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Contamination of the medullary canal following pin-tract infection

J C Clasper1, S J Parker, A H Simpson

  • 1Department of Biomedical Sciences, Defence Evaluation and Research Agency, Salisbury, Wiltshire, England. medts@dera.gov.uk

Journal of Orthopaedic Research : Official Publication of the Orthopaedic Research Society
|January 13, 2000
PubMed

Insights

An ovine model demonstrated that external-fixator pin-tract infections are challenging to diagnose and can spread to the medullary canal. Even contaminated pins remained stable, highlighting the need for improved diagnostic methods for pin-tract infections.

Area of Science:

  • Orthopedics
  • Infectious Disease
  • Veterinary Medicine

Background:

  • External-fixator pin-tract infections are a common complication in orthopedic surgery.
  • Early diagnosis and effective treatment are crucial to prevent complications such as bone infection and implant loosening.

Purpose of the Study:

  • To develop and validate an ovine model for studying external-fixator pin-tract infections.
  • To investigate the diagnostic challenges and bacterial spread in pin-tract infections.

Main Methods:

  • Development of an ovine model with external-fixator pin insertion.
  • Contamination of pins with Staphylococcus aureus to induce infection.
  • Novel tissue sampling techniques for assessing medullary canal infection.
  • Clinical, radiographic, and microbiological evaluation of infected pins.

Main Results:

  • Confirmed medullary canal infection in all contaminated pins (10/10) and adjacent pins (5/5).
  • Demonstrated that clinical diagnosis can be difficult, with 20% of infected pins showing no signs of infection or loosening after 1 week.
  • Isolated Staphylococcus aureus from all 15 pin tracts and identified nine other organisms.
  • The majority of infected pins remained well-fixed after 2 weeks.

Conclusions:

  • The ovine model effectively replicates external-fixator pin-tract infections, including medullary canal involvement.
  • Pin-tract infections can be insidious, with subclinical presentation and potential for bacterial spread.
  • Current diagnostic methods may be insufficient for early detection, necessitating further research into improved diagnostic strategies.

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