Genetic influences in the aetiology of anteromedial osteoarthritis of the knee

Cigarette smoking and knee osteoarthritis in the elderly: Data from the Korean National Health and Nutritional Examination Survey

BACKGROUND

The relationship between smoking and osteoarthritis (OA) has not been investigated in a large-scale study. The aim of this study was to examine the relationship between smoking and knee OA in the elderly.

METHODS

This study included 5117 subjects aged >60 years who responded to questionnaires on their history of smoking and knee OA diagnosed by a physician taken from the Korean National Health and Nutritional Examination Survey (KNHANES-VI) 2013-2015. We classified all 5117 subjects into 2 groups (the OA group and non-OA group) and compared the demographics and characteristics between the 2 groups. A multivariate logistic regression analysis was conducted to investigate the possible association between knee OA and smoking.

RESULTS

The prevalence of current smoking in the OA group (5.1%) was significantly lower than in the non-OA group (14.6%; p < 0.001). Furthermore, the proportion of moderate smokers who smoked >10 cigarettes per day or heavy smokers who smoked >20 cigarettes per day was significantly higher in the non-OA group. In the multivariate analysis, current smoking history was a preventative factor for the prevalence of OA in a multivariate model that included age, sex, body mass index, waist circumference (OR: 0.752, 95% CI: 0.571-0.989, p = 0.042).

CONCLUSIONS

This large-scale national study highlights an inverse association between smoking and the prevalence of knee OA in the general Korean elder adult population, primarily in males. Further investigation of this relationship between smoking and knee OA is needed to determine smoking's specific mechanism of protection against knee OA.

The twin peg Oxford knee - Medium term survivorship and surgical principles

BACKGROUND

A multicentre study of single peg Oxford knees reported failure associated with osteoarthritis progression, femoral component loosening, unexplained pain and meniscal bearing dislocation. Suboptimally positioned femoral components and intraoperative MCL damage could explain these problems. We hypothesised that modifying implantation technique to optimise femoral component positioning and MCL preservation, and introducing the twin peg Oxford knee would address these problems and improve longer term survival. Moreover, its better congruency in high flexion could reduce wear. This study aims to investigate this hypothesis by asking 1) Is the 98% survivorship up to nine years found in an earlier study sustained at longer term (up to 13 years)? 2) What are the remaining causes of failure?

METHODS

We described our modified implantation technique. A cohort of all patients treated by the senior author using this modified technique and the Oxford twin peg cemented knee replacement between September 2003 and August 2013 was investigated. A survival analysis was performed and the causes of failure were analysed.

RESULTS

The cohort consisted of 468 patients with 554 medial cemented implants. In all, 16 implants were revised and the 12-year survivorship was 95%. Patients with extended indications had a lower survivorship than those with anteromedial osteoarthritis (10-year survival rate 78% vs 97%, p<0.001). There were no failures due to femoral loosening.

CONCLUSIONS

Using our surgical principles the cemented twin peg Oxford knee can result in good medium to long-term implant survival, comparable to those obtained by the originating centre for the single peg Oxford knee.

Familial effects on structural changes relevant to knee osteoarthritis: a prospective cohort study

OBJECTIVE

Genetic factors play an important role in the pathogenesis of knee osteoarthritis (OA), but which knee structural changes mediate this is unclear. This study aimed to describe the differences in knee structural changes over 8-10 years between offspring having at least one parent with total knee replacement (TKR) for severe primary knee OA and controls with no family history of knee OA.

DESIGN

115 offspring (mean age 45 years) with a family history of TKR for severe knee OA were compared with 104 (mean age 46 years) controls. T1 or T2-weighted fat saturated magnetic resonance imaging (MRI) was performed respectively to evaluate knee cartilage defects, bone marrow lesions (BMLs), meniscal extrusion and tears at baseline and 10 years. Multivariate logistic regression model was used to adjust for potential confounders.

RESULTS

Offspring had a greater increase in cartilage defect score (1.03 vs 0.52, P = 0.007) and meniscal extrusion score (0.28 vs 0.10, P = 0.027) over 10 years, and a greater increase in meniscal tear score (0.40 vs 0.10, P = 0.012) over 8 years in the medial but not the lateral tibiofemoral compartment. Changes in BMLs over 8-years were not different between the two groups. These associations were independent of potential confounders, and strengthened after further adjustment for each other.

CONCLUSION

With the exception of BMLs, offspring with a family history of knee OA have a greater risk of increases in multiple knee structural abnormalities in the medial tibiofemoral compartment suggesting pleiotropic familial effects.

