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Treatment of Fractures of the Tibia and Radius-Ulna by External Coaptation
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TREATMENT OF FRACTURES OF THE TIBIA AND RADIUS-ULNA BY EXTERNAL COAPTATION Stephen B. Adams, DVM, MS, and John F. Fessler, DVM, MS
Tibial and radial-ulnar fractures in cattle are not as common as fractures of the bones of lower limbs, but they occur with enough frequency to cause significant economic loss to the cattle industry. Greenough8 indicated that radial-ulnar fractures comprised 7% and tibial fractures comprised 12% of all cattle fractures. Tulleners12 reported that radial-ulnar fractures accounted for 8.3% and tibial fractures accounted for 13.3% of limb fractures. In a summary of data provided by 29 veterinary medical schools to a common veterinary medical data base (Veterinary Medical Data Base, Purdue University) during a la-year period from 1985 to 1994, 102 cattle had radial-ulnar fractures and 297 cattle had tibial fractures of 84,828 cattle examined at these schools. By comparison, during this same time period metacarpal and metatarsal fractures were reported in 629 cattle. A number of methods have been described for management of tibial and radial-ulnar fractures. Tibial fractures have been treated with fulllimb casts, modified Thomas splints, Walker splints, modified Thomas splint-cast combinations, transfixation pins and bone plates. 1, 3, 4, 6, 8, 11-13 Radial-ulnar fractures have been treated with full-limb casts, modified Thomas splint-cast combinations, transfixation pins, intramedullary pins, and bone plates. 1, 3, 5, 8, 12 The same methods may be used to repair tibial and radial-ulnar fractures because the bones and the fractures are similar. The tibia and the radius have a similar size and a similar location on the respective rear and fore limbs. They have limited soft-tissue cover
From the Department of Veterinary Clinical Sciences, Purdue University School of Veterinary Medicine, West Lafayette, Indiana
VETERINARY CLINICS OF NORTH AMERICA: FOOD ANIMAL PRACTICE VOLUME 12 • NUMBER 1 • MARCH 1996
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on the medial side and good muscle coverage laterally. Major joints occur at each end of these bones and immobilizing the proximal joints with casts is difficult due to heavy musculature. When fractured, both tibia and radius-ulna may be comminuted; open fractures occur less frequently than do closed fractures. 2, 3, 11 Tibial and radial-ulnar fractures occur in all ages of cattle from very young lightweight calves to large, heavy adult cattle. These factors ensure that no one standard method of treatment will be suitable for every fracture. Methods of internal fixation have been described for the treatment of tibial and radial-ulnar fractures in cattle. Internal fixation with immediate stabilization of fractured bones and early return to weightbearing can be successful. Internal fixation of fractures usually requires general anesthesia, adherence to aseptic technique, special equipment, assistance during implantation, and expertise in application of implants. Internal fixation usually is performed in referral practices. External coaptation may produce poorly aligned fracture fragments and healing often occurs by large callus production. These factors make internal fixation or transfixation pinning of greater consideration in show cattle. I , 3, 4 External coaptation is not ideal for the treatment of open fractures because of lack of fracture stability. Internal fixation or transfixation pinning and casting may provide additional stabilization and aid in preventing osteomyelitis and delayed union. S Transfixation pinning and immobilization with a walking bar cast were successful in an open radial-ulnar fracture in a 405-kg heifer. s We are unaware of successful management of open radial-ulnar fractures in adult cattle with external coaptation alone; however, open tibial fractures have been successfully treated with Thomas splint-cast combinations. 3,4 External coaptation is the treatment of choice for severely comminuted fractures of the tibia and radius:..ulna and fractures in large cattle that are too heavy for satisfactory use of implants. The practicing veterinarian may use methods of external coaptation in the field. Specialized training is not necessary, though experience is helpful. A minimum of equipment is necessary to adequately treat most fractures with external coaptation. Cast material can be purchased from many vendors and splints can be made from steel rods and equipment purchased at hardware stores. Alternatively, permanent splints of several sizes can be prefabricated in metal shops and kept on hand for use when needed. General anesthesia is seldom required. A strong argument for the use of external coaptation is the cost of treatment. Methods of external coaptation are usually far less expensive than internal fixation. External coaptation is often economically feasible for commercial cattle and can allow return to production soundness. 3,4 Economic advantages and wide availability to practitioners make external coaptation a practical choice for many tibial and radial-ulnar fractures. In this article the use of casts and Thomas splint-cast combinations to treat radial-ulnar and tibial fractures in cattle is described.
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PRINCIPLES OF CALLUS HEALING
External coaptation assists bone healing by maintaining fractured pieces in relatively close apposition and by reducing motion at the fracture site. Bone ultimately heals by production of new bone. This is in contrast to most other tissues, in which fibrous connective tissue is the final substance uniting disrupted tissues. Incompletely immobilized fractures cannot heal directly with bone. Bone has a low elongation-tofailure ratio and is disrupted with minimal strain.lO Small amounts of motion at a fracture site prevent bone formation. Healing of incompletely immobilized fractures occurs by the ordered deposition of different tissues at the fracture area, whereby one stronger tissue substitutes for another. This causes a gradually increasing stiffness and strength and a gradually decreasing tolerance to deformation until the fracture is stable enough to allow bone production. The sequence of tissue substitution in the fracture area is hematoma, granulation tissue, connective tissue, fibrocartilage, mineralized fibrous tissue and fibrocartilage, and bone.lO The collection of these tissues at the fracture area is termed callus. The beauty of callus is its ability to strengthen and stiffen the fracture in the presence of motion. Tissues are formed that are suitable for mechanical conditions and a point is reached at which bone can unite the fragments. Strong forces tend to displace the fragments in long-bone fracture because of the long lever arm of the fragment. This may create significant dislocation from minimal force. External callus formation increases the cross-sectional diameter of the bone and increases its resistance to bending. The gain in stability that is provided by placing the repair tissue (callus) away from the axis of the fractured bone is exponentially related to the distance of the callus from the center of rotation. lO External callus provides excellent mechanical stability. The strength of the bone crosssection in the fracture area takes longer to reach normal values with internal fixation and primary bone healing than with external coaptation and callus formation. Callus formation is considered undesirable with methods of internal fixation. Callus formation is not only desirable but necessary for fracture healing with external coaptation. Cattle generally produce callus effectively and rapidly. External coaptation and callus healing have some disadvantages. These disadvantages may include impingement of callus on joints, adhesions of callus to surrounding soft-tissue structures including nerves and muscles, poor alignment of fracture fragments, and pain during the early phases of fracture repair because of incomplete fragment immobilization. I The term fracture disease has been used to describe the poorly functioning limb after external coaptation that results from disuse atrophy of muscles, poor fracture alignment, and prolonged immobilization of joints with secondary stiffness. Fracture disease is seldom a problem in commercial cattle. Cattle are not used for racing, as are many horses, and they generally do not need perfectly functioning limbs to be useful.
