below the carpus or tarsus.
Comminuted or compound fractures of the digits usually require a more rigid immobilization in order to get adequate healing in a reasonable amount of time. Of great value in complete immobilization is the traction/pin cast, which involves incorporation of wires passing through holes drilled in the rear abaxial walls of the hoof. This also serves to allow the assistant to properly position/align the limb for casting. Transfixation or transcortical pins are usually placed at some point in the lower to mid‐third of metacarpal (MCIIII) or metatarsal III (MTIII) to provide for weight transfer to the cast. Predrilling of a slightly smaller hole (0.5 m or less than the pin diameter) will reduce thermal injury to the bone during pin placement. Oftentimes, only one pin is needed to properly provide for weight transfer in younger animals. Threaded transcortical pin systems are preferred in older, heavier cattle, usually requiring placement of two pins at least 1.5 inches apart from each other. During casting, the pins are incorporated into the cast, with the pin ends cut even with the cast and protected by an acrylic compound placed over them, as well as acrylic applied to the bottom of the cast to protect it. The wires placed in the hoof wall are incorporated into the wall of the cast under tension before completion of the procedure. Most of these casts can be removed at four to six weeks post casting.
Full Limb Casting
When dealing with fractures below the carpus/tarsus, it is always best served to apply a full limb cast. Single or multiple transcortical pins can be of value when incorporated with the cast as a complete fixation. This system provides complete immobilization and can even allow for “windows” to be placed in the casting to allow for local wound treatment in compound fractures. Single cortical fixators may be made with polyvinyl tubing. The one drawback to a large window in a cast is the local tissue edema that can occur at the site of tissue exposure at the opening. This can be controlled somewhat with pressure dressing at the wound site. The more complicated the fracture, the longer the cast may be required to stay in place. Be aware that young animals incurring extended time with a cast on are more predisposed to developing joint stiffness post removal. Fractured limbs that present with a large amount of edema should have the cast replaced 2–3 weeks after initial casting, at this time evaluating bone configuration and examining for any loose pins that may need to be replaced. Be aware if the animal's performance has been good in using the limb; if it becomes reluctant to use the casted limb there may be a problem with the transcortical device (pin fracture or osteomyelitis or both), which is commonly seen in the fourth to fifth week after application. If this is observed, removal of the pin should occur with lavage of the pin site after removal and possibly a course of antibiotics administered. This problem can specifically occur when too much heat is generated as the transcortical device is inserted in the bone. Occasionally a sequestrum may form within one or both cortices at the pin site, requiring aggressive curettage and lavage of the area. These areas will heal quickly. Once again, young animals heal rapidly and four weeks may be ample time for cast placement, yearlings usually require six weeks, and grown cattle require eight weeks of immobilization before cast removal.
Fractures of MCIII and MTIII respond very well to the use of transfixation pinning and casting or external skeleton fixation. In valuable individuals where cosmetic appearance is important, transfixation pinning/external skeletal fixation provides more complete immobilization and improved fracture healing, along with better overall alignment of the fracture fragments.
Special approaches are needed for fractures of the tibia and radius/ulna because external immobilization is difficult. Internal fixation with dynamic compression plates and screws should be considered in the extremely valuable individual, although clinical outcomes have not been very rewarding due to implant failure and postoperative sepsis. Success is more often seen with several different external coadaptations, along with skeletal fixators. In animals of lower genetic and economic value, the modified Thomas splint and a cast can be used to immobilize the limb. This system works well for fractures at the mid‐shaft or the lower one‐third of the affected bone and can be adapted as needed to allow for treatment of open wounds associated with the fractures. External skeletal fixation should be considered in the fractious individual since they seem prone to continually casting themselves on the splinted side, and therefore unable to rise on their own. This form of repair is especially desired when dealing with rough stock [19].
The Walker splint is another versatile splint device used for immobilization of the entire limb and is particularly valuable in tibial or radial fractures involving the proximal one‐third of the bone. It is nearly always combined with casting of the distal limb. The design of the support structure as it relates to the groin area helps to protect the proximal limb from damage caused by abduction. It provides lateral support by cradling the gluteal muscles and keeping the stifle and upper limb more upright as opposed to being abducted. It is amazing how well calm cattle will handle these devices and heal the long bone fractures without additional coadaptation (Figures 16.27–16.29).
Figure 16.27 Excellent treatment for transport of a comminuted fracture of MCIII. Notice a rebar stirrup support for the Robert Jones applied bandage. Stabilized fracture for an 800‐mile ride.
Figure 16.28 Use of a pin cast and external fixators to stabilize a comminuted fracture of the Hereford heifer.
Figure 16.29 Thomas splint/cast and external fixators to immobilize severely comminuted fractures in a mature Longhorn steer.
Fractures of the Proximal Limb
Fractures of the humerus usually occur after a fall or during a traumatic episode such as a bullfight or breeding injury. These fractures are best treated with stall rest, supportive bandaging of the weight‐bearing limb, and NSAIDs. Concurrent damage to the radial nerve can occur with fractures of the humerus, and supportive care with acupuncture and electrical stimulation has proven helpful. If tendon contracture of the affected limb starts to occur, the limb should be bandaged and splinted (Figure 16.30).
Figure 16.30 Fractured humerus with mild radial nerve involvement in a mature cow. Splintage of the lower leg was required to reduce deep digital flexor (DDF) contracture.
Surgical repair of femoral fractures using dynamic compression plates is not often successful in adults because of the difficulty in attaining alignment and compression with fixation screws, and only marginally successful in neonates. Salter‐Harris fractures of the distal femur may be seen in calves delivered by forced extraction during dystocia. If attempted in the calf, it must receive appropriate colostrum supplementation and its health status should be thoroughly evaluated. Use of dynamic compression plates is difficult in neonates because the cortices of the femur are not strong enough to offer good purchase for the fixation screws. Stacked intramedullary pins or locking nail devices may be