Miscellaneous Conditions of the Proximal Interphalangeal Joint and Fetlock



Chip Fracture on the First Phalanx

Figure 43 demonstrates a common radiographic finding, a chip fracture along the cranial and proximal aspect of the first phalanx. As long as there is no radiographic evidence of other degenerative joint disease, consisting of osteolytic or proliferative changes involving the first phalanx or distal aspects of the third metacarpal bone, this chip fracture is considered to be of little or no radiographic significance unless it is accompanied by heat and swelling, and pain on flexion of the joint. Unfortunately, this type of chip fracture of the first phalanx is often unnecessarily incriminated as a cause of lameness, as it is rarely associated with clinical signs of disease.


Similar chip fractures or separate ossification centers may be seen along the caudal and proximal aspect of the first phalanx (Figs. 44 and 45). Changes of the size illustrated could be of future clinical significance, whereas smaller changes (fractures or separate ossification centers) in this region, in a clinically sound animal that has been in work, are not.
Figure 44. Figure 45.
Lateral radiograph of the fetlock demonstrating a separate ossification center or old chip fracture along the caudal and proximal aspect of the first phalanx. In this radiograph there does not appear to be evidence of bony activity at this time. There also appears to be a small fragment proximal to the large fragment of bone. Oblique radiograph of the fetlock of the same horse radiographed in Figure 44 demonstrating the separate ossification center or old fracture of the proximal aspect of the first phalanx.