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Most cattle presented to our clinic for fracture repair are being salvaged for breeding or milking. We strive for perfect limb function, but when economic considerations, fracture configuration, or other factors preclude perfect limb function, salvaging cattle for useful lives is both acceptable and desirable. ASSESSMENT OF THE FRACTURE
Many factors must be considered before repairing fractures of the tibia or radius-ulna in cattle. The veterinarian should ascertain the feasibility of fracture repair. The characteristics of the fracture are important. These include its location and configuration and whether it is open or closed. Owners usually want to know if the fracture can be repaired, and if so how much repair will cost. The prognosis for successful repair is also desired by most owners. The veterinarian should accurately answer these questions when possible. Fracture assessment should also provide the information needed for determination of the proper method of treatment. Young cattle and calves, because of their small size, are better orthopedic risks than are adult cattle. Casts and splints are more easily constructed and applied to the smaller animal and are less likely to break. Fractures in younger cattle may heal more rapidly than in older animals. Young animals are also easier to manage during the convalescent period. Cattle are surprisingly adept at managing casts or Thomas splintcast combinations after their application. The well-broken, haltered cow (in contrast to the wild range cow) should be a superior orthopedic patient. Range cattle, when left alone, can learn to care for themselves. Cattle that will injure themselves or their caretaker when approached may behave perfectly well after application of a modified Thomas splintcast combination if left alone in a large stall. Continual assessment of these patients during the recovery period is impossible, but fractures can heal. Animal disposition varies among breeds and individuals, and predicting how a certain animal will behave after application of a cast or splint is difficult. The bottom line in cattle, however, is that even a wild animal may become an acceptable orthopedic patient. No substitute exists for a thorough physical examination. The veterinarian should look closely near the fracture site for small puncture wounds of the skin or for skin abrasions. Running a hand over the fracture and checking for wet spots of blood or serum is helpful. Any fracture with an associated skin wound must be considered open, even if the wound does not extend directly to the fracture site. The dermis provides a natural barrier to infection, and loss of dermis destroys tha t barrier. Radiographs of fractures are extremely useful for determining configuration. Multiple positions will allow the veterinarian to determine the number and position of fragments, the involvement of joints, and
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the presence of gas in tissue planes. Gas would indicate infection or an open fracture. Fractures near or extending into joints carry a poorer prognosis than fractures in the middle of long bones. Radiographs should be taken if equipment is available, but the veterinarian should not be hesitant to repair fractures without radiographs when circumstances dictate. Open fractures are more difficult to manage than are closed fractures. Young cattle seem more likely to develop osteomyelitis after open fractures than older cattle. 1 Open fractures that cannot be immobilized have a poor prognosis in any size animal. Fractures of forelimbs are easier to treat with external coaptation than are fractures of the rear limbs. Cattle tolerate casts on the forelimbs better than on the rear limbs. Full-limb casts or splints can usually be made to fit the straight forelimb better than the angulated rear limb. Many adult cattle are heavily muscled, have short, thick gaskins, large udders, or pendulous scrotums that compound the difficulty of fitting a rear full-limb cast or splint. Fracture immobilization in the forelimbs is usually superior to that of the rear limbs because a better-fitting nonangulated cast or splint can be applied. The full-limb cast in the forelimb is easier to construct and less likely to break. Delay in fracture repair results in additional soft-tissue and bone damage and increases the risk of infection. Extensive soft-tissue swelling after a long delay in fracture imrriobilization may make cast or splint change necessary 4 to 7 days after the initial coaptation. This adds to the cost of treatment and the risk of the fracture becoming open. Long delays between injury and evaluation by the veterinarian should not preclude fracture repair with external fixation. In one study, six cattle with radial-ulnar or tibial fractures of 72 hours' duration or longer were repaired successfully with modified Thomas splints combined with plaster casts. 3
SELECTION OF METHODS OF EXTERNAL COAPTATION FOR FRACTURES OF THE TIBIA AND RADIUS-ULNA Casts
Full-limb casts may be useful for treatment of distal diaphyseal or physeal fractures of the radius-ulna and for distal tibial fractures in very young calves. Casts alone do not effectively immobilize the joint directly ab
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Modified Thomas Splint-Cast Combinations
The application of a modified Thomas splint-cast combination is our preferred method of external coaptation for all but open or very distal fractures of the radius-ulna (Fig. 1). The modified Thomas splintcast combination treatment is suitable for most tibial fractures (Fig. 2). The splint-cast combination is also the method of choice for severely comminuted tibial and radial-ulnar fractures in all cattle and for fractures in cattle weighing more than 400 kg in which internal fixation may be disrupted. The Thomas splint-cast combination has been used successfully to treat radial-ulnar fractures in cattle weighing up to 545 kg and tibial fractures in cattle weighing up to 775 kg. 3 APPLICATION OF FULL-LIMB CASTS Materials
Synthetic casting materials, most of which are composed of fiberglass tapes impregnated with polyurethane resin, are commonly used for cast construction. The newer synthetic materials have largely supplemented plaster of Paris. Synthetic casts cure much more quickly than
Figure 1. A, Radial-ulnar fracture in a 2-year-old cow that was treated with a modified Thomas splint-cast combination. B, The cow was able to ambulate easily in modified splintcast combination.
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Figure 2. This oblique comminuted tibial fracture occurred in a 204-kg cow and was treated successfully by external coaptation in a modified Thomas splintcast combination for 7 weeks.
does plaster of Paris, allowing earlier weightbearing. They are also stronger and more durable than plaster of Paris casts. 7 Synthetic casting materials can cure rapidly enough to allow weightbearing in 30 minutes. Maximum strength, however, may not be reached for 24 hours after application. Many synthetic casting materials are available to veterinarians. These products include Vet Cast II (3M, St. Paul, MN), Scotchcast Plus (3M), Zim-Flex (Zimmer, Warsaw, IN), Delta-Lite (Johnson & Johnson Products, New Brunswick, NJ) and Dynacast Extra (Smith and Nephew Casting, Menomonee Falls, WI). The synthetic casting materials do not all reach the same strength when curing. 14 Scotchcast Plus, Vet Cast II, and Zim-Flex casting tapes set quickly and after 2 hours casts are stronger than casts constructed with Delta-Lite casting tapes. However, after 24 hours Delta-Lite casts are strongest. 14 Synthetic casts do not deteriorate when wet; they are porous and light in weight, and radiographs can be made of bones within the casts. Most of the synthetic tapes do not contour and mold to limbs as readily as does plaster of Paris, and when cured the tapes can be abrasive. To reduce cast sores, synthetic casting tapes should be placed over two layers of stockinette or alternatively over a foam bandage (3M Custom Support Foam, 3M) placed on the limb just before casting. Casting tapes should be applied carefully with little tension. They should be conformed to the limb as well as possible. Some casting tapes have considerable stretch capacity, making conforming to the limb easier during application. However, casting materials with elastic tapes may be significantly weaker than standard tapes. 14 Delta Lite Conformable (3M) is significantly weaker than Delta Lite (3M),14 for example. Application of
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narrow 2- or 3-inch wide tapes for the first layer of the cast may aid in contouring the cast to the limb. Wider casting tapes should be used after the first layer is applied to reduce costs and because casts constructed of wider tapes may be stronger. In one study casts constructed of 5-inch wide casting tapes were significantly stronger than casts constructed of 2-inch and 3-inch tapes, but not 4-inch tapes. 14 Methods
Casts should be constructed so that limbs are left in a position suitable for ambulation. 1 The carpus should be flexed slightly in a fulllimb cast with the foot nearly flat on the ground. 9 This position will decrease the torsional forces on the fracture, slightly shorten overall limb length to accommodate for the added length of the cast material on the bottom of the foot, and reduce collapse of comminuted metacarpal fractures by decreasing the piston-like action of the bones when the limb is in straight alignment. Rear limbs should be cast with a natural angle to the hock when traction is not necessary during cast application. The fetlock should be flexed slightly to relax the digital flexors and shorten the limb length to accommodate cast material on the bottom of the foot. Cattle immobilized in full-limb casts with hocks extended are able to flex their stifles because the peroneus tertius and superficial digital flexor muscles are fleshy and can elongate; this eliminates the reciprocal function of the hock and stifle that is present in the horse. The overextended limb, however, is difficult for cattle to manage during ambulation. For cast application, cattle should be restrained in lateral recumbency with the fractured limb uppermost. The foot should be cleaned and trimmed when overgrown. Manure, bedding material, and dirt should be cleaned from the hair because this material irritates the skin when trapped under a well-fitting cast. The skin should be dry. Open wounds should be cleaned, debrided, and covered with a sterile dressing. Stabilization of the limb during casting and traction on the limb may be provided by drilling holes in the hoof, placing wire loops in the holes, and attaching the wire to a bar. Baling wire is suitable. The holes should be drilled near the heel of the hoof in the forelimb to provide traction along the axis of the limb and to position the hoof in a normal weight-bearing position. In the rear limb, the wires should be attached nearer to the toe to cause slight flexion of the fetlock during traction. The natural angulation of the rear limbs in cattle makes excessive traction undesirable; fragments tend to distract in a cranial or caudal direction. The proximal limb must be supported in heavy cattle to prevent deviation of the limb at the fracture site. No amount of traction will counteract this tendency to sag in an unstable, fractured limb. Support during casting may be maintained by an assistant or by slinging a rope around the limb proximal to the top rim of the cast and attaching the rope to
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an overhead object. The claws of the hoof should be spread open to a natural weightbearing position by padding the interdigital space. Two layers of stockinette should be placed next to the skin before application of a fiberglass cast. Waterproof synthetic stockinette is desirable, because fiberglass casts are porous and allow moisture to seep through to the skin. The coronary band and the dewclaws should be lightly padded with cast padding and a band of orthopedic felt 6-cm wide should be positioned over the stockinette at the top of the cast. The top rim of the cast should extend to the proximal radius or crest of the tibia. Custom Support Foam (3M) can be applied over the stockinette as an option. We rarely use this foam support in cattle because of cost and the fact that thick skin in cattle is less likely to sustain cast sores than that of other species. The surgeon should wear lightweight disposable examination gloves while applying the fiberglass casting tapes. Activated resin in the tapes will adhere firmly to skin or clothing. The casting tapes are individually immersed in tap water at room temperature. The casting tapes will gain rigidity 2 to 6 minutes after immersion. The cast is constructed by spirally wrapping the tapes over the limb with one-third to one-half width overlap. Excessive tension should be avoided. The tapes are closely contoured to the limb. Folding, twisting, or tucking the tapes may be necessary, but should be minimized. Caution must be exercised not to leave a depression, wrinkle, or fingerprint in the first layers of cast, which could result in pressure sores. Longitudinal splints are generally unnecessary but may be added to casts for cattle weighing more than 450 kg. Splints should be four to five layers thick and they should be placed on the compression side of the cast or on both the compression and tension sides. 15 The surgeon should incorporate the foot into the cast by working around the wire loops. The position of the limb should be checked and adjusted after several layers of casting tape have been applied and before the tape hardens. Cattle generally require six layers of fiberglass casting tape for adequate cast strength. Calves may require fewer layers, and heavy adult cattle require more. Table 1 gives an approximate number of 12.5cm (5 inch) wide rolls of polyurethane impregnated fiberglass casting
Table 1. APPROXIMATE NUMBER OF ROLLS OF 12.5-cm WIDE BY 3.6-m LONG SYNTHETIC CASTING MATERIAL NEEDED FOR FULL-LIMB CAST CONSTRUCTION IN CATTLE Animal Size (kg)
RolIs*
<70 70-225 225-460 460-675 >675
4-5 6-7 8-9 10-11 12-16
*Rear limb casts generally require more rolls than forelimb casts because of hock angulation.
