D? CARNOCHAN’S CASE or OSTEO ANEURISM. 
a. bi'anehes of the femoral artery ramifying over the outer 
surface of the aneurismal sac,, and terminating upon its 
inner surface . 
b. the'sac of the osteo aneurism laid opens. 
C . a portion of the sac everted. 
d. the- contents of the sac the' infection haring been removed 
e. the articular surface of the. inner condyle. 
f the articular surface of the outer condyle 
g. the abrupt termination of the shaft of the lemur, 
forming the upper boundary of the cavity of the sac. 
Jr: the periosteum continuous with the outer layer of the sac 
J the shad of the femur. 
A. the upper part of the tihias. E E M A E K S 
ON 
O STEO-ANEURISM, 
WITH A CASE INVOLVING THE 
CONDYLES OF THE LEFT FEMUR. 
BY 
J. M. CARNOCHAN, M. D. 
PROFESSOR OF THE PRINCIPLES AND OPERATIONS OF SURGERY IN THE NEW-YORK MEDICAL 
COLLEGE J SURGEON TO THE STATE EMIGRANTS’ HOSPITAL ? OPTHALMIC 
SURGEON TO THE SAME INSTITUTION, ETC. ETC. 
ftaor pates. 
From the New-York Medical Gazette , January, 1853. 
N E W - Y O R K : 
D. Facahaw, Printer, 35 Ann-street, corner of Naiaau. 
1853. 3 
REMARKS ON OSTEO-ANEURISM, 
WITH A CASK INVOLVING 
me ©©Enira.ES m me iem eehuuib. 
The pathological condition met with, at times, in certain portions 
of the osseous system, under the name of Osteo-aneurism, has as yet 
received notice from surgical writers in this country. As 
generally it involves the cancellated structure of the extremities of 
the long bones, and even encroaches, at the early period of its deve- 
lopement, upon the contiguous articulation, the diagnosis may be 
found embarrassing, and the disease mistaken for some of the other 
diseases of the joints, attended with abnormal enlargement and a mor- 
bid condition of the articular surfaces. The case related below, and 
from which the accompanying drawings were taken, passed into my 
hands after having been pronounced a strumous affection of the knee 
joint by very good surgical authority; and it was only after several 
careful examinations, that the pulsative and aneurismatie character 
of the tumor was detected. 
The first description of this disease dates no farther back than the 
close of the last century, when Pearson, of England, in 1790, and Scar- 
pa, in 1792, reported each a case of this disease of the osseous tissue. 
More than a quarter of a century elapsed before any new facts were 
recorded; and it was not until the year 1826 that science was again 
enriched by the observations of Dupuytren, Lallemand, and Breschet, 
on the pulsatory tumors of the bones. More recently, cases of pul- 
sative tumors of the bone have been furnished, principally by M. M. 
Roux and Velpeau, of France, and by Liston and Handy side, of Scot- 
land ; but it is to be inferred from the descriptions of some of these 
cases, that they were not strictly cases of Osteo-aneurism. 4 
REMARKS Oft 
Tim distinctive feature of true Osteo-aneurism, or aneurism of 
Bone, appears to be the existence of a pulsatory tumor, formed by an 
osseous shell, the cavity of which contains blood or eoagula, and com- 
municates with* the interior o>f the arteries of the bone. 
There are other tumors of bone which present pulsations, and are 
of a sanguineo-fungoid composition ; but they are malignant, and are to 
be classed as medullary or encephaloid cancers. There may, also, exist 
tumors of bone where the osseous tissue has expanded into a cyst, 
containing a sero-sahguinolent fluid, but having no pulsation and no 
direct communication with the arteries of the bone. 
A perusal of the cases of pulsative tumor of bone, recorded by 
surgical writers, would induce the belief that the true Osteo-aneurism, 
disconnected with other disease, is rarely to be met with; but it is 
probable that in many cases the tumor has commenced as Osteo-an- 
eurism, and that the encephaloid degenerescence becomes superadded 
to the original disease, during its progress. 
