Allografts

Allografts have the obvious advantage over autografts that they leave your own body intact. You’re not sacrificing any part of your body. But cadaveric allografts are expensive, and, more significantly, there is always the small chance that some disease will be transmitted. With your luck the cadaver will have had some hidden, horrible disease, right?. Because of this small chance, these grafts are heavily radiated to the point where cynics have likened them to a piece of bacon. That’s not really fair, but the point is that allografts are an acceptable but not ideal solution. Allografts tend to be used when multiple grafts are needed or when the patient is going for a second operation and an autograft has already been used during the first procedure.

All autografts sacrifice healthy useful tissue to create a new ligament, robbing Peter to pay Paul so to speak. In the future we can expect to either grow a new ligament or find an acceptable synthetic ligament. In the meantime, there are three sources of autografts: the patellar tendon, the hamstring tendons, and the quadriceps tendon, in order of current popularity.

The Patellar Tendon Graft

The patellar tendon graft includes the middle third of the tendon connecting your kneecap (patella) to your tibial tuberosity (the knob at the top of your shin bone), as well as a piece of bone at each end of the tendon. One piece of bone comes off the kneecap and the other comes off the tuberosity. You would think that this would leave the rest of the patellar tendon quite weakened and prone to rupture, but with cautious rehabilitation that has not been the case. This is fortunate because a rupture of the patellar tendon is an orthopedic disaster requiring at the very least one major operation and a long period of recovery.

Once the graft is harvested, it has to be placed inside the knee. For this, holes (“tunnels”) are created, and the graft is passed into those holes. The graft has to be locked to one of the tunnels, made taut, and, finally, fixed to the other tunnel. Within a few months, the graft is forever secured. Unfortunately, as Jerry Rice of the San Francisco 49’ers will tell you, the fact that the graft has healed does not mean that the recovery is over. If stressed too soon or too vigorously, the kneecap may fracture, or the remaining tendon may rupture. The rope that was just placed in the knee also needs time to start looking and acting like an ACL. Opinions are divided with regards to how long this takes. Some say 2 years, but nobody wants to wait that long. The party line is 1 year. 1 year, therefore, before resuming contact sports.The very long-term effects of harvesting a graft of any kind are not known.

The “Hamstring” Graft

You have 3 hamstring muscles: the biceps (the same name as the muscle in your arm) which runs down the outer part of your thigh, the semitendinosus, and the semimembranosus both of which run along the back part of the thigh. In the hamstring graft, the semitendinosus is harvested, often along with another tendon, the gracilis, which runs along the inner thigh. These tendons are there for a purpose, so for the surgeon it is emotionally painful to sacrifice them. Yet, athletes appear to function well even after the harvesting of these tendons. There is less donor site morbidity, as we say in medical lingo, than with the patellar tendon: nothing bad is going to happen to the site from which the graft was taken if the athlete makes a hasty return to sports. As with all grafts, there are umpteen ways of fixing a hamstring graft to the bone, but they all involve hardware - a screw, a staple, etc. These products are still evolving.

The Quadriceps Tendon Graft

The quadriceps tendon joins the quadriceps muscles at the front of your thigh to the kneecap. It has some of the advantages and disadvantages of the other two grafts and is equally acceptable.

At the present, a surgeon’s comfort level with a certain graft is probably more important than the graft itself.