INFECTION RATE AND RISK FACTORS FOLLOWING PRIMARY TOTAL HIP ARTHROPLASTY

Introduction Surgical site infection (SSI) remains a concern following total hip arthroplasty (THA). We aimed to identify risk factors for post-operative SSI in THA. Patients/Materials & Methods All primary THAs performed in our institution during 2009–2010 were included, giving 1832 cases in 1716 patients. Cohort demographics were mean age 67.9 years (SD10.2), mean BMI 29.6 (SD5.3), 60% female and 90.2% primary indication of osteoarthritis. Post-operative SSI within one year was identified either through hospital infection control records or from Information Services Division (NHS Scotland). Demographic and peri-operative data for known or suspected risk factors for SSI were collected from clinical records. Groups were compared using independent t-tests and chi-squared tests as appropriate. Results Within one year post-operatively, 27 patients (1.5%) developed SSI, with 23 (1.3%) being deep infections. The infected group had a higher mean BMI than the non-infected group (33.1 vs 30.0, p=0.001). 40.7% of the infected group had operative times ≥90 minutes compared to 22.7% in the non-infected group (p=0.026). Peri-operative blood transfusions were received by 25.9% of those developing infections but only 3.9% of those who did not (p Discussion The deep infection rate is similar to the national average and within the often quoted 2%. In keeping with other studies, these data have shown higher BMI, extended operative time and peri-operative blood transfusions to be risk factors for post-operative SSI. Obesity, along with other factors such as surgeon experience, may prolong surgical time and increase the risk of peri-operative blood transfusion, therefore leading to higher SSI rates. These results reinforce the importance of pre-operative weight loss for reducing SSIs. Conclusion This study highlights that the rising incidence of obesity presents a serious ongoing challenge to surgeons performing THAs in terms of increasing risk of SSI. Reports of hospital infection rates should include the patient population BMI and be interpreted accordingly.