Houston Methodist. Leading Medicine

Knee News

First Report on the Surgical Treatment of Hamstring Tendinopathy

Athletes suffer their fair share of tendon problems. Most often there's knee pain from patellar tendon disorders or ankle pain from Achilles tendinopathy. Tendinopathy is another term for any disorder affecting the tendon.

In this study, a less common but equally disabling tendinopathy is examined: hamstring tendinopathy. The hamstring muscle is located along the back of the thigh. This muscle helps bend the knee and extend the hip. The muscle is made up of three main parts: the semimembranosus, semitendinosus, and the biceps femoris. The semimembranosus is the specific area affected by hamstring tendinopathy.

Surgery for buttock pain coming from the upper or proximal end of the hamstring is presented as a possible treatment option. This may be the first report of such an approach and its results. Athletes involved in sprinting and middle- to long-distance running events are affected most often.

Several questions are part of this study. First, when conservative care fails to relieve painful symptoms, can surgery help? And second, what's going on in the tendon that's causing this painful syndrome? If a tissue sample is examined under a microscope, what will we find that might help us better understand the problem?

Everyone in the study was diagnosed with proximal hamstring tendinopathy. Athletes between the ages of 16 and 63 (men and women) were included. Some were professional (competitive) track, cross country, or soccer athletes. Others were recreational sports enthusiasts involved in endurance sports such as running, mountain or rock climbing, and cross-country skiing.

Symptoms were similar for everyone: pain in the buttock area that was worse with activity and better with rest. Sitting for long periods of time would cause pain at the ischial tuberosity. That's a bony bump also referred to as the sit bones. The term sit bones is used because you can usually feel them at the base of the buttocks when sitting on a hard surface.

No one had pain that went past the midthigh. Stretching the hamstring muscles often made the symptoms worse. Treatment was geared toward modifying aggravating activities. Sometimes complete rest was advised. Gentle stretching, antiinflammatory drugs, and physical therapy were also possible nonoperative (conservative) approaches to care. When those didn't work, then surgery was considered.

Surgery involved first cutting the lower edge of the gluteus maximus (buttock) muscle. This allowed the surgeon to get down to the level of the hamstring tendon attachment to the ischial tuberosity. The portion of the hamstring muscle referred to as the semimembranosus tendon was then cut about three to four centimeters away from its insertion point on the tuberosity. This procedure is called a tenotomy.

The cut tendon and muscle were allowed to retract (pull back) away from the tuberosity. Then the surgeon reattached the tendon with sutures (stitches) to another part of the hamstring muscle (to the biceps femoris tendon). This is a way to shield the affected tendon from ongoing mechanical stress. The goal is to give the semimembranosus a chance to heal by protecting it from overuse.

The surgeon checked the sciatic nerve to see if there were any adhesions or fibrous strictures holding it from moving freely. There were a couple of patients who had minor adhesions around the sciatic nerve, which were cut free. But for the most part, the nerves in the area looked fine. And no one really had any sign of hamstring rupture at the time of the operation.

The authors provided detailed step-by-step descriptions of the operation with drawings to give the surgeon an idea of how to do the procedure. They took samples of the tendon tissue from 15 patients and compared them with normal hamstring tendon samples. The normal samples were from one young athlete who had been treated for a fracture of the ischial tuberosity.

Results were reported in two ways. First in terms of function, motion, strength, and return-to-sports. Second, based on histologic findings. Histology refers to how the cells look under a microscope. In the case of the first measurements, a majority of the patients were considered a surgical success. They could participate in sports activity at a level equal to (or better) than before their symptoms developed.

In a small number of athletes, pain and tightness persisted. They could no longer play at the same competitive level and had to reduce their activity to recreational participation only. Four of the 90 patients had to have a second operation because their results were considered poor with continued symptoms keeping them from pursuing their athletic careers.

What about the lab results? Did they find anything that would help explain what was going on? What they saw were changes in the cell structure to suggest tendon damage but not active inflammation. This was described as rounding of the tendon cell nuclei, increased ground substance (base material making up the tendon), and disintegration of the collagen (tissue) structure.

There were no signs of extra calcium, cartilage, or bone formation within the tissue samples. There were increased blood vessels to the area indicating an attempt by the tendon to heal itself. Added fat cells were interspersed between the bundles of collagen fibers. This suggests a degenerative process within the tendon. All of these findings were helpful in understanding why the semimembranous tendon looked thickened on MRI images.

The authors recommend using the term tendinopathy instead of tendinosis whenever the patient presents with pain, swelling, and impaired athletic performance caused by those symptoms. The old term hamstring syndrome to describe this condition is no longer used.

They say their histologic study sheds some light on tendinopathy as a pathologic process. Specifically, the lab samples support the theory that the tendon tried to heal but failed. Possibly repetitive stretching and overuse contributed to the damage done. The swollen and thickened tendon/muscle complex puts pressure on the sciatic nerve causing the painful symptoms. It's not always clear when the pain is coming from the tendon versus from the nerve.

No one knows exactly why the semimembranosus portion of the hamstrings tendon thickens and creates this painful condition. When other areas of the hamstrings are affected, recovery is faster than when the semimembranosus is involved. Perhaps this portion of the muscle has a slower or decreased healing capacity compared to the other parts of the muscle.

The authors note that often proximal hamstring tendinopathy becomes a chronic problem before it is properly diagnosed. The delay makes treatment more difficult. Even with steroid injections early on, many patients end up with recurrence of the painful symptoms. This study doesn't prove it, but it does present some evidence that perhaps early tenotomy may prevent future hamstring tears or ruptures.

This is just the start of researching ideas around this particular diagnosis. There are many other variables and factors to explore. For example, what's the effect of eccentric muscle training on proximal hamstring tendinopathy? Eccentric refers to a process of lengthening the muscle from a shortened position as a means of strengthening it. This type of therapy has worked for other types of tendon/muscle problems. Research to explore other (less invasive) ways to perform the tenotomy should also be carried out.

For now we can say the surgical procedure of tenotomy as described in this study was both safe and effective in reducing pain from hamstring tendinopathy. Athletes were able to return to sports activities and avoid an early end to their athletic careers.

Lasse Lempainen, MD, et al. Proximal Hamstring Tendinopathy. Results of Surgical Management and Histopathologic Findings. April 2009. Vol. 37. No. 4. Pp. 727-734.


*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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