Deep sepsis following total knee arthroplasty. Ten-year experience at the University of California at Los Angeles Medical Center

Management of acute periprosthetic knee infection: a comparison of arthroscopic and open debridement

INTRODUCTION

In acute periprosthetic knee infections, debridement and implant retention (DAIR) is the preferred treatment prior to one- and two-stage revisions. The aim of this study is to compare the outcomes of arthroscopic and open debridement of infected primary total knee arthroplasties (TKA).

MATERIAL AND METHODS

We analyzed clinical, laboratory, and antibiotic treatment data, collected in patients with periprosthetic knee infection treated with DAIR at a Swiss Level 1 orthopedic and trauma center over a 10-year period between January 2005 and May 2015. Inclusion criteria were primary total knee arthroplasty and early postoperative or acute hematogenous periprosthetic joint infection (PJI). The primary endpoint was the need for further revision surgery due to persistent infection. The secondary endpoint was the prosthesis salvage in further infection surgeries.

RESULTS

Forty-two patients with 44 acute or hematogenous periprosthetic knee infections were included. We recorded 20 recurrent infections (45%) in our study population: 10 (77%) out of 13 in the arthroscopic DAIR group and 10 (32%) out of 31 in the open DAIR group. Two-stage revision, meaning complete removal of the TKA, insertion of a spacer and replantation at a second stage, had to be performed in three patients treated initially arthroscopically (23%) and in six patients treated initially with an open surgical procedure (21%).

CONCLUSIONS

Open debridement for acute periprosthetic knee infection shows clear benefits in terms of infection eradication and prosthesis salvage compared to arthroscopic DAIR.

GraXRS-Dependent Resistance of Staphylococcus aureus to Human Osteoarthritic Synovial Fluid

Osteoarthritis is the most prevalent joint disease in the United States, with many patients requiring surgical replacement of the affected joint. The number of joint arthroplasty procedures performed each year is increasing, and infection is a leading cause of implant failure. Staphylococcus aureus is the most frequently isolated organism associated with periprosthetic joint infections of the knee or hip, and due to the emergence of antibiotic-resistant strains, treatment options are limited. Here, we show that synovial fluid from osteoarthritic patients is iron restrictive toward S. aureus and, for strains representing the clonal lineages USA100, USA200, USA400, and USA600, bactericidal. Remarkably, community-associated methicillin-resistant S. aureus (CA-MRSA) strain USA300-LAC was highly resistant to synovial fluid killing but could be sensitized to killing by mutation of the GraXRS regulatory system and GraXRS-regulated mprF gene or by small-molecule inhibition of GraR. Thus, we propose the GraXRS-VraFG regulatory system and mprF as targets for future therapeutics for treatment of S. aureus bone and joint infections.

IMPORTANCE Osteoarthritis, a degenerative disease that results in the breakdown of joint cartilage and underlying bone, is the most prevalent joint disease in the United States. Surgical intervention, including total joint replacement, is a clinically effective procedure that can help to restore the patient’s quality of life. Unfortunately, joint replacement procedures come with a risk of infection that is estimated to occur in 1 to 2% of cases, and periprosthetic joint infection (PJI) is a leading cause of implant failure, requiring revision surgery. Staphylococcus aureus is well known for its ability to cause PJIs and was found to be the most frequently isolated organism from PJIs of the knee or hip. Antibiotic-resistant strains can often limit treatment options. In this study, we demonstrate that the MRSA strain LAC can resist killing and grow in human synovial fluid from osteoarthritic knees. Furthermore, we show that the GraXRS regulatory system is required for the displayed synovial fluid resistance. We further demonstrate that a small-molecule inhibitor of GraR sensitizes LAC to synovial fluid, validating the Gra system as a therapeutic target for the treatment of PJIs in humans.

