Primary care physicians frequently encounter fractures of the lower extremity. Improved orthotic bracing, surgical procedures, and nonsurgical techniques have transformed the treatment of lower extremity fractures. Despite these advances, placement of short leg casts is a cost-effective intervention for many lower extremity fractures and musculoskeletal disorders in primary care practice.
Improved fracture healing occurs with functional treatment, allowing normal movement of the lower extremity while limiting abnormal movement. Functional treatment provides improved and more rapid healing of the fracture site through the stimulation of axial loading (i.e., ambulation). Functional treatment also produces improved cartilage repair from joint motion and improved tendon function, and it reduces the osteoporosis induced by immobilization.
Immobilization is the major benefit of casting, allowing for stabilization and bone callus formation. Casts also provide pain relief, maintain position after reduction of a fracture, and protect the soft tissues surrounding the fracture site. Because casts are rigid and circumferential, they generally should not be applied immediately after a fracture. Fractures can produce a significant amount of bleeding and swelling, and the cast can compromise vascular flow to the tissues if significant swelling increases in the tissues beneath a rigid cast. Most lower extremity fractures should be splinted for at least 72 hours before cast placement is attempted.
Plaster of Paris has been extensively used historically to achieve immobilization. Plaster is easy to use and inexpensive. Walking short leg casts experience extensive stress from weight bearing, and when composed of plaster, these casts require added splint material incorporated within the cast to enhance durability. Splint enhancement can be incorporated within fiberglass casts, but the increased strength of the fiberglass material usually is adequate.
A waterproof cast liner made of multiple square cushions can be used in place of stockinette and gauze beneath fiberglass casts (seeChapter 67). The cast liner allows individuals to shower, bathe, and swim when wearing the cast. The liner works well in forearm casts but can bunch up in the heel in short leg walking casts. Seal-tight cast covers may provide a better option to permit bathing for individuals with short leg casts.
Three rolls of 4- to 6-inch plaster or 4-inch fiberglass material are usually adequate for a short leg casts. The extra cast material incorporated into a short leg
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cast requires additional time during removal. The cast saw blade also generates additional heat when cutting through thicker material, especially fiberglass. The practitioner should avoid trying to cut off the cast posteriorly where the additional splinting is placed and should allow additional time for the cast saw blade to cool to avoid patient burns. A protective strip can be placed beneath the cast to protect the patient's skin during cast removal. The strips do not add bulk to the cast and should be considered in children's casts.
PRIMARY CARE INDICATIONS FOR A SHORT LEG CAST
RELATIVE CONTRAINDICATIONS
Practitioners would be wise to heed the 2001 guidelines for physiotherapists in Australia for the application and removal of casts (http://www.physioreg.health.nsw.gov.au/hprb/physio_web/pdf/plaster.pdf).
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PROCEDURE
When applying a cast, place the injured part in the position of function, unless alternate positioning is required by the clinical situation. The position of function for the foot is with the toes held horizontal and the ankle in neutral dorsiflexion and plantar flexion (i.e., foot is 90 degrees to the lower leg) and in neutral eversion and inversion (Figure 1A). This positioning is critical to maintain throughout cast application; pain and swelling may cause the foot to dangle. An assistant can grasp the toes during cast application to maintain the ankle-foot position (Figure 1B). Alternately, the practitioner can wear a plastic apron and lean against the foot with the torso to maintain position of the foot while leaving the hands free to apply the cast (Figure 1C).
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(1) Place the injured part in the position of function while applying the cast unless the clinical position requires alternate positioning. |
PITFALL: Do not let the foot dangle. If the cast is placed and the foot is not 90 degrees to the lower leg, the heel will be elevated. Weeks in a cast in this position can cause significant shortening of the Achilles' tendon.
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Apply a single layer of stockinette from the end of the toes to the knee (Figure 2A). The extra length on each end helps to smooth the ends of the cast. Because the stockinette is in direct contact with skin, do not leave any bunched-up stockinette. Cut out a thin oval of overlapping stockinette where the dorsal foot meets the lower leg (Figure 2B).
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(2) Apply a single layer of stockinette from the end of the toes to the knee, and cut out a thin oval of overlapping stockinette where the dorsal foot meets the lower leg. |
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Apply the cast padding. Begin ½ inch inside one end of the stockinette and proceed to within an inch of the other end. The cast padding is applied to a double thickness by overlapping the roll 50% on each turn (Figure 3A). If desired, apply the padding (and cast material) with the thenar eminence, keeping the roll flat (like unrolling carpet) and not reversed to avoid dropping the roll during application (Figure 3B). Apply the protective strips down one or both lateral sides of the cast at this time (Figure 3C).
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(3) Begin by applying the cast padding. |
PITFALL: Do not overpad, because this makes the cast too loose.
PITFALL: Extra padding should be applied over bony prominences to avoid injury to these sites under the cast. Break off two 6-inch sections of padding, and place them over the malleoli and over the metatarsal heads on the plantar surface.
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Place the plaster or fiberglass roll in lukewarm or room temperature water. Allow the plaster to sit in the water for a few seconds until the bubbling ceases. Remove the roll, and gently twist or gently squeeze the roll to remove excess water.
