HAMSTRING STRAIN

Common Causes

A strain is a degree of tearing of the muscle fiber. Tearing or straining of hamstring muscles, particularly the long head of the biceps femoris, occurs frequently in athletics, particularly in sports that require brisk accelerations of speed and cutting, such as rugby, American football, soccer, and tennis. Although complete tears can occur, most tears are partial and occur at the myotendinous junction because of a failed lengthening of the muscle (eccentric contraction) while contracting (Ramos et al. 2017).

As stated already, the hamstring muscle group includes three distinct muscles: the biceps femoris, the semitendinosus, and the semimembranosus. This group crosses two joints: the hip and the knee. Injuries to the hamstrings generally occur at the musculotendinous junction. Of the three muscles in the hamstring group, the biceps femoris is most likely to be injured. Factors that predispose an athlete to hamstring strains include insufficient warm-up, fatigue (strains tend to occur later in training or competition and later in the competitive season), poor muscular coordination, excessive pelvic tilt, prior hamstring injury, and imbalance in muscle strength between the hamstring and quadriceps (in which the hamstring is weaker).

Poor flexibility of the hip flexors and quadriceps alters the lumbopelvic mechanics by causing the pelvis to tilt anteriorly and increases the degree of lumbar lordosis (the curve in the low part of the back), which places extra tension on the hamstrings. Poor running mechanics in which the athlete has excess forward lean causes the gluteus maximus, the prime hip extensor in sprinting, to function poorly. This results in overstriding, increasing the hamstring length and making strain more likely.

Hamstring tendinopathy, a related injury, is an overuse injury resulting in dense fibrosis (thickening of the fibers of the tendon) and occasionally, hyaline degeneration at the attachment of the hamstring to the ischium. It differs from tendinitis in that tendinopathy represents more of a chronic injury whereby the actual tendon fibers begin to remodel and undergo structural changes. In tendinitis, the fibers are intact but there is local inflammation due to acute injury. This injury can occur in sprinters and in sports requiring quick starting and stopping, or change of direction while running at high speed.

Identification

The athlete often becomes aware of the injury by hearing or feeling a “pop” in the hamstring followed by immediate pain in the posterior thigh. This generally occurs during sprinting or cutting activities.

A palpable defect can often be detected in the area of injury. The athlete might feel tenderness in a focal area, especially soon after the injury. By 24 hours after the injury, the tender area becomes more diffuse and difficult to localize. The easiest way to isolate the area of tenderness is to palpate (explore via touch) the hamstring with the athlete prone and the knee flexed. Resisted knee flexion generally reproduces discomfort in the area of injury. A mass in the proximal posterior thigh might appear, especially in more severe strains. Functionally, if athletes with a hamstring injury attempt to run, they shorten the stride length to reduce pain. Grade III strains, involving complete tearing of the musculotendinous unit and causing severe functional deficits and significant weakness, often occur at the origin of the hamstrings on the ischium and might even be accompanied by a bony avulsion at this site (see hamstring avulsion, p. 247) (Malliaropoulos et al. 2013).

Perform a slump test to eliminate the possibility of neural injury as a cause of the posterior thigh pain. To perform the test, ask the athlete, while seated, to extend each leg individually. Then ask the athlete to tuck the chin into the chest and repeat the extensions. If pain is exacerbated on the involved side when the leg is extended and the chin is tucked (rather than when the chin is not tucked), the slump test is positive and can signify a nerve problem. Some athletes experience a “back-related” hamstring injury with a more gradual onset of pain. In such cases, MRI typically does not suggest a hamstring injury but may reveal injuries to the L5/S1 disc level and hypertrophy of the lumbosacral ligament resulting in impingement of the nerve roots. These nerve roots provide the nerve input to the hamstrings. If this input is impaired the muscle can weaken, making it more vulnerable to injury. This tends to be more common in older athletes, leading to a higher incidence of hamstring and calf strains in athletes over the age of 30 (Orchard et al. 2003).

