Rotator Cuff Injury: Repair Strategy Benefits Of Gender Considerations
Overview
Rotator cuff (RC) disorders are a leading cause of shoulder disability. This study aimed to quantify sex-related differences in RC repair outcomes. A systematic review and meta-analysis were conducted in January 2023 using PubMed, Wiley Cochrane Library, and Web of Science databases, focusing on studies involving surgical treatment of RC tears in humans. The Downs and Black score and the modified Coleman methodology score (MCMS) were used to evaluate the studies.
A total of 401 studies, comprising 39,909 patients (45% women, 55% men), were analyzed. Over time, a trend towards more balanced recruitment by sex was observed. However, only 4% of the studies, representing 1.5% of the total patients, provided disaggregated outcome data suitable for quantitative analysis. The analysis revealed a tendency for women to have lower postoperative external shoulder rotation, averaging 39.9° ± 6.9°, compared to 45.3° ± 4.1° in men (p = 0.066). According to the Downs and Black scores, four studies were rated as good and twelve as fair, with an average MCMS score of 69/100.
The study concluded that there is a significant lack of sex-specific data documentation in rotator cuff repair research. Only a small fraction of the studies provided disaggregated data, making it challenging to draw representative conclusions. This highlights the urgent need for increased awareness and action to study sex differences in RC repair more thoroughly. Providing sex-specific information is crucial for optimizing rotator cuff tear management and improving clinical outcomes for both men and women.
Introduction
Rotator cuff (RC) disorders are the leading cause of shoulder-related disability. The prevalence of rotator cuff tears varies significantly, ranging from 5% to 39% in the general population, with higher rates observed in older adults and the working population. This condition is particularly significant due to its chronic nature, tendency to recur, and the substantial direct and indirect healthcare costs it incurs, including missed workdays and disability payments.
Various treatment options have been explored, from non-surgical methods to surgical interventions, which have evolved to include open, mini-open, and arthroscopic techniques. Despite most patients experiencing significant pain relief and functional improvement following surgery, certain risk factors for poor outcomes and surgical failure have been identified. These include fatty degeneration, diabetes, dyslipidemia, obesity, and osteoporosis.
Research has suggested that being female may be associated with worse functional and pain outcomes after rotator cuff surgical repair. Women often report lower pain thresholds, higher pain ratings, and increased use of post-operative analgesia. The role of female hormones, such as estrogens, is hypothesized to influence these differences by inhibiting collagen synthesis and affecting tendon characteristics. During menopause, tendon thinning is more common, leading to a higher incidence of tendon pathologies. Some studies suggest hormone replacement therapy may benefit the musculoskeletal system in women.
Despite these biological differences, there has been a lack of extensive analysis focused on gender-specific outcomes in RC repair. Understanding these differences could help surgeons better manage rotator cuff tears by tailoring treatment approaches based on gender. This study aims to review the current literature to quantify the evidence regarding gender-specific results and differences in rotator cuff surgical repair outcomes.
Method
A review protocol, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, was developed and registered with the PROSPERO International Prospective Register of Systematic Reviews (code CRD42021260510). A systematic literature review was conducted on January 24, 2023, across PubMed, Wiley Cochrane Library, and Web of Science databases, using the search terms: ‘rotator cuff’ AND (tendinopath* OR tendinitis OR tendinosis OR injur*) AND (treatment OR repair*). Filters were applied for English language and human subjects.
The initial screening of titles and abstracts, removal of duplicates, and full-text eligibility assessment were independently performed by two reviewers (M. A. S. and G. C. G.), with disagreements resolved by a third reviewer (C. M. T. D. L.). Inclusion criteria required research articles on human subjects with rotator cuff tears treated surgically and written in English, excluding in vitro or in vivo studies, nonoperative treatments, and surgical technique descriptions.
Data extracted included publication year, authors, title, journal, study type, patient demographics, baseline data, outcome data, sex-related limitations and adverse events, and follow-up duration. An Excel table was used for data organization. Articles with demographic or outcome data disaggregated by sex underwent statistical analysis.
Risk of bias and quality of evidence were assessed using the Downs and Black checklist for nonrandomized studies and the modified Coleman methodology score (MCMS) for both randomized and nonrandomized studies. The MCMS evaluates domains such as study size, follow-up, surgical procedures, type of study, diagnostic description, rehabilitation, outcomes, outcome assessment, and subject selection, with scores ranging from 0 to 100. Downs and Black’s checklist evaluates reporting, external validity, bias, confounding, and power, with a total score of 32. Quality assessments were independently performed by M. A. S. and G. C. G., with discrepancies resolved by C. M. T. D. L.
The statistical analysis and forest plot were performed following the methodology outlined by Neyeloff et al. (2012) using Microsoft Excel. To determine the expected value, the Mantel-Haenszel method was employed. Group comparisons were conducted through analysis of variance (ANOVA). In the absence of heterogeneity, the expected value and its 95% confidence interval (CI) were estimated using a fixed effect ANOVA model. Statistical heterogeneity was assessed using the I² statistic and Cochran’s Q, with results displayed in funnel plots. Additionally, the proportions of articles and the corresponding patient data were reviewed at five-year intervals.
