Sexual dimorphism in articular tissue anatomy - Key to understanding sex differences in osteoarthritis?

OBJECTIVE

Osteoarthritis (OA) prevalence and incidence varies between women and men, but it is unknown whether this follows sex-specific differences in systemic factors (e.g. hormones) and/or differences in pre-morbid joint anatomy. We recognize that classifications of sex within humans cannot be reduced to female/male, but given the lack of literature on non-binary individuals, this review is limited to the sexual dimorphism of articular morphotypes.

METHODS

Based on a Pubmed search using relevant terms, and input from experts, we selected articles based on the authors' judgment of their relevance, interest, originality, and scientific quality; no "hard" bibliometric measures were used to evaluate their quality or importance. Focus was on clinical rather than pre-clinical studies, with most (imaging) data being available for the knee joint.

RESULTS

After introducing "sexual dimorphism", the specific literature on articular morphotypes is reviewed, structured by: radiographic joint space width (JSW), meniscus, ligaments, articular cartilage morphology, articular cartilage composition and deformation, and articular tissue response to treatment.

CONCLUSIONS

Sex-specific differences were clearly observed for JSW, meniscus damage, ligament size, and cartilage morphometry (volume, thickness, and surface areas) but not for cartilage composition. Ligament and cartilage measures were smaller in women even after matching for confounders. Taken together, the findings indicate that female (knee) joints may be structurally more vulnerable and at greater risk of OA. The "one size/sex fits all" approach must be abandoned in OA research, and all observational and interventional studies should report their results for sex-specific strata, at least in pre-specified secondary or post-hoc analyses.

Unraveling sex-specific risks of knee osteoarthritis before menopause: Do sex differences start early in life?

OBJECTIVE

Sufficient evidence within the past two decades have shown that osteoarthritis (OA) has a sex-specific component. However, efforts to reveal the biological causes of this disparity have emerged more gradually. In this narrative review, we discuss anatomical differences within the knee, incidence of injuries in youth sports, and metabolic factors that present early in life (childhood and early adulthood) that can contribute to a higher risk of OA in females.

DESIGN

We compiled clinical data from multiple tissues within the knee joint-since OA is a whole joint disorder-aiming to reveal relevant factors behind the sex differences from different perspectives.

RESULTS

The data gathered in this review indicate that sex differences in articular cartilage, meniscus, and anterior cruciate ligament are detected as early as childhood and are not only explained by sex hormones. Aiming to unveil the biological causes of the uneven sex-specific risks for knee OA, we review the current knowledge of sex differences mostly in young, but also including old populations, from the perspective of (i) human anatomy in both healthy and pathological conditions, (ii) physical activity and response to injury, and (iii) metabolic signatures.

CONCLUSIONS

We propose that to close the gap in health disparities, and specifically regarding OA, we should address sex-specific anatomic, biologic, and metabolic factors at early stages in life, as a way to prevent the higher severity and incidence of OA in women later in life.

Sex differences in osteoarthritis prevalence, pain perception, physical function and therapeutics

OBJECTIVE

Women have a higher prevalence of osteoarthritis (OA) and worse clinical courses than men. However, the underlying factors and therapeutic outcomes of these sex-specific differences are incompletely researched. This review examines the current state of knowledge regarding sex differences in OA prevalence, risk factors, pain severity, functional outcomes, and use and response to therapeutics.

METHODS

PubMed database was used with the title keyword combinations "{gender OR sex} AND osteoarthritis" plus additional manual search of the included papers for pertinent references, yielding 212 references. Additional references were added and 343 that were reviewed for appropriateness.

RESULTS

Globally, women account for 60% of people with osteoarthritis with a greater difference after age 40. The higher risk for women may be due to differences in joint anatomy, alignment, muscle strength, hormonal influences, obesity, and/or genetics. At the same radiographic severity, women have greater pain severity than men, which may be explained by biologically distinct pain pathways, differential activation of central pain pathways, differences in pain sensitivity, perception, reporting, and coping strategies. Women have greater limitations of physical function and performance than men independent of BMI, OA severity, injury history, amount of weekly exercise. Women also have greater use of analgesic medications than men but less use of arthroplasty and poorer prognosis after surgical interventions.

CONCLUSIONS

The recognition of sex differences in OA manifestations and management could guide tailoring of sex-specific treatment protocols, and analysis of sex as a biological variable in future research would enhance development of precision medicine.

