As your surgeon has already told you, there are some differences between the bone-patellar tendon-bone (BPTB) and hamstring tendon graft. Results have improved over time with both types of grafts.
This is because surgical techniques have improved. Better methods of attaching the tendon graft material are available. There is less slippage with the hamstring grafts. Patients report less knee pain and less joint stiffness with both graft types compared to even just 10 years ago.
The surgeon's skill and experience with ACL repairs is an important factor. Surgeons who perform many of these procedures each year have better results. It's important to pay close attention to correct graft placement. Treatment of other meniscal or ligament damage to the knee is as important as the choice of graft materials.
There is one new study that may be of interest. Researchers from the bioengineering lab of Harvard Medical School and Orthopedic Research Lab from Duke University studied knee motion after a BPTB graft.
With special testing, imaging, and computer software, they were able to measure the position, angle, and movement of the patellofemoral joint (PFJ) after ACL reconstruction. Both knees were tested for each patient. This gave a comparison between the involved (surgical) side and the uninvolved (normal) knee.
They found that ACL surgery does improve patellofemoral joint function. But it does not fully restore rotational stability of the knee. There was altered patellar tracking (kneecap moving up and down over the femur) and changes in cartilage contact between the patella and femur.
As a result, the patellofemoral joint may be at increased risk for degenerative changes. BPTP graft for ACL reconstruction is still the "gold standard" method of repair right now. Further study is needed to pay attention to fine tuning these procedures. New technology and new studies may guide patients and surgeons to favor the hamstring tendon graft.