Canis ISSN: 2398-2942

Fracture fixation: pin

Synonym(s): Intramedullary pin, i/m pin, Rush Pin,

Contributor(s): Susan Rackard

Introduction

  • See also fracture: internal fixation Fracture: internal fixation.
  • To stabilize a fracture using an intramedullary (i/m) pin inserted down the medullary canal of the bone providing axial alignment and preventing bending until healing is complete.
  • Compression of the fracture site is provided by bodyweight and muscle action.
  • Rotational stability is dependent upon the line of the fracture, contact of pin with endosteal surface of medullary cavity, and its points of fixation in the cortical bone of the proximal fragment and trabecular bone of distal fragment.

Uses

  • → Simple well-interdigitated, transverse fracture in the limb bone of a young, small to medium sized dog (i/m pin).
  • → Epiphyseal fractures (Rush pins).

Advantages

  • Relatively inexpensive.
  • Relatively quick procedure.
  • Not technically difficult.
  • Easy to remove.
  • Limited surgical exposure necessary.
  • Paired modified pins (Rush pins) can be used where size of patient precludes use of single i/m pin.
  • Closed or open reduction possible (open method preferred - allows direct visualization of fracture site, easier introduction of pin into distal fragment with minimal tissue damage, and assessment of reduction of fracture).
  • Normograde (from selected entry point) (mandatory for tibia) or retrograde (from fracture site) insertion methods.
  • Normograde insertion allows: more control over point of entry, reduced chance of damage to adjacent joint by pin end, reduced soft tissue damage at entry point, improved stability as pin may bow slightly when passing down medullary cavity.

Disadvantages

  • Same as: Fracture - internal fixation Fracture: internal fixation.
  • Canine long bones have a medullary cavity of irregular diameter, their metaphyses are often curved and taper towards the diaphyses - making them not entirely suitable for intramedullary fixation.
  • Size of pin necessary to fit medullary cavity precludes the use of a single i/m pin in large breeds.
  • Normograde insertion technically more difficult than retrograde.
  • Retrograde insertion requires cutting of pinin situmay → protruding end → interference in adjacent joint.
  • Provides little resistance to all but angular deformity - not suitable for comminuted fractures alone - can be used in conjunction with other implants or fixation methods to improve results, eg external skeletal fixator Fracture fixation: external skeletal fixator , cerclage wires Fracture fixation: wire , plates (comminuted fractures Fracture fixation: plate ).

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

  • Good when correctly inserted.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Gibson K L & van Ee R T (1991) Stack pinning of long bone fractures - a retrospective study. Vet Comp Ortho Traum (2), 48-53 Thieme.
  • Martin R A, Milton J L, Shires P K et al (1988) Closed reduction and blind pinning of selected fractures and luxations in dogs and cats. Comp Contin Educ Pract Vet 10 (7), 784-798 VetMedResource.


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