Diagnosis of a hamstring injury is made primarily by obtaining a detailed history to help identify the cause of the injury and by performing a physical examination, which includes examining the lumbar spine, the knee, and the lower leg. Initially, the injured athlete will have worsening pain with either a passive stretch or resisted contracture of the hamstring. Often an area of point tenderness and a palpable fascial defect or balling of the torn muscle appear. Bruising below the level of the tear can be quite impressive and widespread. In instances in which a complete tear of the hamstring muscle or proximal tendon is suspected, MRI of the thigh will more clearly define the extent of injury and help determine treatment. Typically, MRI is extremely useful in localizing and detailing the extent of injury as well as in making a prognosis and helping to determine readiness to return to play. Plain X-rays are helpful only in ruling out bony avulsion injury of the ischial tuberosity (see p. 230). Musculoskeletal ultrasound is being used more often to identify the location and extent of a muscle injury.

In the case of grade II or III hamstring tears with resultant hematoma, the sciatic nerve can become entrapped. If this occurs, athletes often complain of pain with sitting, deep buttocks pain, or posterior thigh and lower leg pain with running at faster speeds. If the sciatic nerve is not compressed, there is usually no pain referral into the thigh or leg, only local discomfort. Direct pressure on the region, such as sitting, can invoke increased symptoms due to compression of nerves and other local structures. Magnetic resonance imaging is helpful in localizing the injury and identifying any scarring along the nerve.

Treatment

The treatment of hamstring strains and hamstring tendinopathy should be approached in phases. In the first phase, the goal is to decrease the amount of local bleeding, swelling, pain, and inflammation. After the first 48 to 72 hours, nonsteroidal anti-inflammatory (NSAID) medications can help limit inflammation and allow earlier rehab, but these should be used for only three to seven days postinjury because they can delay muscle regeneration and interfere with healing (Ramos et al. 2017).

During the first phase of treatment, acute conservative care of hamstring strains follows the guidelines for most soft tissue injuries (PRICE; see p. 62). Start icing and light compression with an elastic bandage wrap as soon as possible. The injured hamstring should be protected by limiting movement on hills, ramps, stairs, and uneven surfaces. The use of a cane or crutches should help reduce weight bearing, but holding the leg flexed at the knee and off the ground with crutches can aggravate the injury. A flat-footed gait or weight bearing as tolerated while using crutches is advocated until the athlete is walking pain free. If formal rehabilitative therapies are available, the use of concurrent electrical stimulation and ice can help reduce pain and inflammation.

About seven or eight days after injury, the second phase begins. Most experts agree that electrical stimulation, passive range of motion, myofascial release, and isometric exercises can be introduced at this point. The athlete should work on varying the position of the hip and knee during contraction. Stretching the hamstring while maintaining an anterior pelvic tilt, and holding each stretch for 20 seconds, has also been shown to be helpful. Pulsed ultrasound and therapeutic massage might further reduce swelling and promote rehabilitation.

Once athletes have achieved 75 to 80 percent of normal range of motion, they begin resisted stretching techniques, such as isometric contract–relax exercises, active isolated stretching, proprioceptive neuromuscular facilitation (PNF), and neural gliding to prevent scar tissue formation along the sciatic nerve. Initial strengthening through concentric resistive exercises (shortening contractures of the muscle), either isokinetic (constant speed) or isotonic (constant weight), are preferred over eccentric resistive (lengthening of the muscle) exercises because they pose less risk for reinjury. Swimming and cycling on a stationary bicycle may be added at this time if pain allows. Strengthening and flexibility of the lumbar spine, pelvis, and other leg muscles like the calf and quadriceps muscles are also added at this point. All exercises should be performed within pain-free range of motion.

The third phase is remodeling and occurs anywhere from one to six weeks after the initial injury. Pain-free static stretching of the hamstring, psoas, and quadriceps continues to be important to the rehab program. Eccentric strengthening, isokinetic strengthening, and PNF are also introduced. Some of the stretching and strengthening exercises should include hip rotation. This is important because many sport movements such as pivoting, cutting, or changing direction involve hip rotation, both internal and external, with hip extension, which places stress on the hamstring. The lumbar and scapular stabilization exercises should also be continued and advanced as tolerated.

In the final phase of treatment, the goal is returning the athlete to sport. This phase includes sport-specific activities, emphasizing increasing hamstring strength and flexibility to preinjury levels or better. The athlete progresses from jogging to sprinting, and performs cutting and pivoting activities as well as drills that incorporate rapid acceleration and deceleration. Plyometric exercises are added during this final phase and are continued as part of the athlete’s regular conditioning program.

