
Literature studies does not reveal great consensus when it comes to classifying muscle injuries, despite their clinical importance. However, the most differentiating factor is the trauma mechanism.  Muscle injuries can therefore be broadly classified as either traumatic (acute) or overuse (chronic) injuries.

Acute injuries are usually the result of a single traumatic event and cause a macro-trauma to the muscle. There is an obvious link between the cause and noticeable symptoms. They mostly occur in contact sports such as rugby, soccer and basketball because of their dynamic and high collision nature.

Overuse, chronic or exercise-induced injuries are subtler and usually occur over a longer period of time. They result from repetitive micro-trauma to the muscle. Diagnosing is more challenging since there is a less obvious link between the cause of the injury and the symptoms.

Mechanism of injury:

There are generally three mechanisms of injury for a quadriceps strain.
1. Sudden deceleration of the leg (e.g. kicking),
2. violent contraction of the quadriceps (sprinting) and
3. rapid deceleration of an overstretched muscle (by quickly change of direction).

Characteristics/Clinical Presentation

Grades of quadriceps strain :

Strains are graded 1 to 3 depending on how bad the injury is, with a grade 1 being mild and a grade 3 involving a complete or near complete tear of the muscle.
Grade 1 symptoms

Symptoms of a grade 1 quadriceps strain are not always serious enough to stop training at the time of injury. A twinge may be felt in the thigh and a general feeling of tightness. The athlete may feel mild discomfort on walking and running might be difficult. There is unlikely to be swelling. A lump or area of spasm at the site of injury may be felt.

Grade 2 symptoms

The athlete may feel a sudden sharp pain when running, jumping or kicking and be unable to play on. Pain will make walking difficult and swelling or mild bruising may be noticed. The pain would be felt when pressing in on the suspected location of the quad muscle tear. Straightening the knee against resistance is likely to cause pain and the injured athlete will be unable to fully bend the knee.

Grade 3 symptoms

Symptoms consist of a severe, sudden pain in the front of the thigh. The patient will be unable to walk without the aid of crutches. Bad swelling will appear immediately and significant bruising within 24 hours. A static muscle contraction will be painful and is likely to produce a bulge in the muscle. The patient can expect to be out of competition for 6 to 12 weeks.

Observation and palpation

The therapist will have a close look at the injured area, observing for swelling and bruising in particular. They should also observe the patient in standing and walking, looking for postural abnormalities.Palpation of the quadriceps muscle should occur along the entire length of the muscles and the aponeuroses. This is required to identify swelling, thickening, tenderness, defects and masses if present.

Differential Diagnosis

• Contusion
• Jumper's Knee
• Femoral Neck Stress Fracture
• Slipped Capital Femoral Epiphysis
• Previous injury seems not to constitute a risk factor

Diagnostic procedures

Most acute injuries in the quadriceps muscles can be found easily by the therapist by just letting the patient tell how the injury occurred and doing a quick examination of the quadriceps muscles afterwards. But when the therapist isn’t too sure, he can always consider medical imaging to give a definite answer. Medical imaging tells us for example the exact type and location of the muscle strain.

After obtaining a thorough history, a careful examination should ensue including observation, palpation, strength testing, and evaluation of motion.

• Observation: Strain injuries of the quadriceps may present with an obvious deformity such as a bulge or defect in the muscle belly. Ecchymosis may not develop until 24 hours after the injury.

• Palpation of the anterior thigh should include the length of the injured muscle, locating the area of maximal tenderness and feeling for any defect in the muscle. Acute compartment syndrome should be considered if there is tenseness of the fascial envelope surrounding the compartment and pain out of proportion to the clinical situation

• Strength testing of the quadriceps should include resistance of knee extension and hip flexion. Adequate strength testing of the rectus femoris must include resisted knee extension with the hip flexed and extended. Practically, this is best accomplished by evaluating the patient in both a sitting and prone-lying position. The prone-lying position also allows for optimum assessment of quadriceps motion and flexibility. Pain is typically felt by the patient with resisted muscle activation, passive stretching, and direct palpation over the muscle strain.

Assessing tenderness, any palpable defect, and strength at the onset of muscle injury will determine grading of the injury and provide direction for further diagnostic testing and treatment.