Trajectory of knee health in runners with and without heightened osteoarthritis risk: the TRAIL prospective cohort study protocol

INTRODUCTION

Running is one of the most popular recreational activities worldwide, due to its low cost and accessibility. However, little is known about the impact of running on knee joint health in runners with and without a history of knee surgery. The primary aim of this longitudinal cohort study is to compare knee joint structural features on MRI and knee symptoms at baseline and 4-year follow-up in runners with and without a history of knee surgery. Secondary aims are to explore the relationships between training load exposures (volume and/or intensity) and changes in knee joint structure and symptoms over 4 years; explore the relationship between baseline running biomechanics, and changes in knee joint structure and symptoms over 4 years. In addition, we will explore whether additional variables confound, modify or mediate these associations, including sex, baseline lower-limb functional performance, knee muscle strength, psychological and sociodemographic factors.

METHODS AND ANALYSIS

A convenience sample of at least 200 runners (sex/gender balanced) with (n=100) and without (n=100) a history of knee surgery will be recruited. Primary outcomes will be knee joint health (MRI) and knee symptoms (baseline; 4 years). Exposure variables for secondary outcomes include training load exposure, obtained daily throughout the study from wearable devices and three-dimensional running biomechanics (baseline). Additional variables include lower limb functional performance, knee extensor and flexor muscle strength, biomarkers, psychological and sociodemographic factors (baseline). Knowledge and beliefs about osteoarthritis will be obtained through predefined questions and semi-structured interviews with a subset of participants. Multivariable logistic and linear regression models, adjusting for potential confounding factors, will explore changes in knee joint structural features and symptoms, and the influence of potential modifiers and mediators.

ETHICS AND DISSEMINATION

Approved by the La Trobe University Ethics Committee (HEC-19524). Findings will be disseminated to stakeholders, peer-review journals and conferences.

Association between increased signal intensity at the proximal patellar tendon and patellofemoral geometry in community-based asymptomatic middle-aged adults: a cross-sectional study

BACKGROUND

Histological and epidemiological data suggest that increased signal intensity at the proximal patellar tendon on magnetic resonance imaging is a response to tendon loading. As patellofemoral geometry is a mediator of loading, we examined the association between patellofemoral geometry and the prevalence of increased signal intensity at the patellar tendon in community-based middle-aged adults.

METHODS

Two hundred-one adults aged 25-60 years in a study of obesity and musculoskeletal health had the patellar tendon assessed from magnetic resonance imaging. Increased signal intensity at the proximal patellar tendon was defined as hyper-intense regions of characteristic pattern, size and distribution on both T1- and T2-weighted sequences. Indices of patellofemoral geometry, including Insall-Salvati ratio, patellofemoral congruence angle, sulcus angle, and lateral condyle-patella angle, were measured from magnetic resonance imaging using validated methods. Binary logistic regression was used to examine the association between patellofemoral geometrical indices and the prevalence of increased signal intensity at the patellar tendon.

RESULTS

The prevalence of increased signal intensity at the patellar tendon was 37.3%. A greater Insall-Salvati ratio (odds ratio 0.80, 95% confidence interval 0.66-0.97 per 0.1 change in the ratio, p = 0.02), indicative of a higher-riding patella, and a larger patellofemoral congruence angle (odds ratio 0.91, 95% confidence interval 0.85-0.98 per 5 degree change in the angle, p = 0.01), indicating a more laterally placed patella, were associated with reduced odds of increased signal intensity at the patellar tendon. Sulcus angle and lateral condyle-patella angle were not significantly associated with the odds of increased signal intensity at the patellar tendon.

CONCLUSIONS

In community-based asymptomatic middle-aged adults, increased signal intensity at the patellar tendon was common and associated with Insall-Salvati ratio and patellofemoral congruence angle, suggesting a biomechanical mechanism. Such work is likely to inform tissue engineering and cell regeneration approaches to improving outcomes in those with tendon pathology.

Gender Differences in Knee Joint Congruity Quantified from MRI: A Validation Study with Data from Center for Clinical and Basic Research and Osteoarthritis Initiative

Objective Gender is a risk factor in the onset of osteoarthritis (OA). The aim of the study was to investigate gender differences in contact area (CA) and congruity index (CI) in the medial tibiofemoral (MTF) joint in 2 different cohorts, quantified automatically from magnetic resonance imaging (MRI). Design The CA and CI markers were validated on 2 different data sets from Center for Clinical and Basic Research (CCBR) and Osteoarthritis Initiative (OAI). The CCBR cohort consisted of 159 subjects and the OAI subcohort consisted of 1,436 subjects. From the MTF joint, the contact area was located and quantified using Euclidean distance transform. Furthermore, the CI was quantified over the contact area by assessing agreement of the first- and second-order general surface features. Then, the gender differences between CA and CI values were evaluated at different stages of radiographic OA. Results Female CAs were significantly higher than male CAs after normalization, male CIs were significantly higher than female CIs after correcting with age and body mass index ( P < 0.05), consistent across the 2 data sets. For the OAI data set, the gender differences were present at all stages of radiographic OA. Conclusion This study demonstrated the gender differences in CA and CI in MTF joints. The higher normalized CA and lower CI values in female knees may be linked with the increased risk of incidence of radiographic OA in females. These differences may help further understand the gender differences and/or to establish gender specific treatment strategies.

