Change in the cross-sectional area of a patellar tendon graft after anterior cruciate ligament reconstruction

The purpose of this study was to clarify the change in the cross-sectional area (CSA) of a patellar tendon graft after anterior cruciate ligament (ACL) reconstruction, and its relationship with postoperative knee laxity. Forty patients (25 men and 15 women) were included in this study. Intraoperative CSA measurements were performed with an instrumented areamicrometer, while a magnetic resonance imaging (MRI) evaluation was utilized for the assessment postoperatively. For intraoperative measurement, the average CSA of a 10-mm wide patellar tendon graft was 32.3 ± 7.0 mm², while the average CSA measured at follow-up (mean: 14.8 months) was 48.8 mm², showing a significant mean increase ratio of 49.4%. This value corresponded to 115% of the native ACL. The average CSA measured in 30 patients at 6 months was 49.7 mm², almost equal to the value at the final follow-up (49.8 mm²) in the same patient group. Among potentially influential factors, postoperative notch width (available space for the ACL graft) had significant correlation with the CSA of the graft at follow-up. Finally, both intra- and postoperative CSA values did not correlate with postoperative knee laxity, indicating that a bigger graft does not guarantee a better laxity.