LUXATION OF THE SACRO-ILIAC ARTICULATION. 
481 
these the rectus abdominis appears to act in opposition to the liga¬ 
mentous apparatus described, and fixes the joint. When, therefore, it 
is relaxed, as during parturition, danger of displacement becomes immi¬ 
nent. Stockfleth believes that movement in the symphysis pubis 
favours displacement. If division occurs in the symphysis pubis, the 
sacro-iliac joint is endangered, hence the simultaneous occurrence of the 
two conditions as related by Golis. It will also be clear that dislocation 
on one side may readily lead to a similar accident on the other. It is 
even the rule to meet with double-sided dislocation, as noted by Albrecht, 
Guillebeau, and others. 
According to Stockfleth, incomplete luxation is often occasioned in 
pregnant cows by pulling on the tail to assist them in rising, and 
complete luxation then follows. It may also be caused by violent 
muscular exertion. The ilio-psoas and longissimus dorsi, together with 
one group of the thigh muscles, draw the sacrum downwards, whilst 
the glutei and other muscles of the thigh move the inner angle of the 
ilium outwards. Powerful contractions in these muscles, produced by the 
animal rising or walking, may thus occasion dislocation of the bones. 
In incomplete luxation, the union between ilium and sacrum is not 
completely broken down. The muscles are partly torn through, and, 
like the sheaths of the great nerve stems, become infiltrated with blood, 
but the ligaments are only partly divided. In complete luxation, on the 
other hand, all the ligamentous structures are ruptured, and the sacrum 
sinks between the inner angles of the haunch, its anterior portion 
especially, so that the articular surfaces may sometimes be 2 to 4 inches 
below the inner angle of the ilium. In consequence, the abdominal 
organs are compressed and sometimes injured; even the passage of 
faeces may be interfered with. 
Symptoms and course. After incomplete dislocation, the animal is 
inclined to rest continuously, rises with difficulty, and when moving, 
takes short stumbling steps with the hind legs. Sometimes large 
quantities of faeces are passed, a symptom which Stockfleth considers 
characteristic of dislocation. Pressure between the inner angles of the 
ilia produces pain, and the separation can sometimes be felt through 
the rectum. 
Complete luxation is characterised by marked depression of the 
sacrum, and by the anterior edge of the ilium being unusually sharply 
defined. The swelling and tenderness in the middle line, and the 
inability to rise or to stand, render the condition unmistakable. On 
examination per rectum, the pelvic cavity is felt to be narrowed, both in 
its perpendicular and transverse diameters. Defecation is sometimes 
interfered with, in consequence of compression of the rectum. 
In incomplete dislocation, recovery may occur in three to four weeks, 
v.s. i i 
