Tribology Laboratory, School of Mechanical Engineering, University of Western Australia, Crawley, Western Australia, Australia.
Osteoarthritis Cartilage. 2010 May;18(5):684-90. doi: 10.1016/j.joca.2010.01.002. Epub 2010 Feb 6.
To evaluate differences in tibial trabecular bone (TB) texture between subjects with and without radiographic knee osteoarthritis (OA) using a variance orientation transform (VOT) method.
Subjects with knee OA (Kellgren & Lawrence grade > or =2) and controls without OA (both n=26, seven women) were matched by sex, age, body mass index and compartment. The VOT method was applied to TB X-ray images and fractal signature and dimension in horizontal (FS(H), FD(H)) and vertical (FS(V), FD(V)) directions and along the roughest part of TB (FS(Sta), FD(Sta)), texture aspect ratio (Str) and signature (StrS), and mean FD (FD(MEAN)) were calculated. The VOT method was compared against an augmented Hurst orientation transform (HOT) method using paired t tests, intraclass correlation coefficients (ICCs) and coefficients of variation (CVs%). Longitudinal sensitivity to OA bone changes was not assessed.
For the reproducibility of texture parameters, ICCs were >0.75 and CVs% were <8.2% for both methods. Compared with controls, FD(MEAN), FD(H), FD(V) and FD(Sta) for OA knees were lower (P<0.001), while Str was higher in both medial (P=0.03) and lateral (P=0.02) compartments. FS(H), FS(Sta) were lower for OA knees than for controls at sizes 0.3-0.7 mm (P<0.001) in both compartments. In lateral compartment, FS(V) for OA knees was lower than for controls at sizes 0.3-0.5 mm (P<0.001) and 0.55-0.70 mm (P<0.02), while in medial compartment at sizes 0.3-0.7 mm (P<0.001). Compared with controls, StrS for OA knees was higher at sizes 0.3, 0.55-0.70 mm in medial (P<0.03) and lateral (P<0.04) compartments.
The VOT method is comparable to HOT method in the reproducibility of texture parameters and the ability to discriminate between non-OA and OA TB textures. However, unlike the HOT method, it quantifies texture roughness along the roughest part of the tibial bone, texture anisotropy at individual trabecular sizes and it works over a larger range of trabecular sizes. The VOT method may be a valuable tool for studying OA changes in TB.
使用方差定向变换（VOT）方法评估有和无放射学膝关节骨关节炎（OA）的受试者之间胫骨小梁骨（TB）纹理的差异。
膝关节 OA（Kellgren 和 Lawrence 分级≥2）患者（n=26，7 名女性）和无 OA 对照组（n=26，7 名女性）按性别、年龄、体重指数和间隔匹配。将 VOT 方法应用于 TB X 射线图像，并计算水平（FS（H），FD（H））和垂直（FS（V），FD（V））方向以及 TB 最粗糙部分的分形特征和维数（FS（Sta），FD（Sta））、纹理纵横比（Str）和特征（StrS）以及平均 FD（FD（MEAN））。使用配对 t 检验、组内相关系数（ICC）和变异系数（CV%）比较 VOT 方法与增强的赫斯特定向变换（HOT）方法。未评估对 OA 骨变化的纵向敏感性。
对于纹理参数的可重复性，两种方法的 ICC 均>0.75，CV%均<8.2%。与对照组相比，OA 膝关节的 FD（MEAN）、FD（H）、FD（V）和 FD（Sta）较低（P<0.001），而内侧（P=0.03）和外侧（P=0.02）的 Str 均较高。OA 膝关节的 FS（H）、FS（Sta）在两个间隔的 0.3-0.7mm 处均低于对照组（P<0.001）。在外侧间隔中，OA 膝关节的 FS（V）在 0.3-0.5mm 处低于对照组（P<0.001）和 0.55-0.70mm 处（P<0.02），而在内侧间隔中在 0.3-0.7mm 处（P<0.001）。与对照组相比，OA 膝关节的 StrS 在 0.3、0.55-0.70mm 时内侧（P<0.03）和外侧（P<0.04）隔室更高。
VOT 方法在纹理参数的可重复性和区分非 OA 和 OA TB 纹理的能力方面与 HOT 方法相当。然而，与 HOT 方法不同，它量化了胫骨骨最粗糙部分的纹理粗糙度、各小梁尺寸的纹理各向异性以及在更大的小梁尺寸范围内工作。VOT 方法可能是研究 TB 中 OA 变化的有用工具。
