The influence of sex hormones on musculoskeletal pain and osteoarthritis

Associations between endogenous sex hormones and multisite chronic musculoskeletal pain

BACKGROUND

Sex-differences in pain perception have been documented; however, the role of sex hormones in chronic musculoskeletal pain (CMP) remains unclear. Therefore, this study investigated whether sex hormones and sex hormone-binding globulin (SHBG) are associated with CMP.

METHODS

We utilised data from the UK Biobank (n=357 424; females: 51.6%; white: 95.2%). Serum concentrations of oestradiol (E2), testosterone (T), and SHBG were measured at baseline. Chronic pain (≥3 months) in the neck/shoulder, back, hip, knee, or 'all over the body' was assessed at baseline and three follow-ups. Mixed-effects multinomial/logistic regression models were used.

RESULTS

In multivariable analyses, greater concentrations of T and T/SHBG were associated with a lower number of CMP sites in both males (T: relative risk ratio=0.81 per standard deviation, 95% confidence interval [0.77-0.86] and T/SHBG: 0.85 [0.80-0.92]) and females (T: 0.85 [0.81-0.89] and T/SHBG: 0.93 [0.89-0.97] [all P-values for trend ≤0.001]). Greater T concentrations and T/SHBG were also associated with lower odds of CMP across all sites, while higher concentrations of SHBG were associated with lower odds of neck/shoulder CMP in both sexes. There was no association between concentrations of E2, SHBG, or E2/SHBG and number of CMP or site-specific CMP in either sex.

CONCLUSION

In both sexes, greater T concentrations and T/SHBG were associated with lower number of CMP sites and site-specific CMP, while greater concentrations of SHBG were linked to lower odds of neck/shoulder CMP. These findings suggest a potential involvement of sex steroids in the pathogenesis of CMP and underscore the need for further investigation into their potential in chronic pain management strategies.

Associations between low sex steroid concentrations and incidence of knee and hip replacement for osteoarthritis in community-dwelling older women

OBJECTIVE

To examine whether low circulating sex steroid concentrations are associated with the incidence of knee and hip replacement for osteoarthritis in community-dwelling older women.

STUDY DESIGN

This prospective cohort study examined 5535 Australian women recruited into the Aspirin in Reducing Events in the Elderly (ASPREE) trial, aged ≥70 years, not taking medications affecting sex steroid concentrations, and with sex steroid concentrations measured by liquid chromatography-tandem mass spectrometry.

MAIN OUTCOME MEASURES

The incidence of knee and hip replacement for osteoarthritis was determined by hospitalisations for knee and hip surgical procedures where osteoarthritis was recorded as the indication.

RESULTS

With a mean follow-up of 3.9 (SD 1.4) years, 311 women underwent knee replacement and 242 underwent hip replacement. A greater incidence of knee replacement was observed in women with the lowest quartile concentrations of oestrone (HR 1.35, 95 % CI 1.04-1.75, p = 0.03) and testosterone (HR 1.35, 95 % CI 1.05-1.72, p = 0.02) compared with quartiles 2 to 4, after adjusting for age, body mass index, socioeconomic status, smoking, alcohol consumption, and comorbidities. A greater likelihood of hip replacement was seen for women with the lowest quartile concentrations of dehydroepiandrosterone compared with quartiles 2 to 4 (HR 1.37, 95 % CI 1.03-1.82, p = 0.03).

CONCLUSIONS

Low concentrations of endogenous sex steroids were associated with a greater likelihood of lower-limb joint replacement for osteoarthritis in community-based women aged 70 years or older. These findings suggest sex steroids contribute to musculoskeletal health in later life, although the mechanisms by which sex steroids might influence joint replacement remain unclear.

CLINICALTRIALS

gov NCT01038583. International Standard Randomized Controlled Trial Number Register ISRCTN83772183.

