Ultra-high-resolution computed tomography (CT) imaging of the lunate in Kienböck's disease: a feasibility study and preliminary observations.

Previous studies of lunate trabecular microstructure in Kienböck's disease have been limited to in vitro analysis. This pilot study evaluated the feasibility of ultra-high-resolution computed tomography (UHR-CT) for in vivo assessment of lunate trabecular microstructure across disease stages. Six patients with Kienböck's disease undergoing X-ray, magnetic resonance imaging (MRI), and UHR-CT were included and staged using the Lichtman classification. Given the small sample size, patients were grouped by carpal alignment for exploratory comparison into a normal alignment group (stage I-IIIA; n=3) and a malalignment group (stage IIIB-IV; n=3). Six cases with an intact lunate served as a reference group (n=6). Trabecular microstructure was assessed qualitatively and quantitatively. UHR-CT demonstrated focal trabecular microfractures in stage I lunates despite no apparent abnormality on plain radiographs. Qualitatively, the malalignment group showed disrupted and fragmented trabeculae with markedly irregular orientation. Quantitatively, the malalignment group had a larger radioscaphoid angle (median 62.8°; range, 61.5-70.4°) and lower Ståhl (median 0.38; range, 0.31-0.39) and Nattrass indices (median 1.39; range, 1.36-1.42) than the normal alignment group (median 40.9°; 39.7-46.5°; 0.53, 0.43-0.65; and 1.52, 1.45-1.61, respectively). A graded microstructural pattern was observed from reference to normal alignment to malalignment groups, with increasing bone volume fraction (bone volume/total volume) (BV/TV) (0.40±0.02, 0.45±0.04, 0.66±0.06 µm) and trabecular thickness (Tb.Th) (539±38, 612±56, 721±9 µm) and decreasing trabecular spacing (Tb.Sp) (1,022±234, 776±92, 521±70 µm). UHR-CT is feasible for in vivo evaluation of lunate trabecular microstructure and may serve as a valuable examination for early diagnosis, staging, and monitoring Kienböck's disease.