The medullary, or encephaloid tumor ofbone should' be regarded as 
a distinct pathological condition from true Osteo-aneurism; the former 
being invariably malignant in its character and progress, and the lat- 
ter being by no means necessarily so. The pathological characteris- 
tics made manifest upon examination, after removal of some of these 
pulsative tumors, and the influence of the application of a ligature up- 
on the principal artery of the limb, in causing the disappearance of 
the tumor, will not allow us to doubt that Osteo-aneurism may exist 
simply as such, and be unaccompanied by any malignant degeneres- 
cence, as a complication. The morbid appearances of the tumor re- 
presented by the accompanying plate, and of which a detailed history 
is subjoined, furnish an example of true Osteo-aneurism; that is to 
sav, the tumor was formed of an osseous shell, the cavity of which 
was filled with fibrinous eoagula; and the enlargement was not accom- 
panied by any cancerous structure. I will here remark that the dis- 
eased part, after removal, was examined by the microscope, by which 
my opinion was confirmed. The entire recovery and present good 
health of the patient, and the total absence of anything like ma- 
lignant cachexia, also corroborate the view that the morbid struc- 
ture, of which the tumor was composed, was not of a malignant 
character. O S 1 E O - A N E .L a I S M . 
It is to Scarpa that we are chiefly indebted for the facts thus far 
known in relation to the morbid anatomy of Osteo-aneurismatie tu- 
mors. Whatever may be the elementary lesion .of tissue in this dis- 
ease ; whether it be of a character analogous to the erectile tumor of 
the soft tissues, or whether the incipient change of structure be de- 
pendant upon a degeneration and dilatation of the coats of the smaller 
arterial tubes by which the spongy portions of the bone are nourished, 
it is to a certain degree established that these tumors of bone invari- 
ably originate in the cancellated structure of the osseous system, and 
most commonly in the tibia, at its upper extremity, and next, in the 
condyles of the femur. The diploc of the flat bones of the cranium 
would also seem, at times, to afford a nidus for the development 
of the pulsative osseous tumor, and even the cancellous struc- 
ture of the scapula has been found to be the original seat of the 
disease. 
The disease once developed, a cavity is formed in the interior of 
the bone, at the expense of the cancellous structure, and this appa- 
rent loss of substance continues as the disease advances, until the ex- 
tremity of the bone becomes enlarged and expanded into a laminated 
shell. This bony cyst, presenting on its external surface, upon manu- 
al examination, irregularities and depressions, will become so thin 
as to be flexible and elastic under pressure, affording to the fingers a 
sensation of crackling or crepitus. As the tumor enlarges, the osseous 
wall may be destroyed, at certain points, by absorption; the interven- 
ing spaces, previously occupied by the lamellated bone, being then 
replaced by thickened periosteum and the super-imposed tissues. In 
some instances, the destruction of the cancelli is so great that a trifling 
force will be sufficient to separate the entire articular extremity of the 
bone from its shaft. This was the ease with the condyles of the femur 
represented in the drawing, [vide plate No. I.] On the external surface 
of the sac, the periosteum is found thickened, and the articular arteries 
are seen enlarged and creeping over the tumor; some of them perfo- 
rating its wall. The inner surface is irregular, unequal and rough, 
presenting at points, where the arteries have been injected, the open 
orifices of the arterial vessels. The interior of the sac, as related by 
Scarpa, presented in one instance clots of blood and strata of coagu 
latcd fibrin, similar in appearance to the contents of a sac of a true REMARKS ON 
arterial aneurism. The principal arterial trunk is not implicated in 
the disease; but according to the last named authority, the vessels 
which enter into the cancellated tissue of the bone are enlarged, and 
terminate abruptly by open mouths, upon the inner wall of the aneu- 
rismatic sac. The contiguous articulation is not invaded by the growth 
of the tumo^; the articular cartilage and synovial membrane main- 
taining their integrity, even where the osseous tissue has disappeared, 
down to the cartilage. 
