Capitate and Lunate Morphology in Normal Wrist Radiographs-A Pilot Study

Background: Morphology may provide the basis for the understanding of wrist mechanics. Methods: We used classification systems based on cadaver dissection of lunate and capitate types to evaluate a normal database of 70 wrist radiographs in 35 subjects looking for associations between bone shapes. Kappa statistics and a log-linear mixed -effects model with a random intercept were used. Results: There were 39 type-1, 31 type- 2 lunates, 50 spherical, 10 flat and 10 V-shaped capitates. There was a significant difference in lunate and capitate shape between the hands of the same individual p <0.001. This may be due to different loads on the dominant vs. nondominant hands in the same individual. Conclusion: Further study to better understand the development of radiographic parameters of the midcarpal joint may aid in our understanding of the morphology and mechanics of the wrist.