Access Keys:
Skip to content (Access Key - 0)

ACL Double-Bundle Reconstruction versus Single-Bundle Reconstruction

Scroll down to respond to the OrthopaedicsOne Poll: Double-bundle ACL reconstruction should replace single-bundle ACL for most patients

We are honoured and privileged to have two world-renowned surgeons with vast experience in anterior cruciate ligament (ACL) reconstruction of the knee — Drs. Freddie Fu and Donald Johnson — debate the merits of single- versus double-bundle ACL surgeries.

Although ACL repair surgery is well established in the surgical armamentarium, recent cadaveric studies have questioned the appropriateness of a single-bundle reconstruction of the ACL. This has generated significant scientific interest into the value of a more anatomic restoration of the ACL (ie, double-bundle) versus the more classic reconstruction using the single-bundle technique.

As with any new surgical techniques in orthopaedics, and stressed by both authors, it is critical that we minimize the learning curve by appropriate patient selection as well as surgical technique. As more research is completed and concrete results are published, it is likely that the role of the double-bundle reconstruction versus single-bundle will be reserved for specific anatomical situations as well as patient requirements.

We thank both authors for their contribution and hopefully all of you will enjoy this stimulating discussion.

Viewpoint 1: Freddie H. Fu, MD, DSc (Hon), DPs (Hon)

Double-Bundle ACL Reconstruction

Anatomy is the foundation of orthopaedic surgery. The advancing knowledge of the anterior cruciate ligament (ACL) has led to the development of modern, improved reconstruction techniques that help restore the anatomy of the native ACL, which consists of two functional bundles: the anteromedial (AM) and posterolateral (PL) bundles. (Figure 1)

Figure 1. Lateral portal view of the two-bundle anatomy of the ACL of a left knee. The anteromedial (AM) and posterolateral (PL) bundle are indicated by the arrows.

Recently there has been much discussion as to whether the ACL should be reconstructed as a single or a double bundle. However, the question should not be about single- or double-bundle reconstruction, but rather about how to restore the anatomy to the fullest extent. Anatomic ACL reconstruction is defined as the functional restoration of the ACL to its native dimensions, collagen orientation, and insertion sites.1 The four principles of anatomic ACL reconstruction are to:

  • Restore the two functional bundles (whether with a single- or double-bundle)
  • Restore the insertion sites
  • Replicate the native tensioning pattern
  • Individualize the surgery for each patient

Non-Anatomic ACL Reconstruction Does Not Promote Long-Term Knee Health

It has been shown that traditional, non-anatomic, single-bundle ACL reconstruction does not prevent the occurrence of early osteoarthritis.2 This traditional ACL reconstruction technique places the ACL graft outside of the native insertion site 3,4 and therefore fails to restore the normal knee kinematics.5 It has been hypothesized that these abnormal knee kinematics contribute to the development of osteoarthritis after ACL reconstruction. Before we discuss whether to perform single- or double-bundle reconstruction, we first need to place the ACL in the anatomic position. Anatomic placement of the graft helps to restore normal knee anatomy and function and therefore helps to promote long-term knee health.

How Much of the ACL Do We Need to Restore?

The ACL comes in a variety of shapes and sizes (Figure 2). The native ACL insertion site size ranges from 12 mm to 22 mm.4 A single tunnel of 10 mm diameter would cover 80-90% of the native ACL insertion site if the native ACL insertion site were only 12 mm. However, if the native ACL were 22 mm, a single tunnel of 10 mm diameter may cover less than half of the native ACL insertion site. Double-bundle reconstruction would result in better coverage of the native insertion site in these cases. This illustrates that ACL reconstruction should be performed in an anatomic fashion and individualized to tailor the ACL to each patient’s specific needs.

Figure 2. Lateral portal view of the tibial ACL insertion site. Tibial insertion site of 14 mm, left, and tibial insertion site of 22 mm, right. These examples show the large variation in ACL insertion site size.

The Two Bundles Work Together

The two functional bundles of the native ACL work synergistically. Together, they provide stability while allowing normal knee range of motion. Anatomic single-bundle ACL reconstruction restores the ACL as one bundle; double-bundle ACL reconstruction restores the ACL as two bundles, allowing each bundle to be tensioned separately to better replicate the native ACL tension pattern.

Outcome Evaluation

To determine if there is a difference in outcome between single- and double-bundle ACL reconstructions, we need high-quality, randomized clinical studies. However, we also need to focus on improving our outcome measures. Physical examination and patient reported outcome scores may not be enough to demonstrate the subtle, yet important differences between the techniques. More accurate, reliable, and precise outcomes measures - including biology, imaging and kinematic testing - are needed. 

The paradigm in ACL surgery is changing. New reconstruction techniques are being developed, and there is a need to compare these various techniques. There is no definitive answer as to whether single- or double-bundle reconstruction is better at this time. The best answer is that it probably depends on the patient's individual characteristics with regards to ACL size, activity level, co-morbidities, and more.

Regardless of the choice for single or double bundle, ACL reconstruction should be performed in an anatomic fashion. By restoring normal knee anatomy and kinematics, we can potentially eliminate risk factors and help to prevent the development of osteoarthritis. Osteoarthritis has a major impact on quality of life and its prevention is part of our vow to provide the best possible care for our patients.

