Chapter 86Bandaging, Splinting, and Casting
Indications for bandaging and cast application include protection of limbs during transport and performance, reduction of soft tissue swelling, protection of surgical wounds, management of skin defects and granulation tissue, protection of surgical implants, management of fractures, and first aid before transport of injured horses. This chapter discusses methods of bandage, splint, and cast application and the acute management of a horse with a suspected fracture or soft tissue injury.
Stable and Traveling Bandages
Bandages used routinely as stable bandages or for transport consist of a padded, quilted, fleece, or an interwoven sheet of cotton as a protective layer, held in place by a flannel wrap or commercially available bandage material. Horses that continually wear stable bandages tend to develop ridges in the hair coat, and this should be noted at a prepurchase examination. Proper bandaging prevents limbs from filling in a stabled horse and helps to prevent injury during transport. The coronary band region is particularly vulnerable during transport, loading, and unloading, and the bandage ideally should extend to cover this area. Alternatively, overreach (bell) boots should be used. Improper bandage application or management can cause the development of white hairs, transient edema, and structural damage to soft tissue structures and, under severe circumstances, pressure necrosis. An excessively tight bandage can result in severe tissue necrosis within 24 hours, resulting in full-thickness skin loss and damage to the underlying soft tissues. The midmetacarpal region seems to be particularly vulnerable. Alternatively, commercially available boots can be used for transport, the best of which extend from proximal to the dorsal aspect of the carpus, or the plantar aspect of the tarsus, to cover the coronary band. The use of exercise bandages and boots for protection and support is discussed in Chapter 37.
Bandaging Wounds
The principles of bandages used to protect wounds are to absorb exudate, reduce soft tissue swelling, and provide an environment conducive to wound healing. Each wound has its own characteristics that make a specific type of bandage, or even the absence of a bandage, ideal. All bandages prevent or reduce edema by providing pressure. A bandage can immobilize a region to a certain extent; the degree of immobilization depends on the type of material used and the manner of its application.
Surgical wounds are generally created under ideal conditions, and proper apposition of the skin edges occurs during suturing. Protection is provided by a nonadherent, porous dressing (Telfa, Kendall Co., Mansfield, Massachusetts, United States) over the wound. The dressing is held in place with a sterile gauze roll (Conform, Kendall Co.), and then a cotton combine roll 45 cm wide (for the lower limb only), or alternatively a soft conforming bandage (Soffban, Smith and Nephew, Hull, North Humberside, United Kingdom). The gauze is held in place with an elastic conforming bandage (Vet-Wrap, 3M Animal Care Products, St Paul, Minnesota, United States; Elastikon, Johnson and Johnson, Arlington, Texas, United States). These dressings are changed every 2 to 3 days, or earlier as needed, until suture removal. In some circumstances bandaging may be prolonged to reduce postoperative swelling and improve cosmetic results. If a full-limb bandage is placed to extend above the carpus or tarsus, an additional bandage 40 cm wide is applied above the first bandage. A layer of gauze is used over the combine and cotton, and an elastic conforming bandage (Elastikon) is then applied. Finally, additional elastic tape is used to secure the top of the bandage to the skin. These types of bandages are used postoperatively for most horses undergoing orthopedic procedures, such as arthroscopy or splint removal, and for most horses with limb wounds, assuming the limb is stable.
In a forelimb the area of the bandage over the accessory carpal bone is incised with a scalpel blade to prevent rub sores from developing. In a hindlimb the point of the hock can be covered by the bandage if duration of bandaging is anticipated to be less than 1 week. If prolonged bandaging is required, the point of the hock should not be covered, to prevent rub sores and potential development of white hairs.
Roll cotton (cotton wool) rather than combine roll may be used for the proximal portion of carpal bandages, because it stays in position best. Roll cotton is particularly useful for reducing soft tissue swelling after desmotomy of the accessory ligament of the superficial digital flexor tendon. A nonadherent layer and conforming gauze are covered by elastic adhesive bandaging tape before application of a full-limb padded bandage. This provides protection of the wound from the environment and prevents hematoma and seroma formation. Care must be taken to avoid excessive tension being applied to the elastic adhesive tape to prevent pressure necrosis.