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tapes for casts construction in cattle of various sizes. Casting material should be concentrated over the fetlock, hock, and carpus because these areas of the cast are most likely to break. After wrapping is completed, the wire loops are cut close to the foot and excessive stockinette is removed. One additional roll of casting tape is used to cover the foot. Fiberglass casts do not wear well at the ground surface. To prevent the foot of the animal from breaking through the cast, a layer of hard acrylic cement should be placed over the sole of the cast or a rubber pad should be taped to the bottom. Exposure of the bottom of the foot will cause the cast to loosen and sores will develop. Elastic adhesive tape is placed around the proximal rim to prevent dirt, bedding, hay, or manure from getting underneath the cast. Fiberglass casts are ready for weightbearing 30 minutes after application.
APPLICATION OF MODIFIED THOMAS SPLINT-CAST COMBINATIONS Materials
The modified Thomas splint can be made of steel rod for the forelimbs of all cattle and for the rear limbs of cattle weighing up to 540 kg. 3 Splints constructed for the rear limbs of cattle weighing more than 540 kg should be made of I-inch conduit pipe or other suitably strong material. The size of steel rod is determined by the weight of the animal (Table 2). Construction of the splint from steel rod requires a 12-foot length of steel with a diameter of 3/8, 1/2, or 5/8 of an inch, a conduit bender, a hacksaw, and a vise (Fig. 3). Welding equipment is not necessary for splints made of steel rod. The splint made from I-inch pipe requires welding. We often construct splints as needed for each animal with a fracture. Alternatively, several sizes of splints can be premade and kept in stock (Fig. 4).4 Premade splints can be made with adjustable
Table 2. PROPER SIZE OF STEEL ROD FOR CONSTRUCTION OF MODIFIED THOMAS SPLINTS FOR CATTLE Forelimb
Rear Limb
Weight (kg)
Rod Size (in)
Weight (kg)
Rod Size (in)
<225 225-450 >450
3/8 1/2
<180 180-360 360-540 >540
3/8 1/2
5/8
5/8 1*
*Conduit pipe From Adams SB: The role of external fixation and emergency fracture management in bovine orthopedics. Vet Clin North Am Food Anim Pract 1:109,1985.
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Figure 3. Modified Thomas splints can be constructed for most cattle from steel rod 3/8inch, 1/2-inch, or 5/8-inch in diameter using a conduit bender to bend the ring.
Figure 4. A, Different sizes of modified Thomas splints can be kept on hand to use for construction of the splint-cast combination. B, This large modified Thomas splint was constructed out of 1-inch diameter conduit pipe and welded together. The length of the struts of the splint can be adjusted. This splint is kept on hand to use for tibial fractures in cattle weighing more than 540 kg.
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leg length. The modified Thomas splint is combined with synthetic casting tape to immobilize fractures. Methods
The animal is positioned in lateral recumbency with the fractured limb uppermost. The foot should be cleaned, trimmed, and drilled for attachment of wire loops in the lateral aspect of the heel of each claw. A template for the ring section of the splint is made from tubing such as a stomach tube. The ring should fit into the axilla or groin without impinging on the point of the shoulder and elbow or the tuber coxae, tuber ischii, and greater trochanter. The points on the ring of the splint where the legs of the splint attach should be noted. Ring formation is begun in the middle of the 12-foot-Iong steel rod; the template should be used to construct the proper size ring (Fig. SA). The steel rod is bent into a ring for 540 degrees with the struts (vertical rods extending to the ground) of the splint continuous with the ring. The struts of the splint are bent approximately 40 degrees away from the plane of the ring, and the splint is checked for fit. The struts of splints constructed for the forelimb are left straight. The struts of splints constructed for rear limbs
Figure 5. Construction of a modified Thomas splint and application to a cow using synthetic casting material. A, The ring is formed using a conduit bender. The template is used to check for proper diameter. B, The ring of the completed splint is padded with foam rubber pipe insulation, and the splint is secured to the limb by wires placed through holes drilled in the lateral aspect of each claw. Padding is placed between the claws and a double roll of stockinette covers the limb. C, After putting casting tapes on the patient's limb, the struts of the splint and the cast are secured with additional casting tapes. 0, The bottom of the completed splint-cast combination is covered with acrylic cement or duct tape to protect the wires and hoof. Figure continued on opposite page
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Figure 5. See legend on opposite page
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can be contoured to the angle of the hock in cattle weighing less than 360 kg but should be left straight for added strength in heavier cattle. The inner aspect of the ring in contact with the axilla or groin can be padded with roll cotton and tape or with foam-rubber pipe insulation. The rods forming the struts of the splint are cut to the length of the patient's limb. A second piece of steel rod is bent into a V-shape with two struts that are the same length as the struts on the ring section. This V-shaped piece is taped to the ring section so that the struts of the completed splint are double rod. Alternatively, the struts can be welded together. The splint is positioned on the limb of the patient and a double layer of stockinette is rolled on the limb (Fig. SB). The claws of the hoof should be separated with cotton or gauge padding placed in the interdigital space. The splint can then be attached to the foot of the patient using the wires previously placed on the hoof. Additional light padding around the dewclaws and coronary band may be necessary. Synthetic casting material is used to complete construction of the modified Thomas splint-cast combination. The first rolls of casting tape are applied to the limb to construct a light cast as described earlier, being careful to avoid wrinkles and indentations. The carpus or hock is supported with a sling of casting tape to prevent medial bowing, and then the limb and splint are incorporated into a single splint-cast unit with additional rolls of casting tape. The casting material should cover the legs of the splint from the ring to the foot to prevent entrapment of the opposite limb, to strengthen the splint, and to prevent urine and manure from accumulating in the cast. The total amount of casting material for construction of the modified Thomas splint-cast combination is similar to that needed for a full-limb cast for the same animal or is slightly more in amount because of the need to span the struts of the splint. Traction on the limb should be adequate to keep the fracture aligned but should be as little as possible. Excessive traction creates pressure sores in the axilla or groin. Pressure on the scrotum in bulls should be avoided when possible. Large udders in lactating dairy cows may prevent the splint from being positioned proximally in the inguinal area as far as would be desirable or may preclude use of the modified Thomas splint-cast combination. Splint-cast combinations on the rear limbs should be placed so that a normal degree of hock flexion is maintained. Complete extension of the joints lengthens the limb and the splint-cast and restricts the ability of the animal to ambulate with the splint-cast combination. An alternative method for Thomas splint-cast application is to immobilize the fracture with a synthetic cast from the midmetacarpus or midmetatarsus extending proximally to the groin or axilla before placing the Thomas splint on the limb. 4 The splint is then positioned, wired to the foot, and incorporated into the cast with additional roles of synthetic casting tapes. This method has the advantage of allowing access to the limb for cast application without having to work around the struts of
