Abstract
Aim
Obese patients are not only more likely to receive total joint arthroplasty, but are also more prone to postoperative complications. The most severe complication is a prosthetic joint infection (PJI), occurring two to four times more often in severely obese patients (BMI ≥ 35kg/m2) compared to non-obese patients. This higher risk for PJI may be attributed to higher glucose levels in case of diabetes mellitus, diminished wound healing or inadequate antibiotic prophylaxis. To ultimately improve the prevention measures for this specific patient category, we aimed to describe the clinical and microbiological characteristics of early acute PJI in severely obese patients.
Method
We retrospectively evaluated patients with early acute PJI of the hip and knee treated with DAIR between 2006 and 2016 in three Dutch hospitals. According to protocol, cefazolin was administered as antibiotic prophylaxis during arthroplasty and adjusted to bodyweight. PJI was diagnosed using the criteria described by the Musculoskeletal Infection Society. Early acute PJI was defined as less than 21 days of symptoms and a DAIR performed within 90 days after index surgery. Several clinical and microbiological variables were collected and analyzed. Severe obesity was defined as a BMI ≥ 35kg/m2.
Results
A total of 356 patients were analyzed, including 73 severely obese patients (20.5%). Compared to patients with a BMI < 35kg/m2, severely obese patients were relatively young (69 years vs 74 years, p=0.001), female (75.3% vs 56.9%, p=0.005), with PJI of the knee (35.6% vs 20.8%, p=0.025) and arthroplasty indicated for osteoarthritis (87.7% vs 63.3%, p=0.001). They had higher incidences of diabetes mellitus (34.2% vs 18.7%, p=0.005) and hypertension (74.0% vs 59.0%, p=0.021). Severely obese patients had more often polymicrobial infections (67.4% vs 45.7%, p=0.009) and higher rates of infection with Enterococcus species (37.0% vs 15.8%, p=0.002) and Gram-negative rods, such as Proteus species (17.4% vs 2.3%, p<0.001). This finding was most prominent in hips, comprising Gram-negative PJIs in 32.6% of severely obese patients compared to 18.1% in non-severely obese patients (p=0.030). There were no differences in the number of infections due to Staphylococcus aureus or Staphylococcus epidermidis.
Conclusions
Our results demonstrate that severely obese patients with early acute PJI have higher rates of polymicrobial infections with involvement of Gram-negative rods and enterococci, especially in the hip region. Our data stress the importance of improving preventive strategies in this specific patient category, which may entail extension of antibiotic prophylaxis to a broader Gram-negative and Gram-positive coverage.