Other modes of treatment that are beneficial for hamstring strains include pulsed ultrasound (late in the treatment), deep friction massage, and neuromobilization. Acupuncture is also helpful and may be used as soon as the injury occurs and throughout the rehab program. One of the newer treatments for hamstring strains of all grades is platelet-rich plasma (PRP; see also p. 343) injections and bone marrow aspirate (Young 2012). The reader is referred to chapter 17 on biologics for further information on these very promising therapies.

For athletes with complete proximal hamstring tendon tears who have persistent strength deficits despite conservative treatment, including regenerative therapies, surgical repair and subsequent rehab have been shown to restore near-complete strength and promote a return to athletic activities (Subbu, Benjamin-Liang, and Haddad 2015).

Return to Action

For hamstring strain and tendinopathy, athletes are cleared to return to play when they can participate in sport-specific activities pain free. Some professionals advocate return when isokinetic testing reveals strength within 10 percent of the sound limb at slow and fast speeds with equal flexibility and endurance. To prevent recurrence of the injury, the athlete should continue regular stretching and strengthening and should always warm up properly. Faithful compliance with hamstring and other hip girdle musculature stretching, as well as continued balanced strengthening of the quadriceps and hamstrings, will help prevent reinjury (Ramos et al. 2017).

One of the greatest risks for hamstring strain is a prior hamstring strain, so it is imperative that the athlete continue rehabilitation exercises. Recovery can occur as quickly as one week or take six weeks or more, depending on the grade of the strain.

FEMORAL STRESS FRACTURE

Common Causes

Fractures of the neck of the femur occur in only 1 to 10 percent of all lower-extremity stress fractures, and femoral shaft stress fractures are even less common. Stress fracture can occur anywhere in the medial femoral shaft but happens most commonly at the junction of the proximal and middle third. The femur is bowed anterolaterally at this junction; it is also the site of origin of the vastus medialis and the insertion point for the adductor muscle group.

The cause of femoral neck stress fracture might be unclear, but biomechanics, training intensity, hormonal influences, and alterations in bone mineral content likely play a part. Typically, athletes involved in endurance sports such as running and soccer experience such injury. Risk factors for the development of femoral neck and shaft stress fractures include sudden increases in mileage, intensity, or frequency of running. A new running surface or new shoes might also be implicated, as might low bone mineral density, short and thin femoral shaft, poor alignment, leg-length differences, weak lower-extremity muscles, overweight, and in females, amenorrhea (Brunet and Hontas 1994, Provencher et al. 2004, Ivkovic, Bojanc, and Pecina 2006). Coxa vara (hip deformity) is a likely risk factor for development of femoral neck stress fractures.

Identification

Because of the high rate of complications with femoral neck stress fractures (avascular necrosis, fracture displacement, malunion, and nonunion), the earlier the diagnosis, the better. Athletes with femoral neck stress fractures generally experience pain in the groin or hip. Athletes with femoral shaft stress fractures might experience thigh or knee pain, which decreases with rest and increases with activity.

Physical exam findings for femoral stress fractures are often limited. Tenderness might be noted in the area but is usually limited because of overlying muscle. Femoral shaft fractures can be diagnosed using various clinical tests (fulcrum test, fist test, or single-leg hop test), but imaging is the best. Femoral neck fractures might cause pain or limited movement with hopping, hip internal rotation and flexion, and resisted hip extension.

X-rays may not reveal a fracture line early on; the fracture site may not be visible in plain X-ray until the repair process begins (2 to 12 weeks after initial pain) and callus formation occurs. At this time a lucent fracture line might be revealed. Radionucleotide bone scan, which can immediately reveal a fracture, has long been considered the gold standard for early detection of stress fractures. Magnetic resonance imaging can also delineate stress fractures and surrounding inflammation in the bone, as well as soft tissue injuries.

