Equis ISSN 2398-2977

Musculoskeletal: external fixation - casts

Contributor(s): Steve Adair, Patrick Colahan, Vetstream Ltd, Chris Whitton

Introduction

  • To provide stabilization and immobilization of a limb following injury.

Uses

Types

  • Foot cast- for hoof wall avulsion injury   External fixation: cast 02 - foot  .
  • Fetlock and foot cast- heel bulb laceration   External fixation: cast 01 - half limb  foot  .
  • Distal or short limb cast- to cover foot up to proximal metacarpus or metatarsus.
  • Full limb cast- extends above the carpus or tarsus to proximal radius or tibia; for trauma proximal to fetlock, distal to mid-radius or mid-tibia; reduces strain deformation of the superficial and deep digital flexor tendons of the hindlimb.
  • Sleeve or tube cast- for carpus or tarsus, eg angular limb deformities; permits weightbearing on limb; from proximal radius/tibia to distal metacarpus/metatarsus.

Advantages

  • Modern materials are fast drying and lightweight.
  • Cheap alternative to surgery.
  • Enables horse to bear weight on affected limb, reducing stress and secondary complications to contralateral leg during recovery period.
  • Can be applied to the foot, lower leg or whole limb.
  • Foot casts can be applied to a compliant horse under sedation.

Disadvantages

  • Some abrasions from prolonged cast wearing are inevitable.
  • Require careful monitoring.
  • Horse may weight bear before cast has 'cured'.
  • If long-term cast - may need to replace during treatment period.
  • General anesthesia necessary for casts beyond the foot.
  • Plaster of Paris casts do not achieve full strength for 24 h.
  • Some horses will not tolerate full-limb cast.

Requirements

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Preparation

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Procedure

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Aftercare

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Outcomes

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Prognosis

  • Duration of cast application depends on injury.
  • Phalangeal or metacarpal or metatarsal III fractures   MC / MT 3: fracture  - recovery only if cast.
  • Heel bulb lacerations , joint wounds, tendon lacerations   Flexor tendon: trauma  - 2-3 weeks immobilization. See picture series of laceration   Coronary band: trauma 01  , two weeks after cast removal   Coronary band: trauma 02 - 2 weeks post-cast  and four weeks after cast removal   Coronary band: trauma 03 - 4 weeks post-cast  .
  • Primary means of fracture immobilization - leave on until fracture has healed, replacing at monthly intervals or sooner if required.
  • Foals - replace cast at 10-14 day intervals.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Milner P (2009) Application of a distal limb (foot) cast. UK Vet 14 (1), 15-18 VetMedResource.
  • Riggs C M (1997) Indications for an application of limb casts in the mature horse. Equine Vet Educ 9 (4), 190-197 Wiley Online Library.
  • Wilson D G & Vanderby R (1995) An evaluation of fiberglass cast application techniques. Vet Surg 24, 118-121 PubMed.
  • McClure S R, Watkins J P, Bronson D G & Ashman R B (1994) In vitro comparison of the standard short limb cast and three configurations of short limb transfixation casts in equine forelimbs. Am J Vet Res 55 (9), 1331-1334 PubMed.
  • Nemeth F & Back W (1991) The use of the walking cast to repair fractures in horses and ponies. Equine Vet J 23, 32-36 (combination of walking bar in cast and cross pins - for 'hopeless' comminuted fractures) PubMed.
  • Bartels K E, Penwick R C, Freeman L J, Lowery R L, Alexander T, Appleman K & Blount C (1985) Mechanical testing and evaluation of eight synthetic casting materials. Vet Surg 14 (4), 310-318 VetMedResource.

Other sources of information

  • Bramlage L R, Embertson R E & Libbey C J (1992)Resin impregnated foam as a cast liner on the distal equine limb.In:Proc 37th AAEP Annual Convention.pp 481-485.


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