Age is an interesting factor in considering graft choice for ACL reconstruction. There are no absolutes about who is ‘too young’ or ‘too old’ to consider reconstruction, the decision should really be made with respect to how knee instability affects a person’s ability to remain active and healthy.
YOUNG PATIENT WITH OPEN GROWTH PLATES
Younger patients who are not skeletally mature (i.e. their growth plates are still open) should not consider bone-patellar tendon-bone (BTB) or quad tendon (QT) graft. This is because placing the bone plug attached to the graft across an open growth plate can cause pre-mature bony “fusion” of a region of the growth plate. If this happens and the remaining “unfused” part of the plate continues to grow and the alignment or length of the limb can be affected. That’s a lot of words for “bad”. Growth plates typically fuse in females between the ages of 12-14 and in males between about age 14-16. So in younger adolescent athletes with ACL instability, BTB grafts and QT grafts, or allografts that have bone on either end may not be the best option. Soft tissue autografts, typically hamstring (HS), are generally utilized in young patients with open growth plates. Allografts (Achilles, Tibialis Anterior or Posterior Tibialis) may offer more robust graft tissue, but the failure rates and potential for disease transmission concern some parents and physicians. Methods have been devised for ACL reconstruction to avoid injury to the growth plates in very young ACL-deficient athletic children. Of note, the healing potential in kids is pretty remarkable, and skeletally immature patients with ACL insufficiency may be an ideal indication to attempt ACL repair, a topic I’ll cover elsewhere, but certainly an option to consider in very young patients or adolescents with partial or “avulsion” type ACL injuries.
YOUNGER = MORE ACTIVE = HIGER RISK OF RE-RUPTURE
Patient age indirectly affects graft choice with respect to athletic exposure and intensity. From childhood to adolescence, the intensity and exposure to cutting athletics often increases. Participation becomes more frequent (e.g. practices several days per week), competition is more frequent, and seasons are extended for long periods of time (elite teams, year-round participation). In addition, the speed and intensity increase as young athletes get bigger, stronger and faster. From a purely statistical standpoint, the more an athlete participates in cutting/pivoting athletics, the more likely that an ACL injury can occur.[i] Therefore, when counseling young patients with ACL tears, an allograft would be ill-advised owning to the high failure rate and the surgeon should recommend either HS or BTB.
OLDER = LESS ACTIVE = LOWER RISK OF RE-RUPTURE
This is a broad generalization, but most adults who are not high-level recreational athletes, collegiate athletes, or professionals experience a decline in exposure to cutting/pivoting athletics. The realities of education, work, family obligations and peripheral interests translate to less frequent exposure to sports/athletics and thus decreased risk of ACL tear or re-tear. This may explain why researchers have noted that statistically in patient populations over 40 years of age, allograft/donated tissue grafts and autografts (HS/BTB) do not have significantly different rates of re-tear or failure, yet in patient populations under 25 years, allografts and HS had a significantly higher failure rate compared to BTB.[ii] Therefore, when counseling older patients on ACL graft choice, some may be able to get away with a allograft, whereas those with routine exposure to cutting athletics would be served better with an autograft option.