The human anterior cruciate ligament: Sex differences in ultrastructure and correlation with biomechanical properties (original) (raw)
Related papers
Sex Comparisons of In Vivo Anterior Cruciate Ligament Morphometry
Journal of Athletic Training, 2019
Context: Females have consistently higher anterior cruciate ligament (ACL) injury rates than males. The reasons for this disparity are not fully understood. Whereas ACL morphometric characteristics are associated with injury risk and females have a smaller absolute ACL size, comprehensive sex comparisons that adequately account for sex differences in body mass index (BMI) have been limited. Objective: To investigate sex differences among in vivo ACL morphometric measures before and after controlling for femoral notch width and BMI. Design: Cross-sectional study. Setting: Laboratory. Patients or Other Participants: Twenty recreationally active men (age ¼ 23.2 6 2.9 years, height ¼ 180.4 6 6.7 cm, mass ¼ 84.0 6 10.9 kg) and 20 recreationally active women (age ¼ 21.3 6 2.3 years, height ¼ 166.9 6 7.7 cm, mass ¼ 61.9 6 7.2 kg) participated. Main Outcome Measure(s): Structural magnetic resonance imaging sequences were performed on the left knee. Anterior cruciate ligament volume, width, and cross-sectional area measures were obtained from T2-weighted images and normalized to femoral notch width and BMI. Femoral notch width was measured from T1-weighted images. We used independentsamples t tests to examine sex differences in absolute and normalized measures.
Journal of Orthopaedic Research, 2011
Anterior cruciate ligament (ACL) injury continues to be at the forefront of sports injury concerns because of its impact on quality of life and joint health prognosis. One strategy is to reduce the occurrence of this injury by identifying at-risk subjects based on key putative risk factors. The purpose of our study was to develop models that predict the structural properties of a subject's ACL based on the combination of known risk factors. We hypothesized that the structural properties of the ACL can be predicted using a multi-linear regression model based on significant covariates that are associated with increased risk of injury, including age, sex, body size, and ACL size. We also hypothesized that ACL size is a significant contributor to the model. The developed models had predictive capabilities for the structural properties of the ACL: load at failure (R 2 = 0.914), elongation at failure (R 2 = 0.872), energy at failure (R 2 = 0.913), and linear stiffness (R 2 = 0.756). Furthermore, sex, age, body mass, BMI, and height were contributors (p < 0.05) to all predicted structural properties. ACL minimal area was a contributor to elongation, energy at failure, and linear stiffness (p < 0.05), but not to load at failure. ACL volume was also a contributor to elongation and energy at failure (p < 0.05), but not to linear stiffness and load at failure models. ACL length was not a significant contributor to any structural property. The clinical significance of this research is its potential, after continued development and refinement of the model, for application to prognostic studies that are designed to identify individuals at increased risk for injury to the ligament.
Location-dependent variations in the material properties of the anterior cruciate ligament
Journal of Biomechanics, 1992
Our recent anterior drawer studies in human cadaveric knees [Guan and Butler, Adu. Bioengng 17,5 (1990); Guan et al., Trans. orthop. Res. Sm. 16,589 (1991)] have suggested that anterior bundles of the anterior cruciate ligament (ACL) develop higher load-related material properties than posterior bundles. This was confirmed when we reevaluated the axial failure data for these bundle-bone specimens from an earlier study [Butler et al., J. Biomechanics 19,425432 (1986)]. The purpose of this study was to determine, in a larger data set, if anteromedial and anterolateral bundles of the anterior cruciate ligament exhibit significantly larger load-related material properties than the posterior ligament bundles. Seven ACL-bone units from seven donors (the three tissues from the original study plus four new ones) were subdivided into three subunits, preserving the bone insertions. The subunits were failed in tension at a constant strain rate (100% s-i) and four material properties were compared within and between donors. The anterior bundles developed significantly larger moduli, maximum stresses, and strain energy densities to maximum stress than the nosterior subunits. Moduli for the anterior vs nosterior subunits averaged 284 MPa vs 155 MPa, maximum stresses averaged 38 MPa vs 15 MPa, and-strain energy densities-averaged 2.7 N mcc-' vs 1.1 Nmcc-' , respectively. No significant differences were found, however, among strains to maximum stress or between any of the other properties for the two anterior subunits. These results are important to the design of ligament replacements and suggest new experiments designed to distinguish in uiuo force levels in these ACL bands, a possible reason for the material differences.
