The association of anthropometric measures and osteoarthritis knee in non‐obese subjects: a cross sectional study

OBJECTIVE: Body mass index (BMI) and knee osteoarthritis have a strong association, but other anthropometric measures lack such associations. To date, no study has evaluated non‐obese knee osteoarthritis to negate the systemic and metabolic effects of obesity. This study examines the validity of the contention that BMI and other anthropometric measures have a significant relationship with knee osteoarthritis. METHODS: In total, 180 subjects with a diagnosis of knee osteoarthritis were recruited and classified according to Kellgren‐Lawrence (KL) grades. Body mass index, mid‐upper arm circumference, waist‐hip ratio and triceps‐skinfold thickness were recorded by standard procedures. Osteoarthritis outcome scores (WOMAC) were evaluated. RESULTS: (1) In both genders, the BMI was significantly higher for KL grade 4 than for grade 2; triceps‐skinfold thickness was positively correlated with the joint space width of the tibial medial compartment. (2) In males, triceps‐skinfold thickness significantly increased as the KL grades moved from 2 to 4; the significantly higher BMI found in varus aligned knees was positively correlated with WOMAC scores. (3) In females, the waist‐hip ratio was significantly higher for KL grade 4 than for grade 2; a significant correlation was found between BMI and WOMAC scores. The waist‐hip ratio was significantly associated with varus aligned knees and it positively correlated with WOMAC scores and with the joint space width of the tibial medial compartment. The mid‐upper arm circumference demonstrated no correlation with knee osteoarthritis. CONCLUSION: This study validates the contention that BMI and other anthropometric measures have a significant association with knee osteoarthritis. Contrary to common belief, the triceps‐skinfold thickness (peripheral fat) in males and the waist‐hip ratio (central fat) in females were more strongly associated with knee osteoarthritis than BMI.