AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Hamstring injuries are common problems that may result in significant loss of on-field time for many athletes because these injuries tend to heal slowly. Once injury occurs, the patient is at high risk for recurrence without proper rest and rehabilitation.

The hamstring muscles are 3 muscles in the posterior thigh, the semitendinosus, semimembranosus, and biceps femoris. The semitendinosus originates at the ischial tuberosity and inserts at the pes anserine; the semimembranosus originates at the ischial tuberosity and inserts at the posterior medial tibia. The biceps femoris has a long head that originates at the ischial tuberosity and a short head at the posterolateral femur and inserts into the head of the fibula. Both muscles serve as knee flexors and hip extensors. At heel strike of the gait cycle, the hamstrings actually contribute to knee extension through closed chain kinetics. During the gait cycle, the biceps femoris contracts eccentrically in terminal swing, which is important in the pathology of the injury, as discussed later.

Frequency

United States

Hamstring strain is a fairly common injury in physically active individuals.

Mortality/Morbidity

No mortality is associated with hamstring strain; however, morbidity is common, due to pain and reinjury if proper rehabilitation does not occur before the patient returns to preinjury activity levels.

Age

While hamstring injuries can occur in people of any age, incidence increases with age.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

Hamstring strain is a noncontact injury and usually occurs with either acute or insidious onset. Strain injuries frequently are seen in athletes who run, jump, and kick. Avulsion injuries are seen in patients who participate in water-skiing, dancing, weight lifting, and ice-skating. The avulsion injury usually follows a burst of speed, and the patient may report a popping or tearing sensation. The most commonly affected muscle area in the hamstring complex is the short head of the biceps femoris, possibly because of its innervation.

• As with most strain injuries, the injury can occur at the following 4 places:
• • Origin of the muscle
  • Musculotendinous junction
  • Muscle belly
  • Insertion of the muscle
• Injury is most likely to occur while the musculotendinous junction undergoes maximum strain during eccentric contraction of the hamstrings.
• The American Medical Association (AMA) has described 3 grades of severity of hamstring injuries.
• • First-degree strain is the result of stretching of the musculotendinous unit and involves tearing of only a few muscle or tendon fibers.
  • Second-degree injury refers to a more severe muscle tear without complete disruption of the musculotendinous unit.
  • Third-degree injury refers to a complete tear of the musculotendinous unit.

Physical

In addition to pain in the posterior thigh, the physical examination may reveal any of the following signs or symptoms:

• Tenderness over the site of injury
• Ecchymosis
• Palpable mass
• • A palpable defect may be felt with severe strains, but swelling and the deep location of the muscle may obscure this finding in the acute stage.
  • Palpate the muscle for a defect with the patient in a prone position and the knee flexed to 90°. This position relaxes the muscle and decreases cramping and pain. Palpate while maintaining slight tension on the muscle.
• Pain with passive extension of the knee and the hip flexed at 90°, as compared with the noninjured side, which stretches the muscle
• Pain with resisted knee flexion, which activates the muscle

Causes

Many different causative factors can contribute to hamstring injuries. The most significant causes include the following:

• Inadequate flexibility of the hamstrings can result in injury. This may be related to the patient having no or a poor stretching routine.
• Inadequate strength or endurance of the hamstrings with either a side-to-side weakness or an imbalance between the hamstrings and the knee extensors can lead to injury.
• Muscle fatigue can lead to dyssynergia of muscle contraction.
• Insufficient warm-up time may be involved.
• Poor running technique may play a role.
• Return to activity before complete healing has occurred can lead to recurrence.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Trigger points
Lumbosacral radiculopathy

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Hamstring strain is diagnosed primarily by physical examination and history. Lab studies are not of significant assistance in making the diagnosis.

Imaging Studies

• The diagnosis is typically clinical, but some imaging studies may helpful if the clinical picture is unclear.
• • X-ray films can rule out an avulsion injury from the ischial tuberosity or other fractures, but they generally are not otherwise of significant help.
  • Ultrasound studies may aid the physician when confirming the diagnosis of hamstring strain, but they do not always indicate definitive results. The quality of the study is related to the expertise of the technician and the cooperation of the patient.
  • When a confirmation or grading of a hamstring strain is necessary, MRI is the most sensitive test used when considering the diagnosis of hamstring strain, but it should be used sparingly because of the cost and patient discomfort. Some data suggest that MRI is helpful when attempting to predict return in a high-performance athlete in combination with supporting clinical evidence. Studies have shown that more than 6 weeks' delay before return to sport has been reported with the following:
    • Complete transection
    • Involvement of 50% of cross-sectional muscle
    • Ganglion-like fluid collections
    • Hemorrhage-like signal
    • Distal myotendinous tears
    • Deep muscle tears

