ABNORMAL CONDITIONS OF THE KNEE-JOINT. 



74 



salient internal border of the articular pulley 

 of the femur, which the patella has abandoned. 

 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 

 capsular 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, 

 set. 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. We 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 

 patella 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 



patella on its edge, we can imagine that a more 

 complete rotation of the bone on its long axis 

 might happen, constituting the complete rever- 

 sion of the position of the surfaces and edges of 

 this bone spoken of by some writers. 



It does not appear that Sir A. Cooper has 

 seen the dislocation of the patella on its edge, 

 but he states that he was informed by Mr. 

 Willing, formerly of Hastings, that he was 

 called to a case in which the patella was dislo- 

 cated on its edge. The nature of the accident 

 was very obvious, as the edge of the bone forced 

 up the integuments to a considerable height 

 between the condyles on the fore part of the 

 joint. Mr. Willing reduced the dislocation, 

 but with considerable difficulty, by pressing the 

 edges of the bone in opposite directions. 



The following case of dislocation of the patella 

 on one of its edges occurred lately in the prac- 

 tice of Mr. Pentland, surgeon to the Drogheda 

 Infirmary, and is very interesting and important, 

 coming as it does from an acute and experi- 

 enced observer. J. M'Greene, ret. 25, of middle 

 stature, was struggling to get down a strong 

 man in play. He succeeded so far as to get 

 him on his knees, when the fallen man took 

 hold of both his legs with his arms closely 

 embraced round them, and when M'Greene was 

 struggling to disengage himself, he heard and 

 felt his right knee give a loud snap. This was 

 attended with the most excruciating pain, and 

 he fell to the ground to the left side; he felt that 

 he had lost all power over the right leg. He 

 was carried to bed, and Mr. Pentland saw him 

 in a few minutes after the accident. The knee 

 was in a flexed state, presenting a most extraor- 

 dinary appearance, but which was readily seen 

 to proceed from the patella having been dislo- 

 cated on its edge. Mr. Pentland stated that 

 he had some difficulty in ascertaining which 

 side was turned out, but he soon concluded 

 that it was the under or articular surface. The 

 man could not move the limb at all, "and never," 

 says Mr. Pentland, " did I witness more dread- 

 ful suffering. You would suppose," he adds, 

 " that the patella would force out through the 

 integuments." After repeated attempts he at 

 length succeeded in getting it into its place ; 

 the reduction was attended with a loud noise, 

 and during the operation the man seemed to 

 suffer frightful torture. Immediately on the 

 reduction, all pain ceased, and in a very short 

 time he recovered the perfect use of the limb. 



A case of dislocation of the patella on its 

 edge is recorded by Dr. Watson in the New 

 York Journal of Medicine and Surgery, 

 October, 1839. He calls the accident a dislo- 

 cation of the patella on its axis, and says, " in 

 the case I have described, the leg could be 

 slightly flexed ; no part of the pulley except 

 its elevated border at the condyles of the femur 

 could be felt. The patella was drawn upwards, 

 and twisted nearly at right angles with its proper 

 position, so that its anterior face was directed 

 inwards, and its outer edge was thrown com- 

 pletely forwards, forming an uneven and very 

 prominent line beneath the skin in front of the 

 joint. The reduction of the bone to its normal 

 position was not effected without difficulty." 



