Tibial plateau size is related to grade of joint space narrowing and osteophytes in healthy women and in women with osteoarthritis.

OBJECTIVE To determine the relation of bone size to radiographic severity in knee osteoarthritis. METHODS 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. RESULTS 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. CONCLUSIONS 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.