Sex matters for orthopedic studies
In the 1970s, American psychologists defined clear differences in the definition of gender vs. sex. The term “gender” was introduced in the 1970s to define characteristics and socially developed traits that were attributed to male and female patients. “Sex” was defined as the biological and genetic mechanisms that separate male and female patients, such as the chromosomes, genes, hormones and areas of cerebral development or other genetic-based physical attributes. Gender can be selected and modified. Sex is what one is born. The physical characteristics of sex can be modified, but this does not determine gender, which is the behavior, cultural and psychological traits of being a man or woman.
The major problem in appreciating the differences in the terms is sex has been too inclusive and broadly defined. Sex is used to describe the genetic composition of an individual, reproductive and secondary physical findings associated with genetic differences, as well as the behavioral and psychological characteristics stereotypically assigned to people based on perceptions of whether they are a male or female patient. Furthermore, sex is broadly used to describe a variety of physical behavior between two individuals. In some dictionaries, the first definition of sex is related to sexual activity and, especially but not limited, to sexual intercourse. Secondary definitions are typically related to reproductive functions.
Importance in orthopedics
Imagine a study of two randomly divided groups of patients who have a similar surgical procedure. Researchers then compare the two groups to determine if any observed differences were by chance or truly significant. Significant findings influence the care provided. If the researchers fail to identify that the sex of the patient plays a role in the decision regarding which operation was provided, or fail to analyze the data with sex as one of the variables, then the conclusions are likely to be biased and may not apply appropriately for both male and female patients.
This has happened in orthopedics and continues to be a problem today. When a small sample of one sex is included in the analysis or there is no sex-specific analysis, we generalize conclusions to both sexes despite different genetic, hormonal and biomechanically unique strategies to the physical activity or underlying medical disease process.
Women were often excluded from clinical research trials before the 1980s. It was not mandated until the 1990s, with passage of the NIH Revitalization Act, that women and minorities be included in clinical trials. However, sex-specific data remains relatively low, especially in orthopedics. This is troubling since numerous studies suggest outcomes of key orthopedic procedures are affected by the sex of the patient, including, but not limited to, total knee arthroplasty, ACL reconstruction, shoulder instability surgery, rotator cuff surgery, spine surgery and the management of fragility fractures. Most orthopedic procedures and nonsurgical interventions have outcomes that vary by the sex of the patient, however, most of the studies reported do not present sex-specific data.
Most practicing orthopedic surgeons are men and most published orthopedic studies are primarily authored by men, thus creating an inherent bias. It is not surprising that analysis of the overall number of research abstracts from the American Academy of Orthopaedic Surgeons Annual Meeting program during an 8-year period found 5.4% of the abstracts reported sex-specific analysis, with less than 1% of presentations focused on the impact of sex on orthopedic conditions or their treatment. The overall impact of this bias is unknown; however, it is likely to adversely affect women when compared with men and inhibit the investigation of new methods to improve outcomes when caring for women.
Not just semantics
- Tisosky A, et al. J Am Acad Orthop Surg. 2019;doi:10.5435/JAAOS-D-17-00366.
- Unger RK. American Psychologist. 1979;34 (11):1085-1094.
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- Anthony A. Romeo, MD, is the Chief Medical Editor of Orthopedics Today. He can be reached at Orthopedics Today, 6900 Grove Road, Thorofare, NJ 08086; email: email@example.com.
Disclosure: Romeo reports he receives royalties, is on the speakers bureau, is a consultant and does contracted research for Arthrex; receives institutional grants from MLB; and receives institutional research support from Arthrex, Ossur, Smith & Nephew, ConMed Linvatec, Athletico and Wright Medical.