Comparison of males' and females' ratios of anterior-cruciate-ligament width to femoral-intercondylar-notch width: a cadaveric study
Rizzo, M.; Holler, S.B.; Bassett, F.H.
American Journal of Orthopedics 30(8): 660-664
2001
ISSN/ISBN: 1078-4519 PMID: 11520024 Document Number: 529474
The relative incidence of anterior cruciate ligament (ACL) injuries has been reported to be significantly higher in females than in males. Although many hypotheses have been proposed for this discrepancy, no conclusive explanation has reached consensus opinion. The purpose of this study was to evaluate and compare fresh-frozen cadaveric knee specimens to determine whether there is a significant difference between males' and females' ratios of ACL width to femoral intercondylar notch (FIN) width. We evaluated 15 male knees and 11 female knees. Data regarding sex, age, side (right or left), and ACL and FIN widths were obtained for all specimens. Age of male specimens ranged from 48 to 84 years (mean, 63.9 y); age of female specimens ranged from 33 to 96 years (mean, 69.9 y). Mean ACL width, mean FIN width, and their ratios were calculated. In the male specimens, mean ACL width was 10.59 mm (SD, 1.30 mm), mean FIN width was 20.18 mm (SD, 2.20 mm), and mean ACL:FIN width ratio was .526 +/- 0.047 (52.6% +/- 4.7% of FIN width); in the female specimens, mean ACL width was 8.09 mm (SD, 1.12 mm), mean FIN width was 20.50 mm (SD, 1.69 mm), and mean ACL: FIN width ratio was .393 +/- 0.03 (39.3% +/- 3% of FIN width). Results showed statistically significant differences between males' and females' ACL widths (P < .001) and between their ACL: FIN width ratios (P< .001) but not between their FIN widths. The significant difference between males' and females' ACL widths may be related to the general size differences between the groups. It has been speculated that female athletes' smaller ACLs may predispose them to ACL ruptures. Perhaps more significant is the difference between males' and females' ACL: FIN width ratios, which are significantly smaller in females compared with males. This may be directly related to the cause of more ACL ruptures in females. Further studies, including a good mechanical model, will help elucidate whether this anatomic discrepancy correlates clinically.