To determine the relation of bone size to radiographic severity in knee osteoarthritis.
149 women (81 healthy and 68 with knee osteoarthritis) underwent knee radiography and magnetic resonance imaging on their symptomatic or dominant knee. Tibial plateau bone area was measured at baseline and at follow up.
Women with osteoarthritis had larger medial and lateral tibial plateau bone area (mean (SD): 1850 (240) mm2 and 1279 (220) mm2, respectively) than healthy women (1670 (200) mm2 and 1050 (130) mm2) (p<0.001 for both differences). For each increase in grade of osteophyte, an increase in bone area was seen of 146 mm2 in the medial compartment and 102 mm2 in the lateral compartment. Similarly, for each increase in grade of joint space narrowing, tibial plateau bone area increased by 160 mm2 in the medial compartment and 131 mm2 in the lateral compartment (significance of regression coefficients all p<0.001). These relations persisted after adjusting for potential confounders, with the exception of the association between grade of medial osteophytes and medial plateau area.
With increasing severity of radiographic knee osteoarthritis, tibial plateau size increases. Whether this bone increase plays a role in the pathogenesis of osteoarthritis remains to be determined.