edom of movement is allowed, acute inflammation resulting in
nature's provisional swelling soon develops and repair is hastened
because of increased vascularity. But where luxation of phalanges
accompanies sprain, reposition and immobilization are necessary--that is
if cases are thought likely to benefit by any treatment.

Luxations--Dislocations.

Luxation or dislocation is a condition where the normal relation between
articular ends of bones has been deranged to the extent that partial or
complete loss of function results. When a bone is luxated (out of
joint), there has occurred a partial or complete rupture of certain
ligaments or tendons; or a bone may be luxated when an abnormal or
unusual elasticity of inhibitory ligaments or tendons obtains.

Luxations may be practically classified as _temporary_ and _fixed_. In
temporary luxations, disarticulation is but momentary and spontaneous
reposition always results; while a fixed luxation does not reduce
spontaneously but remains luxated until reposition is effected by proper
manipulation and treatment. Fixed luxation may be of such character as
to be practically irreducible because of extensive damage done to
ligaments or cartilage. Where a complete luxation of the
metacarpophalangeal joint exists, it is probable that in most cases
sufficient injury to collateral and capsular ligaments has been done to
render complete recovery improbable, if not impossible.

Temporary luxation of the patella is a common affection of the horse and
fixed luxation of this bone also occurs. As a matter of fact, in the
horse, patellar luxation is the one frequent affection of this kind.

As a rule, complete disarticulation immobilizes the affected joint and
in most instances there is noticeable an abnormal prominence in the
immediate vicinity--in patellar luxation, the whole bone. In other
instances the articular portion only, of the affected bone is
malpositioned. Usually, luxation and fracture may be differentiated in
that there is no crepitation in luxation and more or less crepitation
exists in fracture.

It is evident, when one considers the symptomatology and nature of the
affection, that fixed luxation is usually caused by undue strain or
violent and abnormal movement of a part. Joints having the greater
freedom of movement are apt to suffer luxation more frequently.

Arthritis.

The study of arthritis in the horse is limited to a consideration of
joint inflammations whic