Summary

This study seeks to compare the outcomes between Single Tendon (ST) and Dual Tendon (DT) ACLR, given there is no prospective randomised controlled trial (RCT) in the literature comparing outcomes between these options

Abstract

Introduction

Hamstring autograft is the most common graft used worldwide for ACL reconstruction (ACLR). Hamstring harvest has been associated with reduced hamstring strength, donor site pain and muscle strains after return to sport. There is conjecture as to the importance of the gracilis tendon in contributing to pain, flexion strength and rotational stability. Traditional hamstring graft requires both tendons to be harvested to achieve a graft of sufficient length and diameter, but newer techniques allow for a shorter, broad single tendon graft. To date there has been no prospective randomised controlled trial evaluating outcomes after single or dual hamstring tendon ACLR. The aim of this study is to compare post-operative clinical outcomes between single (semitendinosus only) versus dual (semitendinosus and gracilis) hamstring tendon grafts.

Methods

In this ongoing double blinded prospective randomised controlled trial (RCT) (registered as a clinical trial with the Australia New Zealand Clinical Trials Registry (ACTRN12620000927921)) patients were recruited and randomised a priori into a single tendon (ST) or a dual tendon (DT) group for ACLR. All anaesthetic and surgical techniques were uniform between the groups aside from graft technique and tibial fixation. Patients were evaluated pre-operatively and at 6-months post-ACLR using patient-reported outcome measures (PROMS) including the IKDC, Lysholm and Modified Cincinnati knee scores, as well as a visual analog scale for pain frequency (VAS-F) and severity (VAS-S). At 6 months post-ACLR, the Graft Morbidity Score (GMS) was completed, while knee laxity (KT-1000), hop performance and peak isokinetic quadriceps and hamstrings strength were assessed.

Results

Overall, 71 patients (ST = 34; DT = 37) were assessed at 6 months post-surgery on a per protocol analysis, with a further 13 patients excluded at time of surgery as their selected graft did not meet a minimum 8mm diameter. No significant group differences (P>0.05) were observed in demographics (age, sex, height and body mass) or surgical characteristics (concomitant meniscal repairs and tenodeses). Graft diameters were significantly smaller in the ST group compared to the DT group (mean difference [MD], -0.67mm; 95% CI, -0.91 to -0.43; P<0.001). A significantly lower GMS was reported in the ST group compared to the DT group (effect size [ES], 0.649; 95% CI, 2.4 to 16.2; P=0.01). No significant group difference were observed for other PROMs (P>0.05) or knee laxity (P=0.362).

Conclusion

ST (versus DT) harvest results in significantly less donor site morbidity and this is the first prospective RCT to determine this. There were no differences between ST and DT hamstring ACLR were observed in PROMs, knee laxity and hamstring strength. Younger female patients tend to have inadequate single tendon size to produce a graft of sufficient diameter, and alternative techniques should be considered. Further endpoints include radiological analysis, longer term donor site morbidity, revision rates and return to sport and will continue to be presented in the future.