## 5 Limitations and Future Directions for Research  
This study contributes to the existing scientific literature on functionality problems in individuals with OA, examining their relationship with health antecedents, including disease severity, bilaterality, OA type (knee, hip, or both), medication use, and physical activity levels. However, several limitations should be noted. Given that the sample size is small, with only 80 participants, the results of this study cannot be generalized.  
Furthermore, it is essential to note that correlations do not imply causation. In this descriptive cross-sectional study, \"explain\" refers to estimating functionality problems based on Lequesne Index scores concerning health antecedents and physical activity levels, which are considered predictor variables rather than suggesting direct causality. The lack of a longitudinal design is a limitation as functionality problems may vary with changes in muscle strength, mental health, self-efficacy, social support, and aerobic exercise [86].  
Another limitation to consider is that the IPAQ-SF is a self-reported tool rather than an objective measurement method like accelerometers or job-specific physical activity questionnaires used in other research [87; 88]. Its limitations include potential biases or inaccuracies compared to objective measurements. Nevertheless, the IPAQ-SF is a well-regarded and widely recommended instrument for evaluating perceived physical activity as it is one of the most commonly employed self-report questionnaires for assessing physical activity across various countries [88].  
Finally, the current study did not account for other comorbidities. Our results showed that functionality was more impaired when both hip and knee OA coexisted, particularly when the condition was bilateral. Although only the coexistence of hip and knee OA was considered in the regression model and was found to be non-significant, it appears to have some connection to functionality in OA patients. Our findings could have been more comprehensive had we examined the impact of other coexisting diseases, similar to previous studies [61; 62; 63]. This is particularly important because the likelihood of developing OA increases with age, and older adults often have additional health conditions, which can further diminish functionality levels [9; 10].  
Despite the limitations mentioned above, this study offers notable strengths that deepen our understanding of the factors influencing functionality problems in individuals with osteoarthritis (OA), underscoring the need for tailored clinical interventions, as highlighted in previous research [89; 90]. Given the prevalence of OA among aging populations, this research addresses a critical public health issue, providing insights into how to enhance the daily lives of those affected by OA and improve their overall quality of life. Our study shows that while physical activity levels do not correlate with OA severity or pain, they significantly enhance physical function, particularly in individuals with low severity. This challenges existing views and emphasizes the need for personalized exercise recommendations. The findings advocate for improved support for older adults and those with comorbidities, setting the stage for future research to refine OA management strategies.