Associations between systemic bone mineral density, knee cartilage defects and bone marrow lesions in patients with knee osteoarthritis

AIM

The relationship between bone mineral density (BMD) and osteoarthritis (OA) remains controversial. This study aimed to explore the cross-sectional associations between BMD at the total body, hip and spine and joint structural abnormalities including cartilage defects and bone marrow lesions (BMLs) in patients with knee OA.

METHOD

One hundred and eight-five subjects with symptomatic knee OA were included in this study. T2-weighted fast spin echo magnetic resonance imaging was used to assess knee cartilage defects and BMLs. Total body, hip and spine BMD were measured using dual-energy X-ray absorptiometry.

RESULTS

After adjustment for potential confounders, total hip BMD was negatively associated with medial tibial cartilage defects, lateral femoral cartilage defects, medial tibial BMLs and lateral tibial BMLs. Spine and total body BMD were negatively associated with lateral femoral cartilage defects, but not with BMLs.

CONCLUSION

We concluded that BMD particularly at the hip was negatively associated with knee cartilage defects and BMLs.

Associations between systemic bone mineral density and early knee cartilage changes in middle-aged adults without clinical knee disease: a prospective cohort study

Background

Osteoarthritis has a high prevalence in people with high bone mineral density (BMD). Nevertheless, whether high systemic BMD predates early structural features of knee osteoarthritis is unclear. This study examined the association between systemic BMD and knee cartilage defect progression and cartilage volume loss in middle-aged people without clinical knee disease.

Methods

Adults (n = 153) aged 25–60 years had total body, lumbar spine, and total hip BMD assessed by dual-energy X-ray absorptiometry at baseline (2005–2008), and tibial cartilage volume and tibiofemoral cartilage defects assessed by magnetic resonance imaging at baseline and follow up (2008–2010).

Results

Higher spine BMD was associated with increased risk for progression of medial (OR = 1.45, 95% CI 1.10, 1.91) and lateral (OR = 1.30, 95% CI 1.00, 1.67) tibiofemoral cartilage defects. Total hip BMD was also positively associated with the progression of medial (OR = 1.63, 95% CI 1.10, 2.41) and lateral (OR = 1.53, 95% CI 1.08, 2.18) tibiofemoral cartilage defects. Greater total body, spine, and total hip BMD were associated with increased rate of lateral tibial cartilage volume loss (for every 1 g/10 cm² increase in total body BMD: B = 0.44%, 95% CI 0.17%, 0.71%; spine BMD: 0.17%, 95% CI 0.04%, 0.30%; total hip BMD: 0.29%, 95% CI 0.13%, 0.45%), with no significant associations for medial tibial cartilage volume loss.

Conclusion

In middle-aged people without clinical knee disease, higher systemic BMD was associated with increased early knee cartilage damage. Further work is needed to clarify the effect of systemic BMD at different stages of the pathway from health through to disease in knee osteoarthritis, as new therapies targeting bone are developed for the management of knee osteoarthritis.

Wolff's law in action: a mechanism for early knee osteoarthritis

There is growing interest in the role of bone in knee osteoarthritis. Bone is a dynamic organ, tightly regulated by a multitude of homeostatic controls, including genetic and environmental factors. One such key environmental regulator of periarticular bone is mechanical stimulation, which, according to Wolff’s law, is a key determinant of bone properties. Wolff’s law theorizes that repetitive loading of bone will cause adaptive responses enabling the bone to better cope with these loads. Despite being an adaptive response of bone, the remodeling process may inadvertently trigger maladaptive responses in other articular structures. Accumulating evidence at the knee suggests that expanding articular bone surface area is driven by mechanical stimulation and is a strong predictor of articular cartilage loss. Similarly, fractal analysis of bone architecture provides further clues that bone adaptation may have untoward consequences for joint health. This review hypothesizes that adaptations of periarticular bone in response to mechanical stimulation cause maladaptive responses in other articular structures that mediate the development of knee osteoarthritis. A potential disease paradigm to account for such a hypothesis is also proposed, and novel therapeutic targets that may have a bone-modifying effect, and therefore potentially a disease-modifying effect, are also explored.

Osteoarthritis and bone mineral density: are strong bones bad for joints?

