The authors establish a finite-element analysis model of the lunate in order to study mechanical factors that might lead to propagation of an incomplete fracture and lunate collapse. Three conditions were found associated with lunate fracture propagation and trabecular collapse: negative ulnar variance, a high lunate uncovering index, and angulated trabeculae (trapezoidal-shaped lunate).
The etiology of Kienbock’s disease remains speculative with theories involving bone architecture, vascular pattern, micro trauma, and fracture. In 1947, Stahl proposed that Kienbock’s disease is initiated by a transverse fracture through the lunate which does not heal (Acta Chirurg Scand, Suppl, 1947). The findings from this biomechanical study would appear to support Stahl’s theory and the idea that some lunate bones are predisposed to Kienbock’s disease because of abnormal internal stresses.