Prevention of infection in orthopaedic joint replacement

Therapeutic assessment of N-formyl-methionyl-leucyl-phenylalanine (fMLP) in reducing periprosthetic joint infection

Despite many preventive measures, including prophylactic antibiotics, periprosthetic joint infection (PJI) remains a devastating complication following arthroplasty, leading to pain, suffering, morbidity and substantial economic burden. Humans have a powerful innate immune system that can effectively control infections, if alerted quickly. Unfortunately, pathogens use many mechanisms to dampen innate immune responses. The study hypothesis was that immunomodulators that can jumpstart and direct innate immune responses (particularly neutrophils) at the surgical site of implant placement would boost immune responses and reduce PJI, even in the absence of antibiotics. To test this hypothesis, N-formyl-methionyl-leucyl-phenylalanine (fMLP) (a potent chemoattractant for phagocytic leukocytes including neutrophils) was used in a mouse model of PJI with Staphylococcus aureus (S. aureus). Mice receiving intramedullary femoral implants were divided into three groups: i) implant alone; ii) implant + S. aureus; iii) implant + fMLP + S. aureus. fMLP treatment reduced S. aureus infection levels by ~ 2-Log orders at day 3. Moreover, fMLP therapy reduced infection-induced peri-implant periosteal reaction, focal cortical loss and areas of inflammatory infiltrate in mice distal femora at day 10. Finally, fMLP treatment reduced pain behaviour and increased weight-bearing at the implant leg in infected mice at day 10. Data indicated that fMLP therapy is a promising novel approach for reducing PJI, if administered locally at surgical sites. Future work will be toward further enhancement and optimisation of an fMLP-based therapeutic approach through combination with antibiotics and/or implant coating with fMLP.

Are high-efficiency particulate air (HEPA) filters and laminar air flow necessary in operating rooms to control acute post-operative endophthalmitis?

Purpose

To compare the five-year incidence of acute post-operative endophthalmitis following cataract surgery, between centers with and without laminar air flow and high-efficiency particulate air (HEPA) filters in operating rooms.

Methods

Retrospective analysis of medical records of patients operated in a single network of a tertiary and four secondary hospitals across north India. Cases of endophthalmitis were identified from the records between January 2013 and June 2018. Protocols and consumables were standardized across all hospitals. The only infrastructural difference being the presence of laminar air flow and high energy particulate air filters in operating rooms of the tertiary center. The type of surgery, along with the demographic and socio-economic details, were captured and analyzed, using z-test for proportions and logistic regression.

Results

Out of 88,297 cataract surgeries conducted, 36 cases of endophthalmitis were reported. The incidence of endophthalmitis across the network was estimated to be 0.041%, (95% CI: 0.027 to 0.054). There was no statistically significant difference between the incidence of POE at the tertiary (0.042%) and secondary centers (0.039%). Certain risk factors for high endophthalmitis incidence were identified, namely patients undergoing small incision cataract surgery and belonging to lower socio-economic status. However, for both factors the difference was not statistically significant.

Conclusion

The five-year incidence of acute post-operative endophthalmitis in our network was found comparable to the best reported in literature. Incidence at secondary centers, without laminar air flow and high energy particulate air filters was found comparable to that in the tertiary center having these facilities.

The value of ring-fenced beds in elective lower limb arthroplasty

BACKGROUND

Infection is a serious complication of prosthetic joint arthroplasty, associated with high rates of morbidity resulting in further surgical intervention and prolonged inpatient hospital admission. Rates of prosthetic joint infection have been reported as 1.5-2.5% following lower limb arthroplasty. This study compared infection rates in patients receiving primary hip and knee joint replacements before and after implementation of ring-fenced beds.

METHODS

Retrospective study of all patients undergoing primary total hip replacement and total knee replacement from April 2013 to February 2014. Group 1 included pre-ring-fencing patients, group 2 included post-ring-fencing patients.

RESULTS

The overall infection rate pre-ring-fencing was 6.3% (n=8). This reduced to 2.7% (n=3) post-ring-fencing. The mean inpatient length of stay for group 1 was 6 days vs 4 days for group 2.

CONCLUSIONS

Ring-fencing beds for patients undergoing elective lower limb arthroplasty significantly reduced rates of prosthetic joint infection and inpatient length of stay.

Economic case for intraoperative interventions to prevent surgical-site infection

BACKGROUND

Surgical-site infection (SSI) occurs in 1-10 per cent of all patients undergoing surgery; rates can be higher depending on the type of surgery. The aim of this review was to establish whether (or not) surgical hand asepsis, intraoperative skin antisepsis and selected surgical dressings are cost-effective in SSI prevention, and to examine the quality of reporting.

