THE REMOVAL OF 
NECROTIC AND CARIOUS BONE 
WITH HYDROCHLORIC ACID AND PEPSIN.* 
ROBERT T. MORRIS, M.D. 
[Reprinted from New York Medical Journal, March 19th, 1892.] 
Sometimes it is desirable to remove dead bone without subjecting a weak 
patient to a dangerous or deforming operation. Attempts have been made 
with some success at clearing out this bone by a process of decalcification, but 
there are two chief reasons why failures have resulted as a rule. In the first 
place, it was discovered that superficial layers of dead bone were decalcified 
easily enough, but the acids did not reach deeply through the mass, especially 
if portions were infiltrated with caseous or fatty debris. In the second place, 
cellulitis was pretty apt to develop during the course of treatment. After much 
experimentation I have finally adopted a method of work which seems to be 
complete. An opening is made through soft parts by the most direct route to 
the seat of dead bone, and if sinuses are present they are all led into the one 
large sinus if possible. The large direct sinus is kept open with antiseptic gauze 
and the wound allowed to remain quiet until granulations have formed. 
Granulation tissue contains no lymphatics, and absorption of septic mate- 
rials through it is so slow that we have a very good protection against cellulitis. 
The next step consists in injecting into the sinus a two or three per cent, solu- 
tion of hydrochloric acid in distilled water. If the patient is confined to bed, 
the injections can be made at intervals of two hours during the day ; but if it is 
best to keep the patient up and about, the acid solution is thrown into the sinus 
only at bed-time. In either case the patient is to assume a position favorable 
for the retention of the fluid. Decalcification takes place rapidly in exposed 
layers of dead bone, and then comes the necessity for another and very im- 
portant step in the process. At intervals of about two days an acidulated pep- 
sin solution is thrown into the sinus (I use distilled water, f § iv ; hydro- 
chloric acid, m xvj ; Fairchild’s pepsin, 3 ss.), and this will digest out decalci- 
fied bone and caseous or fatty debris in about two hours, leaving clean dead 
bone exposed for a repetition of the procedure. The treatment is continued 
until the sinus closes from the bottom, showing that the dead bone is all out. 
* Read before the Southern Surgical and Gynaecological Association, November 
12th, 1891. s Even in distinctly tuberculous cases the sinuses will close if apparatus for 
immobilizing diseased parts and tonic constitutional treatment are employed, as 
they should be in conjunction with our efforts at removing the dead bone. 
If suppuration is free in any cavity in which we are at work, it is well to 
make a routine practice of washing out the cavity with peroxide of hydrogen 
before each injection. 
It is a popular impression in the profession that living bone is not attacked 
by dilute mineral acids, but, as it makes a good deal of difference whether the 
impression is correct or not, I experimented as follows : A portion of the kera- 
tinoid layer was removed from the carapace of a turtle {Natumys guttatus), and 
the animal was then placed tail downward in a glass of five per cent, hydro- 
chloric acid solution. In the same glass I placed also a segment snipped from 
the plastron of the turtle, and a transverse section of an old dried humerus of a 
man. The piece of humerus was completely decalcified in six hours, the seg- 
ment from the plastron was soft in about twenty hours, and the carapace of 
living bone was decalcified at the exposed part in thirty hours. I was then 
curious to know what effect the acid had had upon the blood-vessels of the de 
calcified bone, and Dr. Smith, of the laboratory of the Post-Graduate Medical 
School, made for me several sections of the carapace which included both 
decalcified and healthy bone. Investigation showed that all the blood-vessels 
were destroyed wherever the bone was softened, and the action of the acid had 
extended farther up along the larger blood-vessels than elsewhere. In the ac- 
companying photomicrographs* the dark portions represent decalcified bone 
stained withcarmin, and in the lighter portions the structure of the normal bone 
cells is readily distinguished. In Fig. 2* can be seen the line of extension of 
decalcification along three blood-vessels. 
The difference in time between decalcification of the dead bone (six hours) 
and of living bone (thirty hours) is significant, a five per cent, solution of 
hydrochloric acid having been used. 
If we use a two or three per cent, solution of hydrochloric acid, a wall of 
lymph and of granulation tissue is thrown out upon the surface of living bone 
for protection, and only dead bone is attacked. This at least has been my ob- 
servation in several cases in which the results of treatment could be easily 
watched. 
The details of treatment in some of the cases would be very interesting 
but if the paper were lengthened to accommodate them my main points would 
be apt to hide. 
* For cuts see New York Medical Journal, March 19th, 1892.