Abstract
Predicting hamstring graft size before anterior cruciate ligament (ACL) reconstruction
is crucial to avoid subsequent graft failure. Our study aims to (1) develop a generalized
algorithm to predict final ACL graft diameter for single- and double-tendon hamstring
grafts consisting of 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 ≥9 mm.
We conducted a retrospective review of 105 patients who underwent primary ACL reconstruction
with either single- (semitendinosus or gracilis only) or double-tendon (both semitendinosus
and gracilis) hamstring grafts from January 2023 to June 2024 at a tertiary institution.
Magnetic resonance imaging (MRI) scans were independently measured by two junior members.
The average of the measurements was taken. Predicted graft diameter is √(x·AB + y·CD),
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.
Pearson correlation shows moderate correlation between predicted and actual graft
diameters (R = 0.602, p < 0.01). Univariate and multivariate linear regression, adjusted for age, gender,
body mass index (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 69.7%, with excellent
discriminative ability (AUC = 0.889). A high 82.9% agreement rate was achieved, with
Cohen's kappa of 0.578 (p < 0.05).
This study has demonstrated a practical generalized algorithm with high sensitivity
(95.8%) to predict the final ACL graft diameter for single- and double-tendon hamstring
grafts consisting of any number of folds using preoperative MRI measurements.
Keywords
knee - ACL - MRI - hamstring graft