Prosthetic Joint Infection After Dental Work: Is the Correct Prophylaxis Being Prescribed? A Systematic Review

Background

Prosthetic joint infection (PJI) of total hip (THA) or total knee arthroplasty (TKA) after dental procedures is uncommon, and antibiotic prophylaxis remains controversial. For high-risk patients, the American Academy of Orthopedic Surgeons recommends amoxicillin prophylaxis. However, no systematic review of the literature of PJIs associated with dental procedures explores if amoxicillin is suitable for the reported organisms.

Methods

A librarian-assisted search of the major databases (PubMed, Medline, Embase, Scopus) identified 954 articles. Only case reports, case series, and reviews with patient level data were included. After exclusions, 79 articles were fully reviewed.

Results

Forty-four PJIs after dental procedures were identified, 22 in primary THA, 20 in primary TKA, one in revision THA, and one in a hip resurfacing procedure. Antibiotic prophylaxis was documented for 5 patients. The dental procedure was invasive in 35 (79.5%). Comorbidities were present in 17 patients (38.7%). The organisms reported were Streptococcus spp. in 44%, other aerobic gram-positives in 27%, anaerobic gram-positives in 18%, and gram-negative organisms in 11%. An estimated 46% of organisms may be resistant to amoxicillin. The outcomes of treatment were reported for 35 patients (79.5%). Twenty-seven patients (61.4%) had no clinical signs of PJI at the final follow-up visit.

Conclusions

Lower extremity PJI associated with dental procedures is often caused by organisms unlikely to be prevented with amoxicillin. Additional studies are warranted to determine the choice and efficacy of antibiotic prophylaxis to prevent dental-associated PJI in the highest risk patients. Insufficient data exist to recommend the optimal treatment for patients with PJI in THA and TKA associated with dental procedures.

Open Debridement is Superior to Arthroscopic Debridement for the Infected Total Knee Arthroplasty

BACKGROUND

Acutely infected total knee arthroplasty (TKA) is commonly treated with debridement, antibiotics, and implant retention (DAIR). There are no direct comparative studies to determine whether debridement should be performed open or arthroscopically for infected TKA. The aim of this study is to compare the outcomes of open vs arthroscopic debridement of infected TKAs.

METHODS

All patients at a university teaching hospital with an infected TKA treated with DAIR between 2002 and 2017 were analyzed. The primary outcome was successful treatment defined using international consensus criteria. Secondary outcomes included antibiotic suppression, prosthesis retention, mortality, postoperative range of motion, and length of stay. Clinical, laboratory, surgical, and antibiotic treatment data were collected. Propensity score matching was performed to control for selection bias.

RESULTS

DAIR was used in 141 patients. The initial DAIR procedure was open for 96 patients and arthroscopic for 45 patients. The success rate was 29% greater for open DAIR (45% open vs 16% arthroscopic; P < .001). After propensity score matching, this benefit was estimated to be 36% (95% confidence interval, 22%-50%; P < .0001). When those on antibiotic suppression were also considered successfully treated, open DAIR was still superior by 34% (95% confidence interval, 18%-51%; P < .0001).

CONCLUSION

For infected TKA, open DAIR is a more successful index procedure compared with arthroscopic DAIR. Open DAIR remained more successful even when antibiotic suppression is considered successful treatment.

Point/Counterpoint: Static vs Articulating Spacers-Static Spacers for Resection Arthroplasty of the Knee

Antibiotic spacers play a significant role in the treatment of periprosthetic joint infections. They help maintain soft-tissue tension and provide delivery of high dose of antibiotics to the local tissue. The use of static or dynamic spacers is based on multiple factors including the extent of soft-tissue, ligamentous and bone compromise, overall patient function, comorbid conditions, and virulence of the organism. There is no difference in reinfection incidence between static vs dynamic spacers following two-stage reimplantation. Static spacers can be customized to treat all cases of periprosthetic total knee infections and offer intraoperative flexibility to vary the cement quantity and amount of antibiotics in the spacer to provide high-dose local delivery of antibiotics to address the dead space, bone loss, and soft-tissue compromise. Static spacers are especially advantageous in cases of extensor mechanism and ligamentous compromise where articulating spacers may not be able to provide adequate stability.