Pressage Bandages
Pressage bandages (S.C. Meades, Cardiff, Wales) are commercially produced elasticized bandages designed specifically for the carpus and hock and available in three sizes. They provide an excellent method of securing a light bandage in place and providing pressure, with a minimal risk of pressure sores, and are used routinely by one author (SJD). Two turns of an elastic conforming bandage over the proximal extent of the Pressage bandage and application of a stable bandage in the more distal part of the limb help to keep the Pressage bandage from slipping.
Ether Bandages
Ether bandages are used to cover surgical incisions, but they do not provide any compression to the incision. For the ether bandage to stay, the area to which it is applied must be clipped or preferably shaved. Cleansing of the skin with surgical scrub, followed by alcohol rinsing, provides the best environment on which to apply this bandage. Strips of adhesive elastic tape approximately 15 cm in length are cut, and ether is applied to the adhesive side of the bandage tape. The ether-soaked bandage is then applied over gauze sponges and held in place while the ether evaporates and the adhesive dries to the skin and elastic tape. Three or four strips of elastic tape typically are used. Ether bandages are extremely adherent and very useful to protect surgical wounds made for stifle arthroscopy, bone grafts from the tuber coxae, and plate fixation of the olecranon (Figure 86-1). Because of the explosive nature of ether, proper precautions should be followed in its use and storage. Commercially available Primapore (Smith and Nephew) or Coverderm (DeRoyal, Powell, Tennessee, United States) dressings provide a simpler alternative but are less adherent.
Stent Bandages
Stent bandages are towels or gauze rolls that are sutured over wounds to protect the wound from the environment or to relieve tension at the sutured site. A sterile hand towel or gauze sponges, rolled like a cigar to the proper width of the wound, are sutured over the wound with No. 2 or larger suture. A cruciate pattern is usually used. Stent bandages are used after shoulder arthrotomy, after olecranon or femur fracture repair, to cover wounds over the point of the hock, and for other incision sites unsuitable for bandaging. If the stent is to be changed routinely, then loop sutures are placed on both sides of the incision, and umbilical tape can be used as suture to hold the bandage in place between changes.
Wet-to-Dry Bandages
Wet-to-dry bandages are used to absorb exudates and to provide an environment conducive to wound healing, particularly in the proliferative phase of wound healing. After cleansing of the wound, sterile sponges moistened with saline solution are applied to the wound and held in place with normal bandaging techniques. The bandage is changed daily, or as needed, and the process can be repeated as often as necessary until a granulation bed has formed.
With any wound there is a combination of dressings, bandaging, immobilization, and systemic therapy that is appropriate. The management changes as the wound heals, and sometimes alternative strategies need to be adapted. Careful attention to the progress of the wound and understanding of wound healing principles optimize outcome.
Foot Poultice
If a subsolar abscess is suspected, applying a poultice may be necessary, along with foot soaks, to soften the sole to permit drainage and to draw the abscess. A commercial poultice such as Animalintex (3M Animal Care Products; Robinson Animal Healthcare, Chesterfield, United Kingdom) is the simplest to use. A half piece is usually adequate. It should be thoroughly soaked in hot water and partially squeezed out before being applied to the sole of the foot. The poultice is covered by a thick layer of cotton wool, and then conforming bandage is wrapped around the foot to hold the poultice in position. To keep the moisture in, the foot can be placed in a used intravenous fluid bag, which is then covered by duct tape to provide a durable bandage.
