Diagnostic Accuracy of an 18.5 mm² Magnetic Resonance Imaging Cross-Sectional Area Threshold for Predicting Graft Adequacy (≥8.0 mm) in Quadrupled Hamstring Anterior Cruciate Ligament Reconstruction.
- 1Department of Orthopaedics and Traumatology, Pushpagiri Institute of Medical Sciences and Research Centre, Tiruvalla, Kerala, India.
Abstract
A quadrupled semitendinosus (ST) graft diameter below 8.0 mm is associated with higher failure and revision rates after anterior cruciate ligament (ACL) reconstruction. Pre-operative identification of patients at risk of an undersized graft may facilitate planning for gracilis augmentation or alternative graft selection. To determine the diagnostic accuracy of a pre-operative Magnetic resonance imaging (MRI)-measured ST cross-sectional area (CSA) threshold of 18.5 mm² for predicting an intraoperative quadrupled graft diameter of at least 8.0 mm. Thirty-seven consecutive patients undergoing arthroscopic ACL reconstruction with a quadrupled ST autograft were enrolled in a prospective observational study. Pre-operative ST CSA was measured on axial MRI at the joint line by a single musculoskeletal radiologist blinded to intraoperative findings. Quadrupled ST graft diameter was measured intraoperatively with a standard graft-sizing block before any gracilis augmentation. A CSA cut-off of 18.5 mm², derived by receiver operating characteristic (ROC) analysis within this cohort, was evaluated against the 8.0 mm adequacy threshold using standard 2×2 diagnostic accuracy statistics. Pre-operative CSA was strongly correlated with graft diameter (Spearman's ρ = 0.948, P < 0.001). At the 18.5 mm² cut-off (adequate graft as the target condition), sensitivity was 100% (95% confidence interval [CI] 85.75-100%), specificity 84.62% (95% CI 54.55-98.08%), positive predictive value 92.31% (95% CI 77.03-97.72%), negative predictive value 100% (95% CI 71.51-100%), and overall accuracy 94.59% (95% CI 81.81-99.34%), with an area under the ROC curve of 0.986 (95% CI 0.957-1.000). All 11 patients with a pre-operative CSA below 18.5 mm² had an inadequate graft (<8.0 mm); two of the 13 patients with an inadequate graft had CSA ≥18.5 mm² (sensitivity 84.62% for detecting an inadequate graft). Pre-operative ST CSA below 18.5 mm² was associated with an intraoperative graft diameter <8.0 mm in all 11 patients below the threshold, although 2 of 13 undersized grafts were missed. This threshold may serve as a useful pre-operative screening metric to anticipate the need for graft augmentation, pending external validation.
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BibTeX
@article{mathew2026diagnostic,
title = {{Diagnostic Accuracy of an 18.5 mm² Magnetic Resonance Imaging Cross-Sectional Area Threshold for Predicting Graft Adequacy (≥8.0 mm) in Quadrupled Hamstring Anterior Cruciate Ligament Reconstruction.}},
author = {Thomas Mathew and Ashish Mathew and Salman Faris and Francis Johnson and Athul Krishna},
journal = {Journal of orthopaedic case reports},
year = {2026},
month = nov,
doi = {10.13107/jocr.2026.v16.i11.8510},
url = {https://europepmc.org/article/MED/42997039},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Diagnostic Accuracy of an 18.5 mm² Magnetic Resonance Imaging Cross-Sectional Area Threshold for Predicting Graft Adequacy (≥8.0 mm) in Quadrupled Hamstring Anterior Cruciate Ligament Reconstruction.
AU - Thomas Mathew
AU - Ashish Mathew
AU - Salman Faris
AU - Francis Johnson
AU - Athul Krishna
PY - 2026
DA - 2026/11/01
JO - Journal of orthopaedic case reports
DO - 10.13107/jocr.2026.v16.i11.8510
UR - https://europepmc.org/article/MED/42997039
AB - A quadrupled semitendinosus (ST) graft diameter below 8.0 mm is associated with higher failure and revision rates after anterior cruciate ligament (ACL) reconstruction. Pre-operative identification of patients at risk of an undersized graft may facilitate planning for gracilis augmentation or alternative graft selection. To determine the diagnostic accuracy of a pre-operative Magnetic resonance imaging (MRI)-measured ST cross-sectional area (CSA) threshold of 18.5 mm² for predicting an intraoperative quadrupled graft diameter of at least 8.0 mm. Thirty-seven consecutive patients undergoing arthroscopic ACL reconstruction with a quadrupled ST autograft were enrolled in a prospective observational study. Pre-operative ST CSA was measured on axial MRI at the joint line by a single musculoskeletal radiologist blinded to intraoperative findings. Quadrupled ST graft diameter was measured intraoperatively with a standard graft-sizing block before any gracilis augmentation. A CSA cut-off of 18.5 mm², derived by receiver operating characteristic (ROC) analysis within this cohort, was evaluated against the 8.0 mm adequacy threshold using standard 2×2 diagnostic accuracy statistics. Pre-operative CSA was strongly correlated with graft diameter (Spearman's ρ = 0.948, P < 0.001). At the 18.5 mm² cut-off (adequate graft as the target condition), sensitivity was 100% (95% confidence interval [CI] 85.75-100%), specificity 84.62% (95% CI 54.55-98.08%), positive predictive value 92.31% (95% CI 77.03-97.72%), negative predictive value 100% (95% CI 71.51-100%), and overall accuracy 94.59% (95% CI 81.81-99.34%), with an area under the ROC curve of 0.986 (95% CI 0.957-1.000). All 11 patients with a pre-operative CSA below 18.5 mm² had an inadequate graft (<8.0 mm); two of the 13 patients with an inadequate graft had CSA ≥18.5 mm² (sensitivity 84.62% for detecting an inadequate graft). Pre-operative ST CSA below 18.5 mm² was associated with an intraoperative graft diameter <8.0 mm in all 11 patients below the threshold, although 2 of 13 undersized grafts were missed. This threshold may serve as a useful pre-operative screening metric to anticipate the need for graft augmentation, pending external validation.
SN - 2250-0685
SN - 2321-3817
ER -