Sex, Collagen Expression, and Anterior Cruciate Ligament Strength in Rats

Romani, William A.; Langenberg, Patricia; Belkoff, Stephen M.

doi:10.4085/1062-6050-45.1.22

Cited by 9 publications

(2 citation statements)

References 60 publications

(82 reference statements)

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“…After the application of a 1-N preload, specimens were preconditioned for 10 cycles from 0 to 0.5 mm at a rate of 0.25 mm/s. 31,32 The specimens were allowed to recover at zero displacement for 30 seconds before being loaded to failure at 0.25 mm/s. Data were recorded at 20 Hz.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Oral Contraceptive Hormones on Anterior Cruciate Ligament Strength

et al. 2019

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Background: Women are 2 to 9 times more likely to experience an anterior cruciate ligament (ACL) injury than men. Various hormones including relaxin, progesterone, and estrogen influence ACL strength. Oral contraceptives (OCs) alter these hormone levels; however, studies have yet to comprehensively compare different OCs’ effects on the ACL. Hypothesis: OCs with increased progestin-to-estrogen ratios will (1) increase ACL collagen expression, (2) decrease ACL matrix metalloproteinase expression, and (3) increase ACL strength. Study Design: Controlled laboratory study. Methods: Untreated female rats were compared with rats treated with 1 of 5 clinically used OCs: norethindrone (NE) only, NE plus ethinylestradiol (EE), etynodiol diacetate (ED) plus EE, norgestimate (NG) plus EE, and drospirenone (DS) plus EE. Doses were scaled from human doses to account for differences in bioavailability and body weight, and OCs were administered daily via oral gavage for 4 rat estrous cycles (20 days). A total of 36 rats were then sacrificed (6 rats/group). ACLs underwent biomechanical testing to assess ACL strength, stiffness, and maximum load before failure. ACL specimens were also isolated for quantitative real-time polymerase chain reaction analysis to assess collagen, matrix metalloproteinase, and relaxin receptor–1 expression. Results: While the primary structural property of interest (ACL maximum load before failure) was not significantly improved by OC treatment, the main material property of interest (ACL strength) in rats treated with NE only, DS + EE, ED + EE, and NE + EE was significantly increased compared with untreated controls ( P = .001, P = .004, P = .004, and P = .04, respectively). The order from strongest to weakest ACLs, which was also the same order as the highest to lowest progestin-to-estrogen ratios, was groups treated with NE only, DS + EE, ED + EE, NE + EE, and lastly NG + EE. Higher ratio formulations also increased the expression of type I collagen ( P = .02) and decreased the expression of matrix metalloproteinase–1 ( P = .04). Conclusion: OC formulations with higher progestin-to-estrogen ratios may be more protective for the ACL than formulations with lower ratios. Clinical Relevance: OC formulations with high progestin-to-estrogen ratios may benefit female athletes by reducing their ACL injury risk by decreasing the effects of relaxin on the ACL.

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Section: Methodsmentioning

confidence: 99%

The Effect of Oral Contraceptive Hormones on Anterior Cruciate Ligament Strength

et al. 2019

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“…In athletic training, examples of very traditional bench research can be found in the literature, such as animal studies examining collagen expression in the anterior cruciate ligament. 15 Promising bench research findings should first be translated into bedside studies that involve actual patient populations. Within the context of athletic training research, the term bedside research is equivalent to the majority of patient-based therapeutic studies that are conducted within research laboratories.…”

Section: Translational Continuummentioning

confidence: 99%

Practice-Based Research Networks, Part I: Clinical Laboratories to Generate and Translate Research Findings Into Effective Patient Care

