Q: How well do hamstrings heal after surgery to re-attach the tendon to the bone at the bottom of the pelvis? I asked my surgeon this question but we got distracted in our conversation and I never did get an answer to that question. I guess I'm worried I'll go through all this and it won't heal at all.

A: A complete tear or avulsion of the proximal hamstring tendon often requires surgery to heal. (Proximal means the tear occurred where the tendon attaches to the pelvis). How well patients recover from this type of surgery was actually the topic of a recent study.

Strength, satisfaction with results, return-to-sports participation, and function were the key areas measured. The number of patients involved was small (13) but the follow-up was good (from two up to five years). Each patient tore the hamstring as a result of a traumatic injury during a sporting event.

Surgery was done within two months of the injury for all but one of those athletes. Ages ranged from 26 to 58 years old, so you can see these weren't just young sports participants. And that makes the findings of this study unique and important. More middle-aged adults are involved in sports and remaining physically active. There are more of these kinds of injuries.

Tools used to assess results included MRI images (a way to visualize tendon healing), leg circumference (assessing muscle atrophy), goniometer (measuring range of motion), Lower Extremity Functional Scale (LEFS; function), Tegner Activity Scale (physical function and activity), and isokinetic machine (strength). Pain and other symptoms such as numbness or nerve palsy were also evaluated.

The goal of the study was to use these clinical, radiological, and functional means of evaluating patient results after surgery to repair proximal hamstring ruptures. It is a retrospective study meaning the authors took a look back after the treatment had been completed to see how everyone fared. Like you, they wanted to know: does the tendon heal?

Here's what they observed. There were no differences in side-to-side muscle circumference measurements but they found strength was not equal. The surgical side was still only 78 per cent as strong as the normal, uninjured leg. The really unusual finding was that these patients thought the surgical leg was at least 90 per cent as strong as the other leg.

All but one patient was completely satisfied with the results. But the authors knew there were four of the 13 who had poor outcomes so they wondered how this could be. A closer look revealed that perhaps the tests used really didn't adequately evaluate patient satisfaction -- the questions asked might not have given the patients the opportunity needed to express dissatisfaction with their particular results. That is something they intend to investigate more fully in future studies.

Almost half of the group (45 per cent) reported a significant decrease in activity level and sports participation after surgery compared with before the injury. Other studies report a much higher return-to-sports (80 per cent or more). So this is another area where closer study is suggested. In future studies, it will be important to find the right tools to accurately measure satisfaction and function after surgical repair of this type of injury.

And finally, MRIs are one way to look for tendon healing. In the study mentioned here, there was a 100 per cent rate of hamstring tendon healing. There were no signs of tendon tears or fraying. In some cases the healing tendon was filling in with a small amount of fat instead of normal collagen tissue. This finding might account for the lower rates of strength and function observed.

The authors concluded that surgical repair of a complete proximal hamstring tendon rupture in athletes of all ages does yield good results. But there were some lingering questions because hamstring function was not completely restored in this group of patients. As noted, this group of researchers intends to continue studying ways to adequately measure outcomes and improve patient results.

Reference: Jaskarndip Chahal, MD, FRCSC, et al. Clinical and Magnetic Resonance Imaging Outcomes After Surgical Repair of Complete Proximal Hamstring Ruptures. Does the Tendon Heal? In The American Journal of Sports Medicine. October 2012. Vol. 40. No. 10. Pp. 2325-2330.