Characteristics of radiographic morphometries of the lower leg in subjects with progression of knee osteoarthritis in the TOEI cohort

Background Knee osteoarthritis is one of the most common orthopedic diseases. However, few studies have reported the morphometric characteristics of the lower leg related to the progression of knee osteoarthritis in regional populations. This study aimed to determine the radiographic morphometries of the lower leg in subjects who showed progression of osteoarthritis of the knee in the TOEI cohort. Methods Data were collected from the TOEI study cohort, during the period from 2014 to 2016, to assess osteoarthritis of the knee and radiographic morphometries of the lower leg. The joints were divided into three groups according to osteoarthritis progression over 2 years. There were 323 legs of females and 163 legs of males. Knees which did not exhibit osteoarthritis were in group 1; knees with osteoarthritis that remained stable for 2 years were in group 2; knees that worsened osteoarthritis over 2 years were in group 3. Morphometric parameters in the lower leg were measured by radiographs taken in 2014. Results In female subjects, group 2 had higher age, lower lever arm ratio and lower hip–knee–ankle angle, and higher height of the hip center compared with group (1). Group 3 had higher age compared with group 1 and lower height of the hip center compared with group (2). In male subjects, group 2 had lower height of the hip center and lower hip–knee–ankle angle compared with group 1. Group 3 had higher patellar shift index compared with group 1, higher height of the hip center and higher femoral neck length compared with group 2. Conclusions Higher age was the risk of osteoarthritis progression of the knee in female subjects but not significant risk in male subjects. Hip morphometries such as height of the hip center and femoral neck length in which showed a sex difference might be associated with the progression of knee osteoarthritis.