Relationship between the McPherson classification and complications after hip spacer implantation

The implantation of antibiotic-loaded cement spacers is established in the treatment of late hip joint infections, and the McPherson staging system has been widely used in this context. The aim of our study was to evaluate the relationship between the McPherson classification and complications at the site of hip spacer implantation. 60 patients were retrospectively identified who fulfilled our inclusion criteria. Using the McPherson classification, 12 patients were categorised as IIIA1, 4 as IIIA2, 19 as IIIB1, 7 as IIIB2, 12 as IIIC1, and 6 as IIIC2. Complications recorded were infection-associated, mechanical, systemic, general, and mortality. Statistical analysis was performed by means of the Mantel-Haenszel and the exact Fisher tests. In relation to complications with respect to the systemic host grade, the Mantel-Haenszel test revealed significant differences regarding only the emergence of a draining sinus. In relation to complications with respect to the local extremity grade, the exact Fisher test revealed significant differences regarding only the emergence of wound healing complications. All other complications showed no significant differences. The McPherson classification, in association with an increasing number of comorbidities, indicates a higher risk of occurrence of a postoperative draining sinus, whereas the grade of compromised local tissues is associated with wound healing complications. Improvement of the general medical condition of patients between stages as well as an anatomical dissection and closure of the wound may lead to a decreased incidence of these complications.