Felis ISSN 2398-2950

Fracture fixation: pin

Synonym(s): Intramedullary pin, IM pin, Rush Pin,

Contributor(s): James Cook, Susan Rackard, J Yovich

Introduction

  • To stabilize a fracture Fracture: overview using an intramedullary (IM) pin inserted down the medullary canal of the bone providing axial alignment and preventing lateral movement until healing is complete.
  • Compression of the fracture site is provided by body weight and muscle action.
  • Rotational stability depends on the line of the fracture, contact of pin with endosteal surface of bone, and its points of fixation in the cortical bone of the proximal fragment and trabecular bone of distal fragment.
  • Regular and straight medullary cavity of long bones and small bodyweight make the cat a good candidate for IM pin use.
  • See also internal fracture fixation Fracture: internal fixation

Uses

  • Simple well-interdigitated, transverse fracture in the limb bone (IM pin).
  • Physeal fractures (Rush pins).
  • Some oblique, spiral and simple comminuted fractures provided auxillary fixation is also used, eg cerclage wires Fracture fixation: wire, external skeletal fixator (ESF) Fracture fixation: external skeletal fixator.
  • Can be used in conjunction with ESF in moderately comminuted fractures.

Advantages

  • Relatively inexpensive.
  • Relatively quick procedure.
  • Not technically difficult.
  • Easy to remove.
  • Limited surgical exposure necessary.
  • 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) - 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

  • Normograde insertion technically more difficult than retrograde.
  • Retrograde insertion requires cutting of pin in situ may   →   protruding end   →   interfere with adjacent joint.
  • Provides little resistance to all but angular deformity, so not suitable for comminuted, long oblique or spiral fractures alone but can be used in conjunction with other implants or fixation methods to improve results, eg cast Fracture fixation: casts, ESF Fracture fixation: external skeletal fixator, cerclage wires Fracture fixation: wire, lag screws Fracture fixation: lag screw, hemicerclage wires, skewer pins.

Requirements

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Preparation

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Procedure

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Outcomes

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Prognosis

  • Good when correctly inserted and used appropriately.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Stigen O (1999) Supracondylar femoral fractures in 159 dogs and cats treated using a normograde intramedullary pinning technique. JSAP 40 (11), 519-23 PubMed.
  • McCartney W (1998) Use of the modified acrylic external fixator in 54 dogs and 28 cats. Vet Rec 143 (12), 330-334 PubMed.

Other sources of information

  • Slatter, D H (1993) Textbook of Small Animal Surgery. 2nd edition. W B Saunders. ISBN: 0 7216 8330 4.


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