Natural history of radiographic first metatarsophalangeal joint osteoarthritis: a nineteen-year population-based cohort study

Objective: To assess the long-term prevalence, natural history, progression and incidence of 73 radiographic first metatarsophalangeal joint (1st MTPJ) osteoarthritis (OA). Methods: A longitudinal, cohort design was used in which radiographic OA at the 1st MTPJ was 75 investigated in participants at year 6 (1995) and year 23 (2013-2015) from the Chingford 1000 76 Women study. Radiographic features of osteophytes (OPs) and/or joint space narrowing (JSN) at the 77 1st MTPJ were scored according to a validated foot atlas. Natural history was determined by the 78 change in prevalence, incidence, progression and worsening of OA in the 1st MTPJ. Results: Complete case matched foot radiographic data were available for 193 of the women 80 currently enrolled in the study, mean age: 75.7 years (SD: 5.2; range 69-90). At the level of the 1st 81 MTPJ, prevalence of OA at year 6 was 21.76% in the left and 24.35% in the right and at year 23 was 82 23.83% in the left and 32.64% in the right. Over the 19-year period, 13.5% of women developed 83 incident OA in the right 1st MTPJ and 8.3% in the left. Both progression and worsening of OA were 84 more evident for OPs and in the right 1st MTPJs. Conclusion: In this longest study of the natural history of radiographic 1st MTPJ OA to date, the 86 prevalence and incidence of 1st MTPJ OA increased over a 19-year period. Progression and/or 87 worsening of 1st MTPJ OA over time appears to be driven by OP development rather than JSN 88 suggestive of a biomechanical cause