Cause and Effect Relationship of Body Weight and Knee Osteoarthritis: Experience from a Tertiary Institution in South-Eastern Nigeria

It is well established that obesity is related to osteoarthritis of the knees. The aim of this study was to investigate the risk of knee osteoarthritis in relation to body mass index (BMI) and specifically, to assess the risk of knee osteoarthritis (OA) attributable to obesity. We also aimed to determine if there is a higher risk with an increase in BMI. This is an observational case-referent study of patients with knee pain. Patients were recruited from the orthopaedics clinic. The cases were patients that presented with radiologically diagnosed knee osteoarthritis, while the referents were other patients that also attended the orthopedic clinic at the same time. The referents were randomly selected. Body Mass Index was calculated and classified based on the WHO international classification. Data were analyzed using SPSS version 21. A total of 152 patients were included in the study and 67.1% were females while 32.9% were males giving a ratio of 2:1. The mean age was 57.72+/-12.5 years, the mean weight was 79.47+/- 13.41kg (95% CI 77.32 – 81.62) and the mean BMI was 27.80+/-6.2kg/m2. 56.6% had knee osteoarthritis. 8.6% (n = 13) were bilateral, 18.4% (n = 28) in the left knee and 29.6% (n = 45) in the right knee. The relationship between obesity and the presence of knee osteoarthritis was statistically significant (p 0.047). A Chi-squared test for trend also did not show an increased risk for knee osteoarthritis with increasing BMI (p 0.105). In conclusion, knee osteoarthritis is a degenerative joint disease that mostly affects the elderly. Our findings give strong support to the already existing knowledge of the positive relationship between obesity and knee osteoarthritis; however, increasing BMI did not increase the risk of knee OA.