Revision anterior cruciate ligament surgery

Anterior cruciate ligament (ACL) reconstruction is one of the most common surgical procedures in orthopedic surgery. In the Netherlands, 9,000 ACL reconstructions are performed each year, and this number increases annually. Many patients are able to return to sports after 9 months. However, approximately ten percent of patients experience a re-tear of their ACL. This is a complex problem with various underlying causes, which are explained below.

Research shows that the most common cause of failure in an ACL reconstruction is attributed to a technical error made during the initial surgery. ACL reconstruction is a highly technical procedure, and the surgical outcomes are favorable among surgeons who perform this operation frequently. This is primarily due to the correct positioning of the new ligament within the knee. The tunnels created during the surgery for the new ligament must be precisely placed in the correct position. If these tunnels are not properly positioned, it can lead to persistent instability or stretching and loosening of the new ligament after the surgery.

Untreated secondary instability is the second most common cause of ACL reconstruction failure. This can involve injuries to the medial collateral ligament, the posterolateral corner (Figure 1), or, for example, the medial meniscus. If these injuries are not recognized and/or treated, instability of the knee joint will persist even after replacing your anterior cruciate ligament. This untreated instability will result in increased forces on the new ACL reconstruction, leading to early re-tearing of the ACL. Therefore, during a revision surgery of the ACL reconstruction, also known as a revision, it is essential to assess the function of the other ligaments and the menisci.

A third cause for the failure of previous ACL reconstructions is the mechanical anatomical factors of the patient. Firstly, it is known that individuals with a stronger X or O-leg alignment have a higher risk of re-tearing their anterior cruciate ligament. This misalignment of the leg leads to increased forces on the ACL reconstruction (Figure 2). Secondly, the anatomical angle of the tibial plateau, known as tibial slope, can play an important role (Figure 3). The steeper this angle, the greater the forces on the new ligament and the higher the likelihood of ACL reconstruction failure. Finally, the space in which the ligaments are positioned, called the notch, also plays a significant role. The narrower the notch, the greater the chances of ACL re-tear.

Fourthly, a patient can sustain a new injury and re-tear the previous ACL reconstruction. The initial surgery may have been perfectly performed, but unfortunately, it does not guarantee that the new anterior cruciate ligament cannot be torn again. However, this is a relatively rare cause.

Lastly, biological factors appear to play an important role alongside mechanical factors in the inadequate incorporation of the new anterior cruciate ligament. There is still limited knowledge about this cause of ACL re-tear. These biological factors are considered a significant reason for a relatively higher rate of re-ruptures in primary ACL reconstructions in patients younger than 25 years. Smoking is another crucial factor that hampers the biological integration of the anterior cruciate ligament. Consequently, smokers have a much higher chance of re-tearing their ACL reconstruction.

In conclusion, the re-tear of the anterior cruciate ligament reconstruction is a complex problem where multiple factors are often involved. If you experience a re-tear of your ACL, it is important to analyze all these different factors to determine the appropriate strategy for the revision of the cruciate ligament.

The re-tear of the anterior cruciate ligament is a complex problem, and the reason for the recurrence is rarely simple. The most important step is to analyze why the ligament has torn again. The aforementioned factors that contribute to the re-tear of the ACL reconstruction must be carefully evaluated. This analysis involves a physical examination of the knee, X-rays of the knee and the entire leg, as well as additional MRI and/or CT scans.

Once all the factors have been evaluated, a surgical plan can be formulated. In the majority of cases, only one surgery is needed to replace the anterior cruciate ligament again. We always strive to replace the new ligament with the patient’s own tissue. This usually consists of hamstring tendons, the patellar tendon, or the quadriceps tendon (Figure 4). If necessary, we obtain these grafts from the other knee. We try to avoid using donor tendons as much as possible, as the results with donor tendons are inferior to using the patient’s own tissue.

If one of the previous factors plays a significant role and needs to be addressed (such as other ligament issues, an O or X-leg alignment, or bone loss), multiple surgeries can be performed to address all the factors that affect the function of the new ligament. This may include bone grafting of the old drill tunnels, limb realignment surgery (osteotomy), or other knee ligament reconstructions.

Generally, the success rates in the literature for ACL revision surgery are around 75%. The rehabilitation program for an ACL revision surgery will progress at a slower pace compared to that of a primary (first-time) ACL reconstruction. Most patients will use crutches for a longer duration during early rehabilitation to minimize the load on the new anterior cruciate ligament. Return to full activities is rarely permitted before 9 months after the surgery.

Have you torn your anterior cruciate ligament again? Please contact us, and we will assist you further with this issue.