Role of mtDNA haplogroups in the prevalence of osteoarthritis in different geographic populations: a meta-analysis

Background

Osteoarthritis (OA) is the most common form of arthritis and has become an increasingly important public-health problem. However, the pathogenesis of OA is still unclear. In recent years, its correlation with mtDNA haplogroups attracts much attention. We aimed to perform a meta-analysis to investigate the association between mtDNA haplogroups and OA.

Methods

Published English or Chinese literature from PubMed, Web of Science, SDOS, and CNKI was retrieved up until April 15, 2014. Case-control or cohort studies that detected the frequency of mtDNA haplogroups in OA patients and controls were included. The quality of the included studies was evaluated by the Newcastle-Ottawa Scale (NOS) assessment. A meta-analysis was conducted to calculate pooled odds ratio (OR) with 95% confidence interval (CI) through the random or fixed effect model, which was selected based on the between-study heterogeneity assessed by Q test and I² test. Subgroup analysis was performed to explore the origin of heterogeneity.

Results

A total of 6 case-control studies (10590 cases and 7161 controls) with an average NOS score of 6.9 were involved. For the analysis between mtDNA haplogroup J and OA, random model was selected due to high heterogeneity. No significant association was found initially (OR = 0.73, 95%CI: 0.52–1.03), however, once any study from UK population was removed the association emerged. Further subgroup analysis demonstrated that there was a significant association in Spain population (OR = 0.57, 95%CI: 0.46–0.71), but not in UK population. Also, subgroup analysis revealed that there was a significant correlation between cluster TJ and OA in Spain population (OR = 0.70, 95%CI: 0.58–0.84), although not in UK population. No significant correlation was found between haplogroup T/cluster HV/cluster KU and OA.

Conclusions

Our current meta-analysis suggests that mtDNA haplogroup J and cluster TJ correlate with the risk of OA in Spanish population, but the associations in other populations require further investigation.

Sibling recurrence risk in Dupuytren's disease

Dupuytren's disease is a complex condition, with both genetic and environmental factors contributing to its aetiology. We aimed to quantify the extent to which genetic factors predispose to the disease, through the calculation of sibling recurrence risk (ls), and to calculate the proportion of heritability accounted for by currently known genetic loci. From 174 siblings of patients with surgically confirmed disease, 100 were randomly selected. Controls were recruited from patients attending an ophthalmology outpatient clinic for eye conditions unrelated to diabetes. There were no statistically significant differences in baseline characteristics between the case and control groups. In siblings, 47% had Dupuytren's disease, compared with 10% of controls, giving a ls of 4.5. Currently known loci that predispose to Dupuytren's disease account for 12.1% of the total heritability of the disease. Dupuytren's disease was significantly more common in siblings than in controls. These results accurately quantify the magnitude of the genetic predisposition to Dupuytren's disease.

Early diagnosis to enable early treatment of pre-osteoarthritis

Osteoarthritis is a prevalent and disabling disease affecting an increasingly large swathe of the world population. While clinical osteoarthritis is a late-stage condition for which disease-modifying opportunities are limited, osteoarthritis typically develops over decades, offering a long window of time to potentially alter its course. The etiology of osteoarthritis is multifactorial, showing strong associations with highly modifiable risk factors of mechanical overload, obesity and joint injury. As such, characterization of pre-osteoarthritic disease states will be critical to support a paradigm shift from palliation of late disease towards prevention, through early diagnosis and early treatment of joint injury and degeneration to reduce osteoarthritis risk. Joint trauma accelerates development of osteoarthritis from a known point in time. Human joint injury cohorts therefore provide a unique opportunity for evaluation of pre-osteoarthritic conditions and potential interventions from the earliest stages of degeneration. This review focuses on recent advances in imaging and biochemical biomarkers suitable for characterization of the pre-osteoarthritic joint as well as implications for development of effective early treatment strategies.

Genetic epidemiology of hip and knee osteoarthritis

Osteoarthritis (OA) is the most common cause of arthritis and represents an enormous healthcare burden in industrialized societies. Current therapeutic approaches for OA are limited and are insufficient to prevent the initiation and progression of the disease. Genetic studies of patients with OA can help to unravel the molecular mechanisms responsible for specific disease manifestations, including joint damage, nociception and chronic pain. Indeed, these studies have identified molecules, such as growth/differentiation factor 5, involved in signaling cascades that are important for the pathology of joint components. Genome-wide association studies have uncovered a likely role in OA for the genes encoding structural extracellular matrix components (such as DVWA) and molecules involved in prostaglandin metabolism (such as DQB1 and BTNL2). A ∼300 kilobase region in chromosome 7q22 is also associated with OA susceptibility. Finally, the identification of individuals at a high risk of OA and of total joint arthroplasty failure might be facilitated by the use of combinations of genetic markers, allowing for the application of preventive and disease-management strategies.

