Correlation of Ankle Joint Position Sense (JPS) and Foot Posture Index (FPI) with Severity and Functional Disability in Individuals with Knee Osteoarthritis

Background: Osteoarthritis (OA) is the second most common musculoskeletal problem after backache. Knee OA causes significant alteration in foot posture and ankle proprioception. The resultant changes in knee and ankle can progress with the progression of the disease and contribute to functional disability in the elderly. Methods: 30 individuals aged 40-70 years were included in the study. Radio-graphically confirmed cases of knee OA (Kellgren-Lawrence scale) were evaluated for Foot Posture Index (FPI), ankle Joint Position Sense (JPS) and functional disability (WOMAC). Bubble inclinometer used in this study for assessing ankle JPS did not have an established reliability. Hence, a preliminary study was conducted with 25 individuals to assess intra-rater reliability of bubble inclinometer. Results: There was a positive correlation of ankle JPS and FPI with functional disability (r=0.5222, r=0.9644 respectively, p value less than0.05) but no significant correlation was found with severity of knee OA (r=0.2083, r=0.2811 respectively, p value greater than0.05). Intra-rater reliability of bubble inclinometer was found to be 0.872 (ICC at 95 % CI) (0.659-0.948) which is suggestive of good to excellent reliability. Also, observed was an extremely significant positive correlation between Foot Posture Index (FPI) and ankle Joint Position Sense (JPS) (r=0.6354, p valueless than0.05). Conclusion: Thus, it can be concluded that altered foot posture and ankle JPS is a contributory factor to functional disability but does not show a linear relationship with progression or severity of disease. Bubble inclinometer can be used as an effective tool for assessing proprioception at ankle.