Research Article: Obese patients have higher rates of polymicrobial and Gram-negative early periprosthetic joint infections of the hip than non-obese patients

Date Published: April 8, 2019

Publisher: Public Library of Science

Author(s): Claudia A. M. Löwik, Wierd P. Zijlstra, Bas A. S. Knobben, Joris J. W. Ploegmakers, Baukje Dijkstra, Astrid J. de Vries, Greetje A. Kampinga, Glen Mithoe, Aziz Al Moujahid, Paul C. Jutte, Marjan Wouthuyzen-Bakker, Holger Rohde.


Obese patients are more likely to develop periprosthetic joint infection (PJI) after primary total joint arthroplasty. This study compared the clinical and microbiological characteristics of non-obese, obese and severely obese patients with early PJI, in order to ultimately optimize antibiotic prophylaxis and other prevention measures for this specific patient category.

We retrospectively evaluated patients with early PJI of the hip and knee treated with debridement, antibiotics and implant retention (DAIR) between 2006 and 2016 in three Dutch hospitals. Only patients with primary arthroplasties indicated for osteoarthritis were included. Early PJI was defined as an infection that developed within 90 days after index surgery. Obesity was defined as a BMI ≥30kg/m2 and severe obesity as a BMI ≥35kg/m2.

A total of 237 patients were analyzed, including 64 obese patients (27.0%) and 62 severely obese patients (26.2%). Compared with non-obese patients, obese patients had higher rates of polymicrobial infections (60.3% vs 33.3%, p<0.001) with more often involvement of Enterococcus species (27.0% vs 11.7%, p = 0.003). Moreover, severely obese patients had more Gram-negative infections, especially with Proteus species (12.9% vs 2.3%, p = 0.001). These results were only found in periprosthetic hip infections, comprising Gram-negative PJIs in 34.2% of severely obese patients compared with 24.7% in obese patients and 12.7% in non-obese patients (p = 0.018). Our results demonstrate that obese patients with early periprosthetic hip infections have higher rates of polymicrobial infections with enterococci and Gram-negative rods, which stresses the importance of improving preventive strategies in this specific patient category, by adjusting antibiotic prophylaxis regimens, improving disinfection strategies and optimizing postoperative wound care.

Partial Text

Obesity is a major health concern worldwide, as obesity has nearly tripled in the last decades. Currently, 39% of adults are overweight and 13% are obese [1]. Obesity is not only associated with an increased risk of comorbidities, such as hypertension, diabetes mellitus and ischaemic heart disease [2], but due to early development of osteoarthritis of weight bearing joints, obese patients are also more likely to receive joint arthroplasty [3]. Implantation of joint arthroplasties may lead to postoperative complications, particularly in obese patients [4]. The most important complication is periprosthetic joint infection (PJI), occurring in approximately 1–2% of patients receiving joint arthroplasty [5]. PJI has a large impact on patient’s quality of life and is accompanied by high healthcare costs. Literature indicates that the risk of PJI increases exponentially with the body mass index (BMI): i.e. severely obese patients have a four times increased risk of PJI compared with non-obese patients [6, 7].

This study describes the differences in clinical and microbiological characteristics of early PJI between non-obese, obese and severely obese patients. Our results demonstrated that obese and severely obese patients with periprosthetic hip infections had higher rates of polymicrobial infections with involvement of Enterococcus species. Moreover, severely obese patients with PJI of the hip had a higher rate of infections with Gram-negative microorganisms than non-severely obese patients. Interestingly, these results were not found in obese patients with periprosthetic knee infections, which indicates that infections of the hip and knee should be perceived as two separate entities and should therefore be approached differently. Even though the outcome after DAIR was comparable between non-obese, obese and severely obese patients, the differences in microbiological profile between obese and non-obese patients indicate that preventive measures should be adapted for hip arthroplasty surgery in obese patients.