Osteoarthritis (OA) is one of the most prevalent conditions resulting to disability particularly in elderly population. OA is the most common articular disease of the developed world and a leading cause of chronic disability, mostly as a consequence of the knee OA and/or hip OA ¹.Osteoarthritis is a second most common rheumatologic problem in India ² OA is most frequently occurring joint disease with a prevalence ranging from 22% to 39% ³.Knee OA accounts for almost four fifths of the burden of OA worldwide and increases with obesity and age ⁴.Up to now, knee OA is incurable except knee arthroplasty which is considered as an effective treatment at an advanced stage of the disease, however, which is responsible for substantial health costs ⁵. The economic costs of OA are high, including those related to treatment, for those individuals and their families who must adapt their lives and homes to the disease, and those due to lost work productivity ⁶. The incidence of OA increases with age, and women have higher rates than men, especially after age 50 ⁷. Osteoarthritis is typically a progressive disease that may eventually lead to disability. The intensity of the clinical symptoms may vary for each individual. However, they typically become more severe, more frequent, and more debilitating over time. The rate of progression also varies for each individual. Common clinical symptoms include knee pain that is gradual in onset and worse with activity, knee stiffness and swelling, pain after prolonged sitting or resting, and pain that worsens over time. Treatment for knee osteoarthritis begins with conservative methods and progresses to surgical treatment options when conservative treatment fails. While medication scan help slow the progression of RA and other inflammatory conditions, no proven disease-modifying agents for the treatment of knee osteoarthritis currently exist ^8,9. Many researchers have shifted their focus to the prevention and treatment in the early stage of the disease ¹⁰. Accordingly, it is essential to understand the prevalence, incidence, and modifiable risk factors of knee OA for providing effectively preventive strategies. The World Health Organization, the International League against Rheumatism, and global OA experts have made substantial efforts over the past few decades, many population-based epidemiological studies of knee OA have been conducted worldwide ¹¹.

Aims & Objectives: This study determine the prevalence and identification of risk factors for knee osteoarthritis among elderly population.

MATERIALS AND METHODS

This was a cross-sectional study conducted in the department of orthopaedics, in a tertiary care teaching hospital, India. All patients suspected with the knee osteoarthritis attending orthopaedics out patient’s department during the study period were enrolled in this study. The subjects those who gave their verbal consent and found eligible for participation in the study were chosen.

KNEE OA: Knee OA was defined according to American College of Rheumatology (ACR) criteria 12 as knee pain plus at least three of the following: age >50 years, morning stiffness, crepitus in motion, bony tenderness, bony enlargement and absence of palpable warmth.

INCLUSION CRITERIA

• Patients ≥ 50 years of age with both gender.
• Patients who provide consent for the study.

EXCLUSION CRITERIA

• Subjects age < 50 years.
• Who not willing for the study.

Data were collected included Socio-demographic details such as age, sex, residential area, per capita income, physical activity, body mass index and socioeconomic status. Detailed history, clinical presentation and local examination of both the knee joint was done. X-ray both the knee joint and relevant laboratory investigation (erythrocyte sedimentation rate, C- reactive protein, RA factor, anti-CCP and Complete blood count) was done.

STATISTICAL ANALYSIS: Data was entered in Microsoft Excel spreadsheet and analyzed using SSPS version 22. Relationship between OA and various variables was assessed by calculating the odds ratio with corresponding 95% confidence interval, and its statistical significance was assessed by using Chi-square test. A P value of < 0.05 was considered statistically significant.

RESULTS

A total of 400 participants with suspected of knee osteoarthritis were enrolled in this study. The prevalence of knee osteoarthritis was 25%. Most of the OA patients (61%) were above 50 years of age. The majority of elderly was females (63%), belonged to the rural area (57%) and majority of them (84%) was literate. Majority of OA subjects (43%) were middle socioeconomic status. Most of the OA patients were obese, higher body mass index was significantly associated with the knee OA (p<0.05).

Fig 1: Prevalence of knee osteoarthritis among study subjects

Table 1: Association between socio-demographic variables and osteoarthritis knee joint

Family history of OA knee, associated co-morbidities and physical inactivity are the common risk factors showed significantly higher chances of suffering from knee OA. But history of trauma, smoking and alcohol consumption were not significantly correlated with the knee OA.

Table 2: Risk factors associated with knee osteoarthritis patients

Pain in the knee was a universal symptom in all cases of osteoarthritis while a majority of positive cases also complained of bony tenderness, crepitus, and bony overgrowth.

Fig 2: Clinical Profile of Study Participants with OA according to  ACR criteria.

DISCUSSION
There is strong evidence shows that age, ethnicity, BMI, the number of co-morbidities, MRI-detected infrapatellar synovitis, joint effusion, and both radiographic and the baseline of OA severity are predictive for clinical progression of knee osteoarthritis ¹³ In the present study, the prevalence of knee OA is based on ACR clinical criteria was 25%, Similar finding also reported by Venkatachalam J,et al.¹⁴ and Hakmaosa A, et al.¹⁵, observed prevalence of knee OA were 27.1% and 23.3% respectively. Much higher prevalence of knee OA (64%) was reported by Salve H et al.¹⁶, whereas lower prevalence of knee OA (12%) reported by Plotnikoff R, et al.¹⁷. The above difference in the prevalence of OA Knee might be different demographical region and also the former study was used ACR criteria; and later, the study was used old ACR criteria.  In our study, as the age increases the proportion of OA was of increasing trend (age >50 years 61%, <50 years 39%), in agreement with the Ajit et al.18 and Haq SA, et al.¹⁹. Current study found the prevalence of knee OA was higher among females (63%) as compared to male (37%), our results comparable with the Moghimi N,et al.²⁰ and Bhaskar A, et al.²¹.Female predominance can be due to hormonal changes after menopause lead to osteoporosis and osteoarthritis. In our study burden of knee OA was more in rural population, concordance to the study conducted by Singh A K et al.²². Family history of OA and physical inactivity were the significant risk factors of knee OA in this study, consistent finding also reported by Yu, D, et al.²³ and Sasidharan M K et al.²⁴. In our study current smoking and alcohol consumption were not significantly associated with the prevalence of knee OA, our results comparable with the Kaur R, et al.²⁵. A study conducted by Coggon D, et al.²⁶, reported that diet and physical activity of an individual play an important role in bone health. Vegetarian diet and are more prone to micronutrient deficiencies, especially calcium, phosphorus, magnesium, iron, etc., due to ignorance, which contributes to bone and joint problems. Vegetarian diet and sedentary lifestyle associated with higher odds of getting knee OA. Present study found significant association between the comorbidities and prevalence of knee OA, concordance to the Ettinger WH, et al.²⁷.  Joint pain, bony tenderness, crepitus and morning stiffness were the common clinical manifestation observed in knee OA patients of this study, our finding correlate with the Zhang W, et al.²⁸ and B Heidari, et al.²⁹. There was a significant difference in quality of life of elderly suffering from knee OA than those who were not suffering from it.

CONCLUSION
We have concluded that the Burden of knee OA was increases with the age, women are more affected than men. Prevalence of knee OA was significantly higher among elderly, obese, family history of knee pain, physically inactive and patients having associated comorbidities (p<0.05). The maximum effect of knee OA was on the physical and psychological domain of quality of life, though social and environmental domains were also significantly lower.

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