Figure 14.

Variation in gap measurement between the scaphoid and lunate depends on where it is measured. (A) In a simulated typical radiographic measurement of the gap between the scaphoid and lunate in a wrist, in neutral flexion-extension, with the SLIL, ST, and RSC ligaments sectioned, a gap of 3.8 mm and labeled as “X,” would be measured. (B) When the motion of these bones is viewed 3-dimensionally from a transverse view, the gap between the scaphoid and lunate can be seen to be opening up, and is labeled as “Y.” In some views part of the minimum distance line may be hidden by the scaphoid or lunate. Therefore the calculated minimum distance between the bones may not completely represent changes in the scaphoid and lunate positions. Furthermore the gap measurement is dependent on which points are chosen on the scaphoid and lunate.