Aims: Data collected on knee replacements from 93 hospitals in England were analysed to identify risk factors for surgical site infection. Methods: Prospective surveillance data collected from hospitals in England to calculate surgical site infection rates and potential risk factors Results: There were 242 (1.6%) infections in 15427 primary TKR, with a 0.11% joint infection rate, and 36 (3.6%) infections in 988 revisions, with a signiþcantly higher joint infection rate of 0.35%. There was considerable variation between hospitals. Multivariable logistic regression found signiþcant association between risk of SSI and type of procedure (p< 0.01), the hospital where the procedure was performed, male sex (p< 0.001), age (p< 0.001) and wound class (p< 0.05). The mean length of stay in primary TKRñs increased from 9 days to 18 days with an infection; and in revision procedures from 12 to 24 days. The median time to diagnosis for SSI was 7.5 days. Staphylococcus aureus accounted for 33%, 66% of which were methicillin resistant (MRSA). Conclusions: There is signiþcant inter-hospital variation in the incidence of SSI following knee replacements in England. Signiþcant risk factors include revision procedures. Male sex, age and wound class. SSIñs doubled the length of post-operative stay and MRSA accounted for 21% of organisms.

Aims: To calculate SSI rates and potential risk factors for primary total hip replacements (THR), hip hemiarthroplasties (HH), revision THR’s, and revision HH’s in England. Methods: Demographic, operative, and infection data was collected prospectively from 104 hospitals in England over 4 years to calculate SSI rates and potential risk factors. Results: There were 353 (2.3%) infections in 15697 THR’s with a 0.2% joint infection rate; 248 (4.6%) infections in 5456 HH procedures (0.9% joint). For revision THRs there were 92 (3.6%) infections in 2563 procedures, and 11 (5.6%) infections in 197 revision HH’s. Staphylococcus Aureus was identified in 52%; 58% were MRSA. With multivariable analysis, only inter-hospital variation (p< 0.001) and ASA score (p< 0.001) remained significant. Mean time to detection of infection varied from 9.2 days (superficial) to 11.3 days (joint). Mean length of stay increased from 9 to 14 days in THR’s; from 14 to 30 days for revision THR’s; from 19 to 34 days for HH’s and from 20 to 28 days for revision HH’s with an infection.

Conclusions: Infection rates are within acceptable levels, however there is a significant inter-hospital variation in infections following hip prosthesis in England. ASA score remains a significant risk factor and MRSA accounted for 30% of organisms.

Data collected on total knee replacements (TKR) from 77 hospitals in England were analysed to identify risk factors for surgical site infection (SSI).

Demographic, operative, and infection data were collected prospectively over a four-year period by the Nosocomial Infection National Surveillance Scheme.

There were 213 (1.8%) infections reported in 11552 primary TKR of which 82% were superficial, 10% deep incisional, and 8% joint/bone infections. The incidence of SSI in 687 revision of TKRs was 4.1% (71% superficial incisional, 18% deep incisional and 11% joint/bone). In the single variable analysis of primary TKRs, significant risk factors were male sex (p< 0.01), age (p< 0.001), ASA score (p< 0.001), wound class (p< 0.001) and NNIS risk index (p< 0.001). In revision of TKRs, only age (p< 0.01) and pre-operative hospital stay of more than one day (p< 0.02) were found to be significant. Significant risk factors with multi-variable logistic regression were type of procedure (TKR or revision TKR), hospital where the procedure was performed, male sex, and age. The mean length of stay in primary TKRs was 10 days (19 days with SSI) and 12 days in revision TKR (22 days with SSI). The median time to diagnosis for superficial SSI was 7 days for superficial SSIs, 9 days for deep incisional SSIs and 7.5 days for joint/bone infections. Staphylococcus aureus accounted for 35% of the infections and nearly one third of these were methicillin resistant (MRSA).

There is significant inter-hospital variation in the incidence of SSI following total knee replacement. Revision TKR procedures are associated with a significantly higher incidence of SSI than primary TKRs (p< 0.001). Male sex and age are also important risk factors. Patients with SSI had a length of post-operative stay approximately twice that of those without SSI.