The association between sex hormones and prevalence of OA in US adults

Background

Age and gender are commonly recognized as risk factors for osteoarthritis (OA), implying a potential association between sex hormones and OA pathogenesis. However, the precise role of sex hormones in OA remains elusive. Meanwhile, testosterone to estradiol (TT/E2) ratio is a new biomarker of sex hormone milieu. In this study, we aimed to investigate the relationship between sex hormones, specifically TT/E2 ratio, and the prevalence of OA among adults in the United States.

Methods

This study is a cross-sectional study, and the data sourced from the National Health and Nutrition Examination Survey (NHANES) 2013-2016 cycles. This study primarily focuses on individuals aged 50 and above, employing multivariable logistic regression to examine the association between sex hormones and OA.

Results

We included 2,615 participants (972 females). No significant association was observed between testosterone or estradiol levels and OA prevalence when analyzed separately. However, the TT/E2 ratio exhibited a robust inverse association with OA, particularly in females (adjusted OR = 0.61, 95% CI: 0.41-0.91, p = 0.02). A nonlinear relationship was observed in females, with a threshold effect indicating reduced OA risk when the TT/E2 ratio exceeded 0.3.

Conclusion

The TT/E2 ratio was inversely associated with OA risk, with a stronger and more consistent effect observed in females. These findings suggest the TT/E2 ratio as a potential biomarker for OA risk stratification, particularly in postmenopausal females. Future longitudinal studies are warranted to clarify the causal role of the TT/E2 ratio in OA.

Effects of Direct and Indirect Suggestions for Analgesia: The Role of Hypnotizability and Expectation of Pain Relief

Among the methods for cognitive control of pain, the suggestions for analgesia-direct or indirect-have been widely and successfully used in experimental and clinical trials. The primary aim of this study was to contribute to the debate about the difference in the effectiveness of indirect and direct suggestions for the management of experimental pain in the ordinary state of consciousness. The secondary aim of the study was to ascertain the role of hypnotizability and expectation of pain relief in the suggestions' effect. A sample of 65 healthy participants with different levels of direct (Harvard Group Scale of Hypnotic Susceptibility: A score) and indirect suggestibility level (Alman-Wexler Indirect Hypnotic Susceptibility Scale score) and different levels of declared expectation of pain relief was submitted to direct and indirect suggestions for analgesia during cold pressure test. The results showed that both direct and indirect suggestions increase the threshold of experimental pain and that the expectation of pain relief is relevant only to the effect of direct suggestions. PERSPECTIVE: Although the reported findings cannot be extended to clinical pain, they suggest that indirect suggestions can be effective independently from the expectation of pain relief, thus evading the possible negative effects of traits such as catastrophism or reactance. Thus, indirect suggestions should be preferred in clinical contexts.

Neuropathic pain in spondyloarthritis: Decoding its prevalence, risk factors, and impact on disease activity

OBJECTIVES

This study aimed to evaluate the prevalence and characteristics of neuropathic pain in patients with various subtypes of spondyloarthritis (SpA), including axial SpA (axSpA), psoriatic arthritis (PsA), and undifferentiated peripheral SpA (p-SpA). Additionally, the study sought to identify potential risk factors associated with the presence or severity of neuropathic pain and to investigate its impact on clinical disease activity assessment.

METHODS

We conducted a cross-sectional study at two tertiary rheumatology centers, enrolling patients diagnosed with SpA. Data on demographic and clinical characteristics, comorbidities, and current therapies were collected. Neuropathic pain was assessed using the PainDETECT Questionnaire (PD-Q) and the Neuropathic Pain Symptom Inventory (NPSI). Statistical analyses included descriptive statistics, t-tests, and Pearson's correlations to evaluate the relationships between neuropathic pain scores and clinical disease activity indices.

RESULTS

The study included 177 patients. Of these, 22.2% had a PD-Q score ≥19, showing a high likelihood of neuropathic pain, while 64.9% scored ≤12, suggesting the absence of significant neuropathic components. The mean PD-Q score was 11.5 ± 10.1. Subgroup analyses showed that females had significantly higher scores for paroxysmal and evoked pain (p < 0.05), and obese patients had significantly higher scores across all NPSI subscores (p < 0.05). Moderate positive correlations were found between neuropathic pain scores and clinical disease activity indices, such as DAPSA (r = 0.46, p < 0.0001) and ASDAS-CRP (r = 0.42, p < 0.01).