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the splint. However, the splint cannot be used to aid fracture stabilization while the cast is being applied. MANAGEMENT OF CATTLE WEARING CASTS OR MODIFIED THOMAS SPLINT-CAST COMBINATIONS
Cattle should be housed on a dirt floor with absorbent bedding. Bedding the stall extremely deep in straw should be avoided because this inhibits ambulation by forcing the animal to drag the immobilized limb. Casts or splint-cast combinations should be kept dry. The strength of fiberglass will not be affected by water, but the material is porous and the limb may get damp causing subsequent skin maceration. The patient must be examined daily to determine if it can stand. Most cattle are quick learners and manage to rise and ambulate within 2 days of immobilization in full-limb casts. Adult cattle may need 4 to 5 days to learn to stand when encumbered by splint-cast combinations on a rear limb, and they require help in the interim. The cast or splint-cast combinations should be inspected daily for cracks, breakage, or protrusion of the foot through the bottom of the cast or splint-cast combination. Broken casts should be replaced immediately. Cracked casts may be patched with additional fiberglass casting tapes. Pressure sores or rubbing sores may be difficult to identify under fiberglass casts. Cattle that become increasingly reluctant to use the immobilized limb and spend increasingly longer periods of time lying down may be developing sores. Pressure sores or rubbing sores develop most commonly at the bulbs of the heel, the plantar or palmar aspect of the fetlock, over the accessory carpal bone, at the point of the hock, at the top rim of the cast, or under the ring of the modified Thomas splint. Visual inspection may show sores at the latter point. Support wraps may be applied to the contralateral limb to prevent tendon strain and limb abrasions. The bony protuberances of all noncast limbs should be wrapped with elastic adhesive tape to prevent skin abrasions from the floor. REMOVAL OF CASTS AND MODIFIED THOMAS SPLINT-CAST COMBINATIONS
Casts and splint-cast combinations may require changing after 4 to 7 days in those cattle with extreme swelling at the time of initial immobilization. Reduced limb size when swelling subsides causes the cast or splint-cast combination to become loose and fit poorly. Full-limb casts and modified Thomas splint-cast combinations should be changed every 3 weeks in young, rapidly growing calves to accommodate the increased limb length. Adult cattle may wear the cast or splint-cast combination up to 6 weeks, providing no complications occur. Few noncomplicated fractures immobilized in casts require immo-
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bilization beyond 6 weeks. The mean time of fracture immobilization of radioulnar and tibial fractures in modified Thomas splint-cast combinations from one study was 5.5 and 7.3 weeks, respectively.3 In another study, the mean time of splint-cast immobilization was 8.4 weeks for tibial fractures. 4 Fractures do not require immobilization until radiographic evidence exists that bone union has occurred. Palpable callus and clinical stability are significant indications that immobilization can be stopped (Fig. 6). These clinical signs usually occur before radiographic evidence of bone union is present. Fiberglass casts and modified Thomas splint-cast combinations should be cut with an oscillating saw for removal. Other techniques such as buried obstetric wire can be used but are more difficult. The limb should be supported with wraps or a temporary splint after removal of the external fixation device, and the animal should be confined to a stall or small paddock for an additional 3 to 6 weeks. Exercise should be increased gradually until normal ambulation returns. This period of confinement is generally sufficient for resolution of decubital sores and ligamentous laxity. Poorly aligned fractures often remodel to a more normal configuration over a 6- to I8-month period. COMPLICATIONS AND PROGNOSIS
Complications of treatment of tibial or radial-ulnar fractures by modified Thomas splint-cast combinations include development of pres-
Figure 6. This tibial fracture was immobilized in a modified Thomas splint-cast combination for 8 weeks. There was sufficient callus to provide clinical stability, and the modified Thomas splint-cast combination was not used any longer.
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sure sores, opening of closed fractures, chronic recumbency, distal physeal fractures, delayed union, poor fracture alignment after healing, ligamentous laxity after splint-cast removal, breakage or damage to the splint-cast, and chronic lameness after healing. 3,4, 5 Complications occur with greater frequency in older, heavier cattle. Cattle weighing more than 800 kg with tibial fractures have a poor prognosis. 4 Most complications can be treated satisfactorily and do not preclude the animal's use for breeding or milking. The combined success for cattle with tibial fractures treated with a Thomas splint-cast combination from two retrospective studies was 86% (24 of 28 successful).3,4 Seven of eight cattle (87.5%) with radial-ulnar fractures were successfully treated with the splint-cast in one study.3 Treatment of three cattle following fracture of the radius-ulna with a full-limb cast incorporating the elbow was reported to be as successful in another study.12 SUMMARY
External coaptation of radial-ulnar and tibial fractures with casts or modified Thomas splint-cast combinations is a useful treatment. The economics of therapy make this method of treatment feasible for commercial animals. Current estimates for the cost of treatment of tibial fractures with Thomas splint-cast combinations are $225.00 for calves and $410.00 for cattle if the metal splints are reused. 4 Casts have similar costs. The availability of external coaptation techniques to all veterinarians and the success of treatment make external coaptation a good method for the treatment of many tibial and radial-ulnar fractures in cattle. I References 1. Adams SB: The role of external fixation and emergency fracture management in bovine
orthopedics. Vet Clin North Am Food Anim Pract 1:109, 1985 2. Adams SB, Fessler JF: Fracture repair. In Oehme FW, Prier JE (eds): Textbook of Large Animal Surgery, ed 2. Baltimore, MD, Williams & Wilkins, 1988, P 317 3. Adams SB, Fessler JF: Treatment of radial-ulnar and tibial fractures in cattle using a modified Thomas splint-cast combination. J Am Vet Med Assoc 183:430, 1983 4. Anderson DE, St. Jean G, Desrochers A: Use of a Thomas splint-cast combination for stabilization of tibial fractures in cattle: 21 cases (1973-1993). Agri- Pract 15:16, 1994 5. Baxter GM, Wallace CE: Modified transfixation pinning of compound radius and ulna fracture in a heifer. J Am Vet Med Assoc 198:665, 1991 6. Denny Hr, Sridhar B, Weaver BMQ, et al: The management of bovine fractures: A review of 59 cases. Vet Rec 123:289, 1988 7. Dingwall JS, Harvey FD, McConnell W, et al: A comparison of breaking strengths of various casting materials. Can Vet J 14:62, 1973 8. Ferguson JG: Management and repair of bovine fractures. Compend Contin Educ Pract Vet 4:5128, 1982 9. Fessler JF, Turner AS: Methods of external coaptation. Vet Clin North Am Large Anim Pract 5:311, 1983 10. Rahn BA: Bone healing: Histologic and physiologic concepts. In Sumner-Smith G
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11. 12. 13. 14. 15.