Other Tests

• For higher-level athletes, isokinetic muscle strength testing may quantify muscle weaknesses or imbalances that may lead to a chronic injury or recurrence.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Rehabilitation Program

Physical Therapy

The key to successful recovery from a hamstring strain is recognition of the injury and of the severity of the stain. Physical therapy (PT) is the mainstay of treatment. The program depends on the severity of the injury and on the time that has elapsed since the injury. Very few scientific data are available to determine specific rehabilitation and treatment protocols for hamstring injuries. The program below is just a guide and should be tailored to individual patient needs.

• Acute phase: During the acute phase (1-5 d), most of the treatment is geared toward decreasing the inflammation and maintaining range of motion. As for most strains, PRICE (ie, protection, rest, ice, compression, elevation) is the initial treatment. When the pain has decreased, the therapist may begin painless gentle passive range of motion and active-assistive range of motion. The patient also may benefit from a cane or crutches to aid in ambulation to keep active. Even if a patient with a first-degree injury is feeling better after a few days and wants to return to participating in his or her sport, it is usually recommended that he or she complete a rehabilitation program to avoid chronic injury. Muscle strengthening, balance, and stretching should be emphasized to the patient as a prevention of recurrence.
• Subacute phase: The subacute phase (5 d to 3 wk) is when the inflammation of the injury appears to be lessening. The goal of treatment in this stage is to begin some active range of motion and start strengthening. Aquatic therapy is helpful in encouraging activity with decreased weight bearing. Pain-free submaximal isometric exercises also are encouraged. A transcutaneous electrical nerve stimulation unit may be used to provide some pain relief at this time. Ice is also helpful to decrease pain and inflammation. The patient also should resume cardiovascular training, which may include swimming with a pull buoy between the legs, and upper extremity exercises.
• Remodeling phase: The remodeling phase (1-6 wk) is when the patient is able to perform isometric exercises at 100% effort without pain. Prone isotonic hamstring exercises are now added to the transcutaneous electrical nerve stimulation unit and ice. Begin unilaterally with ankle weights, using low weight and a high number of repetitions. Slowly increase the weight as tolerated as long as the patient's pain is not increased afterwards. Importantly, do not increase the weight too rapidly because this could lead to a chronic injury.

  Once concentric strengthening is tolerated at a normal level, the patient may begin eccentric strengthening. Because this exercise puts the most strain on the muscle, supervised exercising and slow progression of weight is recommended. In the prone position, the patient performs a unilateral contraction to 90° of knee flexion and then slowly lowers the weight. If the patient experiences pain or stiffness, then decrease the weight to a more tolerable amount. When the affected leg is within 10% of the unaffected leg, then the patient may advance to a more aggressive therapy program. Continued stretching of the hamstring is essential and should occur prior to exercise. Moist heat prior to exercise may provide improved results. A posterior pelvic tilt may help eliminate lumbar compensation.

• Functional stage: The functional stage is 2 weeks to 6 months. At this point, the patient should have a normal gait pattern and can begin fast walking. When the patient can ambulate for 20-30 minutes at a fast speed without pain or stiffness, short periods of jogging can be added to the fast walking. When the patient can perform a 15- to 30-minute jog, then short periods of sprinting may be added to the jog. Eventually, more sport-specific exercises may be added. Have the patient continue with the hamstring strengthening and stretching throughout this stage.

  During the later stages of therapy, plyometric exercises may be used to increase speed and power during training. These exercises consist of muscle stretching followed by concentric contraction, allowing for a stronger contraction because of muscle facilitation and decreased inhibition. Low-level exercises may be used initially (eg, jumping rope), followed by higher-level exercises as tolerated (eg, side jumping over a low object, jumping onto and off a box). Because the higher level exercises are associated with a higher rate of injury, they should be performed with supervision.

