Studies in the Dynamics of Histogenesis

Abstract

THE main objectives of this paper are the following: that the structure of cancellous bone is determined by the capacity for movement in the chief plane or planes of action at the related joint; that the structure of cancellous bone related to monasial, biaxial, and triaxial joints is characteristic and definite for each type of joint; that the pattern of cancellous bone is the product of the remittent back-pressure vectors of muscle action in joint range of mobilization and not the product of the immobile static load of body weight; that skeletal bone is the product of an adequate pressure of differential growth,2 as well as adequate pressure of myogenic function; that tension although transmitted by bone is not a trophic stimulus to bone origin; that by local muscular excision there is a focal atrophy of corresponding cancellous bone trabeculæ; that prior to birth there is a growth relativity leading to a mutual antagonism between the length growth of the femur and the back-pressure of the developing thigh musculature that results in a relative decrease of femoral volume and length, and corresponding to thigh muscular development an increase of femoral density or consolidation and weight. The clinical significance of this study reveals the rôle of action as well as the reciprocal dependency of the muscular and skeletal tissues as mutual maintainers of each other's normal structural integrity and the logical use of a timed early mobilization after rest in the treatment of derangements of the locomotor apparatus, such as fractures and dislocations, advocated by Lucas-Championniere,3 Hey Groves,4 Jones and Lovett,5 Dean Lewis6 and many others. II. Brief Historical Review of the Architectural Significance of Cancellous Bone Ward7 and Wyman8 compared the femoral neck to a derrick supporting a load; the stresses in the cable in the derrick are tensile and in the boom compressive. Humphry9 stated that the two groups of cancellous trabeculæ in the head and neck of the femur cross at right angles and are perpendicular to the articular surface at all points. In 1866 H. von Meyer,10 at the Zurich meeting of the “naturforschende Gesellschaft,” demonstrated a frontal section of the proximal end of the femur, and Culmann, the founder of graphostatics, thought that the cancellous bone elements crossed at right angles like the directions of greatest tension and greatest pressure in the crane to form stress trajectories. The resemblance between the trajectories in Culmann's crane and the cancellous pattern in the femoral neck was considered as identical. The trajectories in Culmann's crane cross at right angles, because in elastic bodies the directions of greatest tension and pressure cross at right angles. Julius Wolff,11 in his treatise on “The Law of the Transformation of Bones,” confined his observations to the proximal extremity of the femur and emphasized what he considered the right angular crossings of cancellous bone which he called “orthogonality.”