Given the fact that anterior cruciate ligament ruptures are very common injuries requiring surgery, you might think the decision about which graft tissue is best would be decided by now. But in fact, despite many studies comparing these different approaches, there are still many unknowns and gray areas.
That’s because different studies use a variety of different outcomes to measure results by. They also don’t follow-up with patients for the same length of time after surgery. Some results may be reported after six months, one year, or two years while others extend outcome measures up to 10-years.
Another factor involves rehabilitation programs. Post-operative protocols may differ from one surgeon to another contributing to differences in results. Not to mention the fact that some patients are athletes who rehab differently while preparing to get back into their sport activity. They may count whether or not they return to full participation in their sport as the litmus test for a successful result.
Not only that but there are different ways to attach each graft type adding to the complexity and challenge for the surgeon in deciding which way to go. Many patients do choose which graft type they want so they aren’t randomly put in treatment groups and compared. This can create a treatment bias.
When we turn our attention to the results, there can be many different ways to measure “success” versus “failure.” For example, results of ACL reconstruction can be measured in terms knee stability, leg strength, function, return-to-sports, patient satisfaction, complications, and cost.
According to the most recent comparative studies, rates of post-operative knee joint stability (joint “give”, laxity, or looseness versus tightness of the joint) may be no different between allografts and autografts. The primary difference is in terms of rupture rate. Improper preparation of allografts (e.g., sterilization, drying) can result in more graft ruptures years later compared with autografts.
Concerning muscle strength. There is agreement among studies that quadriceps strength seems to be equal among the various autografts. The hamstring muscle group is more likely to lag behind in recovering full strength, especially for patients who have a hamstring graft.
Return of overall function seems to be equal among all graft types. But return-to-sports varies widely. The majority of patients (75 per cent) get back to playing but not all return to their preinjury level of participation. Some athletes have to gear down to a lower intensity level of activity while others change the sports activity altogether.
One more area of concern and comparison is complications (e.g., pain, infection, graft failure or rupture). Most patients expect a certain amount of pain right after surgery. But when pain lasts months-to-years later, this symptom becomes a complication. Kneeling pain persists more often with patellar donor grafts. Other long-term annoying symptoms at the harvest site can include numbness, tenderness, or irritation.
Finally, graft failure or rupture is more likely occur when there is significant joint laxity (looseness) after surgery. Another significant risk factor is return to sports that require sudden turns or changes in direction (pivoting), sidestepping, and jumping. Studies show that younger, more active patients are the most likely to experience ruptures with an allograft.
So you can see how evaluating results using different graft types isn’t really a matter of it works or it doesn’t. The factors to consider are much more broad and complex than that. Hopefully, this information will give you some additional thoughts to consider and perhaps generate a few more questions for your surgeon to help you sort through this decision.