What is an ACL Injury?

The anterior cruciate ligament, or ACL, is the most important ligament of the knee to prevent the knee from sliding forward or rotating anterolaterally. Patients who sustain an ACL tear often have problems with twisting and turning activities, such as in playing football, soccer, or skiing, and will often require an ACL reconstruction to provide stability to their knee.

In addition to its stability role in the knee, the ACL also provides protection for the menisci of the knee. When the knee continues to have instability episodes, it is not uncommon to have either the medial or lateral meniscus tear. However, when menisci tear there is much higher risk of the development of osteoarthritis. Because of this, Dr. LaPrade usually recommends ACL surgery and that an ACL reconstruction be performed in young or otherwise active patients and in almost all patients who report instability with twisting or turning activities.

An ACL injury is classified by the amount of injury to the ligament:

• Grade I: a partial ACL tear
• Grade II: near complete ACL tear
• Grade III: a complete ACL tear – the ligament is non-functional

Depending on the patient’s age, activity level and grade of tear will determine the correct treatment option.

Description of ACL Reconstruction

An ACL surgery requires precise knowledge of the anatomy of the knee, attachment sites of the ACL and knowledge on the other ligaments and structures of the knee. If one fails to replace an anterior cruciate ligament at its correct attachment sites or if other concurrent injuries are not treated, there is a much higher risk of failure of the ACL graft.

While there are two bundles of the ACL, the anteromedial and posterolateral bundles, there is still controversy as to whether both should be reconstructed as a single ligament or as two separate ligament grafts. While the double-bundle ACL reconstruction technique appeared very promising initially, many research groups, including ours, have significantly narrowed the indications for double-bundle ACL surgery and found there is very little difference between a single and double-bundle ACL reconstruction for the vast majority of patients.

The most important technical issue is to have the ACL reconstruction graft placed in the correct position. On the tibia (shinbone), the tunnels should be in line with the posterior margin of the anterior horn of the lateral meniscus. On the femur (thigh bone), the reconstruction tunnel should be placed at the midpoint of the attachment bundles of the anteromedial and posterolateral bundles, with the main portion of the reconstruction tunnel being posterior to the lateral intercondylar ridge (resident’s ridge).

A large number of ACL reconstruction graft failures are in those patients who have the graft placed too posterior (central) on the tibia with an inability to control rotation of the knee or too anterior on the femur (anterior to resident’s ridge) or too central on the femur (effectively only reconstructing the anteromedial bundle), which leads to either stretching of the reconstruction graft or failure to control knee rotational laxity.

Are you a candidate for an ACL Reconstruction?

There are two ways to initiate a consultation with Dr. LaPrade:

You can provide current X-rays and/or MRIs for a clinical case review with Dr. LaPrade.

You can schedule an office consultation with Dr. LaPrade.

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(Please keep reading below for more information on this treatment.)

ACL Surgery Technique

The technique of ACL reconstructions has changed dramatically over the last decade in orthopaedics. ACL reconstruction grafts performed prior to 5-10 years ago were usually placed more centrally on both the tibia and femur and many of these patients have continued problems with rotation instability. This problem became recognized through extensive clinical and biomechanical research and the surgical technique has currently changed dramatically to where the reconstruction tunnels are now placed more anatomically to provide better stability to the knee.

Dr. LaPrade’s primary surgical reconstruction technique involves using a patellar tendon autograft (from the patient’s own tissues) during ACL surgery. The reconstruction tunnel is drilled at the anatomic attachment site of the ACL on the tibia and a closed socket tunnel is drilled at the ACL attachment site on the femur. The patellar tendon graft is pulled into the joint and fixed in place with titanium interference screws. Dr. LaPrade utilizes one incision for this surgical technique, as well as an autograft to place it in the correct position. The utilization of fewer incisions results in less pain post-operatively for the patient, while the use of the autograft allows the patient to return to activities sooner with a lesser risk of reconstruction graft failure.

