Long leg cast

A long leg cast may be required to support the fixation and neutralize muscle forces.

• Pressure sores
• Skin irritation
• Thermal burns (avoid using hot water)

The leg should not be immobilized in hyperextension as this puts the anterior cruciate ligament under excessive tension and can also cause pre-patellar skin necrosis.

• Tubular bandage (stockinette) of appropriate size
• Cast padding
• Felt
• Casting material: synthetic, plaster of Paris, or a combination of both
• Water

The water temperature should ideally be between 22° and 25° C.

An assistant supports the ankle with the knee in 30° of flexion. A second assistant or triangle supports the thigh.

The distal edge of the cast extends to the base of the toes. The proximal edge lies just below the groin.

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

The assistant holds the toes, not the stockinette, with the ankle in a neutral position.

Add thick felt or additional padding at the free edges of the cast and prominent areas (eg, fibular head, patella, tibial crest, malleoli, and heel) to prevent pressure sores.

Apply cast padding without creases, overlapping each layer by 50%.

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

The assistant holds the ankle in a neutral position, with the knee in 20°–30° of flexion, if the fracture configuration allows.

Apply the first layer of cast material down to the malleoli and overlap each layer by 50%.

Mold the cast to correct deformity.

When the cast starts to harden, extend it to include foot and ankle.

Apply further layers of cast material to produce sufficient stability.

Avoid sharp edges at the ends of the cast.

Fold the tubular bandage and padding over the lower edge of the cast before applying the final layer of casting material.

Ensure that all toes are visible for vascular assessment.

Parents/carers should understand the following precautions and instructions:

• Elevate the foot to the level of the heart to avoid swelling
• Check daily for swelling, discoloration, and impaired toe circulation (any of which should be reported urgently)
• Immediately report signs suggesting skin irritation ulceration, and cast soiling
• Make sure the cast padding remains dry and avoid inserting anything between the cast and skin