A CONTRIBUTION TO THE STUDY OF THE MECHANICS 
OF THE SPINE, 
BY 
ROBERT W. LOVETT, M.D., of Boston. 
From the Anatomical Laboratory, Harvard Medical School. 
Our present knowledge of spinal mechanics and of the motions 
of the spine is of an inexact and unsatisfactory character. The books 
on anatomy contain for the most part loose descriptions of spinal move- 
ments and few careful investigations have been made. An exception is 
the work of Hughes (3) on the rotation movements of the spine. 
The chief study of spinal mechanics has been made in connection with 
lateral curvature by orthopedic surgeons rather than by anatomists. 
They have done this in the attempt to explain the phenomenon of “ rota- 
tion ” which occurs in lateral curvature. Any patient who develops a 
marked degree of side bending of the spine shows also a twisting of the 
laterally curved portion of the spine upon a vertical axis. To the latter 
phenomenon the name “ rotation ” has been applied. This association of 
twisting with lateral curvature has always been regarded as a most 
obscure phenomenon and Lorenz (1) in his book on scoliosis agrees with a 
quotation from Bouvier (2) “ Man miisste ein Euklides sein, um dieses 
Rathsel zu losen.” 
In the attempt to solve this problem a very large amount of literature 
has accumulated without obvious practical result (4). But essentially, 
all of this work has been done from one point of view and the human 
spine has alone been investigated with the exception of occasional reports 
of cases in animals (5) and some experiments on dogs by Wullstein (6). 
The question has either been taken up from the point of view of the path- 
ological changes found in scoliosis and theories constructed to account for 
these, or suppositions of a purely theoretical character have been formula- 
ted embodying general mechanical principles. The shape of the indivi- 
dual vertebrae, normal and distorted, has been studied, the physiological 
curves have been investigated, the shape of the articular processes has 
been formulated and the most complicated and confusing results have 
1 Read before the Boston Society of Medical Sciences, May 19, 1903. 
