506 SYMPHYSEOTOMY. 



might, rigorously speaking, be carried artificially to the extent of 

 three inches, without disorganising the posterior articulations: when 

 the cartilage is divided, the coxal bone somewhat resembles a lever 

 of the first kind; the centre of motion is found at the posterior part 

 of the articular facette of the sacrum; the posterior branch of this 

 lever, very short, and formed by the tuberosity of the ilium, is drawn 

 backwards and towards the median line by the posterior sacro-iliae 

 ligaments; its anterior branch, which is very much bent, (coudee) 

 separates (from the corresponding pubis) in proportion to its excess 

 of length over the branch, which represents tlie power; the fore part 

 of each posterior symphysis becomes somewhat open; the fibrous 

 tissue which covers them yields, is elongated, stretched, and detached 

 the elastic cushion which is behind them becomes relaxed, and the 

 sacrum compressed from behind forwards, tends to escape towards 

 the interior of the pelvis. When the surgeon adds still more to the 

 separation of the pubes by pressing upon the cristas of the ileum, 

 the power is transferred to the anterior branch of the lever, and it 

 is evident, that thenceforth no very violent effort would be required to 

 tear away all the bonds of the posterior articulations. This is the 

 situation, particularly, where the displacement of the sacrum in front 

 must cause the increase of the length of the antero-posterior diameter 

 to disappear as fast as it tends to take place. In the empty pelvis and 

 upon pieces of paper this is really the case; but in the living subject, 

 while the pubes are separating, the child's head pushes the sacrum 

 backwards, beyond its natural limits, rather than admits of its 

 advancing into the excavation. Nevertheless, it would, in most 

 women, be dangerous to separate the ossa pubis from each other 

 more than one or two inches: we could not go beyond that without 

 lacerating the loose and abundant cellular tissue of the excavation, 

 the anterior sacro-iliac ligaments, and part of the posterior ones, 

 without giving rise to the most violent pain, and causing the most 

 redoubtable inflammation, unless the symphyses should happen to 

 be already very much softened beforehand, under which circum- 

 stance it is not likely that symphyseotomy would ever be required. 

 Since you agree, say the antagonists of the operation, on the one 

 hand, that it is not prudent to attempt a greater degree of separation 

 than two inches or two inches and a half; and on the other, that 

 the antero-posterior diameter is never enlarged more than two lines 

 for one inch, four lines for two inches, and six or eight lines for 

 three inches* of separation, it is manifest that you can depend upon 



* Boer even asserts that, when carried to the extreme, this separation can 

 never give more than three lines additional to the antero-posterior diameter. 