Sauers¹,

McLeod

Bay

2012

Journal of Athletic Training

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Context: To improve patient care, athletic training clinicians and researchers should work together to translate research findings into clinical practice. Problems with patient care observed in clinical practice should be translated into research frameworks, where they can be studied. Practice-based research networks (PBRNs) provide a compelling model for linking clinicians and researchers so they can conduct translational research to improve patient care.Objective: To describe (1) the translational research model, (2) practice-based research as a mechanism for translating research findings into clinical practice, (3) the PBRN model and infrastructure, (4) the research potential using the PBRN model, and (5) protection of human participants in PBRN research.Description: Translational research is the process of transforming research findings into health behavior that ultimately serves the public and attempts to bridge the gap between research and clinical practice. Practice-based research represents the final step in the translational research continuum and describes research conducted by providers in clinical practices. The PBRNs are characterized by an organizational framework that transcends a single site or study and serves as the clinical research ''laboratory'' for conducting comparative-effectiveness studies using patient-oriented measures. The PBRN approach to research has many benefits, including enhanced generalizability of results, pooling of resources, rapid patient recruitment, and collaborative opportunities. However, multisite research also brings challenges related to the protection of human participants and institutional review board oversight.Clinical and Research Advantages: Athletic training studies frequently include relatively few participants and, consequently, are able to detect only large effects. The incidence of injury at a single site is sufficiently low that gathering enough data to adequately power a treatment study may take many years. Collaborative efforts across diverse clinical practice environments can yield larger patient samples to overcome the limitations inherent in single-site research efforts.Key Words: translational research, comparative effectiveness, clinical outcomes, HIPAA, FERPA, institutional review board Key PointsTo assess the effectiveness of preventive and health care services athletic trainers provide, clinicians and scholars should collaborate in translational research to guide clinical decision making. Practice-based research networks bring together groups of clinicians and academic centers, eliminating the problems posed by single-site practice-based research. Such networks must meet requirements for infrastructure, protection of human participants, and compliance with federal guidelines, but they offer numerous advantages, including generalizability of results, pooling of resources, and rapid patient recruitment.

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Why Do Girls Sustain More Anterior Cruciate Ligament Injuries Than Boys?

2012

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Sport is the leading cause of injury among adolescents and girls incur more non-contact anterior cruciate ligament (ACL) ruptures than boys, with this gender disparity in injury incidence apparent from the onset of puberty. Although the mechanisms for this gender disparity in ACL injuries are relatively unknown, hormonal, anatomical and biomechanical factors have been implicated. Puberty is associated with rapid skeletal growth and hormonal influx, both of which are thought to contribute to alterations in ACL metabolic and mechanical properties, as well as changes in lower limb strength and flexibility, ultimately influencing landing technique. Therefore, the aim of this review is to explain (i) the effects of changes in estrogen levels on the metabolic and mechanical properties of the ACL; (ii) changes in musculoskeletal structure and function that occur during puberty, including changes in knee laxity, and lower limb flexibility and strength; and (iii) how these hormonal and musculoskeletal changes impact upon the landing technique displayed by pubescent girls. Despite evidence confirming estrogen receptors on the ACL, there are still conflicting results as to how estrogen affects the mechanical properties of the ACL, particularly during puberty. However, during this time of rapid growth and hormonal influx, unlike their male counterparts, girls do not display an accelerated muscle strength spurt and the development of their hamstring muscle strength appears to lag behind that of their quadriceps. Throughout puberty, girls also display an increase in knee valgus when landing, which is not evident in boys. Therefore, it is plausible that this lack of a defined strength spurt, particularly of the hamstring muscles, combined with the hormonal effects of estrogen in girls, may contribute to a more 'risky' lower limb alignment during landing, in turn, contributing to a greater risk of ACL injury. There is, however, a paucity of longitudinal studies specifically examining the lower limb musculoskeletal structural and functional changes experienced by girls throughout puberty, as well as how these changes are related to estrogen fluctuations characteristic of puberty and their effects on landing biomechanics. Therefore, further research is recommended to provide greater insight as to why pubescent girls are at an increased risk of non-contact ACL injuries during sport compared with boys. Such information will allow the development of evidence-based training programmes aimed at teaching girls to land more safely and with greater control of their lower limbs in an attempt to reduce the incidence of ACL ruptures during puberty.

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Sex, Collagen Expression, and Anterior Cruciate Ligament Strength in Rats

Cited by 9 publications

References 60 publications

The Effect of Oral Contraceptive Hormones on Anterior Cruciate Ligament Strength

The Effect of Oral Contraceptive Hormones on Anterior Cruciate Ligament Strength

Practice-Based Research Networks, Part I: Clinical Laboratories to Generate and Translate Research Findings Into Effective Patient Care

Why Do Girls Sustain More Anterior Cruciate Ligament Injuries Than Boys?

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