Mechanical properties of the human anterior cruciate ligament
Clinical Biomechanics, 1995
The aim was to measure the stiffness and strength of the femur-anterior cruciate ligament-tibia complex tested in a physiological manner with a force exerted anteriorly on the tibia, at knee joint flexion angles of 0 °, 10 ° and 30 ° and at speeds of 50 and 500 mm/min. Ligaments were preconditioned by cycling five times, with data from the fifth cycle used to determine the stiffness of the ligament in a low-load range. The ligaments were then tested to failure with the knee at 30 ° flexion. The specimens were divided into two groups, middle-aged (40–60) and old (>60). For each group no statistical difference was observed between stiffness of the ligament at different joint flexion angles or speeds. Seven of the 21 specimens in the older age group failed by avulsion at the bone-ligament interface. All the other specimens failed by tears in the substance of the ligament. Ultimate failure load was found to have a significant correlation with bodyweight. It was 1.6 and 1.3 times bodyweight for the middle-aged and older age groups respectively. This study has highlighted the importance of identifying different modes of failure, of making corrections for bodyweight and testing in a physiological manner. The results allow a better understanding of the mechanical behaviour of the anterior cruciate ligament and provide design data for anterior cruciate ligament grafts and prostheses.
Sex, Collagen Expression, and Anterior Cruciate Ligament Strength in Rats
Journal of athletic training, 2010
Context:Sex-specific responses to steroid sex hormones have been suggested as a potential cause for the disparate anterior cruciate ligament (ACL) injury rates between male and female athletes. Type 1 collagen (T1C) and type 3 collagen (T3C) are crucial structural components that define the ligament's ability to withstand tensile loads. Messenger RNA (mRNA) is an important mediator of downstream collagen synthesis and remodeling, but the sex-specific mechanisms of collagen mRNA expression and ACL strength are unknown.Objective:To examine the influence of sex on T1C and T3C mRNA expression and mass-normalized stiffness and peak failure load in the ACLs of skeletally mature rats.Design:Observational study.Setting:Basic sciences and biomechanical testing laboratories.Patients or Other Participants:Nineteen 12-week-old male (n = 9) and female (n = 10) Sprague Dawley rats.Main Outcome Measure(s):We used real-time polymerase chain reaction to determine T1C and T3C mRNA expression and a hydraulic materials testing device to measure ACL stiffness and failure load. Nonparametric Wilcoxon rank sum tests were used to compare the groups.Results:Female rats had lower amounts of T3C mRNA expression and higher normalized ACL tangent stiffness and failure load than male rats.Conclusions:These findings suggest that sex-specific differences in T1C and T3C mRNA expression may play an important role in the downstream mechanical properties of the ACL.
Anterior Cruciate Ligament Biology and Its Relationship to Injury Forces
Orthopedic Clinics of North America, 2006
The anterior cruciate ligament (ACL) is one of primary stabilizers of the knee, and disruption of this ligament is three to ten times more common in female athletes than male athletes who participate in the same sports at the same level of competition . These knee injuries are a growing cause for concern because of the association with earlyonset, posttraumatic osteoarthritis after severe ligament tears. Despite an abundance of theories about why female athletes are more susceptible to this injury and proposed neuromuscular training programs designed to protect the knee, no definitive causal link has been found among mechanisms of injury, sex, and ACL rupture.
2014
ABSTRACT Introduction Ligament reconstruction of the anterior cruciate ligament (ACL) is one of the most frequent arthroscopic procedures. According to the Technical Agency for Information on Hospitalizations (ATIH) 41,122 ligament reconstructions were performed in France in 2012. Treatment of the injury is costly and not always successful at returning patients to their preinjury activity level. Identification of all factors associated with increased risk of ACL injury during sport is important to provide an appropriate level of counseling and programs for prevention. These factors have been categorized as intrinsic (inherent to the individual athlete) or extrinsic (external to the athlete). Risk of ACL injury in female athletes depending on sports Female athletes have been identified at increased risk of injuring their ACL during certain sports, with reported injury rates that are 3.6 times greater for basketball and 5.1 times greater for handball when compared with male athletes who participate in these sports at similar levels of play. Extrinsic risk factors Several extrinsic factors seem increase the risk of ACL injury in both female and male athletes with a slightly increased risk in female: competition, wet and rainy weather, the type and number of cleats, the design of the shoe, the type of grass, artificial grass or floor surface and previous ACL reconstruction. Intrinsic risk factors Several anatomic risk factors have been identified, mainly an increased anterior-posterior knee laxity, a smaller intercondylar notch width with a shorter ACL, and a greater condyle offset ratio. Neuromuscular and biomechanical risk factors are also involved as increased dynamic valgus and muscle and proprioceptive deficit of the non-dominant leg in female. The hormonal theory is based on several reports of elevated ACL tear rates in pre- as compared to postovulatory phase. Other risk factors were evocated: a familial predisposition to noncontact ACL tears, genetic factors and a higher body mass index. Multivariate risk factor analysis Given the multiplicity of risk factors it seems important to develop multivariable models but very few studies have followed this approach. Conclusion Several intrinsic factors may explain the sex-ration in ACL tear but intrinsic and extrinsic risk factors act in combination to increase the risk of ACL injury. The identification of these factors has led to the development of appropriate prevention programs with good but still insufficient results. Optimizing prevention requires the organization of large cohort studies for each sport, involving all participants. A generalization of multivariate statistical analyzes would take into account the possible interactions and to quantify the risk for each factor. Comprehensive prevention programs specific to each sport, incorporating all the factors, could then be developed.
