I am most distressed over the turn of events with my knee. I tore my ACL two years ago playing basketball in a college-level tournament. Biggest disappointment of my life. Did rehab and ended up in surgery anyway. Due to the long period of inactivity, I gained quite a bit of weight. Ended up retearing the reconstructed ACL. It’s possible the added weight was part of the reason for this unfortunate result. I’m afraid to have another surgery if it’s just going to go bad on me again. Is there any way to predict what may happen with a second surgery?

As you might expect, athletes make up a very large part of the patients who end up needing anterior cruciate ligament (ACL) surgery. And with 200,000 cases reported each year, it is not that uncommon to find patients like yourself who experience a failed result and potential need for another surgery.

For the most part, surgery to reconstruct the torn ligament is quite successful. But studies do show up to a 10 per cent failure rate after the primary (first) surgery. A recent report by surgeons from the Mayo Clinic in Rochester, Minnesota may be of interest to you. They tell us about the results for patients who have two or more ACL surgeries.

Repeat or revision surgery for ACL reconstruction is often needed because the tunnels drilled through the femur (thigh bone) for the graft tissue to go through are placed too far forward the first time. In other cases, damage to the cartilage on the surface of the knee joint and misalignment of the lower extremity contribute to failure of the primary (first graft) procedure.

Looking back over the records of patients who had at least two ACL reconstructions at the Mayo Clinic, they found a total of 15 charts. The patients ranged in ages from 18 up to 57. Two-thirds of those cases required new femoral tunnels. Two-thirds had severe chondral (cartilage) lesions. And three-fourths had a meniscal tear.

As it turned out, the first two factors (placement of the femoral tunnels and chondral lesions) were risk factors for graft reconstruction failure. The third factor (damaged meniscal cartilage) was not directly linked with graft failures. A graft failure was defined as a rupture of the graft tissue or knee joint instability. Another risk factor for a failed ACL reconstruction was obesity. Patients with a body mass index (BMI) measure of 29 or higher had fair to poor results after the first surgery.

ACL revision of primary reconstructions can be a difficult and challenging surgery. There are many factors to consider including a limited choice of graft tissue, fixing the graft in place to create a stable response, unusual/unnatural anatomy, and difficulty finding the right spot and then creating correct tunnels for the final step of the initial surgery.

But according to this study from the Mayo Clinic, good-to-excellent results are possible even after repeated ACL surgical revisions.