I’m Dr. Richard Cunningham, a Knee and Shoulder Sports Medicine Physician at Vail-Summit Orthopaedics & Neurosurgery. I specialize in the treatment of ACL injuries. Today I want to shed some light on a crucial aspect of sports-related injuries and surgeries: ACL graft failure after ACL surgery. The anterior cruciate ligament (ACL) is a vital structure in the knee that helps stabilize the joint during sports and everyday activities. When an ACL injury occurs, surgical reconstruction with a graft is often necessary in order to provide athletic people with a stable knee so that they can once again cut and pivot without their knee giving way. Unfortunately, ACL graft failure can occur after ACL surgery. There are a number of factors that may predispose one to this. In this blog post, we will explore the causes, symptoms, diagnosis, and treatment of ACL graft failure.

Understanding ACL Graft Failure

ACL graft failure occurs when the tendon used to reconstruct one’s torn ACL tears after ACL surgery. This setback can be very disheartening for both the patient and their orthopedic surgeon, as it often requires a redo ACL surgery to restore knee stability and function.

Causes of ACL Graft Failure

Understanding the causes of ACL graft failure is pivotal in both the prevention and management of this challenging condition. Common causes of ACL graft failure are:

• Graft Choice: Certain types of tendon grafts have proven to provide lower incidences of retearing than other types of graft. For instance, allografts (donor tendons) have been shown in many studies to tear at a higher rate than autografts (a piece of one’s own tendon graft), especially in patients under the age of 35. In a skier population, I recommend using autograft even in middle aged patients. Amongst autograft choices, some are better than others. I favor quadriceps tendon autografts for ACL reconstruction over a patellar tendon or hamstring tendon graft for a number of reasons. Firstly, a quadriceps tendon graft is 88% thicker than a patellar tendon graft. Secondly, a patellar tendon graft requires the surgeon to harvest a section of the knee cap bone as well as a section of the tibia bone along with the graft as the graft is otherwise too short. As a result of this, there has been shown to be a higher incidence of kneeling pain in patients who have a patellar tendon graft in orthopedic studies. However, a patellar tendon graft has a long track record of success and in most studies provides success rates comparable to a quad tendon graft. A hamstring tendon graft is another option and has demonstrated good outcomes, but in female athletes there is a higher retear rate than quad or patellar tendon as hamstrings are more elastic and the graft diameter is usually not as large, and thus a hamstring graft can more easily stretch and retear particularly in female athletes.
• Surgical Technique: ACL surgeons have to create bone sockets in both the femur and the tibia to seat the ACL graft into and then secure it in place with hardware. Surgeons putting these bone sockets in the wrong position is another common cause of ACL graft failure. Orthopedic knee surgeons have learned a lot about ACL anatomy over the years. Placing an ACL graft perfectly in the knee where the original ACL once attached is critical. The surgeon has to pay particular attention to the “ACL footprints” which are the attachment sites of the original ACL on the femur and tibia. Oftentimes, surgeons might malposition the graft and not place the ACL graft into sockets that reside perfectly in these footprints. If the ACL graft is not perfectly situated and secured in these footprints, then the graft will see abnormal stresses and most likely retear in the future. Using the appropriate hardware to secure the ACL graft is another factor to ensure success. Today there are numerous choices of hardware that a surgeon can use. I prefer hardware that is strong, low profile, and allows for re-tensioning of the graft, meaning I can tighten the graft further if needed once it is secured in place.
• Other Ligament or Bony abnormalities predisposing to retear: I often have patients sent to me after they have had their ACL reconstructed at another facility and it subsequently fails. Not infrequently, there are other ligament injuries that were not recognized and corrected at the time of the index ACL surgery that then put the ACL at risk for future failure. Most commonly, the MCL is torn and this laxity predisposes to one’s ACL graft retearing. Patients might also have laxity in what is called their posterolateral corner which can predispose to ACL graft tears. These other ligamentous structures must also be reconstructed along with the ACL at the time of revision surgery. In addition, some patients may have bony anatomy that can place increased stresses on an ACL graft causing it to tear. For instance, there might be excessive posterior tibial slope or the patient may be excessively knock kneed or bowlegged. If so, this bony anatomy must be corrected with an osteotomy procedure at the time of the ACL revision surgery.
• Physical Therapy: Working with a good physical therapist after surgery is critical to a good outcome. A physical therapist will help you more quickly reduce swelling and increase range of motion and strength. They also have experience assessing and correcting muscle imbalances. A physical therapist will be able to educate you on what you can and cannot do at different stages of your recovery.
• Avoiding reinjury: Certain sports (ie. skiing and soccer) are particularly risky for ACL tears. Some patients will elect to simply limit certain sports, but most want to get back to all their normal sports and activities. The most important factor to limit your chances of reinjuring your ACL when returning to high level cutting and pivoting sports such as skiing or soccer is to not return to these sports until you have restored full strength to the muscles that support and stabilize the knee and then also maintain this strength into the future. Good quad, hamstring, and glute strength is key. However, having good core strength so that you, for instance, do not land in the back seat when skiing and instead staying centered over your skis is critical. Therefore, a lifelong strength and conditioning regimen is very important to avoid reinjuring your ACL.