CONCLUSIONS

Neuropathic pain is prevalent among patients with SpA and is significantly associated with disease activity assessments and management. This study highlights the importance of integrating neuropathic pain evaluation into the clinical assessment of SpA to tailor treatment approaches effectively and improve patient outcomes.

Unraveling the complex interplay of sex, endocrinology, and inflammation in post-Injury articular cartilage breakdown through in silico modeling

The onset of degenerative joint diseases such as post-traumatic osteoarthritis (PTOA) are associated with joint injury, biomechanical changes, and synovial biochemical anomalies. Sex and reproductive endocrinology have been emerging as potential risk factors, with epidemiological evidence revealing that female's exhibit higher PTOA risk and poorer outcomes post-injury compared to males. Sex hormones, including estradiol, progesterone, and testosterone, have been shown to regulate inflammatory signaling in immune and synovial cells, yet their collective impact on injury-induced joint inflammation and catabolism is poorly understood. Using an in silico kinetic model, we investigated the effects of sex-specific endocrine states on post-injury mechanisms in the human synovial joint. Our model results reveal that heightened estradiol levels in pre-menopausal females during the peri-ovulatory phase increase interleukin (IL)-1β expression and suppress IL-10 expression within the synovium after a simulated injury. Conversely, elevated testosterone levels in males decrease post-injury IL-1β, tumor necrosis factor alpha (TNF)-α, and stromelysin (MMP)-3 expression while increasing IL-10 production compared to females. Gaining insight into the effects of sex hormones on injury-induced inflammation and cartilage degradation provides a basis for designing future experimental and clinical studies to explore their effects on the synovial system, with a particular focus on the female sex.

ICF based comparison of musculoskeletal health in regions of Poland and Spain

The International Classification of Functioning, Disability and Health (ICF) is the framework for describing disability. The aim of the study was to compare differences in health status between the populations of the Podkarpackie region of Poland and the Castilla y León region of Spain, using the ICF core set for post-acute musculoskeletal conditions. A total of 840 people were included in the study. The brief version of ICF core set for post-acute musculoskeletal conditions was used in the study. Information obtained from semi-structured interviews and a physiotherapy assessment was recoded into ICF qualifiers to obtain comparable data. Significant differences in functioning were found between the two samples, with a higher prevalence in all the ICF entities for the Spanish sample. Similarities were found in the ICF components 'Body Functions' and 'Environmental Factors', with the most prevalent ICF entities being 'b280 Sensation of pain' and 'e225 Climate' respectively. For 'Activities and Participation', differences were observed, with 'd430 Lifting and carrying objects' being the most common for the Spanish sample and 'd450 Walking' for the Polish sample. Significant differences were found between the two samples, indicating better musculoskeletal health in the Polish sample. Future research using the ICF Core Sets in practice should be expanded and carried out in other countries to improve the ability to make comparisons between populations and to develop policies for territorial equity in health.Trial registration: NCT06283407.

Therapeutic Controlled Release Strategies for Human Osteoarthritis

Osteoarthritis is a progressive, irreversible debilitating whole joint disease that affects millions of people worldwide. Despite the availability of various options (non-pharmacological and pharmacological treatments and therapy, orthobiologics, and surgical interventions), none of them can definitively cure osteoarthritis in patients. Strategies based on the controlled release of therapeutic compounds via biocompatible materials may provide powerful tools to enhance the spatiotemporal delivery, expression, and activities of the candidate agents as a means to durably manage the pathological progression of osteoarthritis in the affected joints upon convenient intra-articular (injectable) delivery while reducing their clearance, dissemination, or side effects. The goal of this review is to describe the current knowledge and advancements of controlled release to treat osteoarthritis, from basic principles to applications in vivo using therapeutic recombinant molecules and drugs and more innovatively gene sequences, providing a degree of confidence to manage the disease in patients in a close future.