The development of Osteo-aneurism is generally preceded by the 
presence of pain, more or less severe. The pain may be slight and 
gradually supervening, occurring at intervals during a certain period 
of time, and then remaining continuous and severe; or it may sudden- 
ly attack the part during some accidental motion; being then ushered 
in by a sensation of crepitus about the neighboring joint, and causing 
much suffering from its first accession. Within two or three months 
from the accession of the pain, evidences of the enlargement of the 
bone, at the seat of the disease, begin to show themselves; and in a 
short time the tumor increases so as to encroach upon the adjoining 
articulation, and to present to the inexperienced, characters similar to 
those of strumous engorgement of the joint. When the extremities 
of the long bones are affected, the tumor projects generally upon one 
side of the articulation; the projection not being abrupt, but gradual. 
The super-imposed skin retains for a time its natural color and 
appearance; but in the progress of the disease it acquires a redish 
tint .and seems to be more tense. The veins in the subcutaneous 
cellular tissue appear to be distended and are seen creeping over 
the surface of the tumor, which now assumes the suspicious aspect 
of a malignant growth. The tumor, at different parts, gives evi- 
dence of varying consistence; the most prominent parts convey to 
the fingers the sensation of elasticity and fluctuation, while resistance 
and hardness become more apparent as the examination is extended 
towards the base of the enlargement; by pressure upon some parts of 
the tumor, a kind of crepitus is distinctly felt, as if the osseous shell 
had become thinned down and cracked into contiguous fragments; 
lastly, the limits of the tumor are not distinctly marked, the base ap- 
pearing to merge gradually into the surrounding healthy structures. 7 
'oSrKO-ASKCRISM. 
Jr* addition to these external characteristics, the tumor is accompani- 
ed by aneurismatic signs, from which it has received its distinctive ap- 
pellation. As in aneurism of the large arterial trunks, there is evi- 
dent pulsation, synchronous with the action of the heart, and marked 
by the expansive dilatation peculiar to aneurismal pulsation; and the 
pulsation also ceases, when the circulation through the principal arte- 
rial trunk is interrupted by pressure, and re-appears when the pressure 
is withdrawn. During the pressure on the artery, the tumor becomes 
somewhat more flaccid and soft; and by examination with the fingers, 
the depression or excavation in the bone can then be, in certain cases, 
more or less distinctly perceived. It has been said that the pulsations, 
although synchronous with the systole of the heart, may not be ac- 
companied with any bruit de soufflet; but in the case here related, the 
bruit de soufflet was distinctly audible. 
By degrees the function of the contiguous joint becomes impeded, 
and after a time entire extension becomes impossible. If it be the 
femoro-tibial articulation that is affected, the limb assumes a semi- 
flexed position, similar to that represented in plate No. II. As the tu- 
mor grows and acquires farther developement, the pain becomes more 
and more aggravated and lancinating. At this stage the patient may 
demand amputation as a relief from the excruciating torture he en- 
dures. 
The march of Osteo-aneurism is not rapid in its course; it may be 
present for one or two years, during which the tumor slowly increases 
in size, without marked constitutional sympathy. The termination of 
the disease, most likely, if left to pursue its course, would be to ulcer- 
ate at some point and to burst, the laceration of the sac being accom- 
panied by profuse and exhausting hemorrhage. Various kinds of 
treatment are resorted to, but they generally prove unavailing; and 
it is generally cut short by amputation and cure, or by death, caused 
by consecutive accidents and subsequent complications. 
Pathological researches induce the belief that the proximate cause 
of Osteo-aneurism, or the initiatory morbid changes of structure which 
accompany its commencement, are to be looked for in the vascular 
tissue of the bone. Whether this be a dilatation of the smaller ar- 
terial tubes, or an erectile developement of the vessels of the osseous 8 
REMARKS ON 
cancelli, have been controverted questions. My own opinion is, that 
the elemental lesion consists in an earthy calcareous and atheroma- 
tous degeneration of the tunics of all the arteries, by which the can- 
celli of the bone, at the seat of the disease, are supplied. It is difficult, 
otherwise, to account for the abrupt termination of the vessels of the 
bone by open mouths upon the inner wall of the sac, for the definite 
character of the excavation of the bone, or for the fibrinous character 
of the contents found in it. 
