Equation-based precise prediction of length of hamstring tendons and quadrupled graft diameter by various anthropometric variables for knee ligament reconstruction in Indian population

Preoperative prediction of hamstring tendon lengths and graft diameter for anterior cruciate ligament (ACL) reconstruction enables better preoperative planning. Presently, no study exists for Indian population where both derivation and verification of a mathematical equation for accurate prediction of hamstring graft dimensions have been done. This study was conducted in two phases: First phase ( derivation cohort): devoted to the study of correlation of length of hamstring tendons and graft diameter with various anthropometric measurements in 123 patients undergoing ACL reconstruction. Length of semitendinosus (ST) was observed to have a strong correlation with leg length ( r = 0.719), whereas that of gracilis (G) had a strong correlation with patient height ( r = 0.768). Quadrupled diameter (QD) had a strong correlation with patient height and thigh length ( r = 0.685 and 0.680, respectively). Using Pearson correlation coefficient, multiple stepwise linear regressions, and analysis of variance test, predictive equations were developed to predict the length of ST and G and QD. Second phase ( verification cohort): This was a blinded prospective study done on 300 patients to further authenticate and test the accuracy of equations developed. Here, a steady correlation was found between the observed and predicted values of length of ST, G and QD, with correlation coefficients being 0.838, 0.847, and 0.767, respectively. Thus, we can safely conclude that clinically measurable anthropometric variables can reliably predict hamstring graft dimensions. This is likely to prove useful in better preoperative planning of ligament reconstructions.