Summary

Multiple-strand hamstring grafts produce statistically bigger graft diameters. There is a trend for a higher failure-rates in traditional four-strand hamstring ACLR techniques

Abstract

Introduction

Recent reports have shown higher failure rates of hamstring anterior cruciate ligament reconstruction (ACLR) in young patients. Studies have also shown a thicker hamstring graft has a lower failure rate. In response to this surgeons have increased the number of hamstring strands to thicken their hamstring grafts or performed more patella tendon grafts. The purpose of this study was to use the New Zealand ACLR registry to determine whether multiple strand hamstring grafts increased graft construct size and whether multiple strand grafts or a patella tendon graft type reduced ACLR reconstruction failure rates in young people.

Methods

All ACLR patients aged 20 years or younger at the time of surgery with a minimum one year follow up were and grouped into one of five cohorts depending on the type of autograft used: traditional 4 strand hamstring two-tendon doubled graft (4STG), 4 strand semitendinosus (4ST), 5-6 strand semitendinosus and gracilis (6STG), 7-8 strand semitendinosus and gracilis (8STG) and Bone-patella-bone graft (BTB) groups. For each group, a mean graft diameter size and graft rupture rate was calculated. Statistical analysis was performed to determine whether a statistically significant difference in graft size and failure rate existed.

Results

Between April 2014 and May 2017, 1072 patients aged <=20 years underwent an ACLR. After one-year minimum follow-up, 26 cases of graft rupture were recorded, giving an overall failure rate of 2.4%. The smallest diameter grafts and highest failure rates were seen in the traditional 4STG grafts at 7.9mm and 3.5% respectively. The largest diameter grafts were seen in patella-tendon grafts at 9.6mm. There was a statistically significant size difference between all graft configurations (P<0.001). There was no statistically significant difference in failure rates between graft cohorts however, a trend was demonstrated when comparing the traditional 4 strand hamstring graft (4STG) against the multiple-strand configurations (P=0.09). The 4STG had a 1.5 times higher failure rate than BPB and a 2.4 times higher failure rate than the combined multiple-strand hamstring grafts.

Conclusion

Multiple-strand hamstring grafts produce statistically bigger graft diameters. Traditional four-strand hamstring grafts, multiple strand configurations and patella-tendon ACLRs show no difference in the failure rate in the New Zealand ACL registry for young patients however the failure rate per 100 component years shows a trend for a higher failure-rates in traditional four-strand hamstring ACLR techniques.