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Immobilisation - Long arm backslab

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Fractures of:

Radial shaft

Ulnar shaft


Distal humeral

Contraindications (absolute in bold)



Open reduction with internal fixation

Informed consent

Verbal consent

Less complex non-emergency procedure with low risk of complications

Potential complications

Failure (reduction or immobilisation)

Thermal burns (from heat released during setting of plaster)

Neurovascular compromise



Abrasions and pressures sores (with risk of infection)

Joint stiffness

Procedural hygiene

Standard precautions

PPE: non-sterile gloves, apron


Plaster room or bed space


Procedural clinician and assistant


Stockinette (optional)

7.5cm cotton padding (slightly narrower than arm diameter)

15cm plaster for backslab (slightly wider than arm diameter)

10cm plaster for stirrup (approximately arm diameter)

Trauma scissors

Bowl of cold water

Crepe bandages



Sitting with elbow supported on table or by assistant

Assistant maintains position of limb while proceduralist applies plaster

Thumb pointing to own shoulder

Shoulder abducted slightly

Elbow flexed to 90 degrees

Forearm in neutral pronation and supination

Wrist in neutral or slight extension


Estimate plaster length by laying dry splint next to the uninjured arm

Layers: 8-10 layers along ulnar arm, 10-12 layers for stirrup from axilla to axilla

Distal margin: distal palmar crease (forearm fracture), proximal to radio-carpal joint (distal humeral fracture)

Proximal margin: 5cm below axilla


Consider paracetamol 1g, ibuprofen 400mg and oxycodone 5mg (pain relief one hour pre-procedure)

Consider fentanyl 25-50mcg IV (pain relief pre-procedure adjusted to co-morbid status)

Consider fentanyl 100mcg IV (1.5mcg/kg pain relief pre-procedure adjusted to co-morbid status)


Ensure adequate analgesia prior to procedure

Inspect the extremity prior before splinting, document lesions repairing or dressing as normal

Apply stockinette to arm beyond margins of plaster (allowing folded to a smooth edge)

Cut a small hole in stockinette for thumb

Apply 2-3 layers of cotton padding beyond plaster margins

Tear or cut cotton padding as it passes through the first webspace

Ensure elbow is well padded and padding overlaps itself by 25-50% with minimal creases

Submerge the pre-prepared dry backslab in water until bubbling stops, then remove

Squeeze out excess water, smooth on a flat surface and apply along ulnar border of forearm

Submerge the pre-prepared dry stirrup splint in water until bubbling stops, then remove

Squeeze, smooth apply along the lateral aspect of forearm extending around elbow to medial axilla

Turn back padding around distal and proximal margins of plaster

Apply crepe bandage firmly over slab and fasten with tape

Gently mould plaster to patient anatomy (palm particularly) maintaining wrist and elbow position until hardened

Post-procedure care

Check X-ray, circulation and limb function:

Confirm fracture reduction with post-procedure X-ray

Check capillary refill and comfort (loosen crepe bandage or re-splint if required)

Check plaster is in correct position at elbow and wrist

Check full MCPJ flexion and extension of digits 1-5 or radio-carpal joint, depending on distal margin of plaster

Provide plaster care instructions:

Elevate limb when possible using a collar and cuff sling (decreases pain and swelling)

Avoid applying pressure and heat to the cast

Do not wet the plaster (use plastic bag to protect plaster while in shower)

Return for assessment if damaged cast, increasing pain, numbness or skin colour changes

Provide temporary cast plaster care patient fact sheet


Temporary casting of open fractures requires covering open wounds with saline-moistened sterile gauze

Always use clean cold water (avoiding thermal injury and allowing for 10 minutes moulding time)

Extra padding at bony prominences avoids pressure areas (olecranon, radial and ulnar styloid)

All backslabs are temporary requiring definitive management after two weeks (e.g. full cast)


There are a variety of splinting techniques in common emergency department practice. Indications for specific casts and recommended methods of application may vary depending on your institution. If in doubt seek local advice from an experienced provider or discuss with your orthopaedic team.

Peer review

This guideline has been reviewed and approved by the following expert groups:

Emergency Care Institute

Please direct feedback for this procedure to


NSW Agency for Clinical Innovation. Orthopaedic/musculoskeletal. Sydney: ACI; 2020. Available from

Roberts JR, Custalow CB, Thomsen TW. Roberts and Hedges’ clinical procedures in emergency medicine and acute care. 7th ed. Philadelphia, PA: Elsevier; 2019.

Dunn RJ, Borland M, O’Brien D (eds.). The emergency medicine manual. Online ed. Tennyson, SA: Venom Publishing; 2019.

Eiff MP, Hatch R. Fracture management for primary care. 3rd ed. Philadelphia PA: Saunders; 2011.

Stracciolini A. Basic techniques for splinting of musculoskeletal injuries In: UpToDate. Waltham (MA): UpToDate. 2019 April 18. Available from:

Liverpool hospital emergency department: Plaster booklet (2019)

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