Background/Purpose:
The rising number of adults with arthritis and associated activity limitations present a serious public health problem.
Although studies have explored lower limb osteoarthritis (OA) at the knee and hip, few have focused on the foot.
Therefore, the purpose of this study is to determine the frequency of foot OA and identify potential associated risk factors.
Methods:
Participants were from the Johnston County OA Project, a community-based study of individuals in rural North Carolina with and without OA.
Weight-bearing anteroposterior and lateral radiographic images of the foot were obtained.
Based on the La Trobe radiographic atlas, foot radiographic OA (rOA) was defined as a score of 2 or more for osteophytes or joint space narrowing in at least one of the following 5 joint sites: 1st metatarsophalangeal joint, 1st & 2nd cuneo-metatarsal joints, navicular-1st cuneiform joint, and talo-navicular joint.
Foot symptoms were assessed via questionnaire by answering the question: “On most days of any one month in the last 12 months did you have pain, aching or stiffness in your [left/right] foot?”
Symptomatic OA (sxOA) was defined as symptoms in the presence of foot rOA.
At the joint level, separate logistic regression models with generalized estimating equations (GEE) to account for intra-person correlations were performed to examine discrete associations (odds ratios [OR]) of foot rOA or sxOA with age, body mass index (BMI), sex (women/men), race (African-American/Caucasian), history of foot injury (yes/no), and foot symptoms ([yes/no],
rOA models only).
Next, multiple logistic regression models with GEE were performed for foot rOA or sxOA outcomes adjusting for all factors (foot symptoms: rOA models only).
Results:
Of the 864 participants with available data (mean age 71 yrs, mean BMI 30.8 kg/m2, 68.2% women, 33.4% African American), 22.1% had rOA, 20.4% had foot symptoms, 5.3% had sxOA, and 3.8% reported prior foot injury.
In adjusted models, symptoms vs. no symptoms were associated with 1.48 times the odds of rOA (Table 1).
Compared to non-obese (BMI<30) participants, obese (BMI≥30) individuals had 1.74 times the odds of rOA (Table 1) and 3.30 times the odds of sxOA (Table 2).
African Americans vs. Caucasians had 1.49 times the odds of rOA; the association was not statistically significant in the adjusted model (Table 1).
Conclusion:
In this community-based cohort, 1 out of 5 older adults had foot rOA and 1 out of 20 had foot sxOA.
Obesity was linked with foot OA, even when considering other factors, suggesting that weight reduction may be an important strategy, especially for individuals with sxOA.
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