Robert Jones Bandage
A Robert Jones bandage is used when additional support or compression is required. The bandage is particularly useful for immobilizing the limb of a horse with a suspected fracture for transport or for recovery from general anesthesia after fracture or wound repair—for example, after lag screw repair of a simple proximal phalangeal fracture or a condylar fracture of the third metacarpal bone. The Robert Jones bandage also can provide limb support if the suspensory apparatus is disrupted, can control severe posttraumatic limb edema, and can provide substantial pain relief to a horse with a severely injured superficial digital flexor tendon. This bandage has a multilayered construction. Compared with a single-layered bandage, a Robert Jones bandage compresses air-filled cotton wool layers to increase rigidity and spread pressure evenly. A half-limb bandage requires four to five rolls of cotton wool, eight to 10 conforming bandages, and three to four rolls of elastic adhesive tape. A full-limb bandage needs twice as much. For a half-limb bandage for a forelimb, the cotton wool should be applied snugly from the foot to the distal aspect of the carpus, incorporating the foot. The first layer, using one and a half to two rolls of cotton wool, should be 2 to 3 cm thick. This layer is then compressed using several conforming bandages at least 15 cm wide. Each bandage is applied using fairly firm, constant pressure to compress the cotton wool evenly. Filler layers of cotton wool usually are needed at the top and bottom of the bandage to create a uniform cylinder. A length of cotton wool is folded in half and placed around the top and bottom of the bandage as a filler layer. Another 2- to 3-cm layer of cotton wool is then applied and is compressed using a conforming bandage. At least three layers are constructed to create a thickness of 6 to 8 cm. The entire length of the bandage is then covered with elasticized tape, which should extend the entire length of the bandage and above and below it, to prevent dirt and bedding material from getting into the bandage. The end of one roll of elasticized bandage and the beginning of the next should overlap to prevent unraveling of the bandage. The end of the last roll is covered by zinc oxide tape. A full-limb bandage is applied similarly. In a forelimb the bandage should extend the entire length of the limb, incorporating the elbow; in a hindlimb the bandage should extend to the proximal aspect of the tibia.
Splinting
Splints should be used to support unstable fractures, when disruption of the suspensory apparatus is suspected, and when a full-limb Robert Jones bandage is used to provide additional support. Proper splinting helps protect bone from further trauma, prevents further soft tissue damage, and may also increase the horse’s comfort. Wood or plastic guttering (diameter about 112 mm), cut in half to give a U shape, can be used. Polyvinyl chloride (PVC) piping is lightweight, inexpensive, and strong, but wood is generally more suitable for lateral splints. The length of the splint depends on the size of the horse and the position of the injury. It is critical that the splints be adequately padded, especially at the top and bottom, to avoid rub sores. A gutter splint can be padded throughout its entire length with cotton wool. Wooden splints should be padded at the top and bottom. The splint should be covered with elastic adhesive tape proximally and distally to prevent it from becoming damaged and developing rough, sharp edges. A splint generally is applied over the dorsum to immobilize the distal aspect of the limb. If a transverse or oblique fracture is suspected, or if support of the suspensory apparatus is lost, the limb should be splinted to align the dorsal cortices of the third metacarpal bone and phalanges to eliminate the bending forces of the metacarpophalangeal joint. An assistant is needed to hold the limb off the ground, supporting it under the antebrachium. One layer of the Robert Jones bandage is applied, and then the splint is strapped to the dorsum of the limb before application of the second layer of the Robert Jones bandage. The splint should be well reinforced at the toe. If a sagittal plane fracture or subluxation or luxation of a joint is suspected, supporting the limb in its normal position is preferable. The splint then can be applied over the full thickness of the Robert Jones bandage. To immobilize the carpal region, or if a fracture in the midmetacarpal region is suspected, caudal and lateral splints are used, extending to the elbow (Figure 86-2). With a fracture of the midradius or proximal aspect of the radius, abduction of the limb is prevented by placement of a lateral splint extending from the ground to the middle of the scapula. The top of the splint must be well padded to prevent rub sores. With a fracture of the ulna and loss of triceps function, it is best to fix the carpus in extension by using a caudal splint extending from the ground to the proximal aspect of the olecranon. In some horses with olecranon fracture this type of splinting makes it more difficult to ambulate, and in those horses this splinting is not used initially. Similar principles apply in a hindlimb. Not all horses tolerate immobilization of a hindlimb, and the clinician must be prepared for the horse to react adversely when it first moves. For horses with fractures of the distal metatarsal region and distally, the limb is held above the hock by an assistant while the Robert Jones bandage and dorsal splint are applied. With a suspected fracture of the midmetatarsal and proximal metatarsal regions, the Robert Jones bandage should be applied with the limb bearing weight, and plantar and lateral splints are applied. The plantar splint should extend up to the proximal aspect of the calcaneus, to fix the tarsus to the distal limb fracture. Wood splints are stronger than gutter splints. Splinting of the hock and distal tibial regions aims to counteract the destabilizing effect of flexion of the stifle through the reciprocal apparatus. To immobilize the hock, a lateral splint is contoured to the angle of the hock by heating PVC gutter pipe over a flame, or by using a 12-mm steel rod that can be shaped by hand but is strong enough to provide support. The splint should extend to the proximal aspect of the tibia. An additional contoured splint can also be placed distal to the stifle and proximal to the fetlock on the plantar (caudal) side.
