Utility of preoperative ultrasound in assessing the adequacy of autograft for anterior cruciate ligament reconstruction: a systematic review and meta-analysis

Anterior cruciate ligament (ACL) reconstruction using tendon autograft requires imaging to evaluate graft adequacy. Ultrasound (US) offers an efficient adjunct to MRI; however, the utility of US is variable in prior literature and should be investigated. The primary aim of this study is to provide a statistical appraisal of literature assessing correlation of preoperative US measurements with intraoperative size of autografts during ACL reconstruction.

PubMed, Embase, and Web of Science databases were queried for studies comparing preoperative US-based measurements to intraoperative measurements of autografts to assess graft adequacy (defined as > 8 mm diameter). Correlation coefficients from studies comparing combined cross-sectional area (CCSA) of autograft tendons on US to intraoperative autograft tendon diameters were collected and pooled. Random-effects models were generated to compare sensitivity, specificity, positive predictive values (PPV), and negative predictive value (NPV) for the identification of adequate graft sizes.

Eleven studies compared preoperative measurements of autograft size to intraoperative measurements. Meta-analysis of studies assessing hamstring tendon CCSA on US in comparison to intraoperative tendon diameters revealed a pooled correlation coefficient of 0.54 (CI 0.41–0.66, I² = 9.6%). Three studies reported if US correctly identified adequate graft sizes, demonstrating sensitivity of 83% (I² = 0.0%) and specificity of 78% (I² = 49.2%). PPV was 91% (I² = 0.0%), and NPV was 62% (I² = 11.7%).

Hamstring CCSA on US has moderate correlation with intraoperative diameter, high sensitivity (83%), moderate specificity (78%), and very high PPV (91%) for identifying adequately sized autografts for ACL reconstruction.