Use of Magnetic Resonance Imaging to Predict Quadrupled Semitendinosus Graft Diameter in All-Inside Anterior Cruciate Ligament Reconstruction.

This study was conducted to evaluate whether preoperative magnetic resonance imaging (MRI) measurements of the cross-sectional area and length of the semitendinosus tendon correlated with graft diameter. The goal of the study was to identify tendons at risk for requiring graft augmentation. The records of 140 consecutive patients undergoing anterior cruciate ligament (ACL) reconstruction between 2013 and 2016 were examined retrospectively. The study included 39 patients who underwent all-inside ACL reconstruction with a semitendinosus autograft. A single researcher used preoperative MRI scans to measure the cross-sectional area and length of the semitendinosus tendon. Graft cross-sectional area was correlated with semitendinosus tendon cross-sectional area with Pear-son's coefficients of 0.50 (95% confidence interval [CI], 0.21-0.70; P=.0013) and 0.59 (95% CI, 0.34-0.76; P=.0001) when measured under 2× and 4× magnification, respectively. In addition, MRI measurements of semitendinosus tendon length were correlated with both intraoperatively measured tendon length (r=0.75; 95% CI, 0.40-0.91; P=.0008) and graft diameter (r=0.43; 95% CI, 0.14-0.66; P=.0058). Average semitendinosus tendon cross-sectional area was 3.10 mm (95% CI, 0.53-5.67; P=.024) greater and semitendinosus tendon length was 14.05 mm (95% CI, 1.25-26.85; P=.035) greater in cases that did not require graft augmentation. Semitendinosus tendons with cross-sectional area of less than 13.2 mm or length of less than 81 mm are most likely to require graft augmentation. In addition, MRI measurements of the length and cross-sectional area of the semitendinosus tendon are significantly correlated with ACL graft diameter and could help to identify patients who may require graft augmentation. [Orthopedics. 2017; 40(4):e617-e622.].