Men and women are not created equal
AAOS workshop examines gender disparities in musculoskeletal problems
By Laura L. Tosi, MD; Barbara D. Boyan, PhD; Adele L. Bosky, PhD
The influence of sex and gender on musculoskeletal health is much stronger than previously thought, according to a workshop convened by the AAOS Women’s Health Issues Committee. The workshop focused on prioritizing areas of research related to how sex (defined in terms of biology) affects health. Results were summarized in the July 2005 issue of The Journal of Bone & Joint Surgery.
Although earlier studies indicated that some chronic musculoskeletal conditions are more prevalent in one sex than in the other, the workshop was the first comprehensive review to explore the causes of these disparities. Its final report called on researchers and physicians to conduct sex-specific research and data analysis to ensure the proper diagnosis and treatment of musculoskeletal ailments.
The workshop covered the cellular and molecular biology of male and female cells and tissues, the influence of chromosomes versus hormones on injury and disease and disparities between men and women in presentation and treatment response of musculoskeletal conditions.
Bone growth and development
Boys and girls stop growing at different ages, leading to differences in peak bone mass between males and females and partially explaining why women are more susceptible to osteoporosis. In females, bones stop gaining width by age 14, while males continue to amass bone until nearly age 20. As a result, male bone is significantly wider than female bone. Because women’s bones are smaller and narrower, they are more apt to fracture than men’s bones.
Muscle injuries, puberty and steroid use
Men and women also have different patterns of athletic injuries, which have been attributed in part to differences in gait and motion patterns. Before puberty, males and females have similar jumping and landing strategies. However, puberty produces changes in sex hormones that lead to differences in muscle behavior between the sexes. Thus, as humans mature, muscle formation, use and joint stability during sports are different for men and women. Women are more limber and use their muscles differently than men. These and other factors may explain why women suffer more anterior cruciate ligament injuries than men.
One intriguing question is whether or not women’s muscles could be trained to mimic the movement of men’s muscles and therefore reduce the possibility of injury. Differences between the sexes are partially modified by glucocorticoid and sex steroid treatment, and steroids drastically alter muscle growth. More research needs to be conducted to determine the long-term effects of steroid use on men and women.
Some painful disorders are more prevalent in women than in men. Recent research demonstrates that this is because female brains have different pain receptors and respond differently to pain. This has major implications on how women and men should be treated pre- and postoperatively, both in prescribing medication types and dosages and in determining the appropriate level and frequency of analgesia and rehabilitation.
Men develop 60 percent more primary musculoskeletal tumors than women, yet women with such tumors have a nearly 15 percent better chance of survival than do men. Breast and prostate cancer both metastasize to the bone, which not only alters the bone’s properties but also increases the likelihood of fracture.
There are currently no sex-specific tools for measuring response to treatment of primary cancers in men and women. The lack of a sex-specific measurement tool could result in false predictions of the impact of the therapy on bone strength and resistance, underscoring the need to develop distinct measurements for each sex.
The workshop underscored that data from musculoskeletal research need to be stratified by age as well as by sex. Workshop data indicate that the sex, age and hormone status of musculoskeletal tissue donors must be considered before the transplantation of bones, muscles or tendons. Female stem cells have been more successful in treating muscular dystrophy in preclinical models than male stem cells.
But in solid organ transplants, organs from male donors have a much higher success rate than those from females. This finding could have major implications on the success of bone grafts and cartilage transplants. More sex-specific research is required to determine how significant a role these factors play.
According to the National Ambulatory Medical Care Survey, musculoskeletal complaints are among the top reasons Americans see a doctor. Thus, it is critical that orthopaedists—as well as other clinicians in the musculoskeletal health field —have the most accurate, sex-specific data possible available at their fingertips. Knowing which sex is predisposed to certain diseases and medical conditions, and why, will enable more effective treatment and prevention of musculoskeletal health conditions. Expanding research on the influence of sex on musculoskeletal health will have a tremendous impact on patients’ quality of life.
Laura L. Tosi, MD, is the immediate past chair of the Women’s Health Issues Committee of the AAOS; Barbara D. Boyan, PhD is on the faculty of the Georgia Institute of Technology and Adele L. Bosky, PhD is on the faculty at the Hospital for Special Surgery in New York.