METHODS

The authors searched MEDLINE via Ovid, CINAHL via EBSCO, Cochrane Central and Scopus databases systematically from 1990 to 2016. Included were RCTs and quasi-experimental studies published in English, evaluating the economic impact of interventions to prevent SSI relative to surgical hand and skin antisepsis, and wound dressings. Characteristics and results of included studies were extracted using a standard data collection tool. Study and reporting quality were assessed using SIGN and CHEERS checklists.

RESULTS

Across the three areas of SSI prevention, the combined searches identified 1214 articles. Of these, five health economic studies evaluating the cost-effectiveness of selected surgical dressings were eligible. Study authors concluded that the interventions being assessed were cost-effective, or were potentially cost-saving. Still, there is high uncertainty around the decision to adopt these dressings/devices in practice. The studies' reporting quality was reasonable; three reported at least 15 of the 24 CHEERS items appropriately. Assessment of methodological quality found that two studies were considered to be of high quality.

CONCLUSION

With few economic studies undertaken in this area, the cost-effectiveness of these strategies is unclear. Incorporating economic evaluations alongside RCTs will help towards evidence-informed decisions.

Impact of Smoking Cessation Counseling Prior to Total Joint Arthroplasty

Perioperative smoking has been linked to surgical complications including poor wound healing, infection, myocardial infarction, prolonged length of stay, need for mechanical ventilation, and death. This study evaluated the effectiveness of preoperative counseling on smoking cessation for patients undergoing elective total joint arthroplasty. Thirty smokers with hip or knee osteoarthritis seeking hip or knee replacement surgery were enrolled prospectively. Interventions included counseling, referrals to smoking cessation programs including the California Smokers' Helpline and the Fontana Tobacco Treatment Program, nicotine replacement therapy (NRT), or instructing patients quit through the "cold turkey" method of abstinence. Patients were scheduled for surgery if they demonstrated abstinence from smoking, confirmed via expired carbon monoxide (CO) breath testing. Short- and long-term smoking cessation rates were evaluated. Thirty patients were enrolled; 21 patients (70%) passed the CO test, whereas 9 patients (30%) failed or did not follow up with a CO test. Thirteen of 21 patients (62%) quit using the "cold turkey" method, 5 of 21 patients (24%) quit using NRT, and 3 of 21 patients (14%) quit using outpatient treatment programs. Eighteen of 21 patients (86%) who quit smoking underwent surgery, and 14 patients had surgery within 6 months of smoking abstinence. Nine of the 14 patients (64%) remained smoke-free 6 months postoperatively confirmed through telephone questionnaire. These results suggest that elective surgery offers a strong incentive for patients to quit smoking, and surgeons can play a role offering a teachable moment and motivating this potentially life-altering behavioral change. [Orthopedics. 2017; 40(2):e323-e328.].

Biofilm formation in total hip arthroplasty: prevention and treatment

This review assesses the current knowledge on treatments, pathogenesis and the prevention of infections associated with orthopaedic implants, with a focus on total hip arthroplasty.

Current Evidence for the Use of Laminar Flow in Reducing Infection Rates in Total Joint Arthroplasty

Since the introduction of laminar air flow in orthopaedic theatres by Sir John Charnley, it has widely become accepted as the standard during orthopaedic procedures such as joint arthroplasty. We present a review of available current literature for the use of laminar flow operating theatre ventilation during total joint arthroplasty and examines the effectiveness of laminar flow ventilated operating theatres in preventing post-operative wound infection. Results of our findings suggest that while bacterial and air particulate is reduced by laminar air flow systems, there is no conclusive effect on the reduction of post-operative wound infections following total joint arthroplasty. We conclude that a combination of strict aseptic technique, prophylactic antibiotics and good anaesthetic control during surgery remains crucial to reduce post-operative surgical infections.

Postoperative antibiotic prophylaxis in total hip and knee arthroplasty: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Postoperative antibiotic prophylaxis is currently the standard of care for patients undergoing total hip and knee arthroplasty. We evaluated the evidence for this practice in the reduction of surgical-site infections.

METHODS

We systematically searched MEDLINE, Embase and the Cochrane Library for randomized controlled trials (RCTs) published up to Aug. 15, 2014. We included all RCTs that compared postoperative antibiotic prophylaxis with postoperative placebo or no treatment in patients undergoing primary total hip or knee arthroplasty for osteoarthritis. We combined outcomes for surgical-site infection using a random-effects model and quantified heterogeneity using the χ2 test and the I2 statistic. We assessed the overall quality of the evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

We identified 4 RCTs (n = 4036) that met the inclusion criteria. Surgical-site infections occurred in 3.1% (63/2055) of patients in the prophylaxis group and 2.3% (45/1981) in the control group. Postoperative prophylaxis did not reduce the rate of surgical-site infections compared with placebo (risk difference 0.01, 95% confidence interval 0.00 to 0.02; I2 = 26%). This result was robust to sensitivity testing for losses to follow-up. According to the GRADE approach, the overall quality of evidence was very low.