Antimicrobial Properties of Extracellular Matrix Scaffolds for Tissue Engineering

The necessity to manufacture graft materials with superior biocompatibility capabilities and biodegradability characteristics for tissue regeneration has led to the production of extracellular matrix- (ECM-) based scaffolds. Among their advantages are better capacity to allow cell colonization, which enables its successful integration into the tissue surrounding the area to be repaired. In addition, it has been shown that some of these scaffolds have antimicrobial activity, preventing possible infections; therefore, it could be used as an alternative to control surgical infection and decrease the use of antimicrobial agents. The purpose of this review is to collect the existing information about antimicrobial activity of the ECM and their components.

Dental assessment prior to orthopedic surgery: A systematic review

BACKGROUND

To reduce the risk of infection after orthopedic surgery, patients are asked to undergo preoperative assessments in various medical domains. However, to our knowledge, there has been no systematic review to evaluate the performance of a preoperative dental assessment before orthopedic surgery. We focus on two questions as follows: (1) is there a link between the presence of preoperative dental assessment and orthopedic infections?; (2) is the probability of an orthopedic infection increased in the presence of dental risk factors and comorbidities?

PATIENTS AND METHODS

Databases including PubMed, the Cochrane Library databases and Google Scholar were searched for English-language articles until November 2018. The inclusion criteria were descriptions of infections of joint prostheses and dental infections, and potential dental origins of pathogenic infections. Studies dealing with oral assessments performed before orthopedic surgery were included.

RESULTS

Based on eligibility criteria, 12 case series, 4 case-control studies and 12 cohort studies were included. In case-controls, prosthesis infection was presumably associated with a dental abscess in 6/224 of cases (2.9%). In cohort studies, exposure was defined as "any dental assessment or dental treatment performed before surgery". Even if only 4 cohort studies provide this information exposure, it would seem that the presence of an infectious complication is less frequent if the preoperative examination has been performed. Dental treatment given before surgery was mainly for scaling-polishing in 78/205 (38%), extraction in 49/205 of cases (24%) and restorative work in 37/205 (18%).

DISCUSSION

The literature review was made complex by the substantial heterogeneity among included studies. Although there is no formal evidence for or against preoperative dental assessment, it is advisable to perform this with the aim of maintaining favorable oral hygiene and thus reduce the risk factors.

LEVEL OF EVIDENCE

Level III, systematic review.

Effect of Physical Parameters on Outcomes of Total Knee Arthroplasty

BACKGROUND

Increasing body mass index (BMI) has been shown to correlate with increased rates of complications after total knee arthroplasty. To our knowledge, body surface area, body mass, and height have not been investigated in this manner. BMI and body surface area are affected differently by changes in height, and they are affected similarly by changes in weight. The purpose of this study was to quantify revision for any reason, mechanical failure, aseptic loosening, polyethylene wear, reoperation, and any infection after total knee arthroplasty using BMI, body surface area, body mass, and height as continuous variables.

METHODS

Prospectively collected data from a single institution's total joint registry were used to analyze 22,243 consecutive knees, in 16,106 patients, treated with a primary total knee arthroplasty from 1985 to 2012. The Kaplan-Meier survival method was used to evaluate revision and other common complications, with outcomes assessed using Cox regression analysis. Smoothing spline parameterization was used on physical parameters in these models.

RESULTS

Increasing BMI, body surface area, body mass, and height were associated with an increased risk of any revision surgical procedure, mechanical failure, and aseptic loosening after total knee arthroplasty. The risk of a revision surgical procedure was directly associated with each 1 standard deviation increase in BMI (hazard ratio [HR], 1.19; p < 0.01), body surface area (HR, 1.37; p < 0.01), body mass (HR, 1.30; p < 0.01), and height (HR, 1.22; p < 0.01). This association was especially demonstrated with revision for mechanical failure (BMI: HR, 1.15; p < 0.01; body surface area: HR, 1.35; p < 0.01; body mass: HR, 1.27; p < 0.01; and height: HR, 1.23; p < 0.01). The risk of failure in the subgroups of mechanical failure including a revision surgical procedure for aseptic loosening or polyethylene wear was also associated with increasing body surface area, body mass, and height. Increasing BMI (HR, 1.22; p < 0.01), body surface area (HR, 2.56; p < 0.01), and body mass (HR, 2.54; p < 0.01) were also associated with increased risk of any infection.