Medical imaging

There are several types of medical imaging which can be used for muscle strains:

• Radiographs: a positive point about radiographs is that they are good to differentiate the etiology of the pain in the quadriceps muscles. Etiologies can be muscular (muscle strain etc.) or bony (stress fracture etc.).
• Ultrasound: Ultrasound is very often used because it is relatively inexpensive. But it also has a quite big disadvantage, namely the fact that it’s highly operator dependent and requires a skilled and experienced clinician. Another advantage of US is the fact that it has the ability to image the muscles dynamically and to asses for bleedings and hematoma formation via Doppler.
• Magnetic resonance imaging (MRI): MRI is a good way to give detailed images of the muscle injury. If it’s not clear whether it’s a contusion or a strain, the therapist must rely on the patient's recollection of the injury in order to deduce whether it is a contusion or strain.

Outcome measures

• Voluntary activation by superimposing percutaneous electrical stimulation on to an isometric quadriceps. When the muscle is fully activated, the electrical stimulation does not generate additional force above the voluntary contraction.
• Muscle test: quadriceps force and ROM. There are 5 grades of manual testing: Grade 0 is the lowest grade where the patient isn’t able to do anything . Grade 5 is the highest grade where the patient can move his leg against a maximum resistance given by the therapist.

Examination

Ely’s test :The Ely’s test (or Duncan-Ely test) is used to assess rectus femoris spasticity or tightness.

Technique

The patient lies prone in a relaxed state. The therapist is standing next to the patient, at the side of the leg that will be tested. One hand should be on the lower back, the other holding the leg at the heel. Passively flex the knee in a rapid fashion. The heel should touch the buttocks. Test both sides for comparison. The test is positive when the heel cannot touch the buttocks, the hip of the tested side rises up from the table, the patient feels pain or tingling in the back or legs.

Other evaluation methods are:

• Hamstrings/Quadriceps ratio (H vs. Q) - A calculation in which the strength (peak torque) of the hamstring muscles in eccentric motion is divided by the strength of the quadriceps in a concentric motion: Asymmetries/dysbalances in the functional H/Q ratio was shown to significantly impact injury incidence .
• Range of motion decrease (ROM)
• Muscle strength loss
• Skin temperature
• Pain (under pressure)
• Bruises (ecchymosis)
• Sore end-feel

Medical Management

The use of NSAID's ( nonsteroidal anti-inflammatory drugs) is still controversial, their benefit, cost and potential adverse effects may be taken into consideration. If used, it should be during the inflamatory period (48h-72h) 

Surgical Intervention may be necessary if there is a complete quadriceps muscle rupture.

There has been an experimental study (1998) about the use of hyperbaric oxygen therapy. The therapy should be applied during the early phase of the repair of the injured muscle.This therapy could accelerate the repair of the injured muscle. Care should be taken to extend these findings to clinical practice, as there is not enough scientific evidence on the use of hyperbaric oxygen therapy in the treatment of muscle or other types of soft tissue injuries in athletes.

Surgery

One should exercise extreme caution in considering surgical intervention in the treatment of muscle injuries, as a properly executed nonoperative treatment results in a good outcome in virtually all cases. In fact, the phrase "muscle injuries do heal conservatively" could be used as a guiding principle in the treatment of muscle traumas.

Having said that, there are certain highly specific indications in which surgical intervention might actually be beneficial.

Indications for Surgery

• large intramuscular hematoma(s),

• a complete (III degree) strain or

• tear of a muscle with few or no agonist muscles, or

• a partial (II degree) strain if more than half of the muscle belly is torn.

• surgical intervention should be considered if a patient complains of persisting extension pain (duration, >4-6 months) in a previously injured muscle, particularly if the pain is accompanied by a clear extension deficit. In this particular case, one has to suspect the formation of scar adhesions restricting the movement of the muscle at the site of the injury, a phenomenon that often requires surgical debridement of the adhesions.

If surgery is indeed warranted in the treatment of an acute skeletal muscle injury, the following general principles are recommended:

Recommended Principles for Surgery

• The entire hematoma and all necrotic tissue should be carefully removed from the injured area.

• One should not attempt to reattach the ruptured stumps of the muscle to each other via sutures unless the sutures can be placed through a fascia overlying the muscle.Sutures placed solely through myofibers possess virtually no strength and will only pierce through the muscle tissue.

• Loop-type sutures should be placed very loosely through the fascia, as attempts to overtighten them will only cause them to pierce through the myofibers beneath the fascia, resulting in additional damage to the injured muscle. It needs to be emphasized here that sutures might not always provide the required strength to reappose all ruptured muscle fibers, and accordingly, the formation of empty gaps between the ruptured muscle stumps cannot always be completely prevented.

