Short leg casts normally are not sturdy enough to bear weight unless they are fabricated to incorporate a walking cast heel and extra casting material to provide strength and distribute the load.
Certain foot fractures
Certain ankle fractures
Significant local swelling
Fractures that require operative care and should be temporarily immobilized with a splint
Thermal injury (caused by the exothermic reaction of plaster or fiberglass hardening)
Compromised circulation and/or nerve function
Plaster or fiberglass casting material*, 10-cm (4-inch) width
Strong scissors and/or shears
Lukewarm water and a bucket or other container
* Both materials are equally effective. Choice depends on availability and user preference. Length and width of materials depend on the body part being immobilized.
The patient should be positioned so that the operator has appropriate access to the affected leg.
The patient is seated comfortably on the treatment table with the leg dangling.
The ankle should be immobilized in neutral position at 90°.
Step-by-Step Description of Procedure
Apply stockinette to cover the area (eg, about 5 to 10 cm) proximal and distal to the anticipated extent of casting material. When finished, the cast should cover the area from just proximal to the metatarsal heads to just distal to the fibular head.
Place several layers of padding (typically 4).
Wrap the padding circumferentially, from distal to proximal, over the area to which the cast will be applied. Overlap the underlying layer by half the width of the padding.
Apply the padding firmly against the skin without gaps but not so tightly that is compromises circulation.
Smooth the padding as necessary to avoid protrusions and lumps. Tear away some of the padding in areas of wrinkling to smooth the padding.
Consider adding padding over bony prominences.
Immerse the casting material in lukewarm water.
Gently squeeze (do not wring out) excess water from the casting material. (Do not wring out plaster.)
Apply the casting material circumferentially from the metatarsal joints to just distal to the fibular head, overlapping the underlying layer by half the width of the casting material.
Smooth out casting material to fill in the interstices in the plaster, bond the layers together, and conform to the contour of the leg. Use your palms rather than your fingertips to prevent the development of indentations that will predispose the patient to pressure ulcers.
Place 4 to 6 layers of plaster (typically) to ensure adequate immobilization. Each layer overlaps by half the width; this requires 2 to 3 passes circumferentially.
For fiberglass, 2 to 4 layers are usually adequate. (Follow product-specific instructions for application.)
Fold back the stockinette before adding the last layer of casting material. Roll back the extra stockinette and cotton padding at the outer margins of the cast to cover the raw edges of the splinting material and create a smooth edge; secure the stockinette under the casting material.
Check for distal neurovascular status (eg, capillary refill, distal sensation) and motor function.
Maintain the ankle in neutral position at 90° until the casting material hardens sufficiently, typically 10 to 15 minutes.
Advise the patient to keep the cast dry.
Arrange or recommend appropriate follow-up.
Instruct the patient not to bear weight until seen in follow-up.
Tell the patient not to cut the cast or insert any objects between the skin and the cast.
Instruct the patient to watch for complications such as worsening pain, paresthesias/numbness, and color change to the fingers.
Instruct the patient to seek further care if pain cannot be controlled with oral drugs at home.
Warnings and Common Errors
Applying a cast to a swollen leg/foot may predispose to compartment syndrome. Compartment Syndrome Compartment syndrome is increased tissue pressure within a closed fascial space, resulting in tissue ischemia. The earliest symptom is pain out of proportion to the severity of injury. Diagnosis... read more
Applying cotton padding too tightly may predispose to compartment syndrome.
If numbness, tingling, or a sensation of tightness develops, the physician must be notified.
Tips and Tricks
Having the patient lie prone with the knee flexed at 90° allows gravity to help the ankle fall to 90° of flexion.