With the aid of flexion-extension lateral radiographs, we investigated
the effect of the canvas corset, the Raney and Baycast jackets, and the
Baycast spica on the segmental sagittal mobility of the lumbosacral spine
in separate groups of five volunteers each. The canvas corset reduced the
mean angular movements at each level to two-thirds of normal. The Raney and
Baycast jackets reduced the mean angular movements in the middle of the
lumbar spine to approximately one-third of normal. The Baycast spica was
the most effective in restricting angular movements below the third lumbar
vertebra, and especially at the fourth lumbar-fifth lumbar level and the
lumbosacral level.