2019 ISAKOS Biennial Congress ePoster #785
Optimizing the Hamstring Graft for Anterior Cruciate Ligament Reconstruction: A Biomechanical Comparison of a Novel Six-Stranded Graft versus the Quadrupled Hamstring Graft
Mitchell Meghpara, MD, Austin, TX UNITED STATES
Walter Kim, MD, Columbus, OH UNITED STATES
Erwin Secretov, MD, Chicago, IL UNITED STATES
Donald Chuang, MD, Chicago, IL UNITED STATES
Giovanni F. Solitro, PhD, Shreveport, LA UNITED STATES
Farid Amirouche, PhD, Evanston, IL UNITED STATES
Mark R. Hutchinson, Professor, MD, FACSM, FAANA, FAAOS, Elmhurst, IL UNITED STATES
Philippe Landreau, MD, Dubai UNITED ARAB EMIRATES
University of Illinois at Chicago, Chicago, IL, UNITED STATES
FDA Status Not Applicable
Our study evaluates if superior biomechanical properties and a consistently larger graft diameter can be achieved using a novel six-strand hamstring construct compared to a previously described six-strand construct and the commonly used four-strand construct.
Quadrupled hamstring autograft for anterior cruciate ligament reconstruction has increased in popularity due to decreased donor site morbidity, anterior knee pain, and potential injury to the extensor mechanism with comparable clinical outcomes to other graft options. However, the hamstring graft size has considerable variability in donor size with need for potential allograft back-up and increased failure rate and revision rate if <8mm in diameter. Our study evaluates if superior biomechanical properties and a consistently larger graft diameter can be achieved using a novel six-strand hamstring construct compared to a previously described six-strand construct and the commonly used four-strand construct.
A total of 24 cadaveric hamstring grafts were divided evenly among three groups consisting of a four-strand (FS), a previously published six-strand (SS), and a novel six-strand construct designed by Phillipe Landreau of Aspetar (LA). All grafts were prepared by a single surgeon utilizing the exact same technique per treatment group. A MTS machine was utilized to perform pre-conditioning, cyclical loading (simulating early rehabilitation), and pull to failure tests for each graft construct. Wilcoxon rank sum test was used to compared the 3 construct groups due to their non-parametric distribution based on the Kolmogorov-Smirnov test. We analyzed graft behavior with load versus displacement, load to failure, and deformation after cyclical loading. Final hamstring diameter as well as mode of failure within each graft was recorded.
The SS (Mean 893.24 N, SD 118.29; p<0.04) and LA (Mean 939.30 N, SD 83.28; p<0.01) constructs had significantly higher load to failure versus the FS construct (Mean 769.90 N, SD 75.86). No difference in load to failure was found between the two six-strand constructs (p=0.80). The FS construct (Mean 1.90mm, SD 0.18mm) demonstrated significantly higher deformation after cyclical loading versus the SS (Mean 1.20mm, SD 0.20; p<0.01) or LA (Mean 1.22mm, SD 0.30; p<0.01) construct. There was no difference in deformation among the six-strand constructs (p>0.9). The SS (10.5mm, SD 0.8mm; p=0.05) and LA (11mm, SD 0.9mm; p=0.02) constructs had significantly larger femoral graft diameter versus the FS construct (9.3mm, SD 1.4mm). The LA (11.0mm, SD 0.9mm; p<0.04) had significantly larger tibial diameter versus the four-strand (9.6mm, SD 1.3mm). There was no difference in graft diameter between the six-strand constructs.
Both of the six-strand hamstring constructs provide significantly higher load to failure and significantly less deformation during simulated early rehabilitation when compared to the commonly used four-strand construct. Additionally, both of the six-strand constructs consistently yield a significantly larger graft diameter at both the femoral and tibial ends. Our novel six-strand (LA) construct had the highest load to failure while providing the largest femoral and tibial graft diameter when compared to the previously described six-strand (SS) and four-strand (FS) constructs.