CONCLUSIONS

Increasing BMI, body surface area, body mass, and height were strongly associated with the rates of revision, aseptic loosening, and other common complications following total knee arthroplasty. Body surface area and body mass appear to correlate more strongly with mechanical failure outcomes than BMI or height.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Rapidly-growing mycobacterial infection: a recognized cause of early-onset prosthetic joint infection

Background

Prosthetic joint infection (PJI) is a major complication of total hip and total knee arthroplasty (THA, TKA). Although mycobacteria are rarely the causative pathogens, it is important to recognize and treat them differently from non-mycobacterial infections. This study aimed to compare the clinical characteristics, associated factors and long-term outcomes of mycobacterial and non-mycobacterial PJI.

Methods

We conducted a retrospective case-control study of patients aged ≥18 years who were diagnosed with PJI of the hip or knee at Siriraj Hospital from January 2000 to December 2012. Patient characteristics, clinical data, treatments and outcomes were evaluated.

Results

A total of 178 patients were included, among whom 162 had non-mycobacterial PJI and 16 had mycobacterial PJI. Rapidly growing mycobacteria (RGM) (11) and M. tuberculosis (MTB) (5) were the causative pathogens of mycobacterial PJI. PJI duration and time until onset were significantly different between mycobacterial and non-mycobacterial PJI. Infection within 90 days of arthroplasty was significantly associated with RGM infection (OR 21.86; 95% CI 4.25–112.30; p < .001). Implant removal was associated with improved favorable outcomes at 6 months (OR 5.96; 95% CI 1.88–18.88; p < .01) and 12 months (OR 3.96; 95% CI 1.15–13.71; p = .03) after the infection.

Conclusions

RGM were the major pathogens of early onset PJI after THA and TKA. Both a high clinical index of suspicion and mycobacterial cultures are recommended when medically managing PJI with negative cultures or non-response to antibiotics. Removal of infected implants was associated with favorable outcomes.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2926-3) contains supplementary material, which is available to authorized users.

Effects of Bacterial Contamination on Dental Implants During Surgery: A Systematic Review

INTRODUCTION

Contamination during surgery negatively influences the prognosis of orthopaedic implants; however, it has not been proven whether contamination influences the success of dental implant treatment. The aim of the systematic review was to investigate if there exists evidence in the literature whether contamination of dental implants during surgery affects osseointegration and clinical success.

MATERIALS AND METHODS

Four data bases were used for the literature search. Primary studies and reviews regarding both clinical and preclinical research were eligible. Rating of the summarized quality of the evidence was performed.

RESULTS

Five preclinical studies were included. Because of the estimated high risk of bias in all included studies and extensive differences in study design between the included studies, meta-analysis was not performed and no reliable aggregated data could be extracted.

CONCLUSIONS

It is suggested that the scientific evidence with regard to the current topic is insufficient. Further controlled studies are warranted.

Effect of Body Mass Index on Reoperation and Complications After Total Knee Arthroplasty

BACKGROUND

High body mass index (BMI) is associated with increased rates of complications after total knee arthroplasty. To date, to our knowledge, studies have examined risk as a dichotomous variable using specific BMI thresholds. The purpose of this investigation was to quantify implant survival and the risk of common complications after total knee arthroplasty using BMI as a continuous variable.