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(ed): Bone in Clinical Orthopedics: A Study in Comparative Osteology. Philadelphia, Saunders, 1982, p 335 St. Jean G, Clem MF, DeBower RM: Transfixation pinning and casting of tibial fractures in calves: Five cases (1985-1989). J Am Vet Med Assoc 198:139, 1991 Tulleners EP: Management of bovine orthopedic problems, Part I: Fractures. Compend Contin Educ Pract Vet 8:S69, 1986 Walker D: Coaptation splinting of the bovine rear limb. Mod Vet Pract 60:629, 1979 Wilson DG, Vanderby R: An evaluation of six synthetic casting materials: Strength of cylinders in bending. Vet Surg 24:55, 1995 Wilson DG, Vanderby R: An evaluation of fiberglass cast application techniques. Vet Surg 24:118, 1995
Address reprint requests to Stephen B. Adams, DVM, MS Purdue University School of Veterinary Medicine Lynn Hall West Lafayette, Indiana 47907
0749-0720/96 $0.00
+ .20
TREATMENT OF FRACTURES OF THE TIBIA AND RADIUS-ULNA BY EXTERNAL COAPTATION Stephen B. Adams, DVM, MS, and John F. Fessler, DVM, MS
Tibial and radial-ulnar fractures in cattle are not as common as fractures of the bones of lower limbs, but they occur with enough frequency to cause significant economic loss to the cattle industry. Greenough8 indicated that radial-ulnar fractures comprised 7% and tibial fractures comprised 12% of all cattle fractures. Tulleners12 reported that radial-ulnar fractures accounted for 8.3% and tibial fractures accounted for 13.3% of limb fractures. In a summary of data provided by 29 veterinary medical schools to a common veterinary medical data base (Veterinary Medical Data Base, Purdue University) during a la-year period from 1985 to 1994, 102 cattle had radial-ulnar fractures and 297 cattle had tibial fractures of 84,828 cattle examined at these schools. By comparison, during this same time period metacarpal and metatarsal fractures were reported in 629 cattle. A number of methods have been described for management of tibial and radial-ulnar fractures. Tibial fractures have been treated with fulllimb casts, modified Thomas splints, Walker splints, modified Thomas splint-cast combinations, transfixation pins and bone plates. 1, 3, 4, 6, 8, 11-13 Radial-ulnar fractures have been treated with full-limb casts, modified Thomas splint-cast combinations, transfixation pins, intramedullary pins, and bone plates. 1, 3, 5, 8, 12 The same methods may be used to repair tibial and radial-ulnar fractures because the bones and the fractures are similar. The tibia and the radius have a similar size and a similar location on the respective rear and fore limbs. They have limited soft-tissue cover
From the Department of Veterinary Clinical Sciences, Purdue University School of Veterinary Medicine, West Lafayette, Indiana
VETERINARY CLINICS OF NORTH AMERICA: FOOD ANIMAL PRACTICE VOLUME 12 • NUMBER 1 • MARCH 1996
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on the medial side and good muscle coverage laterally. Major joints occur at each end of these bones and immobilizing the proximal joints with casts is difficult due to heavy musculature. When fractured, both tibia and radius-ulna may be comminuted; open fractures occur less frequently than do closed fractures. 2, 3, 11 Tibial and radial-ulnar fractures occur in all ages of cattle from very young lightweight calves to large, heavy adult cattle. These factors ensure that no one standard method of treatment will be suitable for every fracture. Methods of internal fixation have been described for the treatment of tibial and radial-ulnar fractures in cattle. Internal fixation with immediate stabilization of fractured bones and early return to weightbearing can be successful. Internal fixation of fractures usually requires general anesthesia, adherence to aseptic technique, special equipment, assistance during implantation, and expertise in application of implants. Internal fixation usually is performed in referral practices. External coaptation may produce poorly aligned fracture fragments and healing often occurs by large callus production. These factors make internal fixation or transfixation pinning of greater consideration in show cattle. I , 3, 4 External coaptation is not ideal for the treatment of open fractures because of lack of fracture stability. Internal fixation or transfixation pinning and casting may provide additional stabilization and aid in preventing osteomyelitis and delayed union. S Transfixation pinning and immobilization with a walking bar cast were successful in an open radial-ulnar fracture in a 405-kg heifer. s We are unaware of successful management of open radial-ulnar fractures in adult cattle with external coaptation alone; however, open tibial fractures have been successfully treated with Thomas splint-cast combinations. 3,4 External coaptation is the treatment of choice for severely comminuted fractures of the tibia and radius:..ulna and fractures in large cattle that are too heavy for satisfactory use of implants. The practicing veterinarian may use methods of external coaptation in the field. Specialized training is not necessary, though experience is helpful. A minimum of equipment is necessary to adequately treat most fractures with external coaptation. Cast material can be purchased from many vendors and splints can be made from steel rods and equipment purchased at hardware stores. Alternatively, permanent splints of several sizes can be prefabricated in metal shops and kept on hand for use when needed. General anesthesia is seldom required. A strong argument for the use of external coaptation is the cost of treatment. Methods of external coaptation are usually far less expensive than internal fixation. External coaptation is often economically feasible for commercial cattle and can allow return to production soundness. 3,4 Economic advantages and wide availability to practitioners make external coaptation a practical choice for many tibial and radial-ulnar fractures. In this article the use of casts and Thomas splint-cast combinations to treat radial-ulnar and tibial fractures in cattle is described.
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PRINCIPLES OF CALLUS HEALING
External coaptation assists bone healing by maintaining fractured pieces in relatively close apposition and by reducing motion at the fracture site. Bone ultimately heals by production of new bone. This is in contrast to most other tissues, in which fibrous connective tissue is the final substance uniting disrupted tissues. Incompletely immobilized fractures cannot heal directly with bone. Bone has a low elongation-tofailure ratio and is disrupted with minimal strain.lO Small amounts of motion at a fracture site prevent bone formation. Healing of incompletely immobilized fractures occurs by the ordered deposition of different tissues at the fracture area, whereby one stronger tissue substitutes for another. This causes a gradually increasing stiffness and strength and a gradually decreasing tolerance to deformation until the fracture is stable enough to allow bone production. The sequence of tissue substitution in the fracture area is hematoma, granulation tissue, connective tissue, fibrocartilage, mineralized fibrous tissue and fibrocartilage, and bone.lO The collection of these tissues at the fracture area is termed callus. The beauty of callus is its ability to strengthen and stiffen the fracture in the presence of motion. Tissues are formed that are suitable for mechanical conditions and a point is reached at which bone can unite the fragments. Strong forces tend to displace the fragments in long-bone fracture because of the long lever arm of the fragment. This may create significant dislocation from minimal force. External callus formation increases the cross-sectional diameter of the bone and increases its resistance to bending. The gain in stability that is provided by placing the repair tissue (callus) away from the axis of the fractured bone is exponentially related to the distance of the callus from the center of rotation. lO External callus provides excellent mechanical stability. The strength of the bone crosssection in the fracture area takes longer to reach normal values with internal fixation and primary bone healing than with external coaptation and callus formation. Callus formation is considered undesirable with methods of internal fixation. Callus formation is not only desirable but necessary for fracture healing with external coaptation. Cattle generally produce callus effectively and rapidly. External coaptation and callus healing have some disadvantages. These disadvantages may include impingement of callus on joints, adhesions of callus to surrounding soft-tissue structures including nerves and muscles, poor alignment of fracture fragments, and pain during the early phases of fracture repair because of incomplete fragment immobilization. I The term fracture disease has been used to describe the poorly functioning limb after external coaptation that results from disuse atrophy of muscles, poor fracture alignment, and prolonged immobilization of joints with secondary stiffness. Fracture disease is seldom a problem in commercial cattle. Cattle are not used for racing, as are many horses, and they generally do not need perfectly functioning limbs to be useful.