! The remote cause of the tumor is generally reported by the pa- 
tient to be some antecedent injury received from a fall or sprain, or 
to some such accidental or sudden violence. 
The diagnosis of an Osteo-aneurismatic tumor, especially in its in- 
cipient stage, is often involved in obscurity. If there be a combina- 
tion of encephaloid degenerescence with the aneurism, it may be im- 
possible to detect its presence until after the removal of the mor- 
bid growth from the living body. Osteo-aneurism, in certain lo- 
calities, may be mistaken for aneurism] of one of the large arterial 
trunks; for Osteo-cephaloma or the encephaloid cancer of bone, 
when accompanied with pulsation ; for strumous engorgement of the 
neighboring articulation, or for the encysted tumor of bone. When 
osseous aneurism is seated near a large artery, as for example, when 
the condyles of the femur are thus diseased, much embarrassment 
may occur in determining whether the pulsatory tumor may not be 
the result of an enlargement of the popliteal artery. The characteris- 
tic differential traits will be the sensation of crepitation, imparted to the 
fingers when pressing upon some points of the surface of the osseous 
sac of an Osteo-aneurism; the structure of the tumor, relatively to 
the course of the artery; the shape of the tumor and its apparent con- 
tinuity with the surrounding structures and the subjacent bone ; its 
entire immobility, while ordinary aneurism is more or less moveable ; 
and lastly, the excavation or loss of substance of the bone, which, to- 
gether with an abrupt bony margin, can be felt, by pressing for some 
time upon the tumor. It has been said, in cancerous pulsatory tumor 
of bone, auscultation will discover the bruit de soufflet, which is ab- 
sent in true Osteo-aneurism; but this diagnostic mark cannot be ad. 
jnitted as invariable or certain, for in the case here recorded, the bruit O8THO-ANEURI8M. 
de soujfflet was distinctly heard over the greater part of the tumor, by 
myself, and also by my colleagues, Drs. Henry Cox, MacNeven, 
and Ford. 
Osteo-aneurism and the encephaloid tumor of bone have many 
symptoms or signs in common]; both may be attended with expansive 
pulsation, crepitation, elasticity and lancinating pain. The greater re- 
duction of the tumor, when compression is applied upon the large ar- 
terial trunk by which it is supplied, the more distinct saccular forma- 
tion of the osseous cyst, the entrance into the sac, by open mouths, of 
numerous small arterial tubes, upon its inner wall, the microscopic 
character of the contents of the sac, showing them to be fibrinous de- 
posit and coagula of blood, and lastly, the passage into the interior of 
the sac, of coarse injection or wax injected into the arterial trunk, are 
the chief signs which distinguish Osteo-aneurism from the encepha- 
loid tumor of bone. 
As regards strumous engorgement of the joint, the absence of pul- 
sation, the more general tumefaction of the joint, and the history of 
the growth of the tumor, are signs sufficiently distinct to prevent the 
observer from confounding the disease with Osteo-aneurism. 
The encysted tumor of bone is so very different in its symptoms 
from Osteo-aneurism, that it is not allowable to suppose that in any 
case one disease can be mistaken for the other. 
The existence of an Osteo-aneurism once discovered, the surgeon is 
warned that he has to contend with a disease of a very serious charac- 
ter. Its tendency, when unimpeded, is to destroy the cancellated struc- 
ture of the entire extremity of the bone where it commenced; so much 
so, that in the long bones, the epiphysis may become completely de- 
tached from the more solid structure of the shaft. Pressure and topi- 
cal applications are unavailing and the ligature of the principal artery 
of the limb, as appears from recorded cases, is a proceeding of doubt- 
ful efficacy; in fact, except in the incipient stage, amputation is al- 
most the only remedy by which the life of the patient may be saved. 
The analogies between ordinary aneurism and Osteo-aneurism, that 
is to say, the pulsation attendant upon both forms of tumor and some 
other characteristics, naturally suggested the idea that the interrup- 10 
REMARKS OX 
tion to the circulation, above the seat of the disease, by ligature or 
by compression, might prove as successful in one disease as it was 
known to be in the other; but in practice, the ligature of the principal 
artery, above the seat of the disease, has not been entirely successful. 
