It's incredible to read that others have gone through exactly what I have! Thank you for your post arniar. I thought I was the only one that has had this rare complication. I have the exact same problem with my hamstring and I've been dealing with it for 14 years! I had an ACL reconstruction in 1996 where the surgeon harvested the gracilis and semitendinosus muscles, and a month after the surgery I had extremely painful cramping in the back of my leg. There was and still is a bulge closer to the knee, and the doctors could never figure out why the bulge wasn't up near my pelvis. They figured if the problem was that the tendon of the hamstring never regenerated, then when the hamstring contracts it should pull upwards and form a bulge there, not down by the knee.

I went through 3 different Wikipedia reference-linkMRI's to figure out what was going on, and it was obvious that my injured leg was very different from my normal leg, but none of the doctors had a clear idea why. They proposed various ideas, and suggested different treatments including just cutting open the back of my leg and having a look. One of the surgeons said he thought it would make a great paper in a journal because he was certain nobody else had gone through what I have.

In the end, I tried lots of physical therapy and while the pain is not as bad as it was, it's never gone away and my leg has never been the same. If I do dead lifts or squats, the hamstring in the back of my right leg immediately cramps up. I decided not to do another surgery because none of the orthopedic surgeons had a clear idea of what was best to do. One doctor thought the problem was due to the release of the fascia covering the hamstrings during the operation, and another thought I actually ruptured my semimembranosus training after the surgery. The doctors said they didn't think it could be the semitendinosus muscle causing the problem because how could it rupture near the pelvis when the lower tendon was cut by the surgery? It's interesting that the doctors say that's what's happened to you arniar.

Has anyone ever been able to figure out a treatment for this problem that was successful? I would love to finally feel normal again after all this time.