TRABECULAR BONE TEXTURE IN RADIOGRAPHS OF THE KNEE

Abstract

Tibio-femoral osteoarthritis (OA) accelerates the degeneration of cartilage which alters the biomechanical environment surrounding the joint. As stresses applied to the proximal tibia increase, subchondral cancellous bone remodels itself in response to biomechanical changes. In order to detect the changes in subchondral trabecular bone, radiographic texture in regions of interest (ROI) in the medial and lateral compartment of the proximal tibia were examined. Dominant knees of 151 subjects were radiographed using the fixed flexion technique. Two radiologists independently graded each radiograph accord ing to Kellgren-Lawrence (KL) scoring. Two ROIs were selected to contain a representative sample of the trabecular pattern in the tibia. Run-length and trabecular strut analysis were applied to measure several indices of ra diographic texture. Aggregate reproducibility of the indices were assessed by analysing duplicate radiographs of 12 patients acquired 1-week apart. In general the reproducibility of the run-length indices were < 5% compared to those derives from strut analysis (< 10%). There was strong evidence of structural change in trabecular bone pattern in groups of subjects with differing Kellgren-Lawrence (KL) scores. For example, the difference in bone surface (p<0.05), bone volume (p<0.0001), trabecular spacing (p<0.005) and connectivity index (p<0.05) were statistically significant between subjects with KL scores of 4 and <1. In subjects with moderate osteoarthritis (KL=2,3), there was a non-significant trend to have greater apparent bone surface and bone volume, reduced trabecular spacing and greater connectivity as identified by strut analysis. It was found that structural change in trabecular bone can be identified by computer-aided analysis of radiographs of osteoarthritic knees. However, this change could not be identified in non-severe OA without greater statistical power.