In 1819 Dupuytren, acceding to the doctrine of Breschet, that Osteo- 
aneurism was formed by an erectile tissue, for the first time, applied 
the ligature upon the artery, above the seat of the disease. Since that 
time we have the records of four cases, treated upon the same princi- 
ple ; one related by Lallemand, two by M. Boux, of Paris, and one by 
M. Nelaton. These five cases comprise all that are known, where the 
ligature has been applied upon the cardiac principle, for real Osteo- 
aneurism. In other instances of pulsatory tumor, where resort was 
had to the ligature, it was ascertained by the progress of the disease 
and by the morbid appearances upon examination, that the supposed 
Osteo-aneurism was, in fact, an encephaloid degenerescence of the osse- 
ous tissue. In the case described in this paper, the trial of the liga- 
ture was made for the sixth time. 
A review of these several cases will show that the efficacy of the 
ligature as a remedy for this disease is not to be relied upon. In the 
case operated on by Dupuytren, pulsation ceased and the tumor so de- 
creased that the patient was declared to be cured; but after a time 
the tumor commenced again to enlarge, and the disease, protracted 
during a period of nearly six years, ultimately required amputation. 
In one of the cases related by M. Boux, where the aneurism was seated 
at the inferior extremity of the radius, the ligature of the brachial ar- 
tery was unavailing, and amputation was afterwards performed. In 
the other case related by that surgeon, and also in the case related by 
Lallemand, the cure of Osteo-aneurism of the upper extremity of the 
tibia, by tying the crural artery, is claimed; but as reported, these 
cases were observed and followed for only a few months after the 
are therefore not altogether satisfactory, as regards 
the affirmation of entire cure. The report of the case in whichAf. 
Nelaton tied the femoral artery for Osteo-aneurism of the inner con- 
dyle of the femur, is not complete; but as far as it goes, it acknow- 
ledges that, within a month after the operation, pulsation had returned 
and the tumor was not decreasing. The use of the ligature, however, 
is expedient, especially in the early stage of the disease. Its applica- 
tion is attended with but little danger to the patient, and if successful, 
saves him from a severe mutilation. 
When the diagnosis is ascertained, before the diseascMias made OS TEO-ANEURISM. 
much progress, and the osseous tissue has not become extensively in- 
vaded, resection of the articular extremity of the long bones is at 
times justifiable. 
In the advanced stage of the disease amputation remains as the 
only remedy; then the osseous sac can no longer be obliterated by 
the interruption of the circulation, and the devastation of the cancel- 
lated structure, at the seat of the disease, becomes too great to admit 
of resection as a remedy. 
No. II.—Showing the appearance of the tumor, Ita projection upon the inner aspect of the 
knee, and the position of the limb before the femoral artery was tied. REMARKS ON 
Case.—Hannah Martin, set. 35, married, a native of England, with 
dark hair and complexion, of nervous temperament and small stature, 
was admitted into the Immigrants’ Hospital on the 13th day of April, 
1852. Sixteen months before her admission she had received a se- 
vere injury on the region of the knee, from a fall. From this, in a 
few weeks she entirely recovered. Eight months after she was sud- 
denly attacked by uneasy sensations about the knee, which were soon 
followed by severe pain and by slight tumefaction. She had applied 
for relief elsewhere, and had been treated for some months for scro- 
fulous disease of the knee-joint; the swelling, meanwhile, continued 
slowly to increase, and the pain became more aggravated. Upon ex- 
amining the diseased part, at the date of her admission, a tumor pre- 
sented itself, apparently commencing at the middle of the lower third 
of the femur, and extending downward in front, to the upper part of 
the patella; but occupying chiefly the anterior and inner aspect of the 
knee, passing downwards and backwards toward the popliteal region, 
and forwards and outwards, beyond the mesial line, anteriorly. The 
patient was unable to walk, and the leg was flexed upon the thigh at 
an acute angle, with entire inability to extend it. There was always 
present considerable pain, which might be much increased by pressure. 