Treatment

Fractures to the neck of the femur occurring on the compression or medial side are considered more stable and can be managed conservatively. Athletes are placed on crutches for four to six weeks to reduce weight bearing on the limb. X-rays can then help monitor healing. Tension-side (outer-lateral) femoral neck fractures have a high rate of displacement, and internal fixation is recommended. Surgical fixation often requires placing pins through the fracture site to stabilize the fragments. For some nondisplaced tension-side stress fractures, strict bed rest and weekly X-rays have provided good results. Athletes with stress fractures that are not well aligned or those who have tension-side femoral neck stress fractures should be referred to an orthopedic surgeon for evaluation for emergent reduction and fixation.

Femoral shaft stress fractures are much less common, making up only 2 to 7 percent of the stress fractures seen in athletes (Ivkovic, Bojanc, and Pecina 2006). Athletes will often complain of vague anterior thigh pain, worse with hopping or running. Diagnosis is made in a similar manner to femoral neck stress fractures. The athlete should be placed on crutches and allowed toe-touch weight bearing at most for one to four weeks. Advancement off crutches occurs if there is no pain when walking and if there is X-ray evidence of healing. Successful treatment algorithms have advanced athletes through increasingly difficult activities based on their response to two different physical exam tests—the hop test and the fulcrum test. These tests are performed every three weeks. Athletes who are pain free with both tests are advanced to the next level. This algorithm has successfully returned athletes back to sport in 12 to 18 weeks. Athletes are also monitored with serial X-rays to ensure complete healing (Ivkovic, Bojanc, and Pecina 2006).

Return to Action

Return to running generally occurs 8 to 16 weeks after the onset of pain. Monthly X-rays for three months are recommended to ensure healing and no displacement. Before the athlete resumes training, the cause of the stress fracture should be determined. Amenorrhoeic females should undergo bone density testing and treatment for the amenorrhea before returning to sport. Training errors should be corrected and caution taken against a rapid increase in training mileage and intensity. Before athletes resume running they should be pain free during a fairly intense activity, such as cycling, swimming, or pool running, and have no pain with single-leg hopping.

Athletes should restrict themselves to no more than 3 to 5 miles (4.8 to 8 km) for weeks 1 to 3, with very slow increase in distance and intensity. If they remain pain free, they can increase distance gradually back to half their normal distance over the next two weeks. If symptoms return, the athlete should stop and return to the previous activity that did not cause pain (e.g., if running caused pain, the athlete returns to biking or swimming).

QUADRICEPS CONTUSION

Common Causes

Quadriceps contusions typically result from blunt trauma (usually from a knee or thigh). Initially, symptoms might seem minor, but significant swelling and pain and decreased range of motion can occur over the next 24 hours. The blunt trauma generally results in damage to the muscular layer adjacent to the bone, thereby injuring deeper muscle than is normally involved in strains. This injury is common in contact sports such as American football, rugby, karate, judo, soccer, hockey, basketball, and lacrosse.

Identification

Contusions are generally classified as mild, moderate, or severe; most are mild to moderate. This classification is determined 24 to 48 hours postinjury, when swelling and hematoma have stabilized. Classification is based on knee range of motion and physical findings. With all quadriceps contusions the athlete generally has an antalgic gait. Mild contusions of the quadriceps have greater than 90 degrees of knee flexion and mild tenderness. Moderate contusions of the quadriceps have 45 to 90 degrees of knee flexion and enlarged, tender thighs. Severe contusions have less than 45 degrees of knee flexion and significant swelling and pain with quadriceps contraction (Kary 2010). If the contusion is severe and there is severe pain and swelling, consideration of compartment pressure testing (CPT) is prudent to rule out compartment syndrome (see p. 260).

Initial X-rays can rule out a fracture. At two to four weeks postinjury, X-rays can also rule out traumatic myositis ossificans (see p. 259). Magnetic resonance imaging and musculoskeletal ultrasound can reveal the specific injury (hematoma, strain, or both) as well as the size and exact location.

Treatment

Early and aggressive treatment is the key for quick return to play and minimal complications. Athletes can return only when knee flexion is at least 120 degrees. Thus, the key is to treat athletes early, when they still have 120 degrees of knee flexion. At that point, the knee is passively flexed and wrapped to maintain 120 degrees of flexion. The athlete is braced or wrapped in this position for 24 hours and uses crutches (Aronen and Chronister 1992). Placing the quadriceps under tension should slow the intramuscular bleeding and maximize the quad stretch.