A systematic review and meta-analysis of the efficacy and safety of iguratimod in the treatment of inflammatory arthritis and degenerative arthritis

Objective

To assess the efficacy and safety of iguratimod (IGU) in the treatment of inflammatory arthritis and degenerative arthritis.

Methods

Initially, randomized controlled trials (RCTs) on using IGU in treating inflammatory arthritis and degenerative arthritis were systematically gathered from various databases up to February 2024. Subsequently, two researchers independently screened the literature, extracted data, assessed the risk of bias in included studies, and conducted a meta-analysis using RevMan 5.4 software.

Results

Fifty-four RCTs involving three inflammatory arthritis were included, including ankylosing spondylitis (AS), osteoarthritis (OA), and rheumatoid arthritis (RA). For AS, the meta-analysis results showed that IGU may decrease BASDAI (SMD -1.68 [-2.32, -1.03], P < 0.00001) and BASFI (WMD -1.29 [-1.47, -1.11], P < 0.00001); IGU may also decrease inflammatory factor [ESR: (WMD -10.33 [-14.96, -5.70], P < 0.0001); CRP: (WMD -10.11 [-14.55, -5.66], P < 0.00001); TNF-α: (WMD -6.22 [-7.97, -4.47], P < 0.00001)]. For OA, the meta-analysis results showed that IGU may decrease VAS (WMD -2.20 [-2.38, -2.01], P < 0.00001) and WOMAC (WMD -7.27 [-12.31, -2.24], P = 0.005); IGU may also decrease IL-6 (WMD -8.72 [-10.00, -7.45], P < 0.00001). For RA, the meta-analysis results showed that IGU may improve RA remission rate [ACR20: (RR 1.18 [1.02, 1.35], P = 0.02); ACR50: (RR 1.32 [1.05, 1.64], P = 0.02); ACR70: (RR 1.44 [1.02, 2.04], P = 0.04)] and decrease DAS28 (WMD -0.92 [-1.20, -0.63], P < 0.00001); IGU may also decrease inflammatory factors [CRP: (SMD -1.36 [-1.75, -0.96], P < 0.00001); ESR: (WMD -9.09 [-11.80, -6.38], P < 0.00001); RF: (SMD -1.21 [-1.69, -0.73], P < 0.00001)]. Regarding safety, adding IGU will not increase the incidence of adverse events.

Conclusion

IGU might emerge as a promising and secure therapeutic modality for addressing AS, OA, and RA.

Systematic Review Registration

Identifier PROSPERO: CRD42021289249.

Sex differences in the radiographic and symptomatic prevalence of knee and hip osteoarthritis

Recognising sex differences in disease prevalence can lead to clues as to its pathogenesis, for example the role of hormonal factors and related influences such as body composition, as well as forming the basis for new treatments. However, if different methods are used to define the disorder it can be difficult to explore differences in prevalence, making it necessary to draw on multiple sources of evidence. This narrative review addresses sex differences in the prevalence of knee and hip osteoarthritis, which are the most common forms of large joint osteoarthritis. Females appear to have a higher prevalence of knee osteoarthritis across a wide range of disease definitions, while findings for the hip vary depending on how the disease is defined. Clinically or symptomatically defined hip osteoarthritis is more common in females, whereas radiographically defined hip osteoarthritis is more common in males. Therefore, understanding sex differences in large joint arthritis requires consideration that osteoarthritis, as defined structurally, more commonly affects females at the knee, whereas the opposite is true at the hip. Furthermore, despite structural changes in hip osteoarthritis being more common in males, symptomatic hip osteoarthritis is more common in females. The basis for these disparities is currently unclear, but may reflect a combination of hormonal, biomechanical and behavioural factors.