Treatment was directed towards improvement of the general health, 
and alleviation of the pain by topical anodyne applications. 
Many days did not elapse before the true nature of the disease be- 
came revealed. Pulsation of an aneurismatic character was detected 
in the tumor, and this symptom, with some other peculiarities, indi- 
cated that the patient was suffering from Osteo-aneurism. From this 
time, the 18th of April, 1852, the House Surgeon, Dr. Bailey, kept a 
correct record of the progress of the case. 
A distinct expansive pulsation is felt extending over the whole tu- 
mor, but is most distinct over the anterior-superior and internal part 
of the region of the knee. The pulsation can also be detected along 
the inner part of the popliteal region, opposite the inner and posterior 
aspect of the inner condyle. 
June 3d.—The tumor has somewhat increased, and at its most 
prominent part a slight degree of fluctuation can be felt. By auscul- 
tation, the bruit de soufflet can be distinctly heard over the entire re- 
gion of the tumor, more clear at some parts than at others. The pa- 
tient experiences great pain when the tumor is handled, but other- 
wise does not complain as much as formerly; the limb remains flexed, 
and the patient is confined entirely to bed. 
It is concluded to try continued compression upon the femoral OSTEO-ANEURISM. 
artery, as practised in cases of ordinary aneurism. For this purpose, 
a suitable instrument is applied so as to compress the artery a little 
above the middle of the thigh. As soon as the circulation is inter- 
rupted through the artery, all pulsation of the tumor ceases, and the 
swelling becomes flaccid and softer. The application of the instru- 
ment was at first well tolerated, but notwithstanding the administra- 
tion of a strong anodyne, the'pain caused by the action of the instru- 
ment became so excessive as to render its removal necessary. The 
catamenia appearing next day, the patient was allowed to rest, taking 
at proper times anodyne draughts. 
June 19th.—As compression could not be borne, in the presence 
of several of my colleagues I applied a ligature upon the femoral ar- 
tery about an inch below the origin of the arteria profunda. The 
pulsation again immediately ceased, the tumor diminished in size and 
became softer and flaccid; while the skin over the tumor, heretofore 
natural in appearance, became livid and shrunken. Although the 
nutrient artery of the shaft of the femur takes its origin from one of 
the branches of the profunda, the condyles of the femur, originally an 
epiphysis, and separately developed from the shaft, receive ramifica- 
tions from the crural trunk immediately before and after it becomes the 
popliteal artery. The experiments of Bellingham and others lead us to 
believe that aneurismatic tumors are cured by retardation alone of the 
circulation through the sac, and seeing the pulsation in the tumor cease 
entirely, when pressure was applied upon the femoral artery below 
the origin of the profunda, I selected as the safer operation, the point 
where I applied the ligature, in preference to an operation which would 
require the ligature to be placed upon the artery between the profun- 
da and the deep epigastric and the circumflex iliac artery. 
Besides the other immediate effects of the application of the liga- 
ture, the pain was much allayed at the seat of disease. 
The operation was followed by little constitutional disturbance, 
and from the 19th of June to the 9th of July, every thing went on 
favorably. 
July 9th.—The shell of bone seems to be collapsing. In rubbing 
the hand over the tumor, abrupt edges can be felt, arising from the 
bony shell giving way under pressure. Elevations and depressions 
can also be felt, as if the osseous shell had become broken up into 
thin irregular fragments. The greater part of the tumor is more or 
less elastic, and the sensation imparted to the fingers would indicate 
that the shell is very thin and yielding. The tumor has greatly di- 
minished in size, and the leg can now be considerably extended. 
July 11th.—The ligature came away, to-day (the 22d day after the 14 
REMARKS OS 
operation,) unattended by any hemorrhage. The knee-joint is still 
larger than natural, but the circumference of the limb around the seat 
of the disease has diminished, by measurement, one and a half inches. 
July 16th.—Patient continues to improve; appetite good; and 
her general health is much better than previous to the operation. 
