Introduction: The current study investigates the influence of the interosseous portion of the scapholunate and the radioscaphocapitate ligaments in the range of movement of the scaphoid and lunate during flexion and extension of the wrist.

Material and Methods: 10 embalmed cadaveric specimens were studied. A jig was designed to clamp the forearms, holding the wrist in a fixed angle. Metal pointers with 1.5mm diameter were inserted into the scaphoid and the lunate. Digital cameras were aligned from the posterior and radial views and sequential photographs obtained during the full range of motion of the specimens. The SL and the RSC ligaments were then sectioned with new series of photographs obtained between each step. The angles in the photographs were measured with specific software.

Results: Sectioning the SL increased the angle between the lunate and the scaphoid by 12° on average, while sectioning the RSC increased the SL angle by a further 2 ° with the wrist in maximal flexion. With the wrist in extension the angle was also increased by 12° after division of the SL and a further 2° after section of the RSC.

Conclusions: Although volar and dorsal inuries may be associated, our study suggests that the SL has a much greater influence on the relative movement of the scaphoid and lunate than the RSC. The method also suggests that in a number of cases the variation in agulation may be small enough not to be detected as significant on x-rays.