METHODS

Using prospectively collected data from our institutional total joint registry, we analyzed 22,289 consecutive knees, in 16,136 patients, treated with primary total knee arthroplasty from 1985 to 2012. The mean BMI of these patients at the time of the surgical procedure was 31.3 kg/m (range, 11 to 69 kg/m). The Kaplan-Meier survival method was used to estimate survivorship, reoperations, and common complications, with associations of outcomes assessed using a Cox regression model.

RESULTS

Utilizing smoothing spline parameterization, we found that reoperation (p < 0.001) and implant revision or removal rates (p < 0.001) increased with increasing BMI after total knee arthroplasty. Increasing BMI also was associated with increased rates of wound infection (hazard ratio [HR], 1.07; p < 0.001) and deep infection (HR, 1.08; p < 0.001) per unit of BMI over 35 kg/m. A BMI of 35 to 40 kg/m was associated with a higher rate of implant revision for aseptic loosening (p < 0.001) and for polyethylene wear (p < 0.001) compared with a BMI of 18 to 24.99 kg/m. There was no correlation between BMI and risk of venous thromboembolism, tibiofemoral instability, or need for knee manipulation.

CONCLUSIONS

The rates of reoperation, implant revision or removal, and many common complications after total knee arthroplasty were strongly associated with BMI.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Effect of extrusion processing on the microstructure, mechanical properties, biocorrosion properties and antibacterial properties of Ti-Cu sintered alloys

Ti-Cu sintered alloys, Ti-Cu(S) alloy, have exhibited good anticorrosion resistance and strong antibacterial properties, but low ductility in previous study. In this paper, Ti-Cu(S) alloys were subjected to extrusion processing in order to improve the comprehensive property. The phase constitute, microstructure, mechanical property, biocorrosion property and antibacterial activity of the extruded alloys, Ti-Cu(E), were investigated in comparison with Ti-Cu(S) by X-ray diffraction (XRD), optical microscopy (OM), scanning electronic microscopy (SEM) with energy disperse spectroscopy (EDS), mechanical testing, electrochemical testing and plate-count method in order to reveal the effect of the extrusion process. XRD, OM and SEM results showed that the extrusion process did not change the phase constitute but refined the grain size and Ti2Cu particle significantly. Ti-Cu(E) alloys exhibited higher hardness and compressive yield strength than Ti-Cu(S) alloys due to the fine grain and Ti2Cu particles. With the consideration of the total compressive strain, it was suggested that the extrusion process could improve the ductility of Ti-Cu alloy(S) alloys. Electrochemical results have indicated that the extrusion process improved the corrosion resistance of Ti-Cu(S) alloys. Plate-count method displayed that both Ti-Cu(S) and Ti-Cu(E) exhibited strong antibacterial activity (>99%) against S. aureus. All these results demonstrated that hot forming processing, such as the extrusion in this study, refined the microstructure and densified the alloy, in turn improved the ductility and strength as well as anticorrosion properties without reduction in antibacterial properties.

Treatment of 50 Deep Infections After Total Knee Arthroplasty

The prevalence of infections caused by methicillin-resistant organisms has increased, causing difficulty in the treatment of prosthetic joint infection. A multicenter study was performed to review 50 patients with deep infections with or without a resistant organism, such as methicillin-resistant Staphylococcus aureus, at the site of total knee arthroplasty. A group of 13 patients with early deep infections and 4 patients with acute hematogenous infections underwent treatment with debridement, antibiotic therapy, and retention of the prosthesis with revision of the polyethylene insert. Thirty-three patients with late chronic infections were treated with challenging prosthesis retention for prostheses that had not loosened or 2-stage exchange arthroplasty for prostheses that had loosened. Mean duration of follow-up was 4.7±1.8 years. No significant differences in resultant functional knees and mean number of operations were observed between 7 patients with resistant early deep infections and 6 patients with nonresistant early deep infections. However, 24 patients with nonresistant chronic infections showed significant improvement in resultant functional knees (24 of 24; 100%) and fewer mean operations (2.8 times) compared with 9 patients with resistant chronic infections (1 of 9, 11%, and 4.3 times, respectively). The remaining 8 patients with resistant chronic infections (89%) had arthrodesis (3 patients) or underwent above-the-knee amputation (1 patient) or spacer arthroplasty (4 patients). Although patients with resistant early postoperative deep infections showed good results that were similar to those in patients with nonresistant early infections, those with resistant late chronic infections had a significantly inferior success rate compared with those who had nonresistant late chronic infections.