Further evidence that peritraumatic 17β-estradiol levels influence chronic posttraumatic pain outcomes in women, data from both humans and animals

ABSTRACT

Chronic posttraumatic pain (CPTP) is common after traumatic stress exposure (TSE) and disproportionately burdens women. We previously showed across 3 independent longitudinal cohort studies that, in women, increased peritraumatic 17β-estradiol (E2) levels were associated with substantially lower CPTP over 1 year. Here, we assessed this relationship in a fourth longitudinal cohort and also assessed the relationship between E2 and CPTP at additional time points post-TSE. Furthermore, we used a well-validated animal model of TSE to determine whether exogenous E2 administration protects against mechanical hypersensitivity. Using nested samples and data from the Advancing Understanding of RecOvery afteR traumA study (n = 543 samples, 389 participants), an emergency department-based prospective study of TSE survivors, we assessed the relationship between circulating E2 levels and CPTP in women and men using multivariate repeated-measures mixed modeling. Male and ovariectomized female Sprague Dawley rats were exposed to TSE and administered E2 either immediately after or 3 days post-TSE. Consistent with previous results, we observed an inverse relationship between peritraumatic E2 and longitudinal CPTP in women only (β = -0.137, P = 0.033). In animals, E2 protected against mechanical hypersensitivity in female ovariectomized rats only if administered immediately post-TSE. In conclusion, peritraumatic E2 levels, but not those at post-TSE time points, predict CPTP in women TSE survivors. Administration of E2 immediately post TSE protects against mechanical hypersensitivity in female rats. Together with previous findings, these data indicate that increased peritraumatic E2 levels in women have protective effects against CPTP development and suggest that immediate post-TSE E2 administration in women could be a promising therapeutic strategy for reducing risk of CPTP.

How do we treat our male and female patients? - A primer on gender-based health care inequities

Health is a fundamental human right, yet disparities in healthcare, based on gender, persist for women. These inequities stem from a patriarchal society that has regarded men as the default standard, leading to women being treated merely as smaller men. Contributing to these disparities are the gender stereotypes that pervade our society. Women possess differences in anatomy, physiology, psychology and social experience than men. To achieve health equity, it is vital to understand and be open to consider and evaluate these aspects in each individual patient. This requires an understanding of our own biases and a commitment to valuing diversity in both patient and caregiver. Improving equity and diversity throughout all aspects of the medical system will be necessary to provide optimal patient care for all.

Low skeletal muscle mass is associated with inferior preoperative and postoperative shoulder function in elderly rotator cuff tear patients

BACKGROUND

The age-related loss of skeletal muscle mass is an important characteristic of sarcopenia, an increasingly recognized condition with systemic implications. However, its association with shoulder function in elderly patients with rotator cuff tears (RCT) remains unknown. This study aimed to investigate the relationship between low skeletal muscle mass and shoulder function in elderly RCT patients.

METHODS

A retrospective analysis was conducted on RCT patients who underwent chest computed tomography (CT) scans for clinical evaluation. Preoperative CT scan images of the chest were used to calculate the cross-sectional area (CSA) of thoracic muscle at the T4 level. The medical records were reviewed. Shoulder function was assessed using the ASES score and CMS score both preoperatively and at the final follow-up. Data on the preoperative range of motion (ROM) for the affected shoulder, were collected for analysis. Subgroup analyses by sex were also performed.

RESULTS

A total of 283 RCT patients, consisting of 95 males and 188 females, with a mean age of 66.22 ± 4.89(range, 60-95 years) years were included in this retrospective study. The low muscle mass group showed significantly higher level of c-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) compared to the normal group(3.75 ± 6.64 mg/L vs. 2.17 ± 2.30 mg/L, p = 0.021; 19.08 ± 12.86 mm/H vs.15.95 ± 10.76 mm/H, p = 0.038; respectively). In the normal group, pre-operative passive ROM, including forward elevation, abduction, lateral rotation, and abductive external rotation, was significantly better than that in the low muscle mass group (127.18 ± 34.87° vs. 89.76 ± 50.61°; 119.83 ± 45.76° vs. 87.16 ± 53.32°; 37.96 ± 28.33° vs. 25.82 ± 27.82°; 47.71 ± 23.56° vs. 30.87 ± 27.76°, all p < 0.01, respectively). Similar results were found in the active ROM of the shoulder. The female low muscle mass group exhibited significantly poorer passive and active ROM (p < 0.05). The post-operative ASES scores and CMS scores of the female low muscle mass group were also statistically worse than those of the female normal group (p < 0.05).

