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Child Orthopedics
Spine - Cervical
Spine - Lumbar
Spine - Thoracic

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I've been diagnosed with a hamstring tendinopathy. I understand how I got it (overstretching and overuse before, during, and after running long distances). What I'm wondering is what actually happens to the tendon to cause so much pain and tightness?

The hamstring muscle is located along the back of the thigh. It helps bend the knee and extend the hip. That's why overuse from running with its repetitive hip and knee motion can cause hamstring problems. Athletes involved in sprinting and middle- to long-distance running events seem to be affected most often. 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. Tendinopathy is another term for any disorder affecting the tendon. 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 results of lab studies of hamstring tendon tissue samples have been reported. Researchers examined the affected cells look under a microscope and compared them with normal tissue samples from the same area taken from one young athlete who had been treated for a fracture of the ischial tuberosity (bone where the hamstrings attach to the pelvis). 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.


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