ACL Size, but Not Signal Intensity, Is Influenced by Sex, Body Size, and Knee Anatomy

Background: Little is known about sex-based differences in anterior cruciate ligament (ACL) tissue quality in vivo or the association of ACL size (ie, volume) and tissue quality (ie, normalized signal intensity on magnetic resonance imaging [MRI]) with knee anatomy. Hypothesis: We hypothesized that (1) women have smaller ACLs and greater ACL normalized signal intensity compared with men, and (2) ACL size and normalized signal intensity are associated with age, activity levels, body mass index (BMI), bicondylar width, intercondylar notch width, and posterior slope of the lateral tibial plateau. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Knee MRI scans of 108 unique ACL-intact knees (19.7 ± 5.5 years, 62 women) were used to quantify the ACL signal intensity (normalized to cortical bone), ligament volume, mean cross-sectional area, and length. Independent t tests were used to compare the MRI-based ACL parameters between sexes. Univariate and multivariate linear regression analyses were used to investigate the associations between normalized signal intensity and size with age, activity levels, BMI, bicondylar width, notch width, and posterior slope of the lateral tibial plateau. Results: Compared with men, women had significantly smaller mean ACL volume (men vs women: 2028 ± 472 vs 1591 ± 405 mm3), cross-sectional area (49.4 ± 9.6 vs 41.5 ± 8.6 mm2), and length (40.8 ± 2.8 vs 38.1 ± 3.1 mm) ( P < .001 for all), even after adjusting for BMI and bicondylar width. There was no difference in MRI signal intensity between men and women (1.15 ± 0.24 vs 1.12 ± 0.24, respectively; P = .555). BMI, bicondylar width, and intercondylar notch width were independently associated with a larger ACL ( R 2 > 0.16, P < .001). Younger age and steeper lateral tibial slope were independently associated with shorter ACL length ( R 2 > 0.03, P < .04). The combination of BMI and bicondylar width was predictive of ACL volume and mean cross-sectional area ( R 2 < 0.3). The combination of BMI, bicondylar width, and lateral tibial slope was predictive of ACL length ( R 2 = 0.39). Neither quantified patient characteristics nor anatomic variables were associated with signal intensity. Conclusion: Men had larger ACLs compared with women even after adjusting for BMI and knee size (bicondylar width). No sex difference was observed in signal intensity, suggesting no difference in tissue quality. The association of the intercondylar notch width and lateral tibial slope with ACL size suggests that the influence of these anatomic features on ACL injury risk may be partially explained by their effect on ACL size. Registration: NCT02292004 and NCT02664545 ( ClinicalTrials.gov identifier).

An osteological study of distal end of femur in adult south Indian population

Background: Need for the study: Anthropometric studies across different population groups have exhibited significant difference between races. Hence the usage of implant for total knee arthroplasty has to be gender specific and race specific. This study was undertaken to analyse the morphometry of distal end of femur in South Indian population. Aims and objectives: To analyse the morphometry of distal end of femur and to study the anteroposterior dimensions of condyles of femur, bicondylar width, intercondylar notch width. Materials and Methods: The study was conducted on 150 femur (80 right and 70 left) obtained from Department of Anatomy of a private medical college. Measurements of anteroposterior dimensions of condyles of femur, bicondylar width, intercondylar notch width were taken using a sliding calipers. Conclusions: In the present study, mean Bicondylar width noted in the present study is 72.63 ±4.13 mm on the right side and 71.25±3.14mm on the left side The mean intercondylar width observed is 21.27±4.18mm on the right side and 20.35±2.14mm on the left side. There was no statistically significant differences observed in the values of anteroposterior length of medial and lateral condyles, bicondylar width, intercondylar width between right and left sides. The results of the study has application in the field of biomedical engineering to design knee implants specific for South Indian population.

The Effect of The Intercondyler Notch Width Index on Anterior Cruciate Ligament Injuries

Objectives: To evaluate the relationship of the intercondylar notch width with unilateral and bilateral ACL injury by using MR images. Methods: The intercondylar notch width index was measured on the MR images of 18 patients with a bilateral ACL injury, 38 patients with a unilateral ACL injury and 53 healthy subjects with a normal ACL and the results of all groups were compared with each other. Results: The mean NWI values were 0.227 (±0.008) in bilateral injured; 0.245 (±0.009) in unilateral injured and 0.272 (±0.01) in control groups and 0.251(±0.01) in unaffected side of the unilateral group. There were statistically significant differences in intercondylar notch width index (NWI) values between all groups and there was a significant difference between the affected and the unaffected sides in group with unilateral ACL injury. A cutoff value of 0.25 for NWI gave an odds ratio of 26.5 for bilateral and 3.23 for unilateral ACL injuries. Conclusion: The finding that NWI is significantly narrowed in patients with bilateral and unilateral ACL tears compared with the healthy controls suggest a relationship between a narrow NWI and an increased risk of ACL injury. The patients with a narrow NWI should also be screened contralaterally for assessment of ACL injury risk on the other knee. So, specialized training programmes for the people with narrow NWI can be prepared for preventing ACL injuries.