Essentially there are three choices that could be made when deciding what type of graft is to be used for reconstruction of the anterior cruciate ligament. Each of the grafts has its positives and negatives, and I would like to outline those for you.
Patellar Tendon Graft
The patellar tendon graft has been the most traditional replacement used for anterior cruciate reconstructions. There is approximately a 30-year history of usage of this graft for ACL reconstructions. The last 20 or so years, the graft has been placed arthroscopically assisted.
The biggest positive of using a patellar tendon graft is the bone plug on either end of the graft coming from the patella and the tibia. These bone plugs are about 2.5 cm long, 1 cm wide, and about 5 mm thick. The bone plugs are actually placed in the tunnels that are made for the reconstruction of the ligament. These bone plugs can be fixed very securely with screws, either metal or plastic. The graft will then heal to the knee in approximately six weeks. The patient can start running at an early point in time, as long as there is no major meniscal damage that would prevent the patient from doing so.
The downside of using a patellar tendon is that the incision is longer, and there is more pain and swelling in the knee in the first two weeks. Likewise, the patient has more difficulty regaining control of his quadriceps muscles during the first several weeks, since the extensor mechanism is used for the surgery. Fifteen years down the road 10% to 20% of patients will have patellofemoral pain and grinding as a result of the disturbance of the extensor mechanism that occurs with procurement of the graft.
It is my feeling that the patellar tendon graft is the best graft choice for teenagers and college athletes that are participating in sports at a very competitive level. The orthopedic literature in the last couple of years has shown that the incidence of reinjury to a patellar tendon graft is less than either a hamstring graft or an allograft in the three to four years after the reconstruction. Teenage girls in particular, in my estimation, have a significantly higher incidence of reinjury to their ACL graft when using a hamstring graft compared to the patellar tendon. Thus, I have a strong preference for a patellar tendon graft choice for teenage and college athletes.
Hamstring Graft
The hamstring graft is an excellent choice as a substitute during ACL reconstructions. The hamstring graft is an entirely soft tissue graft with no bone plug on either end, like we have with the patellar tendon graft. Thus, the fixation of the graft to the knee is slightly less rigid than with the patellar tendon graft with its bone plugs. In light of this, we usually have to delay the onset of running until two and a half to three months after surgery, and actual participation in harsh twisting and turning sports will not occur until the patient is five or six months after surgery. This is in contrast to patients with patellar tendon grafts, who can sometimes return to their cutting and twisting sports at three and a half to four months after surgery, if rehabilitation goes well.
Patients with hamstring graft ACL reconstructions, however, have less pain than those patients with ACL reconstructions with patellar tendon graft. The incision is smaller, and patients likewise gain control of their quadriceps mechanism a lot faster and a lot more easily than those patients who have patellar tendon graft ACL reconstructions. Usually, the physical therapy just goes more easily in general with a hamstring ACL graft compared to a patellar tendon graft. Around the country, amongst those surgeons who do a high volume of ACL reconstructions, the hamstring graft has become the graft of choice, for the most part.
I feel that the hamstring graft is a very good reconstruction for adult athletes who wish to continue doing twisting and turning sports. Although I feel that the patellar tendon has been a better choice for teenage and college athletes with ACL tears, the hamstring graft is a very good choice for adults with ACL tears. The incidence of reinjury is low in adults. (less than 10%) Adult athletes expose their knee to injury for much smaller amounts of time than do teenage and college athletes who are playing a sport on a regular basis.
Allograft
Allografts are an excellent choice for the adult who has other problems in the joint. These may be arthritic problems or previous meniscal surgery. The allograft will require no graft harvest incision and no procurement of the graft from the patient. The surgery is shorter in time, and obviously no disturbance of the extensor mechanism occurs in the knee. It can be done through a 2 cm incision with minimal disturbance of the knee. The tissue is tested extensively for viral disease like AIDS and hepatitis. An allograft is an excellent choice for a patient who wishes to have minimal disturbance of the knee in order to have the ACL reconstruction done. It is also an excellent choice for someone who has other problems in the joint, for which we do not want to take any autograft from his own knee.
Summary
All three grafts work quite nicely for ACL reconstruction. The most important consideration is actually putting the graft in the proper position, fixing it securely, and doing proper physical therapy after the reconstruction. These factors are certainly equally as important as the actual graft selection. Obviously the choice of the graft is very dependent on the age of the patient and what sports the patient participates in. Teenage girls in particular have a very high incidence of ACL tears because of their body alignment and they also have a higher incidence of reinjury after reconstruction than adults and teenage males. As stated previously, this is the reason that I prefer patellar tendon grafts in that group. We hope this information is useful in your decision about graft choice selection for ACL reconstruction.
Article by Frank P. Mannarino, M.D.