Patellar tendon allografts (donor grafts) or soft tissue graft material may be required in patients with open growth plates or in older patients (women greater than 40 years, men greater than 45-50 years) due to the desire not to have any bone across an open growth plate and for older patients to have a strong enough graft. Cadaver grafts can be larger than ones harvested from one’s own knee and it is well known the patellar tendon and the other grafts around the knee are approximately three times weaker in someone who is 60 years of age compared to someone who is 20 years of age.

Post-Operative Protocol for ACL Reconstruction

It is absolutely essential for a physical therapist to be consulted and to work with one’s surgeon post-operatively following ACL surgery. Reactivation of the quadriceps mechanism, edema control, patella mobilization, maintenance of full knee extension and regaining knee motion are absolutely essential to obtaining optimal post-operative outcomes.

In our practice, we strongly suggest and require patients remain in Vail to work with our physical therapists at Howard Head Sports Medicine for a minimum of 5-7 days post-operatively to make sure they are having appropriate care post-operatively and also so that their rehabilitation will advance to higher levels sooner.

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Frequently Asked Questions

When to have ACL surgery after injury?

Athletes who have any difficulty with twisting, turning, or pivoting after an ACL tear should consider having their ACL reconstructed.  This is because repeated twisting and turning mechanisms can damage both the cartilage in the joint and also the menisci.  The medial meniscus is the most at risk to injury with an ACL tear because the medial meniscus takes over a lot of the function of the ACL when it is torn to prevent the knee from slipping forward.  In addition, patients who may have a repairable meniscus tear at the time of their ACL tear should consider surgery to prevent the tear from becoming non-reparable.  In general, most people who tear their menisci will be developing arthritis and having symptoms within 8-10 years after their ACL tear.  Thus, one of the main reasons for the general public to consider having an ACL reconstruction is both to repair any meniscal tears which are repairable, and also to prevent meniscal tears from developing if their knee is unstable.

What is ACL reconstruction surgery?

ACL reconstruction surgery consists of replacing a torn ACL with another ligament or tendon.  This can be from one’s own body (an autograft) or from a donor (an allograft).  In an ACL  surgery, tunnels are reamed at the normal attachment site of the ACL on both the femur and tibia and the graft is secured either inside or outside these tunnels.  The type of graft from one’s own body and whether one should use a cadaver graft tissue or not can depend on multiple factors.  This can include the patient’s age, if they have hyperlaxity, where they participate in contact sports, and other factors.

How is an ACL reconstruction done?

An ACL reconstruction is done by replacing the torn ACL with tissue that is placed at the normal attachment sites of the native ACL.  This involves reaming a tunnel in the femur (posterior to the lateral intercondylar ridge) and also in the tibia (adjacent to the anterior horn of the lateral meniscus) and then securing the graft within those tunnels.  There are multiple ways to secure the graft, and this can include fixation within the tunnels with metal or bioabsorbable/plastic screws or through a loop and button placed on the outside of the tunnels.  In general, the fixation of the grafts is performed according to the way the surgeon was originally taught, with the gold standard being screws placed within the tunnels for patellar tendon grafts and looped sutures with cortical buttons or screws within tunnels for hamstring ACL reconstruction grafts.

When should an ACL be repaired?

The main time that  ACLs can be repaired is when an ACL is torn with a piece of bone, usually off the tibia, which is much more common than when torn off the femur.  In this circumstance, if there is not a lot of intrasubstance stretch within the torn ACL, the bony can be refixed at its normal attachment site and secured such that early motion can be started.  In those instances where the tissue is not strong enough to allow early motion, there is a much higher risk of stiffness if immobilization is required after surgery.

In terms of a repair of the ACL, there are perhaps 10% of patients who may have injury only to the attachment site on the femur or tibia and sutures can possibly be placed in to do a repair.  In those circumstances, research is still ongoing to try to improve outcomes because attempts at repairs in the literature previously have not shown good outcomes over time.  Thus, more research is necessary to define better techniques to perform ACL repairs in those circumstances.  It is important that these techniques be based upon good science and not on marketing by device companies because previous attempts at ACL repairs did not show failures until after two years after surgery.

How long is an ACL surgery recovery?