Fig. 86-2 Full-limb forelimb bandage with lateral and caudal polyvinyl-chloride splints for an unstable diaphyseal third metacarpal bone fracture in a foal.
Several commercial splints are available that are particularly useful in an emergency situation, being easy to apply and rapidly providing pain relief by immobilization of the limb. These include the Kimzey Leg Saver Splint (Figure 86-3) (Kimzey, Woodland, California, United States) and the Monkey Splint (Kruuse, North Yorks, United Kingdom). They are all designed to align the dorsal cortices of the distal limb bones and are appropriate for fractures and luxations distal to the distal third of the metacarpal or metatarsal regions or suspensory apparatus breakdown. The Kimzey Splint also has an extension that reaches to the proximal aspect of the antebrachium and is suitable for use in horses with fractures up to the carpus.
Transport of an Injured Horse
With appropriate immobilization of a limb, a horse with a suspected fracture or major soft tissue injury can be safely transported long distances to a clinic with suitable diagnostic and surgical facilities and a skilled surgeon. Ideally the horse should be transported in a low-loading vehicle. Alternatively the horse should be loaded via a loading ramp, or with the ramp of the vehicle placed on a slope, so that the incline up the ramp into the vehicle is shallow. Ideally a horse with a forelimb injury should travel facing backward so that major load is placed on the hindlimbs when the vehicle decelerates. A horse with a hindlimb injury should travel facing forward. Appropriate but not excessive sedation may be required for transport of a fractious horse. A clinic expecting to receive such horses also should have a loading ramp to minimize the incline down which the horse has to walk when unloaded.
Cast Bandage
Cast bandages are a combination of a standard bandage, casting tape, and splint material (typically PVC). Clinical indications for this technique include management of wounds over the carpus, including transverse lacerations or hygroma resection. After placement of a standard bandage, two layers of cast material are placed over the bandage in the area to be splinted. The splint is then applied and held in place while at least two additional layers of casting tape are applied. In 2 to 3 days the cast material is split to create a bivalve to allow access to the surgical site. The cast can then be reapplied to provide immobilization.
Cast Application
Indications for cast application include after fracture repair or suturing of lacerated tendons or for wound management. Commonly used materials include plaster of Paris, resin-augmented plaster, and fiberglass. Fiberglass casting tape consists of knitted fiberglass fabric impregnated with polyurethane resin and is preferred and used most commonly because of its greater strength, lighter weight, and quicker setting times, despite increased cost. Full-limb (up to elbow or stifle) and half-limb (up to carpus or tarsus) casts can be applied. Full-limb casts are not well tolerated by all horses, and the horse’s temperament should be assessed carefully, particularly before application of a full hindlimb cast. Casts are changed as needed because of rub sores, suture removal, inspection of the limb, and/or breaking or buckling of the cast, usually within 4 weeks after placement. In some circumstances a cast can be left on for up to 6 to 8 weeks; however, the risks of cast rubs increase the longer the cast is left on the horse The use of hydrocolloidal dressings (Tegaderm, 3M Health Care, St Paul, Minnesota, United States) directly over pressure points is useful to prevent and/or treat cast rubs. The placement of a cast effectively lengthens the injured limb. Placement of a shoe equalizes the limb lengths and helps to prevent excessive weight bearing in the unaffected limb. Support of the contralateral foot with a wedge cuff shoe (Nanric Ultimate, Nanric, Lawrenceburg, Kentucky, United States) and sole support (Advanced Cushion Support, Nanric) is recommended if a horse is to be maintained in a cast for a long time.
