Background

Anterior cruciate ligament (ACL) injuries are commonly encountered, with ACL reconstruction surgery shown to improve patient outcomes. With increasing numbers of these surgeries performed each year, there has been a corresponding increase in the number of graft failures; in tandem with this, there is burgeoning interest in the predictors of graft failure in attempts to improve the success rates of surgery. Studies have shown graft size to be an important determinant of failure – graft sizes of less than 8mm are believed to be associated with increased rates of revision surgery. With increasing focus on personalised ACL reconstruction, we thus aimed to ascertain if these factors applied universally within the context of a smaller Asian population. Secondarily, we sought correlation between other anthropometric factors, graft size and graft failure.

Methods

A retrospective analysis of all consecutive patients who underwent primary ACL reconstruction with a hamstring autograft over a 3 year period from January 2016 to December 2018 was performed. We excluded revision surgeries, use of an allograft or alternative autografts, as well as those lost to follow up. Data collected included basic demographic and anthropometric data, length of follow up, graft size, as well as any occurrence of failure, clinically or radiologically. Patients were analysed both in cohorts – graft size <8mm and >/=8mm – as well as separately via simple logistic regression. P-values were considered significant at p </=0.05.

Results

193 patients were analysed, with a mean follow up duration of 12.6 months. 70.4% had concurrent procedures, most commonly meniscus repair and partial meniscectomy. There was a total of 9 failures (4.7%) – 4 and 5 in the <8 and >/=8 groups respectively – with no significant difference in failure rates seen between both cohorts (p=0.752). Additionally, there was no correlation found between graft size and failure. 4 of these 9 patients underwent revision surgery (2 and 2 in the <8 and >/= 8 groups respectively). The patients in the smaller graft size cohort were significantly shorter (167.7 vs 172.5 cm, p<0.001) and lighter (68.0 vs 77.2 kg, p<0.001) with lower BMIs (24.1 vs 25.9 kg/m2, p=0.0112) overall, with a higher proportion of females (31.6 vs 9.4%, p<0.001). The mean age was not significantly different between the two groups (p=0.466). Height, weight, BMI and gender were significantly correlated with graft size but not with graft failure (p-values 0.226 – 0.977).

Conclusion

Our study involved a patient cohort which is overall smaller in stature to that reported in the literature, and did not show a correlation between graft size and failure rates. This highlights the need for a more tailored approach to ACL reconstruction, and that the need for large grafts may not apply universally particularly in smaller patients – inappropriately sized grafts may lead to increased risk of complications including impingement and tunnel blowout.