Athletes involved in all sorts of activities can suffer a complete tear of the hamstring muscle. The hamstring is the large muscle along the back of the thigh. It goes from the pelvis down to the knee. In this report, falls, waterskiing, running or sprinting, soccer, football, hockey, in-line skating, dancing, tennis, and wrestling were reported as the events linked with hamstring injuries.

There were 23 cases of proximal hamstring rupture in this study. Proximal refers to the place where the muscle attaches at the top. For the hamstrings, the proximal muscle attachment is to the ischial tuberosities -- the bump of bone you feel in your buttocks when sitting down.

There are three separate tendons that meld together at this site. For a complete rupture, all three tendons are torn. The rip or tear could be anywhere along the muscle but this study focuses on tears at the ischial tuberosities. If it's the tendon that is torn and the attachment is pulled away from the bone, it's called an avulsion.

Treatment is based on several factors. First, how far from the bone did the tendon retract (pull away)? If the tendon only springs back a little bit (less than two centimeters), then surgery isn't usually needed.

If the tendon pulls back more than that (and especially if it pulls a bit of bone along with it), then surgery is most likely needed. That's because larger displacement of the tendon usually means more pain, weakness, and loss of function.

The surgeon also relies on the bowstring sign and MRI findings to make the diagnosis and determine the severity of the problem. A positive bowstring sign (indicating full rupture of the hamstrings) occurs when the examiner presses on the back of the knee just above the joint. There should be a cord of tendon that is easily felt on either side of the knee back there. But with a proximal rupture, the tension on the hamstring muscle is less so those tendons don't tense up or form a palpable cord.

A second factor guiding treatment is how long ago was the injury? Chronic injuries (those that occurred more than a month ago) that are asymptomatic (no symptoms, no pain) can be treated conservatively (without surgery). But for the athlete with significant pain who can't fully engage in his or her sport, surgery is indicated.

But to make sure that following these guidelines really provides the intended results, these surgeons followed their 23 cases for at least one full year (and up to nine years in some participants) to see what kind of results they got. When you think about it, there's no sense having surgery if the results aren't going to be better than letting it heal on its own. And that's what this report is about.

Tests were done to measure muscle strength and endurance. Level of return to activity was reported along with any symptoms (pain, weakness, numbness, stiffness). One-third of the group had acute injuries repaired surgically within four weeks after the trauma. The remaining two-thirds were considered chronic because the injury occurred more than a month before the surgery was done.

The researchers looked to see if age (athletes ranged in age from 19 to 65 years old), sex (male versus female), and time-to-surgery (acute versus chronic) made a difference in the final results. The majority of patients (18 of the 23) had an excellent result with full return to their preinjury level of sports participation. Five athletes never had that full (100 per cent) assurance that they could engage in all activities normally.

Those same 18 athletes with excellent results had no symptoms of pain, stiffness, or numbness. Their strength was measured as equal to or better when compared with the other (uninjured) leg. Those athletes who achieved full return of hamstring strength and endurance got back into their sport faster. Larger hamstring tears seemed to lag in endurance but not necessarily strength. Age was not a significant factor.

As far as postoperative complications go, the 18 patients who reported an "excellent" result did have some loss of sensation around the incision site. There was also a puckering of the skin where the tendon was reattached but this was not painful. Four of the remaining patients continued to have numbness (sciatica) but these four patients had the sciatica before surgery and they were all in the chronic group.

In summary, there are still many debates about the need for surgery to repair a ruptured hamstring muscle. Some studies show poorer results when the surgery is delayed. Other studies report no difference between groups of patients who are treated conservatively (nonoperatively) versus those who have surgery.

The authors of this study suggest that larger tears observed in patients with a positive bowstring sign may be the best candidates for surgery. In other words, the degree of displacement or retraction of the ruptured tendon is a reliable factor in pointing to the need for surgery. Chronic injuries can and do heal and patients recover fully. Patients who have sciatica before surgery may not get relief from those symptoms.

Reference: Patrick Birmingham, MD, et al. Functional Outcome After Repair of Proximal Hamstring Avulsions. In The Journal of Bone and Joint Surgery. October 5, 2011. Vol. 93-A. No. 19. Pp. 1819-1826.