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Most cattle presented to our clinic for fracture repair are being salvaged for breeding or milking. We strive for perfect limb function, but when economic considerations, fracture configuration, or other factors preclude perfect limb function, salvaging cattle for useful lives is both acceptable and desirable. ASSESSMENT OF THE FRACTURE
Many factors must be considered before repairing fractures of the tibia or radius-ulna in cattle. The veterinarian should ascertain the feasibility of fracture repair. The characteristics of the fracture are important. These include its location and configuration and whether it is open or closed. Owners usually want to know if the fracture can be repaired, and if so how much repair will cost. The prognosis for successful repair is also desired by most owners. The veterinarian should accurately answer these questions when possible. Fracture assessment should also provide the information needed for determination of the proper method of treatment. Young cattle and calves, because of their small size, are better orthopedic risks than are adult cattle. Casts and splints are more easily constructed and applied to the smaller animal and are less likely to break. Fractures in younger cattle may heal more rapidly than in older animals. Young animals are also easier to manage during the convalescent period. Cattle are surprisingly adept at managing casts or Thomas splintcast combinations after their application. The well-broken, haltered cow (in contrast to the wild range cow) should be a superior orthopedic patient. Range cattle, when left alone, can learn to care for themselves. Cattle that will injure themselves or their caretaker when approached may behave perfectly well after application of a modified Thomas splintcast combination if left alone in a large stall. Continual assessment of these patients during the recovery period is impossible, but fractures can heal. Animal disposition varies among breeds and individuals, and predicting how a certain animal will behave after application of a cast or splint is difficult. The bottom line in cattle, however, is that even a wild animal may become an acceptable orthopedic patient. No substitute exists for a thorough physical examination. The veterinarian should look closely near the fracture site for small puncture wounds of the skin or for skin abrasions. Running a hand over the fracture and checking for wet spots of blood or serum is helpful. Any fracture with an associated skin wound must be considered open, even if the wound does not extend directly to the fracture site. The dermis provides a natural barrier to infection, and loss of dermis destroys tha t barrier. Radiographs of fractures are extremely useful for determining configuration. Multiple positions will allow the veterinarian to determine the number and position of fragments, the involvement of joints, and
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the presence of gas in tissue planes. Gas would indicate infection or an open fracture. Fractures near or extending into joints carry a poorer prognosis than fractures in the middle of long bones. Radiographs should be taken if equipment is available, but the veterinarian should not be hesitant to repair fractures without radiographs when circumstances dictate. Open fractures are more difficult to manage than are closed fractures. Young cattle seem more likely to develop osteomyelitis after open fractures than older cattle. 1 Open fractures that cannot be immobilized have a poor prognosis in any size animal. Fractures of forelimbs are easier to treat with external coaptation than are fractures of the rear limbs. Cattle tolerate casts on the forelimbs better than on the rear limbs. Full-limb casts or splints can usually be made to fit the straight forelimb better than the angulated rear limb. Many adult cattle are heavily muscled, have short, thick gaskins, large udders, or pendulous scrotums that compound the difficulty of fitting a rear full-limb cast or splint. Fracture immobilization in the forelimbs is usually superior to that of the rear limbs because a better-fitting nonangulated cast or splint can be applied. The full-limb cast in the forelimb is easier to construct and less likely to break. Delay in fracture repair results in additional soft-tissue and bone damage and increases the risk of infection. Extensive soft-tissue swelling after a long delay in fracture imrriobilization may make cast or splint change necessary 4 to 7 days after the initial coaptation. This adds to the cost of treatment and the risk of the fracture becoming open. Long delays between injury and evaluation by the veterinarian should not preclude fracture repair with external fixation. In one study, six cattle with radial-ulnar or tibial fractures of 72 hours' duration or longer were repaired successfully with modified Thomas splints combined with plaster casts. 3
SELECTION OF METHODS OF EXTERNAL COAPTATION FOR FRACTURES OF THE TIBIA AND RADIUS-ULNA Casts
Full-limb casts may be useful for treatment of distal diaphyseal or physeal fractures of the radius-ulna and for distal tibial fractures in very young calves. Casts alone do not effectively immobilize the joint directly ab
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Modified Thomas Splint-Cast Combinations
The application of a modified Thomas splint-cast combination is our preferred method of external coaptation for all but open or very distal fractures of the radius-ulna (Fig. 1). The modified Thomas splintcast combination treatment is suitable for most tibial fractures (Fig. 2). The splint-cast combination is also the method of choice for severely comminuted tibial and radial-ulnar fractures in all cattle and for fractures in cattle weighing more than 400 kg in which internal fixation may be disrupted. The Thomas splint-cast combination has been used successfully to treat radial-ulnar fractures in cattle weighing up to 545 kg and tibial fractures in cattle weighing up to 775 kg. 3 APPLICATION OF FULL-LIMB CASTS Materials
Synthetic casting materials, most of which are composed of fiberglass tapes impregnated with polyurethane resin, are commonly used for cast construction. The newer synthetic materials have largely supplemented plaster of Paris. Synthetic casts cure much more quickly than
Figure 1. A, Radial-ulnar fracture in a 2-year-old cow that was treated with a modified Thomas splint-cast combination. B, The cow was able to ambulate easily in modified splintcast combination.
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Figure 2. This oblique comminuted tibial fracture occurred in a 204-kg cow and was treated successfully by external coaptation in a modified Thomas splintcast combination for 7 weeks.
does plaster of Paris, allowing earlier weightbearing. They are also stronger and more durable than plaster of Paris casts. 7 Synthetic casting materials can cure rapidly enough to allow weightbearing in 30 minutes. Maximum strength, however, may not be reached for 24 hours after application. Many synthetic casting materials are available to veterinarians. These products include Vet Cast II (3M, St. Paul, MN), Scotchcast Plus (3M), Zim-Flex (Zimmer, Warsaw, IN), Delta-Lite (Johnson & Johnson Products, New Brunswick, NJ) and Dynacast Extra (Smith and Nephew Casting, Menomonee Falls, WI). The synthetic casting materials do not all reach the same strength when curing. 14 Scotchcast Plus, Vet Cast II, and Zim-Flex casting tapes set quickly and after 2 hours casts are stronger than casts constructed with Delta-Lite casting tapes. However, after 24 hours Delta-Lite casts are strongest. 14 Synthetic casts do not deteriorate when wet; they are porous and light in weight, and radiographs can be made of bones within the casts. Most of the synthetic tapes do not contour and mold to limbs as readily as does plaster of Paris, and when cured the tapes can be abrasive. To reduce cast sores, synthetic casting tapes should be placed over two layers of stockinette or alternatively over a foam bandage (3M Custom Support Foam, 3M) placed on the limb just before casting. Casting tapes should be applied carefully with little tension. They should be conformed to the limb as well as possible. Some casting tapes have considerable stretch capacity, making conforming to the limb easier during application. However, casting materials with elastic tapes may be significantly weaker than standard tapes. 14 Delta Lite Conformable (3M) is significantly weaker than Delta Lite (3M),14 for example. Application of
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narrow 2- or 3-inch wide tapes for the first layer of the cast may aid in contouring the cast to the limb. Wider casting tapes should be used after the first layer is applied to reduce costs and because casts constructed of wider tapes may be stronger. In one study casts constructed of 5-inch wide casting tapes were significantly stronger than casts constructed of 2-inch and 3-inch tapes, but not 4-inch tapes. 14 Methods
Casts should be constructed so that limbs are left in a position suitable for ambulation. 1 The carpus should be flexed slightly in a fulllimb cast with the foot nearly flat on the ground. 9 This position will decrease the torsional forces on the fracture, slightly shorten overall limb length to accommodate for the added length of the cast material on the bottom of the foot, and reduce collapse of comminuted metacarpal fractures by decreasing the piston-like action of the bones when the limb is in straight alignment. Rear limbs should be cast with a natural angle to the hock when traction is not necessary during cast application. The fetlock should be flexed slightly to relax the digital flexors and shorten the limb length to accommodate cast material on the bottom of the foot. Cattle immobilized in full-limb casts with hocks extended are able to flex their stifles because the peroneus tertius and superficial digital flexor muscles are fleshy and can elongate; this eliminates the reciprocal function of the hock and stifle that is present in the horse. The overextended limb, however, is difficult for cattle to manage during ambulation. For cast application, cattle should be restrained in lateral recumbency with the fractured limb uppermost. The foot should be cleaned and trimmed when overgrown. Manure, bedding material, and dirt should be cleaned from the hair because this material irritates the skin when trapped under a well-fitting cast. The skin should be dry. Open wounds should be cleaned, debrided, and covered with a sterile dressing. Stabilization of the limb during casting and traction on the limb may be provided by drilling holes in the hoof, placing wire loops in the holes, and attaching the wire to a bar. Baling wire is suitable. The holes should be drilled near the heel of the hoof in the forelimb to provide traction along the axis of the limb and to position the hoof in a normal weight-bearing position. In the rear limb, the wires should be attached nearer to the toe to cause slight flexion of the fetlock during traction. The natural angulation of the rear limbs in cattle makes excessive traction undesirable; fragments tend to distract in a cranial or caudal direction. The proximal limb must be supported in heavy cattle to prevent deviation of the limb at the fracture site. No amount of traction will counteract this tendency to sag in an unstable, fractured limb. Support during casting may be maintained by an assistant or by slinging a rope around the limb proximal to the top rim of the cast and attaching the rope to
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an overhead object. The claws of the hoof should be spread open to a natural weightbearing position by padding the interdigital space. Two layers of stockinette should be placed next to the skin before application of a fiberglass cast. Waterproof synthetic stockinette is desirable, because fiberglass casts are porous and allow moisture to seep through to the skin. The coronary band and the dewclaws should be lightly padded with cast padding and a band of orthopedic felt 6-cm wide should be positioned over the stockinette at the top of the cast. The top rim of the cast should extend to the proximal radius or crest of the tibia. Custom Support Foam (3M) can be applied over the stockinette as an option. We rarely use this foam support in cattle because of cost and the fact that thick skin in cattle is less likely to sustain cast sores than that of other species. The surgeon should wear lightweight disposable examination gloves while applying the fiberglass casting tapes. Activated resin in the tapes will adhere firmly to skin or clothing. The casting tapes are individually immersed in tap water at room temperature. The casting tapes will gain rigidity 2 to 6 minutes after immersion. The cast is constructed by spirally wrapping the tapes over the limb with one-third to one-half width overlap. Excessive tension should be avoided. The tapes are closely contoured to the limb. Folding, twisting, or tucking the tapes may be necessary, but should be minimized. Caution must be exercised not to leave a depression, wrinkle, or fingerprint in the first layers of cast, which could result in pressure sores. Longitudinal splints are generally unnecessary but may be added to casts for cattle weighing more than 450 kg. Splints should be four to five layers thick and they should be placed on the compression side of the cast or on both the compression and tension sides. 15 The surgeon should incorporate the foot into the cast by working around the wire loops. The position of the limb should be checked and adjusted after several layers of casting tape have been applied and before the tape hardens. Cattle generally require six layers of fiberglass casting tape for adequate cast strength. Calves may require fewer layers, and heavy adult cattle require more. Table 1 gives an approximate number of 12.5cm (5 inch) wide rolls of polyurethane impregnated fiberglass casting
Table 1. APPROXIMATE NUMBER OF ROLLS OF 12.5-cm WIDE BY 3.6-m LONG SYNTHETIC CASTING MATERIAL NEEDED FOR FULL-LIMB CAST CONSTRUCTION IN CATTLE Animal Size (kg)
RolIs*
<70 70-225 225-460 460-675 >675
4-5 6-7 8-9 10-11 12-16
*Rear limb casts generally require more rolls than forelimb casts because of hock angulation.
