Scaphoid and lunate translation in the intact wrist and following ligament resection: a cadaver study

Abstract

Purpose: To determine the amount of scaphoid and lunate translation that occurs in normal cadaver wrists during wrist motion, and to quantify the change in ulnar translation when specific dorsal and volar wrist ligaments were sectioned.

Methods: We measured the scaphoid and lunate motion of 37 cadaver wrists during wrist radioulnar deviation and flexion-extension motions using a wrist joint motion simulator. We quantified the location of the centroids of the bones during each motion in the intact wrists and after sectioning either 2 dorsal ligaments along with the scapholunate interosseous ligament or 2 volar ligaments and the scapholunate interosseous ligament.

Results: In the intact wrist, the scaphoid and lunate statistically translated radially with wrist ulnar deviation. With wrist flexion, the scaphoid moved volarly and the lunate dorsally. After sectioning either the dorsal or volar ligaments, the scaphoid moved radially. After sectioning the dorsal or volar ligaments, the lunate statistically moved ulnarly and volarly.

Conclusions: Measurable changes in the scaphoid and lunate translation occur with wrist motion and change with ligament sectioning. However, for the ligaments that were sectioned, these changes are small and an attempt to clinically measure these translations of the scaphoid and lunate radiographically may be limited. The results support the conclusion that ulnar translocation does not occur unless multiple ligaments are sectioned. Injury of more than the scapholunate interosseous ligament along with either the dorsal intercarpal and dorsal radiocarpal or the radioscaphocapitate and scaphotrapezial ligaments is needed to have large amounts of volar and ulnar translation.

Figure 1

Centroid motion of the scaphoid and lunate in the intact wrist, in the radial-ulnar direction, during wrist radioulnar deviation. The scaphoid and lunate both moved radially as the wrist moved into ulnar deviation.

Figure 2

Centroid motion of the scaphoid and lunate in the intact wrist, in the dorsal-volar direction, during wrist flexion-extension. The lunate moved dorsally and the scaphoid moved volarly as the wrist moved into flexion.

Figure 3

Changes in the scaphoid and lunate centroid positions from the corresponding intact location, in the radial-ulnar direction, during wrist flexion-extension, after the dorsal ligaments and SLIL were sectioned. The scaphoid moved radially and the lunate moved ulnarly, especially as the wrist flexed. The “initial change” in displacement is just after the ligaments were sectioned whereas the displacement “after 1000 cycles” is the response after repetitively flexing and extending the wrist for 1000 cycles after the ligaments were sectioned.

Figure 4

Changes in the lunate centroid positions from the corresponding intact location, in the dorsal-volar direction, during wrist radioulnar deviation, after the dorsal ligaments and the SLIL were sectioned and after the volar ligaments and the SLIL were sectioned.

Figure 5

The minimum cortical to cortical bone distance between the scaphoid and lunate during wrist flexion-extension, in the intact wrist, after the dorsal ligaments and SLIL were sectioned and after the volar ligaments and SLIL were sectioned.

Figure 6

The minimum cortical to cortical bone distance between the scaphoid and lunate during wrist radioulnar deviation, in the intact wrist, after the dorsal ligaments and SLIL were sectioned and after the volar ligaments and SLIL were sectioned.