Editorial Commentary: Single-Bundle Versus Double-Bundle Anterior Cruciate Ligament Reconstruction … Are We Barking up the Wrong Tree?

As techniques in anterior cruciate ligament reconstruction continue to evolve, studies comparing single bundle to double bundle continue to mount in numbers. Although there have been great strides in identifying anatomic tunnel placement, how many tunnels (bundles) are created, and how those tunnels are placed, we still seem to be stuck with grossly similar results with respect to both patient-related and objective outcome measures. It seems to me that we can do a very good job reproducing what we do to a cadaver in a lab. Unfortunately, that cadaver does not get up and walk after our job is done as surgeons. Nearly 20% of our athletes do not return to their prior level of sport, and 30% of our patients develop radiographic signs of osteoarthritis. There must be something we are neglecting.     

Editorial Commentary: Déjà Vu: Double-Bundle Anterior Cruciate Ligament Reconstruction Revisited

Regardless of the technique utilized, tunnel expansion following anterior cruciate ligament reconstruction remains a mystery and a clinical challenge. No procedure seems to be immune to this, even anatomic double-bundle reconstruction. This technique was introduced more than 20 years ago and showed great promise while also contributing significantly to our current knowledge of anterior cruciate ligament anatomy and biomechanics. However, we must remember that new techniques do carry with them new side effects that we must document and acknowledge if we hope to improve our surgical outcomes.     

Editorial Commentary: Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction Makes More Sense Than Triple-Bundle: Three’s a Crowd

Recent research reports impressive patient-reported and objective stability outcomes after triple-bundle anterior cruciate ligament (ACL) reconstruction with hamstring autograft. However, the results are similar to those reported in the orthopaedic literature for single-bundle ACL reconstruction. If the triple-bundle technique does not reduce graft failure rates, and bearing in mind that it is more complex, more expensive, and more difficult to revise, then an anatomically-positioned single-bundle ACL reconstruction makes more sense. If the data supporting double-bundle ACL reconstruction is inconclusive, then why add a third bundle?     

Can Joint Contact Dynamics Be Restored by Anterior Cruciate Ligament Reconstruction?

Background

Rotational kinematics has become an important consideration after ACL reconstruction because of its possible influence on knee degeneration. However, it remains unknown whether ACL reconstruction can restore both rotational kinematics and normal joint contact patterns, especially during functional activities.

Questions/purposes

We asked whether knee kinematics (tibial anterior translation and axial rotation) and joint contact mechanics (tibiofemoral sliding distance) would be restored by double-bundle (DB) or single-bundle (SB) reconstruction.

Methods

We retrospectively studied 17 patients who underwent ACL reconstruction by the SB (n = 7) or DB (n = 10) procedure. We used dynamic stereo x-ray to capture biplane radiographic images of the knee during downhill treadmill running. Tibial anterior translation, axial rotation, and joint sliding distance in the medial and lateral compartments were compared between reconstructed and contralateral knees in both SB and DB groups.

Results

We observed reduced anterior tibial translation and increased knee rotation in the reconstructed knees compared to the contralateral knees in both SB and DB groups. The mean joint sliding distance on the medial compartment was larger in the reconstructed knees than in the contralateral knees for both the SB group (9.5 ± 3.9 mm versus 7.5 ± 4.3 mm) and the DB group (11.1 ± 1.3 mm versus 7.9 ± 3.8 mm).

Conclusions

Neither ACL reconstruction procedure restored normal knee kinematics or medial joint sliding.

Clinical Relevance

Further study is necessary to understand the clinical significance of abnormal joint contact, identify the responsible mechanisms, and optimize reconstruction procedures for restoring normal joint mechanics after ACL injury.