Authors of section

Authors

Arnold Besselaar, Daniel Green, Andrew Howard

Executive Editor

James Hunter

General Editor

Fergal Monsell

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Long leg cast

1. General considerations

Choice of immobilization

If there is severe soft-tissue swelling, it is safer to initially splint the limb, converting to a long leg cast when swelling has resolved.

It is important not to immobilize the limb for longer than 4 weeks to avoid knee stiffness. Conversion to a brace allows early mobilization of the knee.

Long leg cast

Complications

  • Compartment syndrome
  • Pressure sore

Splinting

If severe swelling is interfering with circumferential casting, a splint may be applied until swelling resolves.

With the knee in 60° flexion, apply slabs of plaster of Paris posteriorly along the whole leg, covering half of the circumference.

Secure the splint with an elastic bandage.

2. Material

  • Tubular bandage (stockinette) sized both for leg
  • Cast padding
  • Felt
  • Casting material: fiberglass, plaster of Paris or a combination of both
  • Water

The water should be tepid, or lukewarm, with an ideal temperature between 22° and 25° C.

Colder water, or a bandage that is wetter, increases working time, while warmer water, or a bandage that is drier, reduces the working time.

Material for cast application

3. Cast application

Patient and leg positioning

Place the anesthetized patient supine on a radiolucent table. The patient should be positioned on the edge of the table or with a bump under the sacrum to facilitate bandaging into the groin.

An assistant supports the leg with 45°–60° hip flexion.

The patient’s knee should be flexed to approximately 60°, which will prevent the cast from slipping.

Patient and leg positioning

Dressing

Apply the tubular bandage and cut it slightly longer than the length of the final cast.

Dressing for long leg cast

Padding

The distal edge of the cast extends to the base of the toes.

The proximal edge lies just above the greater trochanter on the lateral side, and just below the groin on the medial side.

Apply a layer of cast padding.

Consider adding thick felt over the padding at the free edges of the cast.

Overlap each layer by 1/2.

The tubular bandage and padding should be applied without creases.

Padding for long leg cast

Apply additional cast padding over the patella, malleoli, ankle, and heel, to protect these areas from pressure sores.

It should be appreciated that, when more padding is applied, there will be less support at the injury site.

Application of first cast layer

Apply a first layer of cast material to the leg starting distally.

Overlap each layer by 1/2.

Take care not to create sharp ridges at the level of the popliteal fossa.

Apply further layers of cast material to produce sufficient stability.

Application of first cast layer
Pearl: Take care to avoid pressure over the fibular head and neck, to prevent compression of the common peroneal nerve that could cause neurapraxia, or permanent nerve damage.

Fold the tubular bandage and padding over the edges before applying the final layer of casting material.

Folding bandage and padding over the edges

Final molding

While the cast is still soft, create a supracondylar mold and a varus or valgus mold to counter the potential direction of displacement, determined by the configuration and level of the fracture.

Gently mold the cast to the curve of the tibia and around the knee.

Pressure should be continued until the cast hardens.

Cast molding