Result
The database search initially identified 12,329 articles, with 3,900 duplicates. Out of the remaining 8,429 articles, 736 were deemed suitable for further eligibility checks. Of these, 344 did not meet the inclusion criteria. However, nine additional studies were found through manual searches of reference lists, resulting in 401 full-text articles published between 1971 and 2023 being included in the final analysis. Among these, 24 articles (6%) provided sex-disaggregated data at baseline, and 16 (4%) presented disaggregated data by sex for a common clinical outcome, which were included in the quantitative analysis.
The 401 studies analyzed enrolled a total of 39,909 patients, with sex not stated for 1,606 (4%) and defined for 38,303 (96%). Of those with stated sex, 17,236 (45%) were women and 21,067 (55%) were men. Despite a higher overall percentage of men, a trend towards more balanced sex recruitment was observed over time, with nearly equal numbers of men and women in the most recent decade. Among patients with stated sex, 638 women (4%) and 640 men (3%) had disaggregated data, with 588 (1.5% of the total) having disaggregated outcome data analyzed quantitatively. This group included 251 women (43%) and 337 men (57%). A decline in studies reporting disaggregated data was noted since 2016.
Out of the 401 articles, 24 (6%) did not specify the sex of enrolled patients, while 377 (94%) did. Of these, one study included only women, two only men, and 374 included both sexes. Among these, 24 (6%) provided sex-disaggregated demographic data, encompassing 1,620 patients (4% of the total population). Sixteen articles (4%) offered disaggregated data by sex for a common clinical outcome and were included in the meta-analysis, comprising 588 patients (1.5% of the overall population), with 251 women (43%) and 337 men (57%). The average age was 58.5 years, with no significant age difference between sexes, and the average follow-up period was 35.8 months. Most studies were published in the last two decades, with a geographic distribution including the United States, Japan, Italy, Taiwan, Switzerland, Spain, and South Korea. Nine studies were retrospective, and seven were prospective. Fourteen were case series, and two were RCTs.
The primary outcomes assessed included preoperative and postoperative UCLA scores, external rotation, forward flexion, and the constant score. No significant gender differences were found in outcome scores before and after surgery. A trend towards lower ROM values in women for shoulder external rotation was noted, but it was not statistically significant. Quality assessment using the Downs and Black checklist and the MCMS showed that four studies were rated good and the rest fair, with the average Coleman score for the 16 studies being 69 out of 100, indicating overall moderate quality.
Conclusion
The primary finding of this study is the significant lack of consideration for sex differences in research on surgical repair for rotator cuff (RC) tears. The meta-analysis revealed that only 4% of studies included sex-disaggregated results, and a mere 1.5% of the overall patient population was analyzed based on sex. This oversight hampers the ability to evaluate sex-specific differences in patient and lesion characteristics, as well as treatment outcomes post-RC repair. The scarcity of gender-disaggregated data and the considerable variability in reported outcomes limited the comparative analysis to a negligible portion of the studied population. Consequently, only a few aspects could be examined, with one outcome showing a slight tendency for men to have better external rotation after surgery. However, the heterogeneity in population data (such as comorbidities and rotator cuff rupture mechanisms) across studies complicated the identification of sex-specific risk factors. The 1.5% representative sample is inadequate for generalizing findings, highlighting the need for more gender-focused analyses in RC repair research.
Most studies fail to address potential sex differences in demographics and lesion-specific factors, which are critical for influencing treatment outcomes. Current literature largely neglects the importance of disaggregating both baseline data and results by sex, impairing the understanding of demographic and lesion characteristics, as well as responses to surgical treatment in men and women. This deficiency in scientific evidence hinders the comprehension of sex-specific etiopathogenetic mechanisms and patient characteristics that might necessitate different management strategies, thereby obstructing the optimization of treatment based on sex-specific needs.
Given the increasing nationwide incidence of surgical rotator cuff repairs, investigating gender-based differences is crucial. RC pathology is reportedly more prevalent in women, especially those aged 70 to 79, influenced by both socially constructed roles and biological characteristics. The exact physiological response of tendons and ligaments to sex hormones remains unclear, with conflicting study results. Postmenopausal estrogen decline has a documented impact on tendon homeostasis, affecting cell proliferation, metabolism, and collagen turnover. Anatomical and biomechanical differences between sexes also play a role, with recent findings indicating lower shoulder muscle volume in females, which could influence treatment outcomes.
The study underscores the pervasive gender bias in clinical and preclinical research. Despite policies promoting women’s participation in research, outcomes are often not reported by sex. Gender bias persists across various medical fields, leading to ineffective therapies or misleading diagnoses for women. For instance, women experience higher mortality and poorer outcomes after heart attacks due to symptoms being labeled as “atypical.” Similarly, female-specific risks and adverse effects in drug treatments and therapies are frequently overlooked.
In conclusion, this systematic review highlights a critical gender bias in rotator cuff repair research, with only 4% of studies reporting sex-disaggregated data. This limited sample size is not representative of the broader patient population, underscoring the urgent need for more comprehensive gender-based analyses in rotator cuff repair research. Addressing these disparities will enhance diagnostic accuracy and therapeutic decisions, ultimately improving treatment outcomes for both men and women.
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