Background

Hamstrings autografts are widely used for anterior cruciate ligament reconstructions (ACLR) with comparable outcomes and failures to bone-patellar tendon-bone autografts. The 4-strand (4S) hamstrings graft comprising of doubled semitendinosus and gracilis tendons is the most frequently used configuration. Mean graft diameter in this configuration is variable and the predictability of hamstrings graft diameter and length have been researched. Many studies have supported the notion that graft sizes greater than 8mm diameter have better patient outcomes and smaller graft sizes have an increased failure. However, obtaining a graft size of 8 mm diameter or more can be challenging in certain populations. The 5-strand (5S) hamstrings autograft configuration obtained by tripling the semitendinosus tendon alongside a doubled gracilis tendon has been suggested as a mechanism to increase overall graft diameter. Equally important to graft choice is restoring a rotationally stable knee, a goal that conventional ACLR was not always able to achieve thus renewing an interest in the anterolateral ligament (ALL) and the addition of a lateral extraarticular tenodesis (LET) procedure to hamstrings autograft ACLR.

Objective

To investigate the differences in clinical outcomes between 4-strand (4S) and 5-strand (5S) hamstring autografts for ACLR in patients who underwent ACLR alone or concomitantly with a lateral extraarticular tenodesis (LET) procedure as part of the randomized controlled STABILITY study.

Study Design: Post hoc subgroup analysis of the data collected in the STABILITY study, Level of evidence, 2.

Methods

The data from the STABILITY study was analyzed to compare a subgroup of patients undergoing ACLR alone or with a concomitant LET procedure (ACLR+LET) with a minimum graft diameter of 8mm, that had either a 4S or 5S hamstrings autograft configuration. Patients with graft diameters lower than 8mm and any other configurations of hamstrings autograft were excluded. The primary outcome was clinical failure, which was a composite of rotatory laxity or graft failure. The secondary outcome measures consisted of two patient reported outcome scores (PROS), namely, the ACL Quality of Life Questionnaire (ACL-QoL) and the International Knee Documentation Committee (IKDC) score at 24 months postoperatively.

Results

Out of the 618 patients randomized in the STABILITY study, 399 (228 males; 57%) fit the inclusion criteria for this study. Of these, 191 and 208 patients underwent 4S and 5S configurations of hamstring ACLR, respectively with a minimum graft diameter of 8mm. Both groups had similar demographic characteristics other than expected differences in anthropometric factors, namely sex, height, and weight, and Beighton scores (as these patients had smaller hamstrings and therefore more 5S grafts). Despite these risk factors, the primary outcomes revealed no difference between the two groups when analyzed based on rotatory stability (odds ratio [OR], 1.19; 95% CI, 0.77-1.84; p=0.42) or graft failure (OR, 1.13; 95% CI, 0.51-2.50; p=0.76). Furthermore, there was no significant difference between the groups in the Lachman (p=0.46) and pivot shift (p=0.53) tests at 24 months postoperatively. The secondary outcomes revealed no differences in the ACL-QoL (p=0.67) and IKDC (p=0.83) between the two subgroups.

Conclusion

There were no significant differences in clinical failure or PROS in an analysis of patients with 4S and 5S hamstring autografts undergoing ACLR or ACLR+LET at 24 months follow-up. The 5S hamstring graft configuration is a viable option to produce higher diameter ACLR grafts.