Background: Recent studies have shown that the success of anterior cruciate ligament (ACL) reconstructions with ham- string autografts are directly related to graft diameter. This study was designed to biomechanically evaluate alternative graft constructs for all-inside ACL reconstruction in the event that the semitendinosus harvested is too narrow or too short to make a graft larger than 8mm.
Methods: Bovine tendons were used to make six different grafts; traditional 4-strand, anastomosis 4-strand, 6-strand semi- tendinosus and gracilis, 3-strand short semitendinosus, 4-strand semitendinosus and gracilis with an ABS button, and loop and tack 4-strand. The grafts were then subjected to a cyclic biomechanical testing followed by failure loading.
Results: Compared to the traditional 4-strand graft, the only graft that demonstrated significant biomechanical differences during the cyclic phase of testing was the 4-strand ABS graft, which was characterized by lower force at 3mm of displace- ment, 74±34N vs. 122±13N, and 5mm of displacement, 122±35N vs. 172±3N. During failure loading, ultimate force was significantly lower in both the 6-strand, 491±186, and 4-strand ABS, 326±27, compared to the traditional 4-strand graft, 778±176.
Conclusions: This study biomechanically evaluated alternative graft constructs for all-inside ACL reconstruction. The re- sults showed that anastomosis, 3-strand, and loop and tack grafts do not biomechanically differ in cyclic loading and ultimate force compared to traditional 4-strand grafts. However, the 4-strand ABS graft performed worse under cyclic and failure loading and the 6-strand showed lower ultimate force. As such, these two grafts should be avoided if the other alternative graft preparations are feasible. In conclusion, this study supports the use of anastomosis, 3-strand, or loop and tack grafts in the event that a traditional 4-strand graft cannot be prepared from a harvested semitendinosus tendon.
