Risk factors and treatment of hip and knee prosthetic joint infections

Prosthetic joint infection (PJI) is a devastating complication of total hip arthroplasty (THA) and total knee arthroplasty (TKA). As annual THA and TKA volumes continue rising and the population continues aging, more PJIs are expected to occur. Factors predisposing patients to a PJI are of great interest. Moreover, continually developing treatment modalities and factors that improve the treatment success of PJI, such as founding a multidisciplinary team, is critical to achieving a pain-free functional joint after a PJI. This dissertation aimed to examine the incidence of dental pathology in patients planned for THA or TKA and to investigate whether certain risk factors in patient history could be used to select patients for dental clearance in the Finnish population (I) and to investigate whether perioperative dexamethasone therapy increases the risk for a PJI after THA or TKA (II). Moreover, we wanted to evaluate the effect of a multidisciplinary team on PJI treatment results (III) and examine the results of debridement, antimicrobials, and implant retention (DAIR) for treating acute streptococcal PJIs in a specialised tertiary care centre (IV). Prospective study I included 952 patients scheduled for elective THA or TKA. Patients filled out a questionnaire regarding potential risk factors for dental pathology, and dentists documented patients’ oral health and interventions performed during their examinations. Data were available for 731 patients. Failure at dental clearance was classified as tooth extraction or root canal therapy or if the patient was diagnosed with severe periodontitis during the dentist’s examination. For study II, 18,872 consecutive primary and revision THA and TKA operations were analysed, and the incidence of postoperative PJI was investigated. In 2,922 of those operations, the patient was given a 5–10 mg dose of dexamethasone to prevent postoperative nausea and vomiting (PONV) or as a part of multimodal analgesia. Study III consisted of 154 postoperative PJIs from three time periods representing the changes in treating PJIs. Group 1 comprised 21 PJIs from 2005 to 2007, Group 2 consisted of 65 PJIs from 2011 to 2013, and Group 3 comprised 68 PJIs from 2015 to 2016. A successful outcome was classified as retaining the original or revised implant and no infection-related death. Study IV comprised 54 PJIs caused by streptococci and treated with DAIR. The PJI had to fulfil strict inclusion criteria: DAIR needed to be the first surgical procedure and carried out within three weeks of the onset of symptoms, and modular components had to be exchanged. A successful outcome was classified as retaining the original implant and no infection-related death. For studies II–IV, data were retrospectively collected from clinical information databases. However, data on PJIs were gathered from a surgical site infection surveillance database using prospective data collection. Study I showed that 30% of patients planned for THA or TKA had dental pathology requiring treatment. Independent risk factors for failure were a history of root canal therapy, using tobacco products, visiting a dentist because of oral symptoms within three months, and seeing a dentist within six months. Regular dental examinations were a preventive factor. However, for clinical practice no sufficiently large group of patients was found to be at lower risk for failing dental clearance in the Finnish population. In Study II of 18,872 primary or revision operations, 189 (1.0%) PJIs occurred during follow-up (0.8% after primary and 1.9% after revision operations). The PJI rate was 1.0% in both patients given dexamethasone (30/2,922) and those not given dexamethasone (159/15,950), with no significant difference in risk of PJI (OR 1.030, 95% confidence interval 0.696–1.525, p = 0.849). In Study III, the median number of operations needed in treating PJIs was reduced from 2.0 (Group 1) to 1.0 (Group 3); the median length of stay was reduced from 49 days (Group 1) to 17 (Group 3) after the multidisciplinary team was founded (p = 0.023 and p = 0.000, respectively). The proportion of PJIs treated with two-stage exchange decreased from 52.4% (Group 1) to 16.2% (Group 3); simultaneously, the use of DAIR increased from 42.9% (Group 1) to 89.7% (Group 3) (p = 0.004 and p = 0.000, respectively). In addition, an improvement in successful DAIR outcome from 55.6% (Group 1) to 85.2% (Group 3) was achieved (p = 0.077). Study IV showed that implant survival of 94% was achieved with DAIR-treated streptococcal PJIs, according to a strict algorithm in a specialised tertiary care centre. We found a high incidence of dental pathology in patients planned for elective arthroplasty; no useful risk factors could be detected to select high-risk patients. We discovered that perioperative use of a low dose of dexamethasone for PONV or as part of multimodal analgesia in THA and TKA did not impact PJI incidence. Treating PJI at a specialised centre with a multidisciplinary team, standardised guidelines for diagnostics, and patient-tailored treatment yields good results while using fewer healthcare resources. Good treatment results with DAIR can be achieved by treating streptococcal PJI at a specialised centre with a multidisciplinary team.