Large Animals Fracture Repair
Figure 25: Anterior cruciate ligament rupture with an associated fracture of the tibial spine in a horse. The associated fracture of the tibial spine is commonly seen in man but rarely, if ever, seen in the dog. The horse had a history of lameness for a prolonged period of time.
Carpitis (Carpal sprain, Popped knee)
In the early phases of carpitis the radiographic signs are usually limited to those due to soft tissue swelling. The swelling can be confined to one aspect of the carpal joint or be distributed over the entire joint. As the condition progress abnormal new bone proliferation begins primarily over the area of the involved bone (s) and may be extend to adjacent surrounding bones.
Figure 26a, b: Extensive abnormal new bone proliferation involving the distal ends of the radii and the proximal row of carpal bones (carpitis). The condition was bilateral. This horse suffered a traumatic injury several months prior to the examination.
Figure 28: Flexed lateromedial project of the carpus of a three-year-old. Thoroughbred injured three months prior to this study. The horse was treated by intraarticular injection of long-acting steroids and returned to racing within a week.
Abnormal new bone proliferation involving the second and/or forth metacarpal or metatarsal bones with secondary ossification of the interoseous ligaments. The first radiographic signs is a thickening or apparent widening of the affected metacarpus or metatarsal bones. As it progresses, the interoseous space become obliterated.
Sesamoiditis is due to strain on the fetlock area and is most common in race horses, hunters, and jumpers. The suspensory ligaments and the distal sesamoid ligaments may also be affected and show calcified areas.
Figure 31, 31m: Sesamoiditis (arrows). Above, There is abnormal bone growth involving the sesamoid bone as well as the attachment of the middle sesamoidian ligament on the posterior surface of the phalanx. Below, Abnormal new bone growth involving both sesamoid bones.
Traumatic Arthritis of the Metacarpo-phalangeal or Metatarsophalangeal joints (Fetlock Joints) (Osselets)
Figure 33: Periosteal new bone growth and calcification in the capsule or avulsion chip fracture at the attachment of the joint capsule involving the proximal end of the first phalamx (osslets). This was a five-year-old Thoroughbred gelding.
Traumatic Arthritis of the proximal and Distal Interphalangeal joints (High and low Ringbone)
Ringbone is caused by a tearing of the extensor tendon attachments, the collateral ligament, or the joint capsule due to sprain as well as to direct trauma. Poor conformation, repeated trauma, or concussion may also be responsible to this condition.
Abnormal new bone growth will form on the anterior, lateral, and medial aspects of the distal end of the first phalanx, the second phalanx (Fig. 14-34), and/or the extensor process of the third phalanx. The growth may be minimal and involved only a small area on the anterior aspect of the affected bones or the entire distal end of the first phalanx and the proximal end of the second phalanx may be extensively involved (see Figs, 14-55 and 14-57) ordinarily, there will be involvement of only the extensor process of the third phalanx.
Caution must be observed in evaluating new bone growth on the anterior aspect of the second phalanx, particularly on the lateral view. If this view is taken at the slightest oblique angle, the normal roughened contour of the extensor tendon attachment on the anterolateral and anteromedial aspects of the second phalanx will show as bone growth. Great dire in correct positioning must be taken for radiography of the phalanges.
Other conditions, such as fractures, hypertrophic degenerative arthritis, and ankylosis in the area of the pastern joint, fall within the broad category of ringbone. For this reason the use of the term "ringbone" should be qualified by a true pathologic description of the lesion.
Ringbone must be differentiated from (1) ypertrophic degenerative arlhritis, (2) fractures. (3) serous arthritis, and (4) simple sprain.
The prognosis of this condition can best be determined by radiography.
Figure 35: Low ring bone. The upper arrow points to new bone growth on the distal end of the second phalanx while the lower arrow shows avulsion of a portion of the extensor process of the third phalanx. These changes are due to tension on the common digital extensor.
Figure 36: High ringbone. The top pointer indicates new bone growth at the edge of the pastern joint. The lower arrow indicates new bone growth on the anterior surface of the proximal end of the second phalanx. These growths resulted from a pulling of the fibrous portion of the joint capsule or from a pulling of the attachment of the common digital extensor.
Rotation of the third Phalanx (Laminitis, Founder)
Laminitis is an inflammation of the laminae of the foot. It may have any of many etiologic factors, not all of which are fully understood. It may be acute or chronic, and may involve both front feet or all four feet. 11 most commonly occurs in the front feet of race horses. Laminitis predisposes to relation of the third phalanx, a condition developing late in the course of the disease. The lateral radiographic view of the foot is the best for evaluating rotation of the third phalanx (Fig. 14-36). In the normal horse the anterior surface of the hoof wall and the anterior surface of the third phalanx should be parallel. Any angulation between these two structures indicates rotation. In horses with advanced cases there will be a fenestration of the distal aspect of the third phalanx due to direct trauma resulting from the one penetrating !he sole of the foot (Fig. 14-38). Pedal osteitis is a common complication of laminitis. The severity of pedal osteitis is best evaluated on an antero-posterior view of the foot.
Figure 37a, b: Rotation of the third phalanx (laminitis) in a pony. B, Rotation of the third phalanx (laminitis) in a horse with extension of the bone through the sole of the foot causing chip fractures (arrow).