• As a general rule of thumb, the surgical repair of the injured skeletal muscle is usually easier if the injury has taken place close to the MTJ, rather than in the middle of the muscle belly, because the fascia overlying the muscle is stronger at the proximity of the MTJ, enabling more exact anatomical reconstruction.

• In treating muscle injuries with 2 or more overlying compartments, such as the muscle quadriceps femoris, one should attempt to repair the fascias of the different compartments separately, beginning with the deep fascia and then finishing with the repair of the superficial fascia.

• After surgical repair, the operated skeletal muscle should be supported with an elastic bandage wrapped around the extremity to provide some compression (relative immobility, no complete immobilization, eg, in cast, is needed).

• Despite the fact that experimental studies suggest that immobilization in the lengthened position substantially reduces the atrophy of the myofibers and the deposition of connective tissue within the skeletal muscle in comparison to immobilization in the shortened position, the lengthened position has an obvious draw-back of placing the antagonist muscles in the shortened position and, thus, subjecting them to the deleterious effects of immobility.

After a careful consideration of all the above-noted information, we have adopted the following postoperative treatment regimen for operated muscle injuries.

Post operative treatment

• The operated muscle is immobilized in a neutral position with an orthosis that prevents one from loading the injured extremity.

• The duration of immobilization naturally depends on the severity of the trauma, but patients with a complete rupture of the m. quadriceps femoris or gastrocnemius are instructed not to bear any weight for 4 weeks,

• Although one is allowed to cautiously stretch the operated muscle within the limits of pain at 2 weeks postoperatively.

• Four weeks after operation, bearing weight and mobilization of the extremity are gradually initiated until approximately 6 weeks after the surgery, after which there is no need to restrict the weightbearing at all.

Experimental studies have suggested that in the most severe muscle injury cases, operative treatment may provide benefits. If the gap between the ruptured stumps is exceptionally long, the denervated part of the muscle may become permanently denervated and atrophied. Under such circumstances, the chance for the reinnervation of the denervated stump is improved, and the development of large scar tissue within the muscle tissue can possibly be at least partly prevented by bringing the retracted muscle stumps closer together through (micro) surgical means. However, in the context of experimental studies, it should be noted that the suturation of the fascia does not prevent contraction of the ruptured muscle fibers or subsequent formation of large hematoma in the deep parts of the muscle belly.

Physical Therapy Management

Knee positioning :

When a quadriceps muscle strain occurs during a competition or training, it is important to react immediately. In the 10 minutes following the trauma one needs to put the knee of the affected leg immediately in 120° of flexion. This avoids potential muscle spasms, reduces the hemorrhage and minimizes the risk of developing myositis ossificans.Practically, this can be done by placing the patient in a hinged knee brace at 120° of knee flexion or using elastic compression wrap to maintain this position of flexion.If the knee is left in extension the healing process will be slower and more painful because the quadriceps will start to heal in a shortened position.

rice tHERAPY

The rest of the therapy during the healing process is based on the RICE therapy, this includes:

1. Rest,
2. Ice treatment
3. Compression
4. Elevation

Rest : Rest prevents worsening of the initial injury.By placing the injured extremity to rest the first 3-7 days after the trauma, we can prevent further retraction of the ruptured muscle stumps (the formation of a large gap within the muscle), reduce the size of the hematoma, and subsequently, the size of the connective tissue scar.During the first few days after the injury, a short period of immobilization accelerates the formation of granulation tissue at the site of injury, but it should be noted that the duration of reduced activity (immobilization) ought to be limited only until the scar reaches sufficient strength to bear the muscle-contraction induced pulling forces without re-rupture. At this point, gradual mobilization should be started followed by a progressively intensified exercise program to optimize the healing by restoring the strength of the injured muscle, preventing the muscle atrophy, the loss of strength and the extensibility, all of which can follow prolonged immobilization.

Ice or cold application : It is thought to lower intra-muscular temperature and decrease blood flow to the injured area.Regarding the use of cold on injured skeletal muscle, it has been shown that early use of cryotherapy is associated with a significantly smaller hematoma between the ruptured myofiber stumps, less inflammation and tissue necrosis, and somewhat accelerated early regeneration. But according to the most recent data on topic (2007), icing of the injured skeletal muscle should continue for an extended period of time (6 hours) to obtain substantial effect on limiting the hemorrhaging and tissue necrosis at the site of the injury. 