Osteoarthritis (OA) is a common and disabling joint disorder affecting millions of people worldwide. In OA, pathological changes are seen in all of the joint tissues including bone. Although both cross-sectional and longitudinal epidemiological studies have consistently demonstrated an association between higher bone mineral density (BMD) and OA, suggesting that increased BMD is a risk factor for OA, the mechanisms underlying this observation remain unclear. Recently, novel approaches to examining the BMD-OA relationship have included studying the disease in individuals with extreme high bone mass, and analyses searching for genetic variants associated with both BMD variation and OA, suggesting possible pleiotropic effects on bone mass and OA risk. These studies have yielded valuable insights into potentially relevant pathways that might one day be exploited therapeutically. Although animal models have suggested that drugs reducing bone turnover (antiresorptives) may retard OA progression, it remains to be seen whether this approach will prove to be useful in human OA. Identifying individuals with a phenotype of OA predominantly driven by increased bone formation could help improve the overall response to these treatments. This review aims to summarise current knowledge regarding the complex relationship between BMD and OA.

Weight change and change in tibial cartilage volume and symptoms in obese adults

INTRODUCTION

There is a paucity of data examining the effects of weight change on knee joint structures and symptoms. This study examined the effect of weight change on change in knee cartilage volume and symptoms in an obese cohort.

METHODS

112 obese subjects (Body Mass Index ≥30 kg/m(2)) were recruited from various community sources to examine the effect of obesity on musculoskeletal health. Tibial cartilage volume, determined by MRI, and knee symptoms, determined by the Western Ontario and McMaster Osteoarthritis Index (WOMAC) were collected at baseline and an average of 2.3 years later.

RESULTS

Percentage weight change was associated with change in medial tibial cartilage volume (β -1.2 mm(3), 95% CI -2.3 to -0.1 mm(3), p=0.03) that was consistent throughout the spectrum of weight loss through to mild weight gain. Percentage weight change was not associated with change in the lateral tibial (p=0.93) or patella (p=0.32) cartilage volumes. Percentage weight change was associated with change in all WOMAC subscales (all p≤0.01): pain (β -1.8 mm, 95% CI -3.2 to -0.4 mm), stiffness (β -1.6 mm, 95% CI -2.5 to -0.7 mm) and function (β -6.9 mm, 95% CI -11.6 to -2.1 mm).

CONCLUSIONS

The linearity of effect implies that weight loss is associated with reduced medial cartilage volume loss and improved knee symptoms, while weight gain is associated with increased medial cartilage volume loss and worse knee symptoms. These results suggest that in obese people, small amounts of weight change may have the potential for a disease modifying effect on both knee joint structure and symptoms. While weight loss is an important primary management strategy in obese individuals, avoidance of further weight gain should also be a clinical goal.

Cross-sectional and longitudinal associations between systemic, subchondral bone mineral density and knee cartilage thickness in older adults with or without radiographic osteoarthritis

OBJECTIVES

To investigate cross-sectional and longitudinal associations between systemic bone mineral density (BMD), subchondral BMD (sBMD) and knee cartilage thickness in older adults with or without radiographic osteoarthritis (ROA).

METHODS

A prospective cohort of 158 randomly selected subjects (mean 63 years, 48% women) including 69 non-ROA and 89 ROA subjects were studied at baseline and 2.7 years later. Knee cartilage thickness was semi-automatically determined from T1-weighted fat-suppressed MRI. Knee cartilage volume was measured from MRI. Systemic BMD and sBMD were measured by dual-energy X-ray absorptiometry (DXA).

RESULTS

Cross-sectionally, total body, total hip, spine BMD and/or lateral tibial sBMD were significantly and positively associated with femoral, lateral tibial and/or patellar cartilage thickness in subjects with ROA after adjustment for potential confounders. Longitudinally, a high total body BMD was associated with an increase in femoral cartilage thickness (β: 0.33 mm/g/cm(2), 95% CI 0.13 to 0.53); a high spine BMD was associated with increases in femoral and lateral tibial cartilage thickness (β: 0.25 mm/g/cm(2), 95% CI 0.10 to 0.41; and β: 0.18 mm/g/cm(2), 95% CI: 0.01 to 0.34, respectively) and a high medial tibial sBMD was associated with an increase in medial tibial cartilage thickness (β: 0.45 mm/g/cm(2), 95% CI 0.02 to 0.89) in subjects with ROA. In contrast, there were no significant associations between baseline systemic BMD, sBMD and cartilage volume loss, nor were there associations between BMD and cartilage thickness in subjects without ROA.

CONCLUSIONS

Both systemic and subchondral BMD are positively associated with increased cartilage thickness in subjects with ROA, suggesting BMD may play a protective role against cartilage loss in knee OA.