CONCLUSIONS

The results of present study revealed that the low skeletal muscle mass is associated with inferior ROM of the shoulder and per- and post-operative shoulder function, especially for elderly female patients.

Toward designing human intervention studies to prevent osteoarthritis after knee injury: A report from an interdisciplinary OARSI 2023 workshop

Objective

The global impact of osteoarthritis is growing. Currently no disease modifying osteoarthritis drugs/therapies exist, increasing the need for preventative strategies. Knee injuries have a high prevalence, distinct onset, and strong independent association with post-traumatic osteoarthritis (PTOA). Numerous groups are embarking upon research that will culminate in clinical trials to assess the effect of interventions to prevent knee PTOA despite challenges and lack of consensus about trial design in this population. Our objectives were to improve awareness of knee PTOA prevention trial design and discuss state-of-the art methods to address the unique opportunities and challenges of these studies.

Design

An international interdisciplinary group developed a workshop, hosted at the 2023 Osteoarthritis Research Society International Congress. Here we summarize the workshop content and outputs, with the goal of moving the field of PTOA prevention trial design forward.

Results

Workshop highlights included discussions about target population (considering risk, homogeneity, and possibility of modifying osteoarthritis outcome); target treatment (considering delivery, timing, feasibility and effectiveness); comparators (usual care, placebo), and primary symptomatic outcomes considering surrogates and the importance of knee function and symptoms other than pain to this population.

Conclusions

Opportunities to test multimodal PTOA prevention interventions across preclinical models and clinical trials exist. As improving symptomatic outcomes aligns with patient and regulator priorities, co-primary symptomatic (single or aggregate/multidimensional outcome considering function and symptoms beyond pain) and structural/physiological outcomes may be appropriate for these trials. To ensure PTOA prevention trials are relevant and acceptable to all stakeholders, future research should address critical knowledge gaps and challenges.

Deciphering nociplastic pain: clinical features, risk factors and potential mechanisms

Nociplastic pain is a mechanistic term used to describe pain that arises or is sustained by altered nociception, despite the absence of tissue damage. Although nociplastic pain has distinct pathophysiology from nociceptive and neuropathic pain, these pain mechanisms often coincide within individuals, which contributes to the intractability of chronic pain. Key symptoms of nociplastic pain include pain in multiple body regions, fatigue, sleep disturbances, cognitive dysfunction, depression and anxiety. Individuals with nociplastic pain are often diffusely tender - indicative of hyperalgesia and/or allodynia - and are often more sensitive than others to non-painful sensory stimuli such as lights, odours and noises. This Review summarizes the risk factors, clinical presentation and treatment of nociplastic pain, and describes how alterations in brain function and structure, immune processing and peripheral factors might contribute to the nociplastic pain phenotype. This article concludes with a discussion of two proposed subtypes of nociplastic pain that reflect distinct neurobiological features and treatment responsivity.

Challenges with embedding an integrated sex and gender perspective into pain research: Recommendations and opportunities

The focus of this article, within this BBI horizons special issue, is on sex, gender, and pain. We summarise what is currently known about sex- and gender-related variations in pain, exploring intersectional biological and psychosocial mechanisms, and highlight gaps in knowledge and understanding. Five key challenges with the exploration of sex and gender in pain research are presented, relating to: conceptual imprecision, research bias, limitations with binary descriptions, integrating sex and gender, and timely adoption/implementation of good research practice. Guidance on how to overcome such challenges is provided. Despite clear evidence for sex and gender differences in pain, there are conceptual and methodological barriers to overcome. Innovation in methods and approach can help develop more effective and tailored treatment approaches for men, women, boys, girls, and gender-diverse people.