Outbreak ofEnterococcus gallinarumInfections After Total Knee Arthroplasty

In September 2006, we investigated a cluster of 9 patients who developedEnterococcus gallinaruminfection after total knee arthroplasty. Isolates recovered from these patients were from the same outbreak strain. Although all 9 patients were monitored by the same healthcare personnel, were given spinal anesthesia, and had the same specific type of wound irrigation procedure performed during their hospitalization, the source or sources of these infections were not identified.

Morbid obesity: a significant risk factor for failure of two-stage revision total knee arthroplasty for infection

BACKGROUND

Obese patients have a higher risk of complications following primary total knee arthroplasty, including periprosthetic joint infection. However, there is a paucity of data concerning the efficacy of two-stage revision arthroplasty in obese patients.

METHODS

We performed a two-to-one matched cohort study to compare the outcomes of thirty-seven morbidly obese patients (those with a body mass index of ≥ 40 kg/m(2)) who underwent two-stage revision total knee arthroplasty for periprosthetic joint infection following primary total knee arthroplasty with the outcomes of seventy-four non-obese patients (those with a body mass index of <30 kg/m(2)). Groups were matched by sex, age, and date of reimplantation. Outcomes included subsequent revision, reinfection, reoperation, and Knee Society pain and function scores. The minimum follow-up time was five years.

RESULTS

Morbidly obese patients had a significantly increased risk for revision surgery (32% compared with 11%; p < 0.01), reinfection (22% compared with 4%; p < 0.01), and reoperation (51% compared with 16%; p < 0.01). Implant survival rates were 80% for the morbidly obese group and 97% for the non-obese group at five years and 55% for the morbidly obese group and 82% for the non-obese group at ten years. Knee Society pain scores improved significantly following surgery in both groups; the mean scores (and standard deviation) were 50 ± 5 points for the morbidly obese group and 55 ± 2 points for the non-obese group (p = 0.06) preoperatively, 74 ± 5 points for the morbidly obese group and 89 ± 2 points for the non-obese group (p < 0.0001) at two years, 72 ± 6 points for the morbidly obese group and 88 ± 3 points for the non-obese group (p < 0.0001) at five years, and 56 ± 9 points for the morbidly obese group and 84 ± 3 points for the non-obese group (p = 0.01) at ten years.

CONCLUSIONS

Morbid obesity significantly increased the risk of subsequent revision, reoperation, and reinfection following two-stage revision total knee arthroplasty for infection. In addition, these patients had worse pain relief and overall function at intermediate-term clinical follow-up. Although two-stage revision should remain a standard treatment for chronic periprosthetic joint infection in morbidly obese patients, increased failure rates and poorer outcomes should be anticipated.

Transfer of patient care during two-stage exchange for periprosthetic joint infection leads to inferior outcomes

The two-stage exchange algorithm is the gold standard for managing chronic periprosthetic joint infection (PJI); this study evaluated the impact of having the stages performed at different institutions. Patients with a chronically infected total joint arthroplasty (hip or knee) with initial resection at an outside hospital and subsequent care at our institution (transferred group) were identified then matched with a similar cohort that received both stages at our institution (continuous group). Eighteen patients (transferred group) were compared to 36 matched controls. There were significantly lower rates of successful reimplantation and retention, longer duration of treatment and more procedures in the transferred group compared to the continuous group. Patients transferred during their care for chronic PJI underwent more surgeries, longer treatment times, and less favorable outcomes.

