Hamstring Autograft (aka “HS”) is a graft made of the patients own hamstring tendons. There are several major hamstring muscles that act to flex (bend) the knee, but there is a lot of redundancy in them. That is, they have multiple origins (places where they attach at the upper thigh end) and multiple insertions (places where they attach at the knee end). Because of this redundancy, the hamstrings are God’s gift to the sports surgeon – we can take 2 hamstrings to use as grafts with arguably very little compromise in function.
During an ACL reconstruction with hamstring autograft, the graft typically comes from the gracilis and semitendinosus tendons, leaving the muscles they are attached to in place. Theoretically, the muscle scars to the remaining hamstring attachments over time, so function is preserved. The gracilis and semitendinosus tendons are then doubled up, forming a multi-strand graft that can be plugged into the bone sockets during reconstruction.
- The surgery is slightly less painful than the bone-patellar tendon-bone (BTB) graft initially, and the long-term risk of graft-related anterior knee pain is avoided.
- The incisions are slightly more cosmetic.
- The rates of arthritis at long-term follow-up are about 20% (half that of the BTB graft)
- In most patient populations, re-tear rates are nearly equivalent to BTB grafts.
- Knee stiffness or loss of motion is rarely an issue.
- The girth and length of the hamstring graft can be variable, this is especially a problem in younger females, children, and (anecdotally) in females of relatively short stature. Occasionally the HS graft needs to be augmented with more graft material to obtain a suitable size.
- In some patient populations (e.g. young female athletes and some male athletes with a high exposure to cutting athletics) hamstrings have a higher re-tear rate than BTB grafts. [i]
- While strength in a typically functional range of motion is preserved (e.g. the range of motion in which we run, jump, squat, etc), patients can sometimes note some strength deficits in the most extreme degrees of knee flexion (e.g. trying to get the heel all the way to the buttock). This is rarely a problem functionally, but people who do a lot of yoga sometimes complain about it. It’s a total Seattle thing…
The Take Home Message: Hamstring autograft is the “4WD SUV of grafts” – It is reliable, it is flexible, it is a workhorse that works great for most people with few exceptions (from taking out the groceries all the way to tennis practice to the marathon). It isn’t too ‘costly’ with respect to pain or arthritis, but high performance individual, elite athletes and folks exposed routinely to contact sports might be looking for a little more.
[i] Barrett, GR, et al. Arthroscopy. 1001 Jan;18(1):46-54.