Compression : This may help decrease blood flow and accompanied by elevation will serve to decrease both blood flow and excess interstitial fluid accumulation. The goal is to prevent hematoma formation and interstitial edema, thus decreasing tissue ischemia. However, if the immobilization phase is prolonged, it will be detrimental for muscle regeneration.Cryotherapy, accompanied by compression, should be applied for 15–20 min at a time with 30–60 min between applications. During this time period, the quadriceps should be kept relatively immobile to allow for appropriate healing and prevent further injury.

Elevation : The elevation of an injured extremity above the level of heart results in a decrease in hydrostatic pressure, and subsequently, reduces the accumulation of interstitial fluid, so there is less swelling at the place of injury. But it  needs to be stressed that there is not a single randomized, clinical trial to validate the effectiveness of the RICE-principle in the treatment of soft tissue injury.

active phase of management :

The acute phase of treatment is subsequently followed by an active phase of management once the injured leg is recovering well. This phase usually begins approximately 3–5 days after the initial injury depending on its severity. Stretching, strengthening, range of motion, maintenance of aerobic fitness, proprioceptive exercises, and functional training are the primary components of this phase..

1. Stretching - Stretching should be done carefully and always to the point of discomfort, but not pain. Various techniques can be utilized including passive, active–passive, dynamic, and proprioceptive neuromuscular facilitation stretching. Generally, ballistic stretching is discouraged due to the risk of re-tearing muscle fibers. If it is pain free , stretch the quad muscles.

• Static quad stretch - This can be performed in either standing, or laying on your front. Pull the foot of the injured leg towards your buttock until you can feel a gentle stretch on the front of the thigh. To increase the stretch, tilt your hips backwards. Hold for 20-30 seconds and repeat 3 times. Do this at least 3 times a day.

File:Quadriceps stretch.jpeg

• Hip flexor stretch-This stretch will focus on the rectus femoris and Iliopsoas muscles. Kneel with one knee on the floor and the other foot out in front with the knee bent. Push your hips forwards and keep the back upright. You should feel a stretch at the front of the hip and top of the thigh.Hold for 20-30 seconds, repeat 3 times, at least 3 times a day.
  File:Physitrack hip flexor stretch.jpg

2.Strengthening exercises

The aim of strengthening exercises is to gradually increase the load that is put through a muscle. Strengthening exercises can start as early as day 5 as long as they are low-level and must be done pain-free.Isometric or static exercises are advised first and then progress to dynamic exercises with resistance band and finishing with sports specific running and sprint drills. scientific evidence is lacking on the consensus of treatment principles of muscle injuries

• Isometrics : Initial isometrics with quadriceps contractions done with the knee fully extended and in different positions at 20 degree increments as knee flexion improves May discontinue isometrics when patient can sit comfortable.

• Straight leg raises : Sit flat on the floor with the legs straight out in front of you. Raise one leg off the floor keeping the knee straight. Hold for 3 to 5 seconds before lowering back to the ground. Repeat 10 to 20 times. This exercise can be done daily. Progress the exercise by increasing the length of hold and the number of reps.

• Isotonics : Once terminal knee extensions are done properly without extensor lag, freeweights are added to the SLRs and terminal knee extensions . Begin with the lightest free weight that patient can lift; three sets of 10 repetitions up to three times per day.Increase weight by no more than 2-3 pounds at any given time and increase no sooner than every two consecutive work days.

• Wall squats : From your starting position, slowly lower your body down and hold for time. As you improve, lengthen the amount of time you hold the wall squat. Be sure to keep your pelvis, back, and head against the wall. Keep the movement pain free.(A variation to increase activation of the VMO would be to squeeze a ball between your knees as you perform the exercise.Typically the ball would be about 12 inches in diameter.)Perform 3 sets of 15-20 seconds holds once per day.

• Step ups : Start with a box height that is comfortable for you to step up on. Be sure to keep your knee in alignment with your second toe. Step up and keep your pelvis level and your knee in alignment. Be sure to engage the buttocks muscles and fully lock out the knee. Return slowly back down to the ground. The focus should be on the slow eccentric (lowering) back to the ground for 1 second up and 3 seconds down.Perform 2 sets of 15-20 repetitions once per day.
  File:Step ups.jpg

Stand facing a step.Place your affected leg up on the step. Step up bringing your other leg onto the step and then step back down to the start position using the same leg. Make sure your knee travels forwards over your toes during this exercise. Your affected leg will stay on the step throughout this exercise.

