Large Animals Fracture Repair

Lameness in Horses

The purpose of this chapter is to illustrate the pathological changes common in lameness in horse to arrive at a diagnosis it is essential that the veterinarian use a systematic approach to radiographic interpretation.

Developmental Anomalies

1. Hereditary multiple exostoses

It is a benign bone tumor (osteochndroma) and is rare in horses. Radiographically, multiple bone protrusion are seen at the metaphyseal areas of long bones above the tendaneous and ligamentous attachment. It must be differentiated from trumatic lesion causing preosteal new bone growth.

Figure 1a, b: Hereditary multiple exostoses in the horse. Exostoses were present on the radius, at the distal end of the tibia and on the ribs; A, left leg; B, right leg; C, the rib. A colt of this horse had the same lesions in the radii and tibiae.

Bipartite navicular bone and anomalous digit

Figure 2a, b: A, Bipartite navicular bone due to non-united center of ossification. The condition is usually manifest bilaterally. The cystic changes within the navicular bone are probably due to the bone's poor vascular supply. B, In contrast to the bone shown in A, this navicular bone has a true fracture line and the fragments are displaced.

Figure 3a, b, c: A, Enlarged metacarpal bone attempting to form an anomalous digit in a horse. B, Normal right leg for camparison. C, Extra digit.

Metabolic Diseases

Metabolic diseases are primary those of a mineral imbalance or deficiency. Enlarged epiphyseal growth palate due to apparent nutritional deficiency are commonly observed in horse.

Epiphysitis

Figure 4a, b, c: Epiphysis (rickets) in a horse. Above, There is a winding at the epiphyseal line with the met: aphysis wider and extending over the line. There is increased bone density at the epiphyseal line. Below, There is widening and increased density at the epiphyseal line. There also appear to be some extension of the metaphysis beyond the epiphyseal line.

Traumatic Conditions

Traumatic injuries account for most of the pathologic changes resulting in lameness. Such injuries may be due to direct trauma and/or sprains.

Figure 5a, b: A, Fracture of the third carpal bone in a four-year-old Thoroughbred gelding. B, Same leg with slightly different angulation with the fracture completely hidden.

Figure 6: False fracture line (arrow) caused by the central sulcus of the frog superimposed over the navicular bone.

Figure 7: Chip fracture of the radial carpal bone of a horse. These radiographs were taken not a slight antero-medial oblique angle to fully outline the fracture fragment. Fractures in this location can be missed easily; and when they are suspected, radiographs should be taken at oblique angles.

Figure 8a, b, c: Vertical fracture of the distal end of the metacarpal bone. Routine view of the forefoot shows a radioopaque vertical line at the distal end of the metacarpal bone (1). The radiograph is slightly underesposed and did not fully outline the extent of the fracture, as demonstrated by a heavier x-ray exposure (2).

Figure 9a, b: Comminuted fracture of the first phalanx involving both metacarpophalangeal (fetlock) and proximal interphalangeal (pastern) joints.

Figure 10a, b: Comminuted fracture of the second phalanx.