One of the most important things for preventing a retear of an ACL reconstruction is to ensure that the patient has gone through the proper recovery phase after surgery.  In the past, many surgeons tried to get their patients back to full activities by 5 or 6 months.  However, more recent data has suggested that waiting up to 9 months may be more advantageous in that the rate of retear goes down significantly after the 9-month timeframe for a return to activities after ACL surgery.  In general, it is important to make sure that an athlete has a full return of proprioception, strength, agility, and endurance to minimize their risk of reinjury.

When I can run after ACL surgery?

The ability to return to running after an ACL surgery is dependent upon many factors.  If the surgery is only the ACL, and there are no other ligaments or meniscus tears treated, and the cartilage surfaces are intact, then one has to go through a proper rehabilitation program first.  In general, we feel that an athlete has to wait a minimum of 4 months after their ACL reconstruction return to running.  In addition, they should have appropriate quadriceps strength.  Our main goal is to be able to have them perform a single-leg squat with no bending of the knee inwards (valgus collapse) during the single leg squat.  In these circumstances, if the patient has a good return of function, good motion, and does not have a valgus collapse when performing a single-leg squat, they are generally able to initiate a  return to their running program at about the 4-month timeframe.  This allows the quadriceps mechanism to be strong enough to prevent extra stress on the knee which can lead to knee swelling (effusions) and possibly damage the cartilage which would not be noticed until several years later.

What causes ACL reconstruction failure?

The number one cause of ACL reconstruction failure in all of the literature is improperly placed ACL grafts at the initial surgery.  This can cause extra stress on an ACL reconstruction graft which can lead to its failure.  In addition, a missed other ligament problem at th time of the ACL surgery, such as an MCL or a posterolateral corner injury, can also put significant stress on an ACL reconstruction graft, which can lead to its failure.  Other factors that can cause an ALC graft to fail can include the lack of the posterior horn of the medial meniscus.  This is because the posterior horn of the medial meniscus is the next structure that prevents the knee from sliding forward.  In patients who may not have their medial meniscus, the ACL graft generally tends to be looser than in patients who do have their medial meniscus.  Thus, in some patients, this can lead to the graft being overloaded and it can cause the ACL graft stretch out over time.

Other factors that can lead to ACL reconstruction failure are patients that have soft tissue grafts, such as hamstrings grafts, that have hyperlaxity.  These patients who have a significant increase of  heel height  (more than 4-5 cm) have a much higher risk of having these grafts stretch out versus a patellar tendon graft.  Other factors include patients with a large increase in their posterior tibial slope (sagittal plane tibial slope) which can cause an ACL graft to be overloaded and stretch out over time.

In my practice, where we perform over 75 revision ACL reconstructions a year, we find that a properly placed ACL reconstruction is the least common cause of failure.  Therefore, patients who have a well-done ACL reconstruction and are exposed to sports activities, are the lowest numbers of athletes that we see that need a revision.  Thus, it appears that when an ACL reconstruction is placed in the correct position and the patients appropriately rehabilitate themselves, the risk of an ACL reconstruction graft failure is much lower.

Patellar tendon ACL reconstruction versus hamstrings ACL reconstruction

Patellar tendon ACL reconstructions have been considered the gold standard now for almost 30 years.  This is because they are the graft of choice for physicians who cover professional teams and for high level athletes; however, hamstrings grafts can also be considered to be appropriate for a large number of patients.  Hamstrings grafts would be most appropriate for patients with open growth plates and in those patients who may have lower levels of activity desired after an ACL reconstruction.  In general, a patellar tendon ACL reconstruction should not be performed in patients with significant arthritis of their kneecap joint, or may have had a previous patellar tendon harvest.  Hamstring ACL reconstruction grafts should definitely not be considered in patients with a lot of hyperlaxity, such as in patients with a large heel height, because these grafts have been shown to stretch out over time.

In general, the large data base series have shown that the rate of retear is lower with a patellar tendon reconstruction compared to a hamstrings ACL reconstruction.  However, a well done ACL reconstruction with either graft can be appropriate for the majority of patients.

NOTICE: Effective June 1, 2019, Dr. LaPrade will be practicing at Twin Cities Orthopedics in both the Edina and Eagan Minnesota Clinics and Surgery Centers

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