THE GROWTH OF BONE 67 



efforts are often made to preserve the periosteum, 

 and sometimes, as for instance in excising the lower 

 jaw, the membrane is preserved even at the risk of 

 leaving septic material behind, in the vain hope that 

 it will form new bone. The only possibility of its 

 doing so is if osteoblasts have been driven out by 

 inflammation and have become adherent to it. It is 

 useless to expect healthy periosteum to regenerate 

 bone, such as a piece of rib removed for empyema, 

 though it may form a guide for the gap to be filled 

 by growth from the epiphyseal end. 



Bone transplantation has now reached a thoroughly 

 established position, and scores of successes have 

 been reported. Parts of the tibia, humerus, skull, 

 and lower jaw have repeatedly been replaced by 

 slips from the fibula, rib, or other situations. Some- 

 times it is possible to maintain the blood-supply by 

 preserving the periosteum and soft tissues over the 

 graft with a pedicle, as when the fibula is put into a 

 gap in the tibia. In other cases the strip of bone or 

 the bone chips have to be detached entirely, or even 

 transplanted from patient to patient, but they will 

 frequently survive in part or in whole, acquire a new 

 blood-supply, and unite up with the divided ends. 

 Very small chips or bone dust are not successful, 

 apparently because the osteoblasts are damaged ; 

 on the other hand, thick pieces of bone will die. If 

 in any way possible, the graft should be taken from 

 a young growing bone, especially that near the 

 epiphyseal cartilage. Perhaps pieces of epiphyseal 

 cartilage itself would be best of all, because it is 

 content with a very small blood-supply. 