Symptoms of ACL Graft Failure

Recognizing the symptoms of ACL graft failure is vital to prevent further damage to the cartilage in your knee. Common signs include:

• • • Persistent Knee Instability: Patients may experience a feeling of knee instability, similar to their pre-surgery condition where their knee gives out or shifts out of place.
    • Swelling and Pain: Swelling and pain often occur but the swelling is typically not as severe as the first time you tore your ACL as the graft is less vascular than your original ACL so it bleeds less when it tears.
    • Decreased Range of Motion: A patient may notice a reduced range of motion in the knee, inhibiting their ability to fully extend or flex the joint.
    • Popping Sensation: A sensation of the knee popping, catching, or grinding can indicate graft failure.

Diagnosis of ACL Graft Failure

When a patient presents with concerns about their knee following ACL reconstruction surgery, I take a good history of what occurred and then do a physical exam of the knee to assess for ligament laxity or other issues such as tearing of the meniscus.

If there are concerning findings on the physical exam, I first order an xray to assess for a fracture or arthritis. I then order a magnetic resonance imaging (MRI) of the knee. An MRI shows all of the soft tissue structures such as ligaments and meniscus tissue. With this information, I can make an accurate diagnosis of ACL graft failure and develop an appropriate treatment plan to help my patients regain knee stability and function.

Treatment of ACL Graft Failure

Treating ACL graft failure is a complex process that requires a tailored approach based on the patient’s unique circumstances. Young patients who wish to resume their normal sports and activities usually need to undergo revision ACL surgery to achieve their goals. During this procedure, I replace the failed graft with a new one, carefully ensuring proper placement and tension to minimize the risk of future failure. I also repair any other associated tears of other ligaments or the meniscus.

Following surgery, an integral component of the treatment plan is an extensive rehabilitation program. Physical therapy is crucial in assisting patients in regaining strength, range of motion, and functional stability. In addition, lifestyle modifications are necessary, including the avoidance of high-impact activities during the recovery period. By addressing the physical and psychological aspects of ACL graft failure, we aim to help patients regain confidence in their knee’s stability and, ultimately, return to the activities they love.

Returning to Play After ACL Graft Failure

ACL graft failure can be a challenging setback for athletes and individuals looking to return to an active lifestyle as they have already been through the surgery and the long recovery process once. There has also been financial losses in paying one’s insurance deductible as well as time away from work and activities with family and friends . Recognizing the causes, symptoms, and treatment options for graft failure is essential to ensure a successful recovery and outcome. If you suspect ACL graft failure or have any concerns about your knee after ACL reconstruction surgery, consult Dr. Cunningham or with a sports medicine orthopedic surgeon for a thorough evaluation and personalized treatment plan.