. Orthopaedic surgery for students and general practitioners : preliminary considerations and diseases of the spine : 114 original illustrations. or osteosclerosisof the trabeculse to stand increased weight bearing and atrabecular resorption or osteoporosis on the convex side onwhich less strain is put. (Fig. 91.) Wolff has clearly shownthat the external contour and internal architecture in bonesare mutually dependent on the function demanded. NON-TUBERCULOUS DISEASES OF THE SPINE. 193 The intervertebral cartilages undergo similar wedge shapechanges and one can well understand that any columnm
. Orthopaedic surgery for students and general practitioners : preliminary considerations and diseases of the spine : 114 original illustrations. or osteosclerosisof the trabeculse to stand increased weight bearing and atrabecular resorption or osteoporosis on the convex side onwhich less strain is put. (Fig. 91.) Wolff has clearly shownthat the external contour and internal architecture in bonesare mutually dependent on the function demanded. NON-TUBERCULOUS DISEASES OF THE SPINE. 193 The intervertebral cartilages undergo similar wedge shapechanges and one can well understand that any columnmade up of quadrilaterally shaped bodies (on section), uponbeing made into an arc, would necessitate the side of eachbody on the concave side of the curve becoming narrowerthan the side on the convex. The changes in the shapes of the spinous, articular andtransverse processes are explained chiefly by the torsionwhich invariably takes place in scoUosis. This is broughtabout by the resistance experienced by bones from ligamen-tous and muscular attachment, thus if the vertebral bodyis rotated to the right, the muscular and ligamentous attach-. FiG. 92. Cross Section op Thorax in Region op Right Dorsal Scoliosis. (Hoffa.) ments resist a coincident rotation of the spinous process tothe left and hence the spinous process gradually yields par-tially and becomes curved somewhat to the right, so thatits tip is no longer directly in an imaginary line drawn fromthe center of the posterior edge of the vertebral body, butto the right of it. (Fig. 92.) Similarly, in the dorsal region, the ribs being attached bystrong hgaments to the transverse processes can permit oflittle movement of the latter in which they do not partici-pate, so that when any rotation backward of a transverseprocess occurs its rib is carried backward also and the costal 194 ORTHOPEDIC SURGERY. angle becomes bent more acutely, while the correspondingrib is carried forward and its angle flattened out or renderedmore obtuse.
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