Factors in pin tract infections.

To determine the factors pertinent to the etiology of pin tract infections, 214 pins in 42 patients were examined prospectively at the time of pin removal. Eighty-nine (41.6%) pin tracts were inflamed, 49 (22.9%) pins had loose anchorages, and 160 (74.8%) pin tips cultured positive for bacteria. The predominant organism cultured was Staphylococcus epidermidis (90.6%), considered nonvirulent, followed by virulent Staphylococcus aureus (37.5%), and Escherichia coli (9.4%). There were 32 loose, inflamed pin tracts. This correlation was statistically significant (P less than .005). There were 40 loose pins whose pin tips had positive cultures. Loose pins correlated for infection with virulent species of bacteria at a highly significant level (P less than .005). Results demonstrate that most pins possess bacterial colonization. Clinically, this means that either inflamed pin tracts or pins with cultures positive for invasive organisms are probably loose and should be removed. Also, mechanical factors are the critical variable in determining the flora of external fixation pins.