Bone-Patellar Tendon -Bone
BTB, patellar tendon grafts, were the gold standard for surgeons during the 1990s. BTB is still a popular graft choice for athletes participating in contact sports, such as football. The patellar tendon is the structure located on the front of the knee that connects the kneecap (patella) to the shinbone (tibia). The patellar tendon typically measures 30 mm in width. When a graft is used, only the central one-third of the tendon is removed. While patellar grafts offer good results, a significant risk is anterior knee pain (or pain during kneeling). Furthermore, recent literature suggests that BTB grafts may have a higher risk of long-term arthritis compared to hamstring tendon grafts, which could be a significant disadvantage for a young athlete.
Hamstring Tendon or Tendons
The hamstring muscles are located on the back of the thigh. The hamstring tendons attach the muscles to the bone. There are three medial hamstring muscles, and only one lateral hamstring. It is possible to remove one, or two, of the medial hamstrings while preserving excellent hamstring function. The hamstring tendons provide a solid graft for ACL reconstruction procedures. In general, the results of hamstring and BTB are equal, and hamstring grafts may result in a lower risk of arthritis. Historically, two medial hamstring tendons are harvested and “bundled” together to create an ACL graft. Dr. Lubowitz pioneered and published “all-inside”, less invasive ACL technique, which generally allows harvest of only one hamstring tendon, which is less invasive. However, if patients have small tendons, harvest of a second tendon is an option. New hamstring fixation technology allows a surgeon to hold the securely fixed graft in place using adjustable buttons, which are the only fixation devices that allow a surgeon to increase tension, and tighten the graft, after the graft has been secured in position. In the 21st century, hamstring grafts are the number one graft choice of the ACL Study Group, probably as a result of the lower risk of arthritis, with otherwise equal outcome.
Another graft option that surgeons will consider for ACL reconstruction surgery is the quadriceps tendon. Similar to the patella tendon, but above the knee, the quadriceps is a very strong graft choice. In revision cases, especially in nations where allograft tissue is not available, the quadriceps is an excellent graft option.
Cadaver (Allograft) Tendon
An allograft is an extremely popular graft choice among patients greater than 40 years of age, and is frequently selected by patients aged 20 to 40 years of age. Allograft is also generally selected for revision ACL reconstruction cases, and for multiligament knee reconstruction, where additional ligaments are reconstructed in addition to the ACL.
Cadaveric donor tissue is provided by a regulated tissue bank. An allograft is a strong graft, and Dr. Lubowitz published that ACL non-irradiated allografts have evidence-based equal results to autografts. On the other hand, some authors have reported that autografts have superior results in young athletes. Since the tissue is not taken from the patient’s own body, there is a theoretical risk for disease transmission. However, the grafts are extensively screened for infectious diseases, and provided by regulated tissue banks. An advantage of allografts is that there is no harvest site morbidity, because your physician does not have to remove the tissue from the patient’s own knee. Because there is no graft harvest from the patient’s own knee, surgical time is decreased, with faster return to work. Unlike heart or other transplants, ACL reconstruction surgery involving allografts are not living tissues. The grafts are frozen below zero degrees, which kills any donor cells. Therefore, allografts are scaffolds, and the patients own cells, with the patients own DNA, grow into the scaffold, and remodel the graft.