The bones in osteoporosis become very brittle in later years, but may be so even at the age of six to eight months. Serious dislocations may thus occur and the ossification of the. callus may be much delayed.
The frequency of fractures depends upon the extent of micromelia, the shortness of the bones and the diminished thicicness of the diaphyses. The less favorable these conditions are, the more frequently will fractures occur. The fractures generally occur in the epiphyseal part of the dia physis, never precisely in the epiphyseal line fIS in Tlarlow's disease or syphilis.
Contrary to chondrodystrophy, the epiphyses show very slight changes.
Microscopical investigation reveals few osseous trabectilie, with absent or but. indistinctly visible structure, amorphous bony corpuscles in sonic, places and lime deposits in others, which directly remind one of calcified cartilage, The margins of the osteoblasts are very cavernous; periosteal and endosteal ossification is minimal. On the other hand, numerous giant cells, with osteoblasts in the cavities of the bone particles, point to unimpeded processes of resorption. The bone marrow consists of abundant fibres and fat., and in many places directly loses itself in the periosteum.
The diminished ossifying function of the periosteum and endosteum, with unimpeded progress of resorption, leads to osteogenesis imperfecta, but not to mieromelia, which can only occur from secondary injury to the epiphyses] cartilage.
The entire process does not commence before ossification sets in, whereas in chondrodystrophy the existing hypoplasia and grave alter ation of the fetal cartilaginous skeleton must unavoidably lead to dis turbance in the development of the tubular bones.
In the first year of life, the differential diagnosis is decided before the occurrence of fraetures by the radiograin whieli will reveal an absence of bone that does not otherwise occur, and also the entire absence of the corticalis.
In later years, the spontaneous fractures and the thickness of the elastic bones will clear up the diagnosis.
The treatment of inicromelia can only be considered when osteo genesis imperfecta has been established as the cause, and then only with slight prospect of success.
All mechanical movements of the bones should be restricted. as much as possible, while, after a fracture has occurred, dislocation should be prevented by slight extension and application of splints. Suspension should not be practised in any ease, as it leads to osteoporosis itself. Over-feeding is to be avoided, and alkaline, vegetable diet should be the principal food. Enallsion of coil-liver oil, iron and arsenic, should be considered, and a stay in an invigorating sea climate is advisable.
NollHeld's observation shows that considerable improvement is possible even at an early period. However, cases with constantly recur ring fractures, as observed by Blanchard, F. Schultze and myself in one ease where fractures occurred up to twenty and thirty years of age, preponderate.
It has already been mentioned that in this form of micromelia the greatest number of eases are stillborn, yet numerous ca.scs caused by congenital ehondrodystrophy survive until an advanced ago.