Minimizing Your ACL Re-Tear Risk

There are generally large graft categories, auto and allograft.  Autograft is when the patient’s own tissue is obtained from a different area of the knee to use as a replacement for the torn ACL.  Allograft is a donor tissue from a cadaver that is the easiest procedure for the surgeon and for the patient because it does not require a different incision to retrieve the new ACL tissue.

Because of the ease of the surgery and the relatively easier recovery, allografts had been historically used at high rates, even in younger athletes, but this trend is no longer continuing.  Now that we have decades of experience of performing ACL procedures we know that rates of re-rupture with allografts are approximately three times higher in competitive athletes.

Many ACL surgeons do not perform allografts at all because of the higher rates of reinjury.  Patients younger than mid-twenties should almost never be treated with an allograft unless under certain select circumstances.

Hamstring tendon is generally considered the easiest procedure to undergo from the standpoint of the taking of the graft. There are bands of tissue taken on the inner thigh from a tiny incision in the front of your knee (which is needed for surgery anyway) which adds a minimal amount of additional invasiveness to the original procedure and makes for an easy recovery.  Hamstring has variability regarding the size and strength of the harvested tendon and has the highest rate of re-rupture of any of the autografts.

Due to the higher rate of re-rupture of hamstrings grafts, there is emerging evidence that in high-risk patients, sometimes an additional procedure (called an extraarticular tenodesis) is needed at the time of ACL reconstruction to eliminate the additional risk of re-injury.  No one wants an additional potentially avoidable procedure at the time of their ACL surgery, so hamstrings grafts are suboptimal in high-risk patients (certain bone geometry, hyperlax joints, young age, risky sports).

Patellar tendon graft has a lower rate of re-tear than hamstrings but has the downside of a slightly more challenging recovery, because of pain from removing plugs of bone on the kneecap and shin bone.  While generating a more robust and durable tissue graft, patellar tendon grafts may come with added risk of kneeling pain and pain in the front of the knee (1).  The risk of anterior and kneeling pain in some reports is greater than 50% for both outcomes at two years(1).

Re-tear risk with patellar tendon graft is significantly lower than hamstrings grafts(2). In a large cohort of high-risk young women undergoing ACL reconstruction, the risk of patellar tendon graft re-tear was around 1% while the risk of hamstrings graft re-tear was almost 8%(2).

Quad tendon grafts are an emerging tissue for autograft because the technology for harvesting and fixating these quad grafts is better than in years’ past.  Quadriceps tendon is a soft tissue graft that is technically fixated to your knee in a similar fashion as hamstrings and is harvested through a small incision above the kneecap.  The difference is the strength of the quad tendon is much more robust than hamstrings and the size of the harvested tendon is specifically selected by the surgeon (and highly predictable) instead of being left with what the patient’s anatomy provides (less predictable).  Pain is much more tolerable with quad than patellar tendon grafts.

Early data suggests the rate of re-tear with quadriceps tendon grafts is very low and comparable to the rate of re-tear with the previous gold standard patellar tendon graft(3).  If you are a young competitive athlete you can rest assured the risk of re-tear with a quad tendon graft is very low.

Regardless of the graft selected, there is an important role for proper rehabilitation in the prevention of ACL re-tear.  In fact, you can specifically reduce your risk of ACL re-tear by 40 to 60 percent by just following an evidence-based rehabilitation protocol prescribed by ACL knee surgeon Dr. Obermeyer.