A Biomechanical Comparison of Alternative Graft Preparations for All-Inside Anterior Cruciate Ligament Reconstruction

Abstract

To biomechanically compare alternative graft constructs for all-inside anterior cruciate ligament (ACL) reconstruction in the event that the semitendinosus harvested is too narrow or too short to make a graft larger than 8 mm. Methods: Bovine extensor tendons were used to make 6 different 9-mm-diameter grafts: traditional 4-strand, anastomosis 4-strand, 6-strand, 3-strand, button-fixation 4-strand, and loopand-tack 4-strand grafts. The grafts were then subjected to cyclic biomechanical testing followed by failure loading. Force at 3 and 5 mm of displacement and ultimate force were recorded for all grafts. Results: Compared with the traditional 4-strand graft, the only graft that showed significant biomechanical differences during the cyclic phase of testing was the button-fixation 4-strand graft, which was characterized by lower force at 3 mm of displacement (74 ± 34 N vs 122 ± 13 N, P =. 004) and 5 mm of displacement (122 ± 35 N vs 172 ± 3 N, P = .006). During failure loading, ultimate force was significantly lower for both the 6-strand graft (491 ± 186 N, P = .041) and button-fixation 4-strand graft (326 ± 27 N, P < .001) than for the traditional 4-strand graft (778 ± 176 N). All other grafts were equivalent for the parameters tested. Conclusions: The anastomosis 4-strand, 3-strand, and loop-and-tack 4-strand grafts do not biomechanically differ in cyclic loading and ultimate force from traditional 4-strand grafts. This study supports the use of anastomosis 4-strand, 3-strand, or loop-and-tack 4-strand grafts in the event that a traditional all-inside 4-strand graft cannot be prepared from a harvested semitendinosus tendon in ACL reconstruction. Clinical Relevance: This study tests and describes alternatives to the traditional 4-strand semitendinosus autograft for all-inside ACL reconstruction in the event that the harvested tendon is not adequate. Interest has peaked recently regarding the size of 4-strand hamstring autografts in all-inside anterior cruciate ligament (ACL) reconstruction and its effect on clinical outcome and graft

Predicting the Effect of Localized ACL Damage on Neighbor Ligament Mechanics via Finite Element Modeling

“…For this reason, it is evident that early intervention when ACL injury occurs will reduce the probability of additional complications in the other ligaments of the knee. Moreover, as the potential benefits and risks of ACL repair are still largely not well known, it is thereby recommended that regular assessment of the knee joint, especially if injury is suspected, should be performed to allow for early intervention [ 33 , 34 , 35 , 36 , 37 ].…”

Editorial Commentary: My Harvested Hamstring Autograft Is Too Small. Now What?

“…At times, new surgical techniques are introduced with expanded text and explanation, but inadequate images prevent their reproducibility and clinical use. I am confident that if my harvested hamstring were inadequate, I would be able to successfully build an anastomosis 4-strand, 3-strand, or loop and 4-strand graft from the illustrations provided by Richardson et al 10 Although the illustrations are excellent, the authors deserve more praise for their pragmatic study design in answering a clinically relevant question not often asked. Although many aspects of ACL reconstruction have been extensively studied, I was appreciative of a study that evaluated a "bail-out" technique.…”

All-Inside Anterior Cruciate Ligament Reconstruction: A Review of Advance and Trends

“…Traditional 4-strand grafts have good biomechanical properties, but when the tendon length or width is not large enough, other construction methods can also be used to ensure sufficient strength of the graft [60][61][62]. A study showed that anastomosis of 4-strand (699.89 ± 196.73 N), 3-strand (576.20 ± 173.64 N), and loop-and-track 4-strand grafts (769.67 ± 151.89 N) do not biomechanically differ in ultimate force from traditional 4-strand grafts (778.84 ± 176.11 N) [60].…”

“…Traditional 4-strand grafts have good biomechanical properties, but when the tendon length or width is not large enough, other construction methods can also be used to ensure sufficient strength of the graft [60][61][62]. A study showed that anastomosis of 4-strand (699.89 ± 196.73 N), 3-strand (576.20 ± 173.64 N), and loop-and-track 4-strand grafts (769.67 ± 151.89 N) do not biomechanically differ in ultimate force from traditional 4-strand grafts (778.84 ± 176.11 N) [60]. Another biomechanical study on the graft preparation technique by Colter et al [61] also found that a 4-strand single tendon graft was preferred for all-inside reconstruction of the ACL, while the 3-strand single tendon technique was preferred when the tendon length was insufficient, and the 2-strand technique (2 tendons) had a much Cyclic displacement (After preloading and cyclic loading occurred for 500 loading cycles from 50 to 250 N at 1.0 Hz, the final extension length of the graft) than the other groups, so the last technique is not recommended for all-inside reconstruction of the ACL.…”