The lunatohamate articulation of the midcarpal joint.

Sixty-one cadaveric wrists were dissected to assess the frequency of a medial lunate facet as well as any associated pathologic changes in the midcarpal joint. Two types of lunate were identified: Type I (39.3%), in which no medial facet was present, and Type II (60.7%), in which there was a medial facet. The medial facets in the Type II lunates ranged from a shallow 2 mm facet to a deep 6 mm facet. Significant cartilage erosion with exposed subchondral bone at the proximal pole of the hamate, which was not identifiable by radiograph, was evident at dissection in 57% of the Type II lunates, whereas none (0%) of the Type I lunates had such associated hamate pathology. Midcarpal joint arthroscopy appears to be the diagnostic procedure of choice to assess the presence of hamate proximal pole arthrosis.