INTERPRETATION

The available evidence did not show efficacy of postoperative antibiotic prophylaxis for the prevention of surgical-site infections in patients undergoing total hip or knee arthroplasty. Multicentred RCTs are likely to have an important impact on the confidence in the effect estimate and to change the estimate itself.

In vivo testing of canine prosthetic femoral components with HA-Ti ladder-type coating on vacuum plasma-sprayed Ti substrate

The purpose of the present study was to observe the structure and functional change of the bone-coating-prosthesis interface in vivo and to evaluate the histocompatibility of self-made prosthetic femoral components in the body and the degree of their bonding with the surrounding bone tissues as well as their stability. Six mature beagle dogs underwent bilateral hip replacement with prosthetic femur components. Three groups were established in terms of different coating of prothesis (four joints in each group): atmosphere (A) plasma-sprayed pure titanium (Ti) prosthetic joint with hydroxyapatite (HA) coating (HA+Ti+A group); vacuum (V) plasma-sprayed pure Ti prosthetic joint with HA coating (HA+Ti+V group); vacuum plasma-sprayed pure Ti prosthetic joint with Ti-HA stepped coating (Ti+HAG+Ti+V group). The hip joints were functionally evaluated, and subjected to X-ray examination, biomechanics inspection, and histological examination. As a result, X-ray imaging revealed all prosthetic joints were in a good location and no dislocation of joint was found. Shear strength of interface was significantly higher in Ti+HAG+Ti+V group than in HA+Ti+V group (P<0.05) and HA+Ti+A group (P<0.05) at 28th week. Histological examination showed the amount of newborn bone in Ti+HAG+Ti+V group was more than in HA+Ti+V group and HA+Ti+A group after 28 weeks. It was suggested that vacuum plasma-sprayed pure Ti prosthetic joint with TI-HA stepped coating could improve the bonding capacity of bone-prosthesis, enhance the stability of prosthesis, and increase the fixion of prosthetic femoral components because of better bone growth. This new type of biological material in prosthetic femoral components holds promises for application in clinical practice.

Economic evaluation of chlorhexidine cloths on healthcare costs due to surgical site infections following total knee arthroplasty

The purpose of this study was to evaluate the overall annual healthcare cost savings of adding a pre-operative chlorhexidine cloth preparation protocol. We used reports from the National Healthcare Safety Network and previously published reports to determine a range of surgical site infection rates following total knee arthroplasty and the cost per revision procedure. The savings listed are potential, but may be less. The cost benefit of using chlorhexidine at our institution per 1,000 total knee arthroplasty patients was a net savings of approximately $2.1 million. The annual healthcare savings ranged from $0.78 to $3.18 billion. This epidemiologic evaluation of using chlorhexidine prior to undergoing total knee arthroplasty has demonstrated the potential to decrease healthcare costs primarily by decreasing the incidence of surgical site infections.

Infection control in operating theatres

The operating theatre complex is the heart of any major surgical hospital. Good operating theatre design meets the functional needs of theatre care professionals. Operating theatre design must pay careful consideration to traffic patterns, the number and configuration of nearby operating rooms, the space required for staff, administration and storage, provisions for sterile processing and systems to control airborne contaminants (Wan et al 2011). There have been infection control issues with private finance initiative built operating theatres (Unison 2003, Ontario Health Coalition 2005). The aim of this article is to address these issues as they relate to infection control and prevention.

Minimising the spread of infection in the operating department

We live in a world of continuing advances in technology, surgical techniques and rapidly improving medicine. Despite these advances, diseases are continuing to thrive and cause infection both in the community and, more disturbingly, in hospitals. Damani (2003) states that medical care is more complex than ever before, and this has resulted in hospital acquired infections (HAls) increasing due to organisms which are resistant to antibiotics such as: methicillin resistant staphylococcus aureus (MRSA) and vancomyan resistant enterococci (VRE). Wilson (2006) explains that hospitals provide a particularly fertile breeding ground for resistant micro-organisms, due to the widespread exposure to antibiotics and the many opportunities that hospitals provide to transfer MRSA between vulnerable patients and into sites which are susceptible to infection, such as wounds and invasive devices. Damani (2003) emphasises again that the key to successful control of antimicrobial resistant pathogens in hospitals is good isolation techniques, and especially rigorous attention to hand hygiene by all members of staff who are in contact with patients affected or colonised with resistant pathogens. The aim should be to eliminate the infection as quickly as possible and to ensure that the patient's period of isolation is kept to a minimum. Advice and knowledge about the control of infection is therefore imperative.