Haw Chong Chang

Anatomic double bundle ACL reconstruction: a literature review

With the abundance of anatomic double bundle ACL reconstruction techniques that currently exist and limited patient outcome data, one has to ask whether or not they should be used and if so, which one, and what is the learning curve for the average knee surgeon to become competent with the technique that they select? The purpose of this literature review is to summarize existing anatomic double bundle ACL reconstruction surgical and rehabilitation techniques and the clinical and biomechanical study evidence that currently exists. In choosing to perform anatomic double bundle ACL reconstruction we suggest that the knee surgeon should look for evidence of: (1) control of the pivot shift phenomenon, (2) improved transverse plane rotatory knee control during the performance of sports type movements, (3) a decreased likelihood of revision procedures either for ACL reconstruction or for treatment of associated primary or recurrent meniscal injuries, (4) improved patient self-reports of perceived function, satisfaction, and quality of life, and (5) radiographic evidence of a lower incidence and/or magnitude of osteoarthritic changes compared to conventional single bundle ACL reconstruction.

Biomechanical comparison of the bioabsorbable retroscrew system, bioscrew XtraLok with stress equalization tensioner, and 35-mm delta screws for tibialis anterior graft-tibial tunnel fixation in porcine tibiae

Background Achieving effective soft tissue graft-tibial tunnel fixation remains problematic. Hypothesis No differences would exist for tibialis anterior graft-tibial tunnel fixation when comparing the RetroScrew System (20-mm retrograde screw, 17-mm antegrade screw), the 35-mm tapered Delta Screw (manual tensioning), and the 35-mm BioScrew XtraLok (applied using an instrumented tensioner). Study Design Controlled laboratory study. Methods Porcine tibiae (apparent bone mineral density, 1.3 g/cm2) and human tendon allografts were divided into 3 matched groups of 6 specimens each before cyclic (500 cycles, 50-250 N, 1 Hz) and load-to-failure (20 mm/min) tests. Results The BioScrew XtraLok (210.9 ± 54.9 N/mm) and the 35-mm Delta Screw (224.3 ± 43.7 N/mm) displayed superior stiffness to the RetroScrew System (114.1 ± 23.3 N/mm) (P =. 0004) during cyclic testing. The BioScrew XtraLok (1.0 ± 0.2 mm) and the Delta Screw (0.9 ± 0.2 mm) also displayed less displacement during cyclic testing than the RetroScrew System (1.8 ± 0.5 mm) (P =. 001). During load-to-failure testing, the BioScrew XtraLok withstood greater loads (1436.3 ± 331.3 N) (P =. 001) and displayed greater stiffness (323.6 ± 56.8 N/mm) (P =. 002) than the 35-mm Delta Screw (load, 1042.2 ± 214.4 N; stiffness, 257.2 ± 22.2 N/mm) and the RetroScrew System (load, 778.7 ± 177.5 N; stiffness, 204.4 ± 52.9 N/mm). Conclusion The BioScrew XtraLok with instrumented tensioning displayed superior fixation to the RetroScrew System and the 35-mm Delta Screw applied with manual tensioning. Clinical Relevance The BioScrew XtraLok may provide superior soft tissue graft-tibial tunnel fixation. Further in vitro studies using human tissue and in vivo clinical studies are needed.

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction: Maximizing Benefits While Minimizing Complexity: A Balanced Potential Approach

The rapid development of anatomical double-bundle anterior cruciate ligament (ACL) reconstruction techniques is unprecedented, especially given the 80% to 90% success rate that has been reported for conventional single-bundle ACL reconstruction. However, in vitro and in vivo biomechanical evidence of poor transverse plane rotatory knee control and 10% to 30% complication rates associated with conventional single-bundle ACL reconstruction techniques suggest that a better method of restoring ACL function and improving patient outcomes is needed. Selection of which technique to use and its associated learning curve may decrease its desirability for the average knee surgeon who performs fewer than 10 ACL reconstruction procedures a year. This article describes an anatomical double-bundle ACL reconstruction technique that provides reciprocating double-bundle ACL function and that can be performed using a modified conventional single-bundle ACL reconstruction approach. The double-bundle function provided by this ACL reconstruction technique simulates the native ACL more closely than conventional single-bundle ACL reconstruction techniques. In addition to the aforementioned surgical innovations, there is a dire shortage of well-designed patient outcome studies regarding any of these anatomical double-bundle ACL reconstruction techniques. When considering use of a particular anatomical double-bundle ACL reconstruction technique, the knee surgeon must consider its complexity, how the procedure would influence revision surgery should it be needed, appropriate selection of patients who would benefit the most, additional patient education and behavioral change needs, rehabilitation and conditioning program modifications, and how this procedure may better protect the menisci and mitigate the onset and progression of knee osteoarthritis better than conventional single-bundle ACL reconstruction.

Effect of Cryoprotectant Incubation Time on Handling Properties of Allogeneic Tendons Prepared for Knee Ligament Reconstruction

Soft tissue tendon allografts prepared for anterior cruciate ligament reconstruction are becoming increasingly popular; although concerns exist regarding increased long-term laxity and traumatic rupture rates. This qualitative study evaluated the tissue handling properties of human tibialis posterior tendons prepared using a patented process to improve allograft remodeling and ligamentization under differing cryoprotectant incubation times over 60-min rehydration. Tendons that had been incubated for 8 h had smaller diameters than those that were incubated for 2 h (8.5 ± 1.5 mm vs. 9.1 ± 1.3 mm, p = 0.02). Qualitative tissue handling property results indicated that the 8-h incubation had a negative affect on tissue color. Both incubation time and rehydration time influenced tensile stiffness, compressive resilience, and ease of tissue handling for allograft preparation with the 8-h group displaying poorer results. This study concludes that an 8-h cryoprotectant incubation time is detrimental to qualitative allogeniec tibialis posterior tendon properties. Both groups tended to improve with longer rehydration times, however the 8-h incubation group remained actively dehydrated as evidenced by its smaller diameter and poorer tissue handling properties. Suboptimally rehydrated tendons would be more likely to accrue damage during allograft preparation or during implantation.