The clinical relevance of genetic susceptibility to osteoarthritis

Osteoarthritis is a major musculoskeletal cause of disability in the elderly, but current therapeutic approaches are insufficient to prevent initiation and progression of the disease. Genetic studies in humans have identified molecules involved in signalling cascades that are important for the pathology of the joint components. These include the bone morphogenetic protein (BMP) signalling, the wingless-type signalling and the thyroid pathway as well as apoptotic-related molecules. There is emerging evidence indicating that inflammatory molecules related to cytokine production, prostaglandin and arachidonic acid metabolism are also involved in susceptibility to osteoarthritis. All of these pathways are likely targets for pharmacological intervention. Genetic variation also affects pain due to osteoarthritis highlighting molecular mechanisms for pain relief. Moreover, combinations of genetic markers can be used to identify individuals at high risk of osteoarthritis and risk of total joint arthroplasty failure, which should facilitate the application of preventive and disease management strategies.

Genetic influences in the aetiology of femoroacetabular impingement: a sibling study

Femoroacetabular impingement causes pain in the hip in young adults and may predispose to the development of osteoarthritis. Genetic factors are important in the aetiology of osteoarthritis of the hip and may have a role in that of femoroacetabular impingement. We compared 96 siblings of 64 patients treated for primary impingement with a spouse control group of 77 individuals. All the subjects were screened clinically and radiologically using a standardised protocol for the presence of cam and pincer deformities and osteoarthritis. The siblings of those patients with a cam deformity had a relative risk of 2.8 of having the same deformity (66 of 160 siblings hips versus 23 of 154 control hips, p < 0.00001). The siblings of those patients with a pincer deformity had a relative risk of 2.0 of having the same deformity (43 of 116 sibling hips versus 29 of 154 control hips, p = 0.001). Bilateral deformity occurred more often in the siblings (42 of 96 siblings versus 13 of 77 control subjects, relative risk 2.6, p = 0.0002). The prevalence of clinical features in those hips with abnormal morphology was also greater in the sibling group compared with the control group (41 of 109 sibling hips versus 7 of 46 control hips, relative risk 2.5, p = 0.007). In 11 sibling hips there was grade-2 osteoarthritis according to Kellgren and Lawrence versus none in the control group (p = 0.002). Genetic influences are important in the aetiology of primary femoroacetabular impingement. This risk appears to be manifested through not only abnormal joint morphology, but also through other factors which may modulate progression of the disease.

The contribution of genes to osteoarthritis

Osteoarthritis (OA) is the most prevalent form of arthritis in the elderly. A large body of evidence, including familial aggregation and classic twin studies, indicates that primary OA has a strong hereditary component that is likely polygenic in nature. Traits related to OA, such as longitudinal changes in cartilage volume and progression of radiographic features, are also under genetic control. In recent years several linkage analyses and candidate gene studies have been performed and unveiled some of the specific genes involved in disease risk, such as FRZB and GDF5. This article discusses the impact that future genome-wide association scans can have on our understanding of the pathogenesis of OA and on identifying individuals at high risk for developing severe OA.

The contribution of genes to osteoarthritis

Osteoarthritis (OA) is the most prevalent form of arthritis in the elderly. A large body of evidence, including familial aggregation and classic twin studies, indicates that primary OA has a strong hereditary component that is likely polygenic in nature. Furthermore, traits related to OA, such as longitudinal changes in cartilage volume and progression of radiographic features, are also under genetic control. In recent years, several linkage analysis and candidate gene studies have been performed and have unveiled some of the specific genes involved in disease risk, such as FRZB and GDF5. The authors discuss the impact that future genome-wide association scans can have on our understanding of the pathogenesis of OA and on identifying individuals at high risk for developing severe OA.

The assessment of early osteoarthritis

Treatment strategies for osteoarthritis most commonly involve the removal or replacement of damaged joint tissue. Relatively few treatments attempt to arrest, slow down or reverse the disease process. Such options include peri-articular osteotomy around the hip or knee, and treatment of femoro-acetabular impingement, where early intervention may potentially alter the natural history of the disease. A relatively small proportion of patients with osteoarthritis have a clear predisposing factor that is both suitable for modification and who present early enough for intervention to be deemed worthwhile. This paper reviews recent advances in our understanding of the pathology, imaging and progression of early osteoarthritis.