Preoperative Ultrasound Evaluation of the Semitendinosus Tendon for Anterior Cruciate Ligament Reconstruction

Abstract

Background: Adequate graft size and length are crucial factors that correlate with improved outcomes after anterior cruciate ligament reconstruction with a semitendinosus (ST) tendon autograft alone. Anthropometric parameters could be used as predictors of graft measurements but they have shown imprecise correlation in some patients. Purpose: To evaluate the accuracy of ultrasound (US) for the preoperative evaluation of ST graft size and length. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: A total of 40 patients were included in this study. Patient sex, age, anthropometric parameters, and preoperative US measurements were recorded. After the ST tendons were harvested, their lengths as well as the diameters of the 4-strand ST grafts were recorded. Correlations between patient US measurements were analyzed. Inadequate ST graft length was defined at <28 cm, and inadequate 4-strand ST graft diameter was defined at <8 mm. Results: The prevalence of patients with an ST graft length <28 cm was 47.5%, and the prevalence of patients with a 4-strand ST graft diameter <8 mm was 42.5%. US measurements had a strong, significant correlation with the ST graft length ( P < .001) and a moderate correlation with the 4-strand ST graft diameter ( P < .001). Absolute agreement between the preoperative US measurement of ST graft length and the intraoperative ST graft length showed good reliability (ICC2,1 = 0.825). The cross-sectional area (CSA) of the ST tendon at the knee joint level by US showed a weak correlation ( r = 0.207) with the 4-strand ST graft diameter ( P = .200). A CSA of 16 mm2 measured by US could be used to predict a 4-strand ST graft diameter ≥8 mm, with a sensitivity of 73.9% and specificity of 76.5%. Conclusion: Preoperative US measurements of ST tendons had a strong correlation with intraoperative ST graft length and provided good sensitivity to detect a 4-strand ST graft diameter ≥8 mm. All other anthropometric parameters showed a weak to moderate correlation with ST graft length and size.