Could sex-specific subtypes of hand osteoarthritis exist? A retrospective study in women presenting to secondary care

Introduction

Hand osteoarthritis is more common in women, and its risk increases around the time of the menopause. We set out to describe the timing between menopause and the onset of symptomatic hand osteoarthritis (OA), and associations with the use of hormone replacement therapy (HRT) or its discontinuation, describing any identifiable subgroups of women.

Methods

Retrospective healthcare-records study of sequential women referred to a specialist hand OA clinic, 2007-2015. Confirmation of hand OA diagnosis was by clinican, by accepted criteria. Demographics and clinical variables were from healthcare-records, recorded by standardised proforma. Outcomes of interest were reported age of onset of hand symptoms, reported age at final menstrual period (FMP), time from FMP to reported onset of hand symptoms and time from cessation of HRT to reported onset of hand symptoms. Exposure categories for systemic HRT use were never users, current users, previous users. Analysis of Variance compared groups; linear regression analysed associations of exposure with outcome.

Results

82/92(89%) of eligible women were post-menopausal, mean age at FMP 49.9 years (SD5.4). In these post-menopausal women, median time from FMP to hand symptom onset was 3 years. 48/82 (59%) developed hand symptoms within the defined peri-menopausal period (FMP ± 4 years), whilst some women developed their symptoms before or after (range -25, 30 years). In women who discontinued HRT prior to symptom onset, the median time from HRT cessation to onset of hand symptoms was 6 months. Past HRT users were older at hand symptom onset than women who had not taken HRT [coeff.4.7 years (0.92, 8.39); P = 0.015].

Conclusions

This study adds to evidence associating the menopause/sex hormone deficiency with hand OA symptom onset in a sizeable subgroup of women (but not all). HRT use/cessation appears to influence the timing of onset of hand OA symptoms. It is not possible to interpret from this type of study whether sex hormone deficiency is causative of disease or modulates its symptoms. It is also not possible to judge whether painful hand osteoarthritis in post-menopausal women is a subtype of disease. Further investigation is indicated of sex-specific subtypes and potential for personalised medicine for post-menopausal women with hand osteoarthritis, as a clearly definable high-risk subgroup.

Lifetime risk and genetic predisposition to post-traumatic OA of the knee in the UK Biobank

OBJECTIVE

Acute knee injury is associated with post-traumatic OA (PTOA). Very little is known about the genome-wide associations of PTOA when compared with idiopathic OA (iOA). Our objective was to describe the development of knee OA after a knee injury and its genetic associations in UK Biobank (UKB).

DESIGN

Clinically significant structural knee injuries in those ≤50 years were identified from electronic health records and self-reported data in 502,409 UKB participants. Time-to-first knee osteoarthritis (OA) code was compared in injured cases and age-/sex-matched non-injured controls using Cox Proportional Hazards models. A time-to-OA genome-wide association study (GWAS) sought evidence for PTOA risk variants 6 months to 20 years following injury. Evidence for associations of two iOA polygenic risk scores (PRS) was sought.

RESULTS

Of 4233 knee injury cases, 1896 (44.8%) were female (mean age at injury 34.1 years [SD 10.4]). Over a median of 30.2 (IQR 19.5-45.4) years, 1096 (25.9%) of injured cases developed knee OA. The overall hazards ratio (HR) for knee OA after injury was 1.81 (1.70,1.93), P = 8.9 × 10-74. Female sex and increasing age at injury were associated with knee OA following injury (HR 1.15 [1.02,1.30];1.07 [1,07,1.07] respectively). OA risk was highest in the first 5 years after injury (HR 3.26 [2.67,3.98]), persisting for 40 years. In 3074 knee injury cases included in the time-to-OA GWAS, no variants reached genome-wide significance. iOA PRS was not associated with time-to-OA (HR 0.43 [0.02,8.41]).

CONCLUSIONS

Increasing age at injury and female sex appear to be associated with future development of PTOA in UKB, the risk of which was greatest in the 5 years after injury. Further international efforts towards a better-powered meta-analysis will definitively elucidate genetic similarities and differences of PTOA and iOA.