Size Variability of the Human Anterior Cruciate Ligament Insertion Sites

Abstract

Background: Current trends in anterior cruciate ligament reconstruction (ACLR) have been toward anatomical reconstruction that restores the normal size and location of the anterior cruciate ligament insertions and its 2 bundles, the posterolateral (PL) and anteromedial (AM) bundles. This has resulted in a more individualized approach to ACLR. Several studies have shown that the size of the anterior cruciate ligament insertion sites is variable; however, these studies are limited by use of relatively small sample sizes and cadaveric specimens. Purpose: This study was undertaken to evaluate the in vivo size variability of the anterior cruciate ligament insertion sites and its AM and PL bundles during arthroscopy in a large series of patients and to correlate these findings with individuals’ physical characteristics (height, weight, and body mass index). Study Design: Cross-sectional study; Level of evidence, 3. Methods: In 137 patients undergoing ACLR during the first 6 months after injury, the femoral and tibial anterior cruciate ligament insertion sites and the 2 bundles were identified, marked with electrocautery, and measured with an arthroscopic ruler. Additionally, physical characteristics of the patients, including self-reported height, weight, and body mass index, were recorded. Results: The tibial anterior cruciate ligament insertion site had a mean length of 17.0 ± 2.0 mm. The tibial AM bundle length was 9.1 ± 1.2 mm and the width was 9.2 ± 1.1 mm. The tibial PL bundle insertion site length averaged 7.4± 1.0 mm and the width averaged 7.0 ± 1.0 mm. The femoral insertion sites had a mean length of 16.5 ± 2.0 mm. The length of the femoral AM bundle insertion site averaged 9.2 ± 1.2 mm and the width averaged 8.9 ± 0.9 mm. The femoral PL bundle insertion site length averaged 7.1 ± 1.1 mm and the width averaged 6.9 ± 1.0 mm. There were significant positive correlations between patient height and weight (P < .05) with femoral and tibial anterior cruciate ligament insertion site length, tibial PL bundle insertion site length, femoral AM bundle insertion site length, and tibial AM bundle and PL bundle insertion site areas. However, the coefficients of determination values were low (1.0% to 19.4%). Conclusion: There is a large variation in size of the anterior cruciate ligament insertion sites and the AM and PL bundles. Additionally, there are significant but weak correlations between the size of the insertions and height, weight, and body mass index of the individual patient.