Are pre-operative anthropometric parameters helpful in predicting length and thickness of quadrupled hamstring graft for ACL reconstruction in adults? A prospective study and literature review

Purpose Cross-sectional diameter of 7 mm or more of graft in anterior cruciate ligament reconstruction is arguably the single most important factor determining the success of the operation. Pre-operative anthropometric parameters have been reported to correlate with diameter of quadrupled hamstring graft, which is the most popular graft choice today. We conducted this prospective study to determine the value of some anthropometric measurements to predict the length of harvested semitendinosus and gracilis tendons and quadrupled hamstring graft diameter. We also assessed the reliability of the mathematical equation in accurately predicting the graft diameter. Methods Height, weight, BMI and thigh length of 160 patients who underwent primary ACL reconstruction was measured before surgery. Using multivariate logistic regression analysis length of harvested semitendinous and gracilis tendons along with quadrupled graft diameter were correlated to height, weight, BMI and thigh length. Results Ninety-six percent had graft diameter of 7 mm or more. Height and thigh length were found to be most strongly correlating to both the length of harvested tendons and the quadrupled graft diameter (p <= 0.001, r=0.25-0.39). Patients with height less than 147 cm were found to be at highest risk for inadequate graft diameter (less than 7 mm). Although the anthropometric parameters were found to be significantly related to height and thigh length, the strength of association is moderate. The mathematical equation for prediction of graft diameter using height was found to inaccurately over-predict the graft diameter in 33.1 % of cases, assessed using Bland-Altman plot. Conclusions Anthropometric parameters, especially height and thigh length, can serve as a guide to plan hamstring graft diameter and length before ACL reconstruction. But, it is not advisable to rely on mathematical equations for absolute values of graft parameters as there is risk of over-estimating hamstring length or graft thickness.