Summary

We present a practical method to predict single and double tendon ACL grafts with any number of folds using pre-operative MRI measurements, achieving high sensitivity.

Abstract

Background

Predicting hamstring graft size before anterior cruciate ligament (ACL) reconstruction is crucial to avoid intraoperative graft failure. Our study aims to (1) develop a generalised algorithm to predict final ACL graft diameter for single and double tendon hamstring grafts consisting any number of folds, (2) evaluate our algorithm with a regression model adjusting for patient and surgical factors, and (3) assess algorithm’s specificity, sensitivity, and discriminative ability, defining adequate graft size as =9mm.

Methods

We conducted a retrospective review of 105 patients who underwent primary ACL reconstruction with hamstring semitendinosus-gracilis grafts from January 2023 to June 2024 at a tertiary institution. MRI scans were independently measured by two junior members. Average of the measurements taken. Predicted graft diameter is v[A*B*X + C*D*Y] - where A and B are the semitendinosus cross-sectional length and breadth, C and D are the gracilis cross-sectional length and breadth, and X and Y are the number of semitendinosus and gracilis folds, respectively.

Results

Pearson correlation shows strong correlation between predicted and actual graft diameters (R=0.568,P<0.01). Univariate and multivariate linear regression, adjusted for age, gender, BMI, and graft type, indicate that males, overweight individuals, and those with single tendon grafts are more likely to have larger actual graft diameters(P<0.05). Our algorithm has a sensitivity of 95.8%, specificity of 60.6%, with excellent discriminative ability(AUC=0.857). A high 78.1% agreement rate was achieved, with Cohen’s kappa=0.468(P<0.05).

Conclusions

We present a practical method to predict single and double tendon ACL grafts with any number of folds using pre-operative MRI measurements, achieving high sensitivity.