1. Postoperative atrophy is seen in muscles as well as in bones. It is subject to considerable variation and is accompanied by angioneurotic symptoms of varying degree.
2. Atrophy in amputations of the lower extremity (and forearm) (See References 1 and 2) is limited in extent and in time. In amputations above the elbow it may be very pronounced indeed, and accompanied by trophic changes in the skin.
3. The atrophy of amputation is more marked than that in spastic palsy, but differs radically from that found in infantile paralysis, leprosy, and brawny oedema because, except in the area of local trauma, the muscle of amputated stumps is never transformed into fibrous tissue.
4. The larger blood vessels retain practically their normal caliber to within a short distance of their termination, when they dwindle rapidly in size and end in the general scar.
5. A special tendency to the development of neuromata on all the nerve trunks severed at operation in amputations above the elbow is evident in our dissections. The tendency is less evident in posterior tibial and sciatic nerves and rarely present in femoral and obturator nerves of lower-extremity amputations.
6. There is no evidence in these dissections to warrant the assumption that false-neuroma formation is in any way related to the degree of bone atrophy.
7. The characteristic atrophy evidenced by loss of weight and osteoporosis identifiable on roentgenograms is present whether or not a prosthesis is worn.
8. Osteophytic production, less marked in amputations of the upper extremity than in those of the lower, has no direct relationship to the degree of bone atrophy.
9. Amputation, at least in the upper arm, may hasten the date of epiphyseal union and thus apparently arrest bone growth.
10. Experimental amputation of the upper arm in rats results in phenomena resembling the postoperative changes in amputations of the lower limb in man and not those in amputations of the upper arm.
11. The rat, being a quadrupedal mammal, is not a suitable animal for a study of postamputation changes as found in man.