After 24 hours, the brace or wrap is removed; icing, electrical stimulation, and passive pain-free quad stretching follow. The athlete is encouraged to perform this passive stretch frequently throughout the day. Athletes use the crutches until they can perform a pain-free isometric quad contraction and until swelling has diminished and the thigh has returned to normal size (Aronen and Chronister 1992). Strengthening begins with knee and hip flexion and proceeds to knee extension as tolerated. Exercises are progressed as motion and strength return (Kary 2010).

If the athlete is not treated until after swelling and muscle spasm have occurred (thus making it difficult or extremely painful to attain 120 degrees of knee flexion), a modified approach to treatment is attempted. The prone athlete performs pain-free isometric knee extension exercises until the quad fatigues, causing the spasms to decrease. Once fatigue sets in, begin passive pain-free stretching of the quad. This pain-free extension, relaxation, and stretching exercise is initially performed three times. The knee is then immobilized in a hinged knee brace at the maximum degree of pain-free flexion. Ice and electrical stimulation are added at the next treatment, and the procedure is repeated. Athletes wear the brace continuously until they have 120 degrees of full-knee flexion (Aronen and Chronister 1992).

Return to Action

Athletes can return to action once they attain full range of motion and strength is equal to that of the noninjured leg. Return time is often within one to three weeks for mild to moderate contusions (Kary 2010). The athlete is fitted with a protective pad, which should be worn for the remainder of the season. Failure to treat a thigh contusion aggressively can delay return time up to four weeks.

QUADRICEPS STRAIN

Common Causes

The quadriceps muscle group consists of four muscles located on the anterior thigh: the vastus medialis, vastus lateralis, vastus intermedius, and rectus femoris. Only the rectus femoris crosses two joints (the hip and knee) and functions as both a hip flexor and knee extensor. The other three muscles are responsible for knee extension only.

Quadriceps strains are common in American football, rugby, soccer, track, basketball, hockey, and other sports that require repetitive sprinting, kicking, and jumping. Strains generally occur with a forceful (near maximal) quadriceps muscle contraction or forceful stretching of the quadriceps. Quadriceps strains generally occur at the musculotendinous junction and can be partial or complete. Grade I strains involve minor muscle fiber disruption. Grade II strains involve more extensive tearing of the muscle fiber with accompanying hemorrhage, and grade III strains are full tears of the musculotendinous junction. The rectus femoris muscle is most often strained, followed by the vastus intermedius and vastus lateralis.

Identification

If the athlete experiences more pain with knee flexion when the hip is extended than with the hip flexed, the rectus femoris is involved. The athlete will have pain and/or weakness with resisted knee extension, hip flexion, or both. Feeling the muscle can help localize the injury site. Defects, swelling, or a mass that occurs with knee extension are more commonly seen with grade II and III strains. It is difficult to palpate a defect in the muscle once swelling or hematoma formation has occurred. Magnetic resonance imaging and musculoskeletal ultrasound are considered the standard for imaging muscle strain injuries. In most cases, they can both identify the exact location and severity of the strain (Kary 2010).

Treatment

Treatment for quadriceps strains is similar to treatment for hamstring strains and follows a similar phase-based approach (see p. 251). Once treatment has progressed to pain-free motion, the athlete begins isometric exercises at full extension and progresses to 90 degrees of knee flexion. Straight-leg raising exercises should be avoided early on because they place the greatest stress on the rectus femoris. Isometric quadriceps strengthening should be done early to facilitate muscle reeducation (Kary 2010). Gentle and cautious active stretching is initiated in this phase. Stretching generally starts with the athlete in a prone position, actively flexing the knee against gravity as tolerated. During the final stage of rehabilitation and prior to return to sport activities, force absorption and production exercises are added—for example, jumping down from a one-foot box, absorbing the force, and then jumping back up from that position. Plyometric exercises are also added at the final stage of recovery.

Acupuncture (see chapter 16), especially in the acute phase, is also helpful in decreasing pain and swelling, which in turn promotes increased range of motion and helps the athlete through rehabilitation more quickly. Acupuncture should be used as early as possible and continued through the rehab process. Platelet-rich plasma therapy and bone marrow aspirate have also been shown to be helpful in speeding recovery; see chapter 17 for more detail on these treatments.

