Microstructure Study of the Normal Lunates and Kienböck Lunates With MicroCT Imaging

Abstract

Objective: To compare the microstructure of normal lunates and Kienböck lunates with MicroCT. Materials and Methods: Seventeen fresh lunates from the patients with stage III Kienböck disease and 8 normal lunates were scanned with MicroCT. Four regions of interest were selected to measure the trabecular parameters. The number and diameter of the nutrient foramina were measured. Results: All the Kienböck lunates had bony discontinuity at the distal surface like a greenstick fracture. Within the 3 regions in the distal surface, the bone volume, bone volume density, and the structure model index were significantly larger in the middle region when compared with those of the palm and dorsal regions. Conversely, trabecular separation and bone surface/bone volume were smaller in the middle region. Comparing the central trabecular bones of the Kienböck lunates with those of the normal lunates, we found the bone volume, bone volume density, and bone surface were significantly larger in Kienböck lunates while the trabecular separation and trabecular pattern factor were significantly smaller. There was no significant difference for the number and diameter of the nutrient foramina between 2 sides of Kienböck lunates. The diameters of the nutrient foramina of the Kienböck lunates were significantly larger on the dorsal side and smaller on the palmar side when compared with normal lunates ( P < .05). Conclusion: In Kienböck lunates, the bony disruptions were mostly located in the palmar or dorsal area where it was shown to be structurally weaker from trabecular bone structure analysis, leading to separation of the distal part of the fracture, disruption of blood supply, poor bone remodeling, and proneness to secondary fracture and eventual collapse.