By Matt Silver
SAN FRANCISCO -- October 14, 2015 -- Novel method combining assessment of joint space width and subchondral bone area shows promise for knee osteoarthritis assessment, according to a study presented here at the 37th Annual Meeting of the American Society for Bone and Mineral Research (ASBMR).
Richard Ljuhar, MD, Braincon Technologies, Vienna, Austria, presented the study on October 12.
Knee osteoarthritis assessment usually involves anteroposterior and lateral radiographs to evaluate medial and lateral joint spaces. However, this technology is limited by perspective errors and low reproducibility.
In addition to joint space width, subchondral bone area may provide important information on the status of osteoarthritis, but no adequate standard to quantify subchondral changes is available.
In this study, researchers evaluated a method combining assessment of joint space width and fractal analyses of the adjacent subchondral bone area for discrimination of patients with and without osteoarthritis.
Images from 274 standardised knee radiographs from 110 patients with osteoarthritis were compared with those of 164 controls. Subchondral bone texture was assessed using fractal analysis at predefined regions of the proximal tibia. Self-similarity of the texture, reflecting 2-dimensional projection of the 3-dimensional trabecular structure, was used to calculate the bone structure value, which provides indirect information on bone quality.
According to the odds ratio, the control group had a 6.5 times higher probability than the osteoarthritis group to be measured with a bone structure value of >0.33. Also, combination of the joint space width and bone structure values further increased the discriminative power between the groups, with the most powerful combination enabling discrimination in 97.83% of cases.
“We were surprised about the low reproducibility and significant differences for osteoarthritis assessments when looking at visual diagnosis of x-rays,” said Dr. Ljuhar. “More important, we did not expect such a significant difference in bone microarchitecture results between cases and controls.”
The researchers noted differences in bone structure value between left and right knees and between men and women. Furthermore, a rising body mass index was linked to lower bone structure values.
The researchers concluded that this novel method is sufficient to discriminate between patients with and without osteoarthritis and that fractal analysis alone may provide information on bone quality aspects.
“We see bone microarchitecture as a source of unique information for assessing not just osteoarthritis but also rheumatoid arthritis and osteoporosis,” Dr. Ljuhar said. “Therefore, ongoing research will focus on combining multiple texture algorithms to develop a toolbox that can be applied to various clinical research questions.”
[Presentation title: A Novel Method for the Assessment of Joint Space Width and Subchondral Bone Texture. Abstract 1009]
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