Rehabilitation protocol example :

• PHASE I: ACUTE PHASE (24-48 hours)

Goals:	Diminish pain and inflammation Gradually improve flexibility and ROM Retard muscular atrophy and strength loss Enhance healing of muscular strain
precautions	Avoid excessive active or passive lengthening of quadriceps
Rehab	RICE–Rest,Cryotherapy, compression wrap, and elevation Use of crutches initially to facilitate rest and immobilization of the quadriceps NSAIDS Soft tissue mobs/IASTM Pulsed ultrasound (Duty cycle 50%, 1 MHz, 1.2 W/cm2) Conventional TENS Ankle pumps, isometric quadriceps sets, hamstring sets, glut sets

• PHASE 2 :SUBACUTE PHASE (WEEK 3 - 12)

Goals	Regain pain-free quadriceps strength, progressing through full ROM Develop neuromuscular control of trunk and pelvis with progressive increase in movement and speed preparing for functional movements
precautions	Avoid end-range lengthening of quadriceps if painful
Rehab	Cryotherapy NSAIDS Electrical stimulation Initial isometrics with quadriceps contractions done with the knee fully extended and in different positions at 20 degree increments as knee flexion improves May discontinue isometrics when can sit comfortably, perform straight leg raises at 0 degrees, 20 degrees, and 40 degrees Isotonics–begin with the lightest free weight that athlete can lift; three sets of 10 repetitions up to three times per day Terminal knee extensions instituted at 20 degree increments as comfort and knee flexion allow Once terminal knee extensions are done properly without extensor lag, free weights are added to the SLRs and terminal knee extensions Increase weight by no more than 2-3 pounds at any given time and increase no sooner than every two consecutive work days As athlete approaches his or her maximum weight, somewhere around 15-20pounds, isokinetic exercises are tried Conditioning via upper body workouts, swimming, treadmill walking Biking when knee ROM greater than 100 degrees of flexion

• Phase 3 ( week 12+)

Goals	Symptom free during all activities Normal concentric and eccentric strength through full ROM and speed Improve neuromuscular control of trunk and pelvis Integrate postural control into sport-specific movements
Precautions	Train within symptoms free intensity
Rehab	Ice – Post exercise – as needed Treadmill moderate to high intensity as tolerated Isokinetic eccentric training at end ROM (in hyperflexion) STM/IASTM Plyometric jump training 5-10 yard accelerations/decelarations Single-limb balance windmill touches with weight on unstable surface Sport-specific drills that incorporate postural control and progressive speed
Eccentric protocol	Include higher velocity eccentric Ex that include plyometric and sports specific activities Examples: include squat jumps, split jumps, bounding and depth jumps, single leg bounding, backward skips, lateral hops, lateral bounding, zigzag hops, bounding, plyometric box jumps, eccentric backward steps, eccentric lunge drops, eccentric forward pulls, single and double leg deadlifts, and split stance deadlift (good morning Ex)

Return to sports criteria

• Full strength without pain in the lengthened state testing position
• Full ROM without pain
• Replication of sport specific movements at competition speed without symptoms.
• Isokinetic strength testing should be performed under both concentric and eccentric action conditions.
• Attain 120° of knee flexion with hip extended

Key research

Kary, Joel M. "Diagnosis and management of quadriceps strains and contusions." Current reviews in musculoskeletal medicine 3.1-4 (2010): 26-31. (level 2C)

Clinical bottom line

Acute strain injuries of the quadriceps commonly occur in athletic competitions such as soccer, rugby, and football. These sports regularly require sudden forceful eccentric contraction of the quadriceps during regulation of knee flexion and hip extension. Higher forces across the muscle–tendon units with eccentric contraction can lead to strain injury. Excessive passive stretching or activation of a maximally stretched muscle can also cause strains. Of the quadriceps muscles, the rectus femoris is most frequently strained. Several factors predispose this muscle and others to more frequent strain injury. These include muscles crossing two joints, those with a high percentage of Type II fibers, and muscles with complex musculotendinous architecture. Muscle fatigue has also been shown to play a role in acute muscle injury.
Therapy is bases on 3 principles:
1. RICE
2. knee mobilisation
3. Training of the quadriceps functions

References