August 10th.—The,patient has now recovered the use of her limb 
to a great extent; being able to extend the leg while standing, so as to 
rest the fore part of the foot and toes on the ground. At her own 
request, she was discharged from the hospital to-day, much improved 
in general health, and with good prospect of the disease being ulti- 
mately entirely cured. 
Upon leaving, she was supplied with a proper apparatus to apply 
equable pressure upon the tumor, and ordered so to use it as not to 
produce pain. 
September 16th—This patient has again been admitted into the 
hospital, having had a relapse, as she states, from falling down some 
stairs and severely hurting the diseased part. The tumor has en- 
larged, and the pain is so intolerable that she is desirous of having 
the limb amputated. The osseous tissue of the condyles had evi- 
dently become too much devastated, from the progress of the disease, 
to admit of any probable benefit resulting from the use of the liga- 
ture higher up the femoral artery, or upon the external iliac. 
On the 18th of September, acceding to the wish of the patient, she 
was placed under the influence of chloroform, and I removed the limb 
through the middle third of the femur. 
The morbid appearance of the tumor confirmed the diagnosis 
which had been formed. 
Before examining the diseased limb, a coarse injection was thrown 
into the trunk of the femoral artery. The skin and subcutaneous 
layers were healthy, and below these, after removal, numerous arteries, 
enlarged, were found ramifying along the surface of the aneurismatic 
sac. [Vide Plate, No. I.] The sac, externally, was formed partly by 
the periosteum of the condyle, which was seen thickened and continuous 
with that investing the shaft, and partly by the layer of tissue which re- 
sulted from the blending of the periosteum with the capsular ligament 
of the knee-joint. Below, and closely adherent to this investing layer, 
was found the osseous shell of the sac, formed chiefly by the external 
bony plate of the inner condyle, expanded into a thin and attenuated lay- 
er of osseous tissue. This osseous layer was not altogether continuous, 
but at parts was broken up into lamellated fragments, between some 
of which there were spaces occupied by the outer soft envelope of 
the sac. A distinct sensation of crepitus was imparted to the fingers, 15 
OSTKO-AySUHISM. 
while pressure was being applied over the sac, particularly at the most 
prominent part of the tumor, where the bony shell was most attenu- 
ated. Upon opening the femoro-tibial articulation, the articular sur- 
faces were found in a state of integrity; the intra-articular arteries 
were injected; the synovial membrane presented not the slightest 
point of ulceration, nor did the articular or the semilunar cartilages. 
[Vide Plate No. II.] At the depression between the condyles the os- 
seous tissue was thinned down to an extreme degree of tenuity, and 
at one point, in this part of the cyst, the bony tissue was entirely ab- 
sorbed ; the synovial membrane and articular cartilage remaining as 
the only barrier between the interior of the aneurismatic sac and the 
cavity of the joint. 
The osseous sac was formed at the expense of the entire internal 
condyle, and of two-thirds of the external condyle, ending above ab- 
ruptly, at the shaft of the bone, and encroaching slightly upon its 
lower extremity. The destruction of the cancellated structure of the 
condyles to the extent just named, was entire; the shell of the sac 
being formed by the expansion of the outer layer of the bony struc- 
ture of the condyles. 
The internal surface of the portion of the sac formed by the ex- 
panded condyles, was irregular, rough, and in close apposition with 
the contents of the sac ; and upon everting the wall of the sac, the 
open orifices of numerous branches ramified upon the outer surface 
of the sac, were seen filled with the injection. The upper wall of the 
sac, internally, is formed by the lower portion of the diaphysis of the 
femur, which also is rough, uneven and irregular. Upon opening 
the aneurismatic sac, at some parts a layer of the injection was found 
between the inner aspect of the wall and the contents. The interior 
of the sac was filled by fibrinous coagula, distributed partly in layers, 
and presenting no characteristic of malignant growth, either upon 
general or microscopic examination. [Vide Plate No. I.] 
After the amputation, no constitutional disturbance or untoward 
complication retarded the union of the flaps and the cicatrization of 
the stump. On the 28th of December, 1852, the patient was discharg- 
ed from the hospital, perfectly cured and in excellent health.