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tapes for casts construction in cattle of various sizes. Casting material should be concentrated over the fetlock, hock, and carpus because these areas of the cast are most likely to break. After wrapping is completed, the wire loops are cut close to the foot and excessive stockinette is removed. One additional roll of casting tape is used to cover the foot. Fiberglass casts do not wear well at the ground surface. To prevent the foot of the animal from breaking through the cast, a layer of hard acrylic cement should be placed over the sole of the cast or a rubber pad should be taped to the bottom. Exposure of the bottom of the foot will cause the cast to loosen and sores will develop. Elastic adhesive tape is placed around the proximal rim to prevent dirt, bedding, hay, or manure from getting underneath the cast. Fiberglass casts are ready for weightbearing 30 minutes after application.
APPLICATION OF MODIFIED THOMAS SPLINT-CAST COMBINATIONS Materials
The modified Thomas splint can be made of steel rod for the forelimbs of all cattle and for the rear limbs of cattle weighing up to 540 kg. 3 Splints constructed for the rear limbs of cattle weighing more than 540 kg should be made of I-inch conduit pipe or other suitably strong material. The size of steel rod is determined by the weight of the animal (Table 2). Construction of the splint from steel rod requires a 12-foot length of steel with a diameter of 3/8, 1/2, or 5/8 of an inch, a conduit bender, a hacksaw, and a vise (Fig. 3). Welding equipment is not necessary for splints made of steel rod. The splint made from I-inch pipe requires welding. We often construct splints as needed for each animal with a fracture. Alternatively, several sizes of splints can be premade and kept in stock (Fig. 4).4 Premade splints can be made with adjustable
Table 2. PROPER SIZE OF STEEL ROD FOR CONSTRUCTION OF MODIFIED THOMAS SPLINTS FOR CATTLE Forelimb
Rear Limb
Weight (kg)
Rod Size (in)
Weight (kg)
Rod Size (in)
<225 225-450 >450
3/8 1/2
<180 180-360 360-540 >540
3/8 1/2
5/8
5/8 1*
*Conduit pipe From Adams SB: The role of external fixation and emergency fracture management in bovine orthopedics. Vet Clin North Am Food Anim Pract 1:109,1985.
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Figure 3. Modified Thomas splints can be constructed for most cattle from steel rod 3/8inch, 1/2-inch, or 5/8-inch in diameter using a conduit bender to bend the ring.
Figure 4. A, Different sizes of modified Thomas splints can be kept on hand to use for construction of the splint-cast combination. B, This large modified Thomas splint was constructed out of 1-inch diameter conduit pipe and welded together. The length of the struts of the splint can be adjusted. This splint is kept on hand to use for tibial fractures in cattle weighing more than 540 kg.
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leg length. The modified Thomas splint is combined with synthetic casting tape to immobilize fractures. Methods
The animal is positioned in lateral recumbency with the fractured limb uppermost. The foot should be cleaned, trimmed, and drilled for attachment of wire loops in the lateral aspect of the heel of each claw. A template for the ring section of the splint is made from tubing such as a stomach tube. The ring should fit into the axilla or groin without impinging on the point of the shoulder and elbow or the tuber coxae, tuber ischii, and greater trochanter. The points on the ring of the splint where the legs of the splint attach should be noted. Ring formation is begun in the middle of the 12-foot-Iong steel rod; the template should be used to construct the proper size ring (Fig. SA). The steel rod is bent into a ring for 540 degrees with the struts (vertical rods extending to the ground) of the splint continuous with the ring. The struts of the splint are bent approximately 40 degrees away from the plane of the ring, and the splint is checked for fit. The struts of splints constructed for the forelimb are left straight. The struts of splints constructed for rear limbs
Figure 5. Construction of a modified Thomas splint and application to a cow using synthetic casting material. A, The ring is formed using a conduit bender. The template is used to check for proper diameter. B, The ring of the completed splint is padded with foam rubber pipe insulation, and the splint is secured to the limb by wires placed through holes drilled in the lateral aspect of each claw. Padding is placed between the claws and a double roll of stockinette covers the limb. C, After putting casting tapes on the patient's limb, the struts of the splint and the cast are secured with additional casting tapes. 0, The bottom of the completed splint-cast combination is covered with acrylic cement or duct tape to protect the wires and hoof. Figure continued on opposite page
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Figure 5. See legend on opposite page
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can be contoured to the angle of the hock in cattle weighing less than 360 kg but should be left straight for added strength in heavier cattle. The inner aspect of the ring in contact with the axilla or groin can be padded with roll cotton and tape or with foam-rubber pipe insulation. The rods forming the struts of the splint are cut to the length of the patient's limb. A second piece of steel rod is bent into a V-shape with two struts that are the same length as the struts on the ring section. This V-shaped piece is taped to the ring section so that the struts of the completed splint are double rod. Alternatively, the struts can be welded together. The splint is positioned on the limb of the patient and a double layer of stockinette is rolled on the limb (Fig. SB). The claws of the hoof should be separated with cotton or gauge padding placed in the interdigital space. The splint can then be attached to the foot of the patient using the wires previously placed on the hoof. Additional light padding around the dewclaws and coronary band may be necessary. Synthetic casting material is used to complete construction of the modified Thomas splint-cast combination. The first rolls of casting tape are applied to the limb to construct a light cast as described earlier, being careful to avoid wrinkles and indentations. The carpus or hock is supported with a sling of casting tape to prevent medial bowing, and then the limb and splint are incorporated into a single splint-cast unit with additional rolls of casting tape. The casting material should cover the legs of the splint from the ring to the foot to prevent entrapment of the opposite limb, to strengthen the splint, and to prevent urine and manure from accumulating in the cast. The total amount of casting material for construction of the modified Thomas splint-cast combination is similar to that needed for a full-limb cast for the same animal or is slightly more in amount because of the need to span the struts of the splint. Traction on the limb should be adequate to keep the fracture aligned but should be as little as possible. Excessive traction creates pressure sores in the axilla or groin. Pressure on the scrotum in bulls should be avoided when possible. Large udders in lactating dairy cows may prevent the splint from being positioned proximally in the inguinal area as far as would be desirable or may preclude use of the modified Thomas splint-cast combination. Splint-cast combinations on the rear limbs should be placed so that a normal degree of hock flexion is maintained. Complete extension of the joints lengthens the limb and the splint-cast and restricts the ability of the animal to ambulate with the splint-cast combination. An alternative method for Thomas splint-cast application is to immobilize the fracture with a synthetic cast from the midmetacarpus or midmetatarsus extending proximally to the groin or axilla before placing the Thomas splint on the limb. 4 The splint is then positioned, wired to the foot, and incorporated into the cast with additional roles of synthetic casting tapes. This method has the advantage of allowing access to the limb for cast application without having to work around the struts of