• Return to play: This can occur anywhere between 3 weeks and 6 months. Isometric strength testing and flexibility testing may be performed prior to returning to play to ensure that no subtle deficits are present that may lead to chronic injury. The clinician must impress upon the patient the importance of stretching and warm-up prior to activities to prevent reinjury. Less than 5 weeks are required before return to play for patients with (1) superficial muscle injury and (2) muscle injury that involves a small cross-section of muscle. In patients whose injury was due to poor biomechanics, care should be taken to correct the underlying cause. The patient should be supervised during stretching and exercise in order to assess poor technique and correct it.

Surgical Intervention

Need for surgical intervention is extremely rare after a hamstring injury. Surgery is recommended only in the case of complete rupture of the proximal or distal attachment of the myotendinous complex into the bone.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

The standard choice for medication is nonsteroidal anti-inflammatory drugs (NSAIDs). These medications not only provide analgesia but also can decrease some of the mediators of inflammation. When to administer NSAIDs to achieve the most beneficial effect is debated. One argument is to administer them immediately following injury to avoid side effects that may interfere with muscle remodeling and repair. The other argument is to delay use until 2-4 days after the injury, so they do not interfere with the chemotaxis required for the laying down of new muscle fibers. No consensus has been reached on which approach to timing yields the best outcome.

Drug Category: Nonsteroidal anti-inflammatory drugs

Have analgesic, anti-inflammatory, and antipyretic activities. Their mechanism of action is not known, but they may inhibit cyclo-oxygenase activity and prostaglandin synthesis. Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell-membrane functions.

Drug Category: COX-2 inhibitors

Cox-2 inhibitors have a lower incidence of GI bleeding as compared with other NSAIDs, although there is still a risk involved. They should be considered for use in patients with a history of GI bleed or those who have a high risk for a bleed.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Outpatient Care

• See Physical Therapy section for a discussion of further outpatient care.

Deterrence

• Prevention of reinjury is dependent upon successful completion of the rehabilitation program and preactivity warm-up and stretching, although there is limited evidence to prove this conclusion.

Prognosis

• The prognosis usually is good for complete or near complete improvement in 6-18 weeks. Unfortunately, there are patients who develop chronic problems, possibly due to repeated stresses on the tendon that cause tendinosis. In this case, the tendon is not healing properly, and fibrotic changes take place in the tendon.

Patient Education

• Once the injury has healed and the rehabilitation program has been completed, emphasize the importance of proper warm-up and stretching before participation in vigorous physical activity.
• For excellent patient education resources, visit eMedicine's Sprains and Strains Center and Sports Injury Center. Also, see eMedicine's patient education articles Muscle Strain and Sprains and Strains.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Failure to diagnose and treat this condition properly could lead to a chronic condition, as well as a possible worsening of the condition. An athlete may lose game time, as well as practice time.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

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• Clanton TO, Coupe KJ. Hamstring strains in athletes: diagnosis and treatment. J Am Acad Orthop Surg. Jul-Aug 1998;6(4):237-48. [Medline].
• Hartig DE, Henderson JM. Increasing hamstring flexibility decreases lower extremity overuse injuries in military basic trainees. Am J Sports Med. Mar-Apr 1999;27(2):173-6. [Medline].
• Hennessey L, Watson AW. Flexibility and posture assessment in relation to hamstring injury. Br J Sports Med. Dec 1993;27(4):243-6. [Medline].
• Laskowski E. Concepts in sports medicine. In: Braddom RL, ed. Physical Medicine and Rehabilitation. Philadelphia, Pa: WB Saunders; 1996:. 930-1.
• Medical Economics Staff. Physician's Desk Reference. 55th ed. Medical Economics Co;2000:2631-4.
• Pomeranz SJ, Heidt RS Jr. MR imaging in the prognostication of hamstring injury. Work in progress. Radiology. Dec 1993;189(3):897-900.
• Scoggin JF 3rd. Common sports injuries seen by the primary care physician. Part II: Lower extremity. Hawaii Med J. May 1998;57(5):502-5. [Medline].
• Speer KP, Lohnes J, Garrett WE Jr. Radiographic imaging of muscle strain injury. Am J Sports Med. Jan-Feb 1993;21(1):89-95; discussion 96. [Medline].
• Worrell TW. Factors associated with hamstring injuries. An approach to treatment and preventative measures. Sports Med. May 1994;17(5):338-45. [Medline].
• Yamamoto T. Relationship between hamstring strains and leg muscle strength. A follow-up study of collegiate track and field athletes. J Sports Med Phys Fitness. Jun 1993;33(2):194-9. [Medline].

Article Last Updated: Sep 30, 2005