Association of Decreased Physical Activity with Rheumatoid Mid-Hindfoot Deformity/Destruction.

Foot/ankle problems remain important issues in rheumatoid arthritis (RA) patients. Although forefoot deformity generally takes a major place in surgical treatment, concomitant mid-hindfoot deformity is also commonly seen. In this situation, it can be easy to overlook that mid-hindfoot deformity can also induce or exacerbate clinical problems behind the forefoot events. Thus, the relationship between mid-hindfoot deformity/destruction and physical activity/ADL was investigated. Radiographic findings of 101 lower limbs (59 patients) were retrospectively evaluated. Alignment parameters in the lower extremity and joint destruction grade (Larsen grade) were measured. The timed-up-and-go (TUG) test, modified health assessment questionnaire (mHAQ), pain, self-reported scores for the foot and ankle (SAFE-Q), and RA disease activity were investigated to assess clinical status. The relationships among these parameters were evaluated. Subtalar joint destruction was correlated with TUG time (r = 0.329), mHAQ score (r = 0.338), and SAFE-Q: social functioning (r = 0.332). TUG time was correlated with the HKA (r = -0.527), talo-1st metatarsal angle (r = 0.64), calcaneal pitch angle (r = -0.433), M1-M5A (r = -0.345), and M2-M5A (r = -0.475). On multivariable linear regression analysis, TUG time had a relatively strong correlation with the talo-1st metatarsal angle (β = 0.452), and was negatively correlated with calcaneal pitch angle (β = -0.326). Ankle joint destruction was also correlated with TUG time (β = 0.214). Development of structural problems or conditions in mid-hindfoot, especially flatfoot deformity, were related with decreased physical activity in RA patients. Wearing an insole (arch support) as a preventative measure and short foot exercise should be considered from the early phase of deformity/destruction in the mid-hindfoot in the management of RA.