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the splint. However, the splint cannot be used to aid fracture stabilization while the cast is being applied. MANAGEMENT OF CATTLE WEARING CASTS OR MODIFIED THOMAS SPLINT-CAST COMBINATIONS
Cattle should be housed on a dirt floor with absorbent bedding. Bedding the stall extremely deep in straw should be avoided because this inhibits ambulation by forcing the animal to drag the immobilized limb. Casts or splint-cast combinations should be kept dry. The strength of fiberglass will not be affected by water, but the material is porous and the limb may get damp causing subsequent skin maceration. The patient must be examined daily to determine if it can stand. Most cattle are quick learners and manage to rise and ambulate within 2 days of immobilization in full-limb casts. Adult cattle may need 4 to 5 days to learn to stand when encumbered by splint-cast combinations on a rear limb, and they require help in the interim. The cast or splint-cast combinations should be inspected daily for cracks, breakage, or protrusion of the foot through the bottom of the cast or splint-cast combination. Broken casts should be replaced immediately. Cracked casts may be patched with additional fiberglass casting tapes. Pressure sores or rubbing sores may be difficult to identify under fiberglass casts. Cattle that become increasingly reluctant to use the immobilized limb and spend increasingly longer periods of time lying down may be developing sores. Pressure sores or rubbing sores develop most commonly at the bulbs of the heel, the plantar or palmar aspect of the fetlock, over the accessory carpal bone, at the point of the hock, at the top rim of the cast, or under the ring of the modified Thomas splint. Visual inspection may show sores at the latter point. Support wraps may be applied to the contralateral limb to prevent tendon strain and limb abrasions. The bony protuberances of all noncast limbs should be wrapped with elastic adhesive tape to prevent skin abrasions from the floor. REMOVAL OF CASTS AND MODIFIED THOMAS SPLINT-CAST COMBINATIONS
Casts and splint-cast combinations may require changing after 4 to 7 days in those cattle with extreme swelling at the time of initial immobilization. Reduced limb size when swelling subsides causes the cast or splint-cast combination to become loose and fit poorly. Full-limb casts and modified Thomas splint-cast combinations should be changed every 3 weeks in young, rapidly growing calves to accommodate the increased limb length. Adult cattle may wear the cast or splint-cast combination up to 6 weeks, providing no complications occur. Few noncomplicated fractures immobilized in casts require immo-
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bilization beyond 6 weeks. The mean time of fracture immobilization of radioulnar and tibial fractures in modified Thomas splint-cast combinations from one study was 5.5 and 7.3 weeks, respectively.3 In another study, the mean time of splint-cast immobilization was 8.4 weeks for tibial fractures. 4 Fractures do not require immobilization until radiographic evidence exists that bone union has occurred. Palpable callus and clinical stability are significant indications that immobilization can be stopped (Fig. 6). These clinical signs usually occur before radiographic evidence of bone union is present. Fiberglass casts and modified Thomas splint-cast combinations should be cut with an oscillating saw for removal. Other techniques such as buried obstetric wire can be used but are more difficult. The limb should be supported with wraps or a temporary splint after removal of the external fixation device, and the animal should be confined to a stall or small paddock for an additional 3 to 6 weeks. Exercise should be increased gradually until normal ambulation returns. This period of confinement is generally sufficient for resolution of decubital sores and ligamentous laxity. Poorly aligned fractures often remodel to a more normal configuration over a 6- to I8-month period. COMPLICATIONS AND PROGNOSIS
Complications of treatment of tibial or radial-ulnar fractures by modified Thomas splint-cast combinations include development of pres-
Figure 6. This tibial fracture was immobilized in a modified Thomas splint-cast combination for 8 weeks. There was sufficient callus to provide clinical stability, and the modified Thomas splint-cast combination was not used any longer.
TREATMENT OF FRACTURES OF THE TIBIA AND RADIUS-ULNA
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sure sores, opening of closed fractures, chronic recumbency, distal physeal fractures, delayed union, poor fracture alignment after healing, ligamentous laxity after splint-cast removal, breakage or damage to the splint-cast, and chronic lameness after healing. 3,4, 5 Complications occur with greater frequency in older, heavier cattle. Cattle weighing more than 800 kg with tibial fractures have a poor prognosis. 4 Most complications can be treated satisfactorily and do not preclude the animal's use for breeding or milking. The combined success for cattle with tibial fractures treated with a Thomas splint-cast combination from two retrospective studies was 86% (24 of 28 successful).3,4 Seven of eight cattle (87.5%) with radial-ulnar fractures were successfully treated with the splint-cast in one study.3 Treatment of three cattle following fracture of the radius-ulna with a full-limb cast incorporating the elbow was reported to be as successful in another study.12 SUMMARY
External coaptation of radial-ulnar and tibial fractures with casts or modified Thomas splint-cast combinations is a useful treatment. The economics of therapy make this method of treatment feasible for commercial animals. Current estimates for the cost of treatment of tibial fractures with Thomas splint-cast combinations are $225.00 for calves and $410.00 for cattle if the metal splints are reused. 4 Casts have similar costs. The availability of external coaptation techniques to all veterinarians and the success of treatment make external coaptation a good method for the treatment of many tibial and radial-ulnar fractures in cattle. I References 1. Adams SB: The role of external fixation and emergency fracture management in bovine
orthopedics. Vet Clin North Am Food Anim Pract 1:109, 1985 2. Adams SB, Fessler JF: Fracture repair. In Oehme FW, Prier JE (eds): Textbook of Large Animal Surgery, ed 2. Baltimore, MD, Williams & Wilkins, 1988, P 317 3. Adams SB, Fessler JF: Treatment of radial-ulnar and tibial fractures in cattle using a modified Thomas splint-cast combination. J Am Vet Med Assoc 183:430, 1983 4. Anderson DE, St. Jean G, Desrochers A: Use of a Thomas splint-cast combination for stabilization of tibial fractures in cattle: 21 cases (1973-1993). Agri- Pract 15:16, 1994 5. Baxter GM, Wallace CE: Modified transfixation pinning of compound radius and ulna fracture in a heifer. J Am Vet Med Assoc 198:665, 1991 6. Denny Hr, Sridhar B, Weaver BMQ, et al: The management of bovine fractures: A review of 59 cases. Vet Rec 123:289, 1988 7. Dingwall JS, Harvey FD, McConnell W, et al: A comparison of breaking strengths of various casting materials. Can Vet J 14:62, 1973 8. Ferguson JG: Management and repair of bovine fractures. Compend Contin Educ Pract Vet 4:5128, 1982 9. Fessler JF, Turner AS: Methods of external coaptation. Vet Clin North Am Large Anim Pract 5:311, 1983 10. Rahn BA: Bone healing: Histologic and physiologic concepts. In Sumner-Smith G
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(ed): Bone in Clinical Orthopedics: A Study in Comparative Osteology. Philadelphia, Saunders, 1982, p 335 St. Jean G, Clem MF, DeBower RM: Transfixation pinning and casting of tibial fractures in calves: Five cases (1985-1989). J Am Vet Med Assoc 198:139, 1991 Tulleners EP: Management of bovine orthopedic problems, Part I: Fractures. Compend Contin Educ Pract Vet 8:S69, 1986 Walker D: Coaptation splinting of the bovine rear limb. Mod Vet Pract 60:629, 1979 Wilson DG, Vanderby R: An evaluation of six synthetic casting materials: Strength of cylinders in bending. Vet Surg 24:55, 1995 Wilson DG, Vanderby R: An evaluation of fiberglass cast application techniques. Vet Surg 24:118, 1995
Address reprint requests to Stephen B. Adams, DVM, MS Purdue University School of Veterinary Medicine Lynn Hall West Lafayette, Indiana 47907