Purpose: The lunate is classified into two types, one with a single distal facet and the other with two distal facets. The effect of lunate type on the incidence of wrist disease and trauma remains unclear. The purpose of this study is to evaluate a potential association between lunate morphology and wrist disorders.
Methods: We retrospectively reviewed the cases of 637 patients who had undergone wrist arthroscopy for wrist disorders. Patient charts and arthroscopic video images were reviewed retrospectively. We defined lunate type based on the Viegas classifications, according to its distal facet from a midcarpal arthroscopic image. Patient wrist disorders were divided into four groups: fractures and dislocations, Kienböck's disease, ulnar wrist pain, and degenerative disease.
Results: A Viegas type 1 lunate was observed in 349 wrists and a type 2 lunate in 288 wrists. Incidence of the type 2 lunate was different between the groups and was significantly lower for the Kienböck's disease and ulnar wrist pain groups than for the trauma and degenerative groups.
Conclusions: The present study revealed a variable incidence of lunate type in wrist disorders. The proportion of type 2 lunates was lower in Kienböck's disease and ulnar wrist pain.