Acute hematogenous infection following total hip and knee arthroplasty

Forty consecutive patients (42 joints; 22 TKA, 20 THA) treated for acute hematogenous infections were reviewed. All patients underwent irrigation and debridement and exchange of the modular components. At a mean of 56 months (range, 25-124 months) recurrent infection, requiring surgery, developed in 9 of the 42 joints (21%); 8 of the 9 recurrent infections were in patients with a staphylococcal infection (P = 0.0004). Ten of the 40 patients (25%) died within 2 years of infection. Irrigation and debridement for the treatment of an acute hematogenous infection was successful in the majority of patients (76% survivorship at 2 years). Non-staphylococcal infections had a particularly low failure rate (96% survivorship at 2 years). The 2 year mortality rate among this subset of patients was strikingly high.

Infection following total knee arthroplasty

For most orthopedists, total knee arthroplasty (TKA) has been regarded as the most effective surgery for patients with severe knee diseases. Though seldom occur, postoperative infection certainly remains one of the most devastating and dreaded complications of TKA. Thus, careful and early diagnosis is needed. After diagnosis, categorize the infection type and choose a rightful and sequential step of treatment are recommended.

Pathogen-driven decision for implant retention in the management of infected total knee prostheses

PURPOSE

In prosthetic joint infections (PJIs) of the knee, debridement with implant retention is associated with a high risk of recurrence.

METHODS

A single-centre cohort study was performed with extensive analysis of the literature covering 1980-2012.

RESULTS

In 21 patients (mean age 80.4 years, 19 immunosuppressed), in association with 1.5-three months of antibiotic treatment, an attempt was made to salvage the prosthesis by open (11 patients) or arthroscopic (ten patients) debridement. After a mean follow-up of seven years (range four-20 years), patients were in remission in seven cases (33 %). Remission was achieved in 0 % of all methicillin-resistant Staphylococcus aureus (MRSA) infections (zero/three), in 0 % (zero/three) of methicillin-resistant coagulase-negative staphylococcal infections, in 29 % (two/seven) of methicillin-sensitive S. aureus infections and in 75 % (three/four) of infections due to streptococci. The literature review focused on implant preserving approaches yielded 599 cases with an overall success rate of 47 % (284/599) and significantly more remissions in streptococcal vs staphylococcal knee PJIs (43/54 vs 144/324; p < 0.01, odds ratio 4.9, 95 % confidence interval 2.4-10.9).

CONCLUSIONS

In addition to established indications for explantation such as implant loosening, sinus tract or methicillin resistance, the decision for debridement and retention of knee PJIs should also depend on the pathogen. Implant preservation is futile with methicillin-resistant staphylococci, but seems to be a valid option for streptococcal PJIs.

Assessing the gold standard: a review of 253 two-stage revisions for infected TKA

BACKGROUND

Periprosthetic joint infection has been the leading cause of failure following TKA surgery. The gold standard for infection control has been a two-staged revision TKA. There have been few reports on mid- to long-term survivorship, functional outcomes, and fate of patients with a failed two-stage revision TKA.

QUESTIONS/PURPOSES

Therefore, we determined (1) the mid-term survivorship of two-stage revision TKA, (2) the function of patients in whom infection was controlled, and (3) the outcome of patients with a failed two-stage revision due to recurrent infection.

METHODS

We retrospectively reviewed 239 patients who underwent 253 two-stage revision TKAs for periprosthetic infection. There were 239 patients (253 knees), 104 men and 135 women, with a mean age of 70 ± 10 years at the time of two-stage revision and a mean BMI of 31.53 ± 6.74 kg/m2. During followup, we obtained WOMAC and The Knee Society Clinical Rating Scores and radiographs. The minimum followup was 1 year (median, 4 years; range, 1-17 years).

RESULTS

Thirty-three patients experienced a failed two-staged TKA. Sixteen patients experienced failure due to recurrent sepsis. There were 17 failures for aseptic causes.

CONCLUSION

The overall infection-free survivorship for two-stage revision TKA was 85% at 5 years and 78% at 10 years.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Previous fracture surgery is a major risk factor of infection after total knee arthroplasty

PURPOSE