Immobilisation - Thumb spica backslab
Indications
Fractures of scaphoid (or suspected fracture)
Fractures of first metacarpal or phalanx
Ulna or radial collateral ligament injuries of thumb
Contraindications (absolute in bold)
None
Alternatives
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
Pruritis
Dermatitis
Abrasions and pressure sores (with risk of infection)
Joint stiffness
Procedural hygiene
Standard precautions
PPE: non-sterile gloves, apron
Area
Plaster room or bed space
Staff
Procedural clinician
Equipment
Stockinette (optional) - small size for thumb, 7.5cm for hand or forearm
7.5cm cotton padding (slightly narrower than arm diameter)
10cm plaster for backslab (slightly wider than arm diameter)
Trauma scissors
Bowl of cold water
Crepe bandages
Tape
Positioning
Sitting with elbow supported on table
Elbow: flexed at 90 degrees
Forearm: neutral pronation and supination
Wrist: 20 degrees extension
Thumb: opposition towards middle finger, interphalangeal joint neutral (if included in backslab)
Cast
Estimate plaster length by laying dry splint next to the area to be splinted
Layers: 8-10 layers
Distal margins: distal palmar crease and below IPJ thumb (beyond tip of thumb for phalangeal fractures)
Proximal margins: three finger-widths below elbow crease
Cut out corners out of backslab at distal end
Medication
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)
Sequence
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 on stockinette for thumb
Apply small stockinette to thumb beyond margins of plaster (allowing folded to a smooth edge)
Apply 2-3 layers of cotton padding beyond plaster margins
Tearing or cutting padding as it passes through the first webspace
Ensure bony prominences are well padded and cotton 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 and apply over radial aspect of forearm and thumb
Turn back padding around the distal and proximal margins of the plaster
Apply crepe bandage firmly over slab and fasten with tape
Gently mould plaster to patient anatomy maintaining POSI 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)
Confirm full MCP flexion and extension through digits 2-5
Confirm full flexion and extension of interphalangeal join of the thumb (if not included in plaster)
Confirm full opposition of thumb to at least middle finger
Confirm full elbow flexion
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
Tips
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 (radial and ulnar styloid)
All backslabs are temporary requiring definitive management after two weeks (e.g. full cast)
Discussion
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 ACI-ECIs@health.nsw.gov.au.
References
NSW Agency for Clinical Innovation. Orthopaedic/musculoskeletal. Sydney: ACI; 2020. Available from https://www.aci.health.nsw.gov.au/networks/eci/clinical/clinical-resources/clinical-tools/orthopaedic-and-musculoskeletal
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: https://www.uptodate.com/contents/basic-techniques-for-splinting-of-musculoskeletal-injuries
Liverpool hospital emergency department: Plaster booklet (2019)