HAMSTRING TEAR
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What is a Hamstring Tear?
Muscle strains are the most common sports injuries. Hamstring and quad muscles are the most commonly injured muscles. These injuries are especially common in "weekend warriors" (guys and gals in their late 30s and early 40s who were former athletes that now work desk jobs all weekband return to their former glory on weekends). A strength imbalance between the hamstring and quad muscles (these are opposing muscle groups) is typically the underlying risk factor for tearing the muscle.
Our hamstrings are a collection of four muscles in the back of the thigh (the semimembranosus, semitendenosus, the biceps femoris longus and brevis). They got the name hamstrings because butchers used to hang pigs by these muscles outside their shops.
They are powerful muscles and they are important for running as they extend your hip and flex your knee (unlike most muscles, which only affect one joint, the hamstrings affect two joints: hip and knee). The hamstring muscles are typically injured during sprinting activities. The muscle can be strained (partial tear) or torn. The weakest link is where the muscle turns into the tendon (called the musculo-tendinous junction, or "myotendinous junction"). Sometimes the tendon is pulled off the bone, which is called an “avulsion” injury. This occurs when the tendon itself is stronger than its attachment to the bone (because a chip of bone actually breaks off, its sometimes referred to as a fracture).
How is a Hamstring Tear diagnosed?
People with this injury will come into the doctors office complaining of pain in their butt or back of the thigh. People will often have a large bruise on the back of their thigh (muscle has a large blood supply because it needs oxygen delivered rapidly for it to function. when muscle is torn, it bleeds a lot and will thus form a large bruise).
A good test for this injury is the “taking off the shoes test”, which involves having the patient removing their shoes by using their feet only (this requires use of the hamstring muscle). If this causes significant pain, a hamstring injury more likely.
Most muscle strains do not require an x-ray because the history of injury and examination are sufficient for diagnosis. X-rays are great at showing broken bones, but they dont show muscle, and therefore are rarely helpful with this injury. In cases of a severe injury and significant pain, x-rays are ordered. Sometimes, they will show a small “chip” of bone, which is pulled off by the hamstring tendon (an avulsion injury).
An MRI is sometimes used to identify the severity of tendon injury, however, it rarely changes the treatment and therefore is not required for most injuries.
How is a Hamstring Tear treated?
Hamstring injuries are notorious for taking a long time to get better. Its common for athletes to sit out for weeks, only to re-injure the muscle their first day back. To minimize the risk of prolonged injury, its important to closely follow your doctors treatment plans. Here is a basic overview:
Treatment should proceed in a stepwise fashion, from less invasive to more involved. The RICE method (Rest, Ice, Compress, Elevate) is an effective treatment for most of these injuries. Patients should use crutches for the first 5-7 days, and limit their activity on the leg for about 4 weeks to allow time for healing. Range of motion exercises, followed by stretching and finally strengthening should be gradually started once the initial pain and swelling as resolved. Some doctors will give a steroid shot within the first 48 hours of injury to reduce inflammation and improve pain.
Mild strains can typically return to sports within a week, while moderate or severe strains typically require 3-6 weeks of healing before the patient is ready for competition.
In rare cases of a complete avulsion injury (the hamstring pulls off the bone, and actually pulls a large size bone chip with it), surgery is helpful to reattach the hamstring using one or two screws. The benefit of a surgery in these severe injuries has been demonstrated for both acute and chronic injuries. There are complication risks associated with surgery, which includes abnormal bone formation within the hamstring muscle, and subsequent pain with sitting.
What is the long term outcome?
The expectation is for people to fully return to their pre-injury activities after complete rehabilitation and strengthening. However, full recovery often takes many weeks. It is important to achieve full recovery before returning to sports because there is a high re-injury rate (up to 33%), but proper conditioning and rehabilitation will reduce this risk.
References
Cellular Muscle Repair
1) Noonan TJ, Garrett WE Jr. Muscle strain injury: diagnosis and treatment. JAAOS 1999; 262-9. full article. review.
2) Gates CB et al . Regenerative medicine for the musculoskeletal system based on muscle-derived stem cells. JAAOS 2008; 16: 68-76. full article. review.
3) Levine et al. Intramuscular corticosteroid injection for hamstring injuries: a 13-year experience in the National Football League. AJSM 2000; 28: 297-300. full article. steroid injects effectively get players back on field.
Complete Rupture Surgery
1) Anderson K et al. Hip and groin injuries in athletes. AJSM 2001; 29: 521-33. full article. review.
2) Klingele KE, Sallay PI. Surgical repair of complete proximal hamstring tendon rupture. AJSM 2002; 30: 742-7. full article. complete prox rupture repair 90% good outcome (10/11 patients), 6 mo return to sport. early and late repairs both did well.
3) Birmingham P et al. Functional outcome after repair of proximal hamstring avulsions. JBJS 2011. 93; 1819-26. full article. complete prox rupture excellent outcome subjective/objective, 95% return to sports, equal strength.