Treatment Plan

Internal fixation is not normally performed in large animals due to the expense and to the "configuration of the long bones and the relationship to joint surfaces."1 However, an external fixation technique involving transfixation pinning and casting has been used successfully in cattle. Given the value of this animal to the owner, it is believed that the use of transfixation pinning and casting would be a medically appropriate and economically reasonable approach.

Even though the original injury did not result in the metacarpus being exposed to the environment, the presence of superficial skin wounds warrants that this case be handled as an open fracture. Before fixation can begin, the affected area of the leg should be clipped free of hair, after which the area should be prepared for sterile surgery. Debridement of any necrotic tissue should follow. Next, the wound should be thoroughly lavaged with a sterile electrolyte solution.

"Transfixation pinning and casting is commonly performed in large animals."2 This approach can involve either a hanging limb pin cast or an external skeletal fixator. A hanging limb pin cast uses Steinmann pins placed through the bone proximal to the injury, followed by application of a full-limb cast. The body weight is transferred to the cast by the pins so that the leg "hangs" inside the pin cast. Alternately, transfixation pins can be placed proximal and distal to the injury and secured with an external skeletal fixator (a Kirschner-Ehmer apparatus). The advantage of this latter technique compared with hanging limb casts is that the fracture is more stable, the fracture fragments are not able to move within the apparatus, and the apparatus may not need to span adjacent joints.

Because this case should be treated as an open wound, a Kirschner-Ehmer apparatus would be the ideal fixation mechanism. This approach would allow for daily inspection and management of the skin wounds. "This fixation approach is best attempted with the calf under general anesthesia in order to reduce the animal's pain and anxiety and facilitate quick, accurate reduction and cast application."3 

A second, though less satisfactory, alternative would involve solely casting the fracture. The calf originally had the fracture bandaged for one month, but the bandage alone was unable to provide sufficient immobilization of the fracture. Additionally, the original bandage was removed well before any appreciable fracture repair could have occurred. An appropriate cast-only approach would involve the use of quick-setting fiberglass fabric cast material, which would be applied over some stockingette material on the calf's leg. A dorsal and a palmar "longitudinal splint extending the length of the limb and incorporating the solar surface of the foot"4 would be placed on top of the cast material and secured in place with additional cast material. "Careful attention must be paid to provide sufficient cast thickness, particularly over joints, to prevent fracture of the cast during recovery and weightbearing. However, creating as light a cast as possible is also important...to facilitate ease of ambulation."5

"Casting the limb with the foot in a semiflexed position under mild traction may help prevent some of the tendency toward severe palmar bowing with caudodistal overriding of the proximal segment."6

Given the presence of open wounds, antibiotic therapy should be aggressively pursued. Ideally, such therapy would begin before the fixation surgery and continue for at least two weeks after. The antibiotic plan must provide for the destruction of the cultured organisms. The culture and sensitivity indicates that both organisms (E.coli and S. aureus) are susceptible to second and third generation cephalosporins or a combination of amoxicillin and gentimicin.  We will want to give ceftiofur (1.1 mg/kg IM SID for a minimum of 14 days), a third-generation cephalosporin because it is approved for use in cattle, has a zero-day withdrawal time and is relatively safe for this young animal.  Because this antibiotic may be nephrotoxic, the animal must be well-hydrated throughout treatment.

Phenylbutazone should be administered during and after surgery on an as-needed basis.

Physical and radiographic evaluations should occur every two to three weeks. Periosteal growth should be expected and, in fact, can be seen on the current set of radiographs. The stabilization apparatus should be left in place until it can be determined radiographically that satisfactory bone healing has occurred.

Following surgery, the calf should be confined to a stall with good footing, such as a dirt floor. Its appetite and overall well-being should be evaluated daily. The injured site "should be checked daily to be certain that no heat, excessive looseness, exudate or cast fractures are present. Any significant changes in the animal's level of comfort with the affected limb may be grounds for cast removal and re-evaluation."7

Calves between one and six months old should be re-evaluated every four weeks. After the stabilization apparatus (Kirschner-Ehmer or cast) is removed, "varying amounts of flexor laxity must be expected."8 Usually during this transition time the limb is supported with a short-limb, Robert Jones bandage, which can be removed in two to four weeks.

The client should be warned that "this particular fracture may be slower to heal than non-calving-related injuries because of the greater propensity for vascular impairment."9 Also, given the delay in applying an appropriate fracture-repair apparatus, there is some potential for the bone to sustain less-than-optimal final healing.



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End Notes

1 VM 8284 class notes, p. 132

2 VM 8284 class notes, p. 138

3 The Veterinary Clinics of North America, Food Animal Practice: Advances in Ruminant Orthopedics, Vol. 12, No. 1, March 1996, p. 201

4,5,7 Ibid, p. 202

8 Ibid, p. 203

6,9 Ibid, p. 205