74 
salient internal border of the articular pulle 
of the femur, which the patella has aban fee 
This last bone forms in front of the external 
border of the pulley a very remarkable tumour, 
upon which the finger may easily distinguish 
the external border of the patella. We can 
also easily recognize through the skin and the 
ular ligament the posterior articular surface 
of the patella, which has passed beyond the 
edge of the trochlea of the femur. 
“ In the course of a long practice,” says 
Boyer, “ I have met with but one case of dis- 
location of the patella,” (and this, it appears, 
was an incomplete luxation.) ‘“ A young man, 
wt. 16 to 18, very tall, fell, running along a 
corridor. The internal part of the knee in 
passing struck violently against the corner of a 
trunk, which produced an incomplete luxation 
of the patella outwards. The surgeon in ordi- 
nary of the family was called; but whether it 
was that he did not recognize the luxation or 
that he did not consider he could reduce it, 
he did not wish to undertake it without having 
the assistance of Sabatier. This celebrated 
professor was at first uncertain as to the species 
of dislocation which the patella had suffered ; 
but having carefully examined it and reflected 
on the phenomena the accident presented, he 
recognized the true nature of the case. He 
then attempted the reduction of the luxation, 
but failed in replacing the bone.” 
When Boyer arrived, he states that the pa- 
tient was lying on his bed, the limb being ex- 
tended and raised by pillows. The ordinary form 
of the knee was altered; the patella formed a 
tumour, which was sensible on the front of the 
external border of the articular pulley of the 
femur; in front of the internal border of the 
same pulley there was a depression, in the bot- 
tom of which could be perceived with the 
finger the same border of this pulley. The 
direction of the patella was changed in such a 
manner that its anterior surface was inclined 
inwards, and its external border forwards; 
finally, the external articular facet of the pa- 
tella could be felt by the touch through the in- 
teguments which covered it. By these signs it 
was easy to recognize the incomplete luxation 
outwards. 
Luxation of the patella on its edge—Some 
very eminent surgeons have doubted the possi- 
bility of such an occurrence as a dislocation of 
the patella on its edge. ‘ Some,” says Boyer, 
“have imagined that the patella could be 
luxated turning half round on its vertical or long 
axis so as to rest on one of its edges on the 
articular trochlea of the femur. e cannot 
conceive,” he proceeds, “ how the tendon of the 
extensor muscles of the leg and the ligament of 
the patella could lend themselves to such a 
rotation of the bone on its long axis; much less 
can we understand how these parts can admit 
of a total reversion of the bone, as authors pre- 
tend to have observed.” Notwithstanding these 
observations, it seems fully proved, that the 
tella can really be dislocated on its edge, and 
if we once admit the possibility of the partial 
rotation of the bone on its long axis, so as to 
constitute what is called a dislocation of the 
ABNORMAL CONDITIONS OF THE KNEE-JOINT. 
patella on its edge, we can imagine that a more _ 
complete rotation of the eS ee ya 
might , constituting the com reve 
sion of peso ht of the surfaces and dges 
this bone spoken of by some writers. 
It does not appear that Sir A. Cooper hi 
seen the dislocation of the patella on its” 
but he states that he was informed by | 
Willing, formerly of Hastings, that he» 
called to a case in which the patella was dis 
cated on its edge. The nature of the acei 
was very obvious, as the edge of the bone for 
up the integuments to a considerable hei 
between the condyles on the fore part of 
joint. Mr. Willing reduced the dislocat 
but with considerable difficulty, by pressing: 
edges of the bone in opposite directions. 
The following case of dislocation of the patel 
on one of its edges occurred lately in the pra 
tice of Mr. Pentland, surgeon to the Droghet 
Infirmary, and is very interesting and important 
coming as it does from an acute and expel 
enced observer. J. M‘Greene, et, 25, of mide 
stature, was struggling to get down a stron 
man in play. He succeeded so far as to ge 
him on his knees, when the fallen man too 
hold of both his legs with his arms ele 
embraced round them, and when M‘Green 
struggling to disengage himself, he heard am 
felt his right knee give a loud snap. This 
attended with the most excruciating pain, an 
he fell to the ground to the left side; he felt tha 
he had lost all power over the right leg. 
was carried to bed, and Mr. Pentland saw 
in a few minutes after the accident. The 
was in a flexed state, presenting a most extrac 
dinary appearance, but which was readily seet 
to proceed from the patella having been dislo 
cated on its edge. Mr. Pentland stated tha 
he had some difficulty in ascertaining whi 
side was turned out, but he soon cone! 
that it was the under or articular surface. 
man could not move the limb atall, “and ne 
says Mr. Pentland, “ did I witness more dread- 
ful suffering. You would suppose,” he adds 
“ that the patella would force out through th 
integuments.” After repeated attempts he 
length succeeded in getting it into its place 
the reduction was attended with a loud noist 
and during the operation the man seemed 16 
suffer frightful torture. Immediately on th 
reduction, all pain ceased, and in a yr 
time he recovered the perfect use of the limb. 
A case of dislocation of the it 
edge is recorded by Dr. Watson in the Ney 
York Journal of Medicine and ger} 
October, 1839. He calls the accident a disle 
cation of the patella on its axis, and says, “ i 
poy I have bapa: bs Bory. b 
slightly flexed ; no of the pu xcep 
its devnek border eed petro of the fem 
could be felt. The patella was drawn upwards 
and twisted nearly at right angles with its proper 
position, so that its anterior face was directet 
mwards, and its outer edge was thrown Cot 
pletely forwards, forming an uneven and very 
rominent line beneath the skin in front of t 
joint. The reduction of the bone to its norm 
position was not effected without difficulty.” 
Surger 
