NAVICULAR DISEASE. 903 



Treatment is only advisable in valuable animals, like those used 

 for the stud. Complete rest is of first importance in all cases of 

 suspected fracture. At a later period plantar neurectomy may 

 be performed. In complicated fracture caused by picked-up nail, 

 resection of the perforans tendon may be attempted. Humbert, 

 in such a case, claims to have completely resected the navicular bone 

 with success. The foot was irrigated night and day for a month 

 after operation. In two and a half months the animal could trot 

 sound. Moller, who made experiments in this direction, failed to 

 obtain good results, and he seems to entertain considerable doubt 

 of the possiblity of cure by resection of the navicular bone. 



IX.— NAVICULAR DISEASE. 



In England, during the latter half of the eighteenth century, attention 

 was first directed to a disease which had become unusually common in 

 thoroughbred horses. At first it was regarded as a disease of the pedal- 

 joint, or was mistaken for contraction of the foot. It is now impossible 

 to say whether the disease described by Bridges and Gibson as " grain 

 of the coffin-joint " was identical with that now under consideration. 

 Moorcroft states that he had previously seen the disease, though he had 

 not directly recognised it. In a letter dated 1804, Moorcroft warns his 

 correspondent against mistaking simple contraction of the foot for coffin- 

 joint lameness. He describes the first condition, and states that it only 

 occurs secondarily in this disease. Coleman and Turner further observed 

 and described the condition, at first under the title of " coffin- joint lame- 

 ness," and later of " navicular disease," or " navicular lameness." The 

 French " maladie naviculaire " is derived from this. 



In Germany the disease was also first termed " coffin-joint lameness." 

 Renner endeavoured more particularly to indentify the seat of the disease by 

 distinguishing an anterior and a posterior coffin-joint lameness, and only 

 applied the latter term to the disease now in question. Brauell first 

 described the disease thoroughly and named it " podotrochilitis." Both 

 names — " navicular disease " and " podotrochilitis " — have the merit 

 of at least indicating the seat of the disease. 



The navicular bone, by its anterior or articular surface forms part of 

 the pedal or coffin-joint, and posteriorly it presents a gliding surface, 

 covered with fibro-cartilage, over which the perforans tendon passes to 

 its insertion on the semilunar crest of the os pedis. The flexor tendon, 

 below its attachment to the os corona?, becomes rapidly expanded as it 

 descends, and this portion is often designated the plantar aponeurosis. 

 It is strengthened behind by a fibrous expansion, which blends with the 

 tendon inferiorly and which is attached above to the os suffraginis by 

 two bands. The navicular sheath or bursa lies between the anterior surface 

 of the expanded tendon and the posterior surface of the navicular bone, 

 forming a closed sac which extends downwards to below the interosseous 

 ligament connecting the navicular to the os pedis, and upwards to the 

 middle of the os coronae, where it is separated from the great sesamoid 

 sheath by an attachment of the perforans tendon. 



