874 



SESAMOID LAMENESS. 



Mascher described the disease, for which Giinther introduced the 

 name sesamoid lameness. Schrader afterwards gave a thorough 

 pathological and anatomical description of it. Acute inflammation 

 of the posterior gliding surface of the sesamoid bones sometimes 

 occurs in consequence of acute tendovaginitis of the flexor sheath. 



James states having found an abscess about 

 the size of a walnut (?) in the sesamoid bones (?) 

 of a draught- horse. It was supposed to have 

 been caused by injury, and was accompanied 

 by acute inflammation of the tendon sheath. 

 Probably the condition was purulent tendo- 

 vaginitis. In two horses treated for local 

 necrosis of the skin of the hind limbs, suppura- 

 tion occurred in the flexor tendon sheath, with 

 rupture of the perforans tendon. Post-mortem 

 examination showed necrosis of the tendon, 

 of the posterior surface of the sesamoid bones, 

 and of the navicular bone. The process had 

 extended downwards in the track of the ten- 

 dons, and had attacked the navicular bursa. 



Pathological anatomy. Changes character- 

 istic of arthritis chronica are found affecting 

 the gliding surface of one or both sesamoid 

 bones ; the cartilage becomes eroded, and 

 its margins proliferate. When the anterior 

 surface is diseased, both it and the posterior 

 articulatory surface of the metacarpus exhibit 

 abraded and eroded spots. In disease of the 

 posterior surface of the sesamoid bones, the 

 flexor tendons appear roughened and fibrillated 

 (Fig. 512), or sometimes partially ruptured. 

 Brauell saw a few cases of adhesion of the flexor 

 tendon to the sesamoid bones. The sides 

 of the bones showed osseous deposits. The 

 tendon sheath and sesamoid ligaments were 

 thickened ; in some cases detached pieces of 

 bone were found in the sheath. In the cases 

 reported by Levens, the sesamoid bones had 

 probably been fractured. 



As a rule, both sesamoid bones are affected ; 

 Mascher, however, found disease of a single sesamoid and of the corre- 

 sponding metacarpal articular surface. 



Causes. Any violent strain of the supporting apparatus or increase 

 of the pressure normally exerted by the flexor tendons on the 

 sesamoid bones may produce this disease, and therefore both 

 Brauell and Mascher regard long, weak fetlocks as the chief predis- 

 posing factor. This formation not only throws a greater strain on 

 the tendons, but increases the pressure on the sesamoid bones, on 

 account of the more oblique angle which the tendons make with the 



Fig. r>li2. The flexor pedis 

 perforans tendon in a case 

 of sesamoid lameness ; at 

 the point where it passes 

 over the sesamoid hones 

 the perforans tendon is 

 fibrillated (after Brauell). 



