BURSITIS OF THE CARPAL SHEATH. 823 



V.— INFLAMMATION OF THE SYNOVIAL SHEATH OF THE CARPAL 

 ARCH. THOROUGHPIN OF THE KNEE. 



The synovial investment of the carpal arch and flexors of the 

 foot, lying at the back of the knee, may become inflamed. For the 

 arrangement of this sheath see under " Rupture of the Flexor 

 Tendons." Acute is commoner than chronic inflammation, and is 

 caused by bruises or wounds. The sheath may be opened by the 

 horse putting its foot into the manger, or by a stab with a fork or 

 other sharp instrument. Sometimes cellular inflammation extends 

 from the metacarpus to this point ; septic inflammation following 

 tenotomy is most dangerous. The chronic form generally starts 

 from the check ligament of the perforans, and often produces dis- 

 tension of this sheath, extending some distance above the knee- 

 joint. As a rule, the swelling appears on the inner side of the joint, 

 both above and below, but in the latter situation may involve the 

 outside. Palpation reveals the connection between the different 

 parts. 



Whilst, then, the chronic form appears as a fluctuating swelling in 

 the carpal arch and over the flexor tendons, and is accompanied 

 by little lameness or pain, the acute open variety shows the following 

 symptoms : — 



(1) Marked lameness ; the limb is held stiffly, and is incompletely 

 flexed. 



(2) Increased warmth ; pain on pressure ; more or less firm, 

 hard swelling, which surrounds the entire joint, and extends for 

 some distance beyond it. In purulent inflammation, periarticular 

 abscesses may form. 



(3) Discharge from the wound of large quantities of synovia, after- 

 wards mixed with pus, sometimes with necrotic fibres of the tendon 

 sheath. 



(4) Usually fever ; in septic cases, the temperature may be very 

 high. 



Course. The acute open form generally takes an unfavourable 

 course, and when caused by extension of infective cellulitis or by 

 punctured wounds, is always dangerous ; little can then be done, 

 and slaughter is advisable. The appearance of fever is, therefore, 

 always threatening. Simple inflammation is less serious, and 

 recovery commonly occurs, though some swelling may be left. 

 Though more difficult to treat, the chronic form, associated with 

 formation of large swellings, does not as a rule interfere with the 

 animal's working powers. 



