Long leg cast

A long leg cast may be required to provide more stability and prevent the child from weight bearing on the injured leg. It may be changed to a below-knee cast when the fracture is sufficiently stable.

The cast may be applied in two stages, initially over the leg and foot and then extending to the upper thigh with the knee flexed. This initially controls the ankle and facilitates casting of the thigh with the knee in the correct position.

• Pressure sores
• Skin irritation
• Loss of reduction
• Compartment syndrome
• Thermal burns (avoid using hot water)

If severe swelling prevents application of a circumferential cast, a temporary splint may be applied as an alternative.

With the knee flexed, apply padding around the leg and slabs of casting material posteriorly, covering half of the circumference.

Secure the splint with an elastic bandage.

• 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 leg with knee flexion.

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.

Consider adding 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 if the fracture configuration allows. 

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

Avoid sharp edges at the ends of the cast. Make sure the upper end of the cast is well below the popliteal fossa.

Apply further layers of cast material to produce sufficient stability.

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

Remove the triangular support.

Do not increase knee flexion while applying the upper part of the cast. This prevents injury to the skin behind the knee by the edge of the lower cast.

Extend the cast to include the thigh, overlapping the upper part of the leg cast.

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