600 ABNORMAL CONDITIONS OF THE SHOULDER JOINT.
been formed for the reception of the enlarged
heads of the humeri behind the glenoid cavi¬
ties, and partly beneath the bases of the spines
of the scapulae just where the head of the
humerus has been found to rest in the ordi¬
nary dislocation backwards from accident ;
but in this case, although the history was
unknown, that these appearances were not
the result of accident is almost certain,
as similar abnormal appearances are ob¬
servable on each side. The notice of this
preparation in the catalogue of the museum
is as follows (p. 108—3*2.) : — “ The bones of
both the shoulder joints of an adult. In each
joint there has been ‘ ulceration,’ or such
absorption as occurs in chronic rheumatism
of the articular surface of the head of the
humerus, and the glenoid cavity. The heads
of the humeri are flattened and enlarged by
growths of bone around their borders; and the
glenoid cavities, enlarged in a corresponding
degree, and deepened, extend backwards
and inwards to the bases of the spines of the
scapulae. The articular surfaces, thus en¬
larged, are mutually adapted, and are har¬
dened, perforated, and in some parts polished
and ivory-like. The changes of structure
are symmetrical, except in that the articular
surfaces of the right shoulder joint are more
extensively polished than those of the left.”
Section II. — Accident. — The principal
accidents the shoulder joint and the bones in
its immediate vicinity are liable to, are frac¬
tures and luxations.
Fractures.—A fracture may traverse the
acromion, the coracoid process, or detach
the glenoid articular portion of the scapula
from the body of this bone by passing directly
across the neck of the scapula.
A. Fracture of the acromion process. — A
fracture of the acromion process may be caused
by the fall of a heavy body on the superior
surface of the acromion ; but this accident
most usually occurs in consequence of falls
in which the patient is thrown from a height
on the point of the shoulder. The fracture
of the acromion will be generally found to
have taken place at a point behind, and within,
the junction of the clavicle with this bony
process ; its direction we always observe to
be in the original line of the junction of the
epiphysis with the rest of the bone. In this
accident, if the distance be measured from
the sternal end of the clavicle to the extre¬
mity of the shoulder, it will be found lessened
on the injured side. Considerable ecchymosis
of the shoulder may be expected soon to suc¬
ceed the injury, and the patient will be unable
to elevate the arm. Sometimes the perios¬
teum of the acromion is not torn, and then,
although the fracture of the bone has been
complete, there is no displacement of the
fragments. If, however, this fibrous invest¬
ment of the acromion, above and below, be
completely torn across, the acromion process
will be found to be depressed, because it will
be pulled down by the weight of the extremity
and contraction of the deltoid muscle. The
portion of the acromion thus detached is
generally very moveable, following the clavicle
whenever the arm is moved. This accident
is best recognised by the surgeon first taking
hold of the elbow of the affected side, and
elevating the whole arm perpendicularly.
“ Having thus restored the figure of the part,
he places his hand upon the acromion, and
rotates the arm, when a crepitus can be dis¬
tinctly perceived at the point of the spine of
the scapula.” *
Fractures of the acromion unite by bone,
sometimes with much deformity, arising from
ossifie depositions, which however do not,
after a time, interfere much with the motions
of the arm. This union has sometimes been
known to take place in forty-eight days, and
in other cases in a much shorter time. The
union, however, is frequently only ligamentous.
Sir A. Cooper speaks of a false joint being
occasionally the result of a fracture. Mal¬
gaigne, alluding to a case in which a false
joint was the consequence of a fracture of
the acromion, says that the fractured surfaces
presented a polished appearance, and were
covered with an ivory deposit, the effects of
friction. He adds, that the union was not
simply a ligamentous connexion, but that an
arthrodial false joint had been formed. In
all the specimens of this fracture examined by
Malgaigne, the superior border of the fracture
was surmounted with small bony crests of
new formation, of which the more consider¬
able number grew from the scapular portion
of the acromion, while those produced from
the detached extremity of this process were
but few, no doubt in consequence of its lesser
degree of vitality. This remark of Malgaigne
coincides with the observations to be found
in Sir Astley Cooper’s Work, that the dis¬
position to ossifie union is very weak in the
detached acromion. Malgaigne, however, re¬
fers to a preparation in the Museum of Du¬
puytren, in which the external fragment pos¬
sessed a thickness almost double that of the
portion of bone from which it had been de¬
tached. This thickness the writer of the
Catalogue of the Museum thought was caused
by an overlapping of the fragments of the
broken portions ofthe acromion ; but Malgaigne
supposes it to have arisen from simple hyper¬
trophy of the detached fragments.
B. Fracture of the coracoid process — is a
rare accident, and when it does occur, it is
generally the result of a severe injury, in
which the fracture of the bone is the least of
the evils attendant on the compound injury.
ThusBoyerf gives us the account of a fracture
of the coracoid process produced by the blow
of a carriage pole ; the patient died in a few
days afterwards, in consequence of the severe
contusion he suffered at the moment of the
accident. The coracoid process, when frac¬
tured at its basis, is pulled downwards and
forwards by the lesser pectoral coraco-bra-
chialis and short portion of the biceps muscle.
We are told}; that if the contusion accom¬
panying this accident be slight, we can seize
* Sir A. Cooper.
f Maladies Chirurgicales. | Sanson.
