Osteophytes, juxta-articular radiolucencies and cancellous bone changes in the proximal tibia of patients with knee osteoarthritis

Objective: To determine differences in tibial cancellous bone organisation in knee osteoarthritis (OA) between the central weight-bearing region and juxta-articular radiolucencies adjacent to small, medium or large marginal osteophytes. Methods: Patients with medial compartment CA (n = 60; F = 39), mean (SD) age 60.0 (9.7) years, and non-OA reference subjects (n = 21; F=5), mean (SD) age 36.8 (11.5) years, had x4 macroradiographs digitised by laser scanner. Using a modified Osteoarthritis Research Society (OARS) Atlas, right and/or left knees were graded according to marginal osteophyte size into those with small (n 30), medium (n = 30) or large (n = 27) marginal osteophytes, identified as OPH1, OPH2 and OPH3, respectively. Non-OA knees (n = 30) were anatomically normal. Computerised method of Fractal Signature Analysis (FSA) quantified differences in cancellous bone structure between non-OA and osteophyte subgroups at two regions of interest (ROls); central weight-bearing and tibial margin. Results: Compared to non-OA, vertical trabecular number increased significantly (P<0.05) in all osteophyte subgroups (width range 0.12-1.14 mm) within both ROls. In OPH3, this increase was significantly (P < 0.05) greater compared to OPH2 in the central ROI, and to OPH2 and OPH1 in the marginal ROI at most trabecular widths (0.12-1.14 mm). In the marginal ROI, compared to non-OA, horizontal trabeculae number decreased in all osteophyte subgroups. This decrease was significantly greater in OPH3 compared to OPH2 and OPH1 at small to medium trabecular widths (0.12-0.54 mm). Conclusion: Compared to disease associated bone loss at the central ROI of the tibia, the extent of juxta-articular bone loss appears to be associated with the size of the marginal osteophytes. (C) 2006 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.