594 
LUXATION OF THE PHALANGES. 
band. Its synovial capsule extends from the margin of the articulatory surface 
of the os corone to the os pedis and os naviculare. Though in front tensely 
stretched, it expands and becomes thinner in a backward direction, and is in 
connection with the tendon of the flexor pedis. Its two lateral ligaments render 
the pedal an incomplete ginglymoid joint. The postero-lateral ligaments are 
physiologically identical with the superior and inferior sesamoidal ligaments. 
They arise from the upper border of the navicular bone, and are inserted on 
the lateral aspects of the os coronae and the lower portion of the os suffraginis. 
The tendon of the extensor pedis passes over the anterior, those of the flexor 
peclis perforans and perforatus over the posterior surface of the phalanges, 
which here are almost entirely surrounded by tendon sheaths. In company 
with the sesamoidal ligaments, these tendons act in fixing the fetlock-joint; 
with the posterior coronary ligaments, and assisted by the postero-lateral 
ligaments, they also fix the coronet and pedal joints, and thus sustain the 
weight of the body. The larger blood-vessels and nerves pass down the outer 
and inner sides of the phalanges. 
The terms dorsal and volar flexion are hereafter used to describe the 
movements occurring in the phalanges : the first indicates the movement 
given by the extensor, the second that given by the flexor, muscles. 
I—LUXATION OF THE PHALANGES. 
^The union of the three phalangeal joints is so strong that displace¬ 
ments (luxations) are exceedingly rare, and must always be preceded by 
extensive rupture of ligaments or tendons. Luxation of the fetlock- 
joint is seen in race-horses after complete rupture of the flexor tendons ; 
the lower end of the metacarpus then passes downwards over the 
postenoi maigin of the articular surface of the os suffraginis, causing 
excessive dorsal flexion of the fetlock-joint. Less frequently, the 
metacarpus is displaced anteriorly ; this indicating rupture of the lateral 
and sesamoidal ligaments. Lateral displacements are exceedingly rare, 
and aie necessarily accompanied by rupture of the lateral ligaments. 
They aie sometimes pioduced by violent struggles to free the foot which 
has accidentally become fixed, as, for example, between railway-metals. 
"Wilhelm saw lateial displacement in the hind leg of a horse which had 
run away, and had fallen. The joint was directed outwards. Siedam- 
grotzky has described three similar cases. In other animals luxations 
of the phalanges are still less common. 
The diagnosis is easy. The altered position of the joint, and the 
changes discovered by manual examination, leave no room for doubt. 
The course of luxations is almost always unfavourable, on account of 
the excessive rupture of tissue. The larger animals either die from 
decubitus, or more or less marked lameness remains which prevents the 
animal working. Eeported cases, however, show that recovery may 
occasionally take place. 
Wilhelm records recovery in eight weeks in the above-described case. 
He placed the horse in slings, and after reducing the dislocation, applied 