Casts can be applied in a conscious, sedated horse but are commonly applied with the horse under general anesthesia, after internal fixation or wound repair. The limb should be clean and dry before cast application. Sterile dressings are applied over the surgical site, and a thin layer of nonbinding material such as cotton cast padding should be used to secure the wound dressings. A double layer of sterile stockinette is applied over the limb and extends above the proximal extent of the cast. Four to 5 cm of orthopedic felt is placed at the proximal extent of the cast. Wider felt is used for full-limb casts. In addition, orthopedic felt with the centers cut out can be placed over bony prominences, such as the styloid processes or accessory carpal bone in full-limb casts, to avoid rubs. The felt is secured with adhesive tape. Wire can be placed through holes made in the hoof wall near the toe and secured to a twitch handle to provide a means for an assistant to hold the limb and maintain the proper angle of the digit. In general, the hoof is placed at or near a weight-bearing position. Alternatively, the hoof can be extended to a lesser extent by manual pressure at the toe. Cast padding is applied and overlapped about 50%. The use of 3M Custom Support Foam (3M Healthcare), which has a polyurethane resin–impregnated cast padding, is helpful in reducing cast rubs. Another cast padding product is Procel Cast Liner (W.L. Gore and Associates, Flagstaff, Arizona, United States), which remains dry and allows the skin to remain dry through evaporation (Figure 86-4). It is important not to use too much cast padding, because the cast will compress it and the cast will become loose, predisposing the horse to rub sores. Casting tape (3M Scotchcast, 3M Healthcare; 10 to 12 cm wide) is applied, beginning on the orthopedic felt at the top of the cast. The material is spiraled down the limb, taking care not to apply it too tightly, while avoiding wrinkles. Because the limb is not a perfect cylinder, wrinkles tend to develop in areas where contouring is necessary. Tension across the width of the casting tape eliminates potential folds or wrinkles. The next roll of casting tape begins where the first leaves off. At least five rolls of casting tape are used on the limb to construct a half-limb cast, and sometimes one or two additional rolls. When this is complete, more casting tape should be applied at the fetlock and distally, because this is the most common site of breakage. If the distal limb is extended using wires through the hoof wall, the toe region is not cast until the rest of the limb is finished and the twitch handle is no longer necessary. The wire and twitch handle are removed and the foot is covered with one to two rolls of casting tape. If a heel wedge is required, folded casting tape or a wood wedge can be incorporated in the casting tape applied to the hoof. Polymethylmethacrylate (Technovit, Jorgenson Laboratories, Loveland, Colorado, United States) is applied to the bottom of the cast, especially if the cast is to remain more than 2 weeks, to prevent wearing through of the casting tape.
For application of a cast in a standing horse the same protocol is followed, except a 2.5- to 5-cm block is placed under the horse’s hoof, so that the heel is left hanging slightly over the edge of the block, and the cast is applied. After the limb has been cast, the limb is lifted and casting tape and polymethylmethacrylate are applied to the hoof. When standing casts are applied for first aid treatment of unstable fractures, a dorsal splint can be incorporated to maintain the bony column in a straight line. Foot casts are useful in managing heel bulb lacerations and in the prevention of support limb laminitis.
Potential cast complications include rub sores and cast breakage. Rub sores can occur over any bony prominence or any area where cast folds or fingerprints are present. Common sites for cast rubs include the proximal dorsal metacarpal and metatarsal regions, proximal sesamoid bones, and heel bulbs in half-limb casts; and the elbow, distal aspect of the radius, accessory carpal bone, stifle, and point of the hock in full-limb casts. Increased lameness, fever, drainage, heat, foul odor, and swelling proximal to the cast are signs of cast rubs. Rub sores are common complications of cast application and usually are managed easily by cast change or removal. Failure to recognize rub sores can lead to serious problems, such as large wound defects, infections of synovial structures, or laminitis in the supporting limb. Proper application and careful monitoring of cast is essential to prevent serious rub sores.