Background Symptomatic osteoarthritis (OA) affects the daily lives of 10% of people aged >60 years. Although foot pain is common, the foot is the least studied joint complex affected by OA. Existing studies have focussed mainly on the 1st metatarsophalangeal joint (MTPJ) and have excluded other foot joints.
Objectives To estimate the population prevalence of symptomatic radiographic OA affecting the 1st MTPJ, 1st and 2nd cuneo-metatarsal joints (CMJ), the navicular-first cuneiform joint (NCJ) and the talo-navicular joint (TNJ) in community-dwelling adults aged ≥50 years.
Methods All adults aged ≥50 years registered with four general practices in North Staffordshire, UK were mailed a Health Survey. Responders who reported having pain in or around the foot within the last 12 months and consented to further contact were invited to attend a research clinic. Weight-bearing dorso-plantar and lateral radiographs of each foot were obtained and were scored at the 1st MTPJ, 1st and 2nd CMJs, NCJ and TNJ by a single blinded reader using a validated atlas. Symptomatic radiographic OA was defined as a score of ≥2 for osteophytes or joint space narrowing on either dorso-plantar or lateral views together with pain reported in the preceding four weeks in the corresponding region of the same foot on a foot manikin. Individuals could have either or both joints affected to be defined as symptomatic OA. Population prevalence estimates for each joint were calculated using a combined approach of multiple imputation and weighted logistic regression modelling. To account for clinic non-attendance or missing radiographic data, multiple imputation of data (age, gender, general practice, social class, marital status, number of days in the last year with foot pain, Manchester Foot Pain and Disability Index, SF-12, HADS, and foot OA regions) from clinic attenders was undertaken. Weighted logistic regression for age, gender and general practice was then used to adjust for the proportion of non-responders to the Health Survey.
Results 5109 Health Surveys were received (adjusted response 56%). Of 1634 invited to attend the research clinic, 560 attended. Those with a diagnosis of inflammatory arthritis (n=24) were excluded from the analysis. Survey responders were representative of the mailed population and clinic attendees were representative of those with foot pain, according to age, gender, sociodemographics and health status. The population prevalence of symptomatic radiographic OA was 16.7% (95%CI 15.3%, 18.0%) overall (ie at any one of the five assessed joints), 7.8% (6.7%, 8.9%) at the 1st MTPJ, 3.9% (2.9%, 4.9%) at the 1st CMJ, 6.8% (5.7%, 7.8%) at the 2nd CMJ, 5.2% (4.0%, 6.4%) at the NCJ, and 5.8% (4.8%, 6.9%) at the TNJ. Prevalence was greater in females than males, increased with age and was higher in lower socio-economic classes at all joints with the exception of the 1st CMJ where age and gender differences were not apparent. Weighted logistic regression to adjust for non-response did not alter prevalence estimates obtained by multiple imputation.
Conclusions Symptomatic radiographic foot OA affects 1 in 6 older adults. The 1st MTPJ is most commonly affected followed by the 2nd CMJ and TNJ. Clinicians should consider OA as a possible cause of chronic foot pain in older people.
Disclosure of Interest None Declared