Reprinted with permission from the Fall 2010 issue of COA Bulletin


  1. van Eck CF, Lesniak BP, Schreiber VM, Fu FH Anatomic Single- and Double-Bundle Anterior Cruciate Ligament Reconstruction Flowchart. Arthroscopy 2010;26-2:258-68.
  2. Lohmander LS, Ostenberg A, Englund M, Roos H. High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury. Arthritis Rheum 2004;50-10:3145-52.
  3. Forsythe B, Kopf S, Wong AK, Martins CA, Anderst W, Tashman S, Fu FH. The location of femoral and tibial tunnels in anatomic double-bundle anterior cruciate ligament reconstruction analyzed by three-dimensional computed tomography models. J Bone Joint Surg Am 2010;92-6:1418-26.
  4. Kopf S, Pombo MW, Szczodry M, Irrgang J, Fu FH. Size variability of the human anterior cruciate ligament insertion sites. Am J Sports Med 2011;39(1):108-13.
  5. Tashman S, Collon D, Anderson K, Kolowich P, Anderst W. Abnormal rotational knee motion during running after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32-4:975-83.

Viewpoint 2: Donald H. Johnson, MD, FRCSC

Single-Bundle ACL Reconstruction

My preference is to do an anatomic single-bundle anterior cruciate ligament (ACL) reconstruction for various reasons.

Even though there is support for the double-bundle concept from the standpoint of both anatomy and biomechanics, the published clinical evidence supporting double-bundle reconstruction is insufficient. Most of the randomized controlled trials comparing single- vs double-bundle ACL reconstruction show no subjective improvement and only a slight reduction in the incidence of a positive pivot shift with the double-bundle reconstruction.


Success of Single-Bundle Technique

Single-tunnel ACL reconstruction has been a successful procedure. In 2008, Lewis et al reviewed 11 clinical trials comparing single-bundle patellar tendon and hamstring grafts consisting of 1,024 reconstructions.1 The outcome measurements included a complication rate of 6%, a graft failure rate of 4%, negative pivot shift 81%, negative Lachman test 59%, and KT SSD less than 5 mm in 86%.1 After review of a considerable body of unbiased outcome data, Lewis et al concluded that single-bundle ACL reconstruction is a safe, consistent surgical procedure that affords reliable results.1 It is true that these are not optimum results, but I think the outcome can be improved more by anatomic tunnel single placement rather than switching to a double-bundle procedure.

If everyone were to switch to the double-bundle procedure, we would have more complications, increased cost of the procedure (twice as many implants), and surgeons frustrated with the very steep learning curve - all with only a very marginal improvement in outcomes. If outcomes were significantly better with double-bundle ACL reconstruction than with single-bundle reconstruction, then perhaps we could justify these issues.

Importance of Anatomic Placement

This is not really an argument for or against double-bundle reconstruction, but it is rather all about anatomic ACL reconstruction. Dr. Fu has brought to our attention the importance of anatomic placement of the tunnels. For the past 15 years, the most common technique in North America was to create the femoral tunnel through the tibial tunnel. This often resulted in a high anterior femoral tunnel.

When this was recognized, the tendency was to place the tibia tunnel more posterior on the tibia to reach the lower position on the femur. We were then creating a tibial PL to femoral AM position with the single tunnel. The position of the femoral tunnel was improved by drilling through the AM portal. This is not without its problems:

  • Damage to the femoral condyle with the drill bit
  • Cutting the anterior horn of the medial meniscus
  • Incorrect placement of the femoral tunnel due to loss of orientation with hyperflexion

All these are overcome as the surgeon becomes more experienced with the technique. Identifying the anatomic site of the ACL, marking it, and confirming the position by viewing from the medial portal all help find this position with hyperflexion.

A new technique of drilling from the outside-in with the flipcutter is another method to place the femoral tunnel in the correct position without putting the knee into hyperflexion. In this situation, the guide is placed through the anterolateral portal and viewing is done via the medial portal. The anatomic position may be determined precisely when viewing from the medial portal. Avoiding the hyperflexion position makes it easier to convert from the tibial tunnel technique.

The position of the anatomic single tunnel should overlap both the AM and PL anatomic sites (Figure 1). The previous concept of going at the 11 o’clock position, and as far posterior as possible, is no longer considered ideal.

Figure 1. The femoral tunnel is low, and overlaps both the AM and PL anatomic sites.

Keep Technique as Easy as Possible

In my opinion, not everyone should be attempting a double-bundle ACL reconstruction. For the surgeon who occasionally performs ACL reconstruction, the technique should be kept as easy as possible. There probably is an indication for double-bundle ACL reconstruction, but right now I am not sure what it is. Should the patient with the gross pivot shift be considered? Or the one that has a touch of posterior lateral laxity?

The current method of evaluating rotational laxity is with the pivot shift test. This is a very subjective evaluation, yet it is the only outcome measurement that is used in these comparison studies. In my mind, that may introduce a significant bias. In one study comparing the single- versus double-bundle, the author quoted a 27% positive pivot shift in the single-bundle group. Either he is not placing the single-bundle in the correct position or there is an element of bias in the data.

In summary, anatomic single-tunnel ACL reconstruction is an easy, reproducible technique that has few complications and a minimal learning curve. The cost of converting to a new variant such as outside-in drilling is minimal.

Reprinted with permission from the Fall 2010 issue of COA Bulletin


  1. Lewis PB, Parameswaran AD, Rue JP, Bach BR Jr. Systematic review of single-bundle anterior cruciate ligament reconstruction outcomes: a baseline assessment for consideration of double-bundle techniques. Am J Sports Med 2008;36(10):2028-36.


Added By

The license could not be verified: License Certificate has expired!

Log In or Sign Up to follow this author.

More From
The license could not be verified: License Certificate has expired!
The license could not be verified: License Certificate has expired!
Content Partner

Learn about becoming an OrthopaedicsOne Content Partner.

Academic Resources

Resources on ACL Double-Bundle Reconstruction versus Single-Bundle Reconstruction from Pubget.

The license could not be verified: License Certificate has expired!
Related Content

Resources on ACL Double-Bundle Reconstruction versus Single-Bundle Reconstruction and related topics in OrthopaedicsOne spaces.

Showing first 5 of 268 results