Abstract
Introduction
The advent of double bundle ACL (Anterior Cruciate Ligament) reconstruction had been hailed as potentially allowing for more anatomically and physiologically functioning graft, however until recently there had been little evidence of enhanced functional outcomes.
The aim of this study is to explore whether the dimensions of hamstring two strand single bundle grafts, are predictive of the combined four strand single bundle graft that results from combining the single bundle grafts, as well as the impact of double bundle grafts upon the available healing and attachment area within the bony tunnels.
Methods
Grafts of all likely two strand single bundle graft sizes, measured to the nearest 0.5mm in diameter using unslotted sizing block, were prepared using porcine flexor tendons,. These two strand single bundles were then systematically combined, and re-measured.
By geometrical calculation, the sum of the circumferences of the two, two strand double bundle grafts were compared to the combined four strand single bundle graft formed by combining the two smaller bundles.
Results
Measuring to the closest 0.5mm, we identified that the predicted four strand single bundle diameters were statistically larger (P < 0.001) than those that were measured.
Geometric assessment reveals that dividing a four stand single bundle graft into it's two stand double bundle components, results in an increase in total graft circumference of 32% to 41%.
Conclusions
We identified a statistically significant difference between measured and predicted four strand single bundle graft sizes. This result suggests that the viscoelastic properties of the tendon tissue increases as the cross sectional area of the graft increases.
Our geometric assessment also demonstrates an increase in available graft to bone contact and healing area, of between 32% to 41%. Therefore one may theorise that double bundle ACL reconstruction results in earlier attainment of graft integration.
