The differential diagnosis is based on the position of these synovial sacs, which are quite close to the insertion of the tendo-Achillis, and on the absence of any swelling in front of the joint.
Treatment is identical with that indicated in the last condition.
Massage and cold water applications should be employed at first, to be followed by aseptic puncture and withdrawal of fluid, supplemented if necessary by firing in points.
DISTENSION OF THE SYNOVIAL CAPSULE OF THE KNEE JOINT.
Fig. 17.—Front view of the ox’s hock, showing the relations of the tendons and synovial sacs.
Fig. 18.—Side view of the ox’s hock. The synovial sac of the true hock joint has been injected to show the relations of the sacs.
This is one of the rarest conditions now under consideration, because the synovial membranes of the knee joint are everywhere strongly supported by very powerful ligaments. The synovial capsules of the carpo-metacarpal and inter-carpal joints are incapable of forming sacs of any size. On the other hand, the radio-carpal may become moderately prominent in front, especially towards the outside above the superior carpal ligament. When weight is placed on the limb, the excess of synovia is expelled from the joint cavity towards this little sac, which then becomes greatly distended. If, on the other hand, the knee is bent, the sac shrinks or disappears.
Treatment. Treatment is restricted to the application of a blister or to firing in points.