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(4) Place the plaster or fiberglass roll in lukewarm water, and allow it to sit for a few seconds until the bubbling ceases. |
PITFALL: Never use hot water, which can cause an exaggerated thermochemical reaction and extremely rapid setting of the cast material. The cast material should never be wrung out.
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Begin on the upper portion of the lower leg at least 2 to 3 fingerbreadths below the fibular head (Figure 5A). The upper portion of the cast should be well below the knee joint. Roll the cast material with moderate tension, applying it in similar fashion to the cast padding, from one end to the other. Overlap 50% of each prior roll. The cast material is rolled to just proximal to the toes. Angle the application so that the toes can all flex and move but all metatarsal heads are covered (Figure 5B).
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(5) Begin applying the plaster or fiberglass roll at least 2 to 3 fingerbreadths below the fibular head, and roll the material with moderate tension, applying it in a similar fashion to the cast padding, from one end to the other. |
PITFALL: A common and dangerous mistake is to apply the cast too high, so that the upper edge of the cast impinges on the peroneal nerve as it passes behind the fibular head. The upper edge of the cast must be well below the fibular head.
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Apply the extra posterior splint material at this time if the cast will be a weight-bearing cast, and certainly if plaster is used. Six-inch splint material that is about ¼ inch thick is used for adults. Place the splint material from the metatarsal heads, over the back of the ankle, and up the posterior calf. Mold the splint so that it adheres and conforms to the first applied roll.
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(6) If the cast will be weight bearing or if plaster is being used, apply extra posterior split material from the metatarsal heads, over the back of the ankle, and up the posterior calf. |
PITFALL: The ankle must be maintained in dorsiflexion to keep the 90-degree angle for the foot. The first roll of cast material is rapidly setting, and if the correct position is not maintained at this stage, the cast will maintain the foot in an incorrect position.
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Apply a second roll over the previous roll on the upper portion of the lower leg and splint material (Figure 7A). After the first circumferential roll, fold back the excess stockinette and padding over the cast material. Reroll over this folded material ½-1inch from the edge of the folded padding to create a smooth edge of cast material and soft edge of padding above the cast material (Figure 7B).
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(7) Apply a second roll over the upper portion of the lower leg and splint material. |
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Roll down the leg. Make sure the cast material adequately covers the heel area (Figure 8A). Excess material can be folded back with tucks or pleats to avoid ridges or creases (Figure 8B).
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(8) Roll down the leg, making sure the cast material adequately covers the heel area. |
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On reaching the distal end of the cast, roll the material over the metatarsal heads to cover the prior roll and splint material. Fold back the cast padding and stockinette to reveal the toes, and then reroll to create a smooth distal end to the cast.
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(9) Roll the material over the metatarsal heads to cover the prior roll and splint material. |
While the cast material is setting, contour or mold the material with the palms of the hands positioned on opposite sides of the cast. After the material sets, make sure a finger can be inserted easily under the cast edge at each end. Give the patient adequate follow-up instructions (see Chapter 67). The patient should wear a cast shoe. Crutches should be used for 24 hours to allow plaster cast material to set and achieve adequate strength for ambulation.
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(10) Contour the cast material while it is setting, making sure a finger can be easily inserted under each end of the cast edge. |
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Cast removal is performed with a vibrating saw. Application of a protective strip down one or both lateral sides of the cast can help prevent injury. The saw is inserted with up-and-down motion as it cuts through the cast material (Figure 11A). After the cast is cut from one end to the other, a cast spreader widens the opening (Figure 11B). Cast scissors can be used to cut the underling stockinette and padding, with extra care used to avoid injuring the patient's skin. If the ankle cannot easily slip out of the cast, perform a cut on the opposite surface to facilitate removal (Figure 11C).
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(11) Use a vibrating saw to remove the cast. |
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CODING INFORMATION
These codes are used only for cast or splint reapplication during a period of follow-up. The initial casting or splinting is considered part of the fracture management code. If no management code is reported, the cast application can be reported at the initial service. A supply code (99070) may be reported in addition to the cast code to help defray the cost of materials (estimated at $12 to $20 for plaster casts, $20 to $50 for fiberglass casts, and $5 to $12 for cast shoes). Insurance such as Medicaid may not cover the cost of materials.
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INSTRUMENT AND MATERIALS ORDERING
Cast care instructions and cast materials ordering information appears in Chapter 67.
Specific materials related to short leg casts include cast shoes (various materials, sizes, colors) at an acquisition cost of $5 to $15 from Darby Drug Co, Inc., Westbury, NY (http://www.darbydrug.com). Seal-tight cast covers, creating a waterproof seal using a nonlatex diaphragm that fits over the upper leg and attaches to a polyvinyl bag, allow daily bathing and showering while preventing water penetration. The acquisition cost is approximately $21 for a reusable cover, which can be obtained from Brown Medical Industries, Spirit Lake, IA (http://www.brownmed.com). De-flex protective strip is a cut-resistant removal aid that provides protection from the cuts and burns from cast saws. The strip does not add bulk to the cast and can be ordered from W. L. Gore & Associates, Flagstaff, AZ (http://www.goremedical.com).
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