Histological Structure of Anterior Cruciate Ligament - Review
Academia Anatomica International
Introduction: Anterior cruciate ligament (ACL) is one of the commonly injured ligaments of the knee joint due to sports activities. Because of the poor healing capacity of the ACL, surgical treatment for ACL injuries was followed for many years. Therefore, understanding the structural knowledge of the ACL will help in reproduce the native ACL. Objectives: To improve the histological knowledge of ACL and to understand the valuation of histology of ACL attachment to the bone. Subjects and Methods: PubMed and Google search was used as a search engine to collect the concerned articles that describing the histology of ACL. The key words were ACL, histology, Ultrastructure. Results: Ultrastructure of ACL observed from proximal to distal attachments showed the more complicated and complex arrangement of collagen bundles with interspersed cells in between. Ultrastructure of ACL also should be borne in mind before preparing ACL grafts. Conclusion: ACL has complex histological structure. It is essential to consider the details of the ACL histological structure in ACL reconstruction surgeries to restore its full functionality. This review may be useful as a reference to investigate the mechanical properties of ACL footprint.
Comparative Study of the Size and Shape of Human Anterior and Posterior Cruciate Ligaments
As an important step toward determination of the function of cruciate ligaments, the cross-sectional shapes and areas of the anterior cruciate, posterior cruciate, and meniscofemoral ligaments were evaluated in situ within the same knee with use of a laser micrometer system. Measurements were made in eight human cadaveric knees at five levels along the midsubstance of each ligament, with the knee at 0", 30". 60", and 90" of flexion. The posterior cruciate ligament was found to be widest in the medial-lateral direction , whereas the anterior cruciate ligament usually was larger in the anterior-posterior direction. The cross-sectional shapes of the anterior cruciate ligament generally were noted to be more circular along the entire midsubstance than were those of the posterior cruciate ligament. In contrast, the cross-sectional shapes of the posterior cruciate ligament were more circular near the tibia, becoming progressively more elongated toward the femur. The meniscofemoral ligaments were more circular than the cruciate ligaments, with an occasional medial-lateral widening similar to that of the posterior cruciate ligament. The cross-sectional area of both the cruciate ligaments changed along the length of the midsubstance, with the anterior cruciate ligament becoming slightly larger distally and the posterior cruciate ligament enlarging proximally. The angle of flexion of the knee was not found to have a significant effect on the cross-sectional areas of the ligaments but was noted to alter the cross-sectional shapes. Using within-specimen comparisons, the cross-sectional area of the posterior cruciate ligament was found to be approximately 1.5 times larger than that of the anterior cruciate ligament at the proximal and midsubstance levels but was only 1.2 times larger at the most distal level. The total cross-sectional area of the meniscofemoral ligaments was approximately 22% that of the posterior cruciate ligament.
Journal of Biomechanics, 1992
The biomechanical properties of the medial collateral and anterior cruciate ligaments from 30 New Zealand White rabbits were measured. Because ofits complex geometry, the ACL was divided into two portions (medial and lateral) to provide uniform loading. This allowed an examination of the intraligamentous properties. A laser micrometer system was used to measure the cross-sectional area for tensile stress and a video dimension analyzer was used to measure the strain. The mechanical properties (stress-strain curves) of the MCL and ACL were different, with the modulus (determined between 4 and 7% strain) in the MCL (1120+ 153 MPa) more than twice that of either portion of the ACL (516+64 and 516 + 69 MPa for the medial and lateral portions, respectively). This higher modulus correlated with the more uniform and dense appearance of the collagen fibrils examined with scanning electron microscopy (SEM).