Chapter 4. Patients and methods

Table of Contents
4.1. Patients
4.2. Methods

4.1. Patients

4.1.1. Patient series

Patients were prospectively allocated in these studies. The inclusion criteria were: prosthesis with clinical symptoms and a clinical suspicion of infection. The symptom was usually pain at exercise or rest, and the diagnostic setting was the need to differentiate infection from aseptic loosening of the prosthesis. The main characteristics of the patients included in this work are presented in Tables 3a and b. The patients in the studies III and IV also underwent 99mTc-labelled leukocyte/bone imaging, in addition to 99mTc-ciprofloxacin imaging.

Table 3. Main patient characteristics in the studies 1–4.

StudyMain tracerProsthesisnInfectionsRe-operations
199mTc-leukocytesHip64630
299mTc-leukocytesKnee30813
399mTc-ciprofloxacinKnee1678
499mTc-ciprofloxacinHip30810

Table 4. Main patient characteristics in the studies 1–4

StudyMean age (range)Female / Male %ArthrosisRheumatoidOther
165 (25–87)72 / 28341515
275 (47–82)87 / 1317130
370 (60–82)75 / 251060
463 (25–86)63 / 3713107

4.1.2. Diagnostic criteria of infections

The patient had prosthesis infection if bacterial cultures taken during the operation yielded bacteria, if there was a purulent finding at surgery or if repeated aspirated samples grew bacteria or were purulent. Purulence, as the sole criterion, was only accepted for the patients who had received prior antibiotic treatment or needed long-term antibiotic therapy for recovery. Correspondingly, operatively treated patients were considered uninfected if their operative cultures showed no growth and there was no purulence at surgery. Un-operated patients were considered uninfected if no clinical signs of infection were present during a follow-up period of at least one year. All patients were carefully assessed by the senior consultant for infectious diseases at Oulu University Hospital and by the orthopaedic surgeon, to evaluate the clinical outcome.