A review of the biomaterials technologies for infection-resistant surfaces.

The current risk of infection in contemporary total knee arthroplasty (TKA) as well as the relative importance of risk factors remains under debate as a result of the rarity of the complication and temporal changes in the treatment and prevention of infection. We therefore determined infection incidence and risk factors after TKA in the Medicare population. The Medicare 5% national sample administrative data set was used to identify and longitudinally follow patients undergoing TKA for deep infections and revision surgery between 1997 and 2006. Cox regression was used to evaluate patient and hospital characteristics. In 69,663 patients undergoing elective TKA, 1400 TKA infections were identified. Infection incidence within 2 years was 1.55%. The incidence between 2 and up to 10 years was 0.46%. Women had a lower risk of infection than men. Comorbidities also increased TKA infection risk. Patients receiving public assistance for Medicare premiums were at increased risk for periprosthetic joint infection (PJI). Hospital factors did not predict an increased risk of infection. PJI occurs at a relatively high rate in Medicare patients with the greatest risk of PJI within the first 2 years after surgery; however, approximately one-fourth of all PJIs occur after 2 years.

Prosthetic Joint Infection Risk after TKA in the Medicare Population

Although the American Society of Anaesthesiologists' (ASA) classification of Physical Health is a widely used grading system for preoperative health of the surgical patients, multiple variations were observed between individual anaesthetist's assessments when describing common clinical problems. This article reviews the current knowledge and evaluation regarding ASA Classification of Physical Health as well as trials for possible modification.

American Society of Anaesthesiologists physical status classification

Periprosthetic joint infection is one of the most challenging complications of total joint arthroplasty. We evaluated the incidence of early-onset (less than 2 years) and late-onset (greater than 2 years) periprosthetic joint infection after primary total hip arthroplasty (THA). The Medicare 5% national sample data set (1997-2006) was used to longitudinally follow primary THA patients. Deep infections were identified with the International Classification of Diseases, Ninth Revision, Clinical Modification code 996.66. Kaplan-Meier survivorship curves were compiled with infection as the end point. Cox regression was used to evaluate patient and hospital characteristics. Eight hundred eighty-seven THA infections were identified from 39 929 THA patients. The incidence of infection was 1.63% within 2 years and 0.59% between 2 and 10 years. Comorbidities, sex, procedure duration, and socioeconomic status were found to be significant risk factors. This is the first study to establish the incidence and risk factors associated with early onset and delayed periprosthetic joint infection in the Medicare patient population.

Prosthetic Joint Infection Risk After Total Hip Arthroplasty in the Medicare Population

Background: Clinical studies have revealed a number of important risk factors for postoperative infection following total knee arthroplasty. Because of the small numbers of cases in those studies, there is a risk of obtaining false-negative results in statistical analyses. The purpose of the present study was to determine the risk factors for infection following primary and revision knee replacement in a large register-based series.

Methods: A total of 43,149 primary and revision knee arthroplasties, registered in the Finnish Arthroplasty Register, were followed for a median of three years. The Finnish Arthroplasty Register and the Finnish Hospital Discharge Register were searched for surgical interventions that were performed for the treatment of deep postoperative infections. Cox regression analysis with any reoperation performed for the treatment of infection as the end point was performed to determine the risk factors for this adverse outcome.

Results: Three hundred and eighty-seven reoperations were performed because of infection. Both partial and complete revision total knee arthroplasty increased the risk of infection as compared with the risk following primary knee replacement. Male patients, patients with seropositive rheumatoid arthritis or with a previous fracture around the knee, and patients with constrained and hinged prostheses had increased rates of infection after primary arthroplasty. Wound-related complications increased the risk of deep infection. The rate of septic failure was lower after unicondylar than after total condylar primary knee arthroplasty, but the difference was not significant. The combination of parenteral antibiotic prophylaxis and prosthetic fixation with antibiotic-impregnated cement protected against septic failure, especially after revision knee arthroplasty. Following revision total knee arthroplasty, diagnosis and prosthesis type had no effect, but previous revision for the treatment of infection and wound-healing problems predisposed to repeat revision for the treatment of infection.

Conclusions: There was an increased risk of deep postoperative infection in male patients and in patients with rheumatoid arthritis or a fracture around the knee as the underlying diagnosis for knee replacement. The results of the present study suggest that the infection rate is similar after partial revision and complete revision total knee arthroplasties. Combining intravenous antibiotic prophylaxis with antibiotic-impregnated cement seems advisable in revision arthroplasty.

Level of Evidence: Prognostic Level II. See Instructions to Authors for a complete description of levels of evidence.

Risk factors for infection after knee arthroplasty. A register-based analysis of 43,149 cases.

We wished to estimate the incidence of surgical-site infection (SSI) after total hip replacement (THR) and hemiarthroplasty and its strength of association with major risk factors. The SSI surveillance service prospectively gathered clinical, operative and infection data on inpatients from 102 hospitals in England during a four-year period.The overall incidence of SSI was 2.23% for 16 291 THRs, 4.97% for 5769 hemiarthroplasty procedures, 3.68% for 2550 revision THRs and 7.6% for 198 revision hemiarthroplasties. Staphylococcus aureus was identified in 50% of SSIs; 59% of these isolates were methicillin-resistant (MRSA). In the single variable analysis of THRs, age, female gender, American Society of Anesthesiologists (ASA) score, body mass index, trauma, duration of operation and pre-operative stay were significantly associated with the risk of SSI (p < 0.05). For hemiarthroplasty, the ASA score and age were significant factors. In revision THRs male gender, ASA score, trauma, wound class, duration of oper...

Infection of the surgical site after arthroplasty of the hip.

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 TKROs 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. SSIOs doubled the length of post-operative stay and MRSA accounted for 21% of organisms.

S. Ridgeway

Papers

Infection of the surgical site after arthroplasty of the hip.

O2612 surgical site infection (ssi) following knee prostheses in england from 1997–2001