Return to Action

The athlete returns to sport when range of motion is full and pain free, when isokinetic strength testing is within 10 percent of the uninjured limb, and when the athlete can complete agility testing and sprinting without difficulty. The athlete should continue using compression sleeves with protective padding throughout the season. Return to full activity generally occurs two to three weeks after injury (Kary 2010).

MYOSITIS OSSIFICANS

Common Causes

Myositis ossificans is the formation of heterotopic (misplaced) bone within muscle that is in close proximity to trauma such as a hematoma, muscle tear, or fracture. It is a complication that often occurs with grade II and III quadriceps contusions, most commonly adjacent to the femur. In a study of military recruits with thigh contusions, myositis ossificans developed in 20 percent of treated contusions (Brunet and Hontas 1994, Kary 2010).

Identification

A sudden increase in pain, along with a decrease in range of motion and a firm mass developing three to four weeks after contusion, might be myositis ossificans. X-rays should confirm diagnosis, but the findings on X-ray often lag behind actual clinical symptoms (Kary 2010). What is often seen on X-ray is a “whiteish” collection. This mass might or might not be connected to the femur. Generally, it takes three to six months to mature (cease forming). Ultrasound can detect the formation of myositis ossificans before it appears on X-ray.

Treatment

Treatment is essentially the same as for quadriceps contusions (see p. 255). If left untreated, persistent loss of range of motion, painful bony mass, and significant limitations in athletic function can result. Therapeutic ultrasound may help to break up the myositic collection.

Additional treatments to consider are single low-dose radiation and the use of NSAIDs (specifically Indocin or Naprosyn) for two to six weeks (Larson et al. 2002, Wang et al. 1999, Kary 2010). Both are advocated to inhibit the formation of further heterotopic bone. Radiation may help in heterotopic bone breakdown.

In rare instances, surgical excision is needed. If so, it is imperative that the heterotopic bone formation reach full maturity before surgical excision, which takes about 12 to 24 months (Kary 2010). If the formation is cut out before it reaches maturity, it might reoccur and be greater than its original size. If surgery is performed, the athlete may be advised to begin a postoperative course of radiation to inhibit the reaccumulation of heterotopic bone.

Return to Action

Myositis ossificans can delay return time beyond what is required for a contusion. A physician or physical therapist should determine when the athlete can safely compete.

COMPARTMENT SYNDROME

Common Causes

In this condition, the “compartment” refers to the quadriceps muscle group enclosed by a layer of protection known as the fascia. Compartment syndrome is an entity in which pressure within a compartment is abnormally elevated. It can occur in the anterior thigh region in contact sports when a knee, helmet, or other hard object forcefully contacts the quadriceps or anterior muscle group. Rarely, excessive bleeding and edema following a quadriceps contusion can result in the compartment filling and causing compartment syndrome. When the swelling in the anterior compartment increases, compartmental pressure rises. This fascia does not have the ability to expand a great deal. Thus, a large amount of swelling causes an increase in pressure within the muscle compartment, which ultimately compresses the blood vessels and nerves within the compartment. This can deprive the quadriceps muscles of an adequate blood supply, effectively starving the muscle of oxygen and nutrients. If this process continues, it can result in muscle death.

Identification

Clinically, pain out of proportion to the injury, pain at rest, pain with passive knee flexion, and a diffusely tender and tense thigh suggest the possibility of compartment syndrome. Sensory deficits might occur along the saphenous nerve (medial knee and tibia). Motor deficits and absent pulses are late findings that imply more severe and permanent muscle damage. If any of these symptoms are present, the athlete is referred for emergent medical evaluation.

Definitive diagnosis is made by obtaining compartment pressures from the anterior thigh compartment. The critical pressure duration that can lead to permanent damage ranges from four to eight hours.

Treatment

The treatment for acute thigh compression is fasciotomy, or surgically cutting the fascia to allow the muscle to receive an adequate blood supply. The fascia is surgically closed again once the swelling resolves. Following surgical decompression, early rehab is begun to limit swelling, pain, and atrophy as well as to improve range of motion.

Return to Action

Following a complete rehab program, most athletes can return to their sports within 8 to 16 weeks, once they are cleared by their physician.

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