18.5 mm² MRI横截面积阈值预测四股腘绳肌腱前交叉韧带重建中移植物尺寸充足性（≥8.0 mm）的诊断准确性
简介
在37例连续接受四股半腱肌自体移植物ACL重建的前瞻性观察研究中，术前MRI测得的半腱肌横截面积与术中移植物直径强相关（Spearman ρ=0.948）。以本队列ROC分析得出的18.5 mm²为阈值预测术中移植物直径≥8.0 mm，敏感度100%、特异度84.62%、阴性预测值100%、AUC 0.986；术前CSA<18.5 mm²的11例术中移植物均…
英文摘要
INTRODUCTION: 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. OBJECTIVE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.