The Diameter of Single Bundle, Hamstring Autograft Does Not Significantly Influence Re-rupture or Clinical Outcomes After Anterior Cruciate Ligament Reconstruction at 7 Years

OBJECTIVES: Increased graft diameters in ACL reconstruction have recently gained popularity as several studies have suggested that this may reduce graft failure rate in young patients, especially those with graft diameters less than 8mm. The purpose of this study was to review the revision rates and outcomes following ACL reconstruction in relation to graft diameter and determine whether increasing graft diameter reduces failure risk. METHODS: A retrospective analysis of 786 consecutive ACL reconstructions from January 2007 to August 2015 was undertaken. Only cases where a single bundle hamstring autograft reconstruction were included. The surgical technique involved suspensory femoral fixation, tibial screw fixation or cortical button fixation, and a transportal femoral drilling technique. Patients were excluded if there were associated fractures, multiple ligament injuries and previous surgery to the knee. A research database with prospectively recorded data was used for the analysis. The primary outcome measure was graft revision with secondary endpoints being KOOS, IKDC and Tegner Activity Score. RESULTS: 786 consecutive cases were identified with 76 lost to follow up for outcome scores at 2 years. The overall graft revision rate was 5.98% at 7 years. There was no significant difference between responders and non-responders with regards to age, gender and BMI. Mean graft diameter for the males was 7.99mm and 7.56mm for females (p<0.0001). Graft diameter did not correlate with revision when controlled for age, gender, concurrent meniscal pathology and Tegner activity score (N=348). Only grafts <7mm in diameter had a trend towards higher revision rate (5.6 versus 13.5%) but this did not reach significance (p= 0.063). No difference in functional outcomes between small and large grafts was noted. Age < 20 had a significant impact on revision risk (12.3% revision rate < 20, 4.2% > 20 years old). There was no significant difference in rupture rates at any dichotomous graft size for those under 20. CONCLUSION: In this series, graft diameter did not correlate with ACL graft revision for failure. The increasingly popular concept that large diameter grafts offer a protective benefit to revision risk was not found. This study once again highlights that age remains a major determinant of graft failure and factors that can reduce risk in this age group need to be addressed.