Association Of Fatigue, Minimum Toe Clearance, And Physical Activity With Falls Among People With Osteoarthritis.

People with hip or knee osteoarthritis (OA) fall more frequently than healthy older adults often due to tripping incidents marked by a low minimum toe clearance (MTC). They also report higher levels of fatigue and generally lower levels of physical activity (PA). While the role of fatigue in tripping has been reported in older adults, its link to falls in people with OA remains unclear. PURPOSE: To examine the associations among fatigue, MTC, and falls in people with OA with different levels of PA. METHODS: Fifty-seven participants with hip or knee OA (knee OA: 37, 77% female, age: 57 ± 9 yrs, and BMI: 33.3 ± 7.0 kg/m2) walked at preferred speeds on an instrumented treadmill synced with motion capture. MTC was assessed as the vertical toe marker position during 50% of the swing phase on the more impaired limb. Fatigue T scores were obtained using the Patient Reported Outcomes Measurement Information System (PROMIS) Computerized Adaptive Test. PA was evaluated via the UCLA PA scale (low 0-3, moderate 4-7, high 8-10). Participants self-reported the number of falls within the last year. We used Spearman correlation and Mann-Whitney test to evaluate associations and to compare fallers and non-fallers, respectively, in the OA group and in subgroups (α = 0.05). RESULTS: Higher fatigue was associated with lower MTC in participants with knee OA (r = -0.380, p = 0.02), while MTC was associated with fallers that had a higher fall incident in our entire sample (r = 0.52, p = 0.04) and knee OA subgroup (r = -0.63, p = 0.04). Falls were reported in 28% of our sample, who reported several falls ranging from 1-20 times. There were no significant differences between fallers and non-fallers in the Mann-Whitney test. The group with moderate PA reported the most falls. CONCLUSION: Increased fatigue was associated with lower MTC in the group with knee OA, which in turn was also associated with recurrent falls in the general OA group. Other factors such as knee flexion angle during swing may help to further explain the association in participants with knee OA. More work is needed to identify fall predictors in people with hip OA. With the fallers reporting moderate PA levels, accounting for PA levels may be important when evaluating fall risk in people with OA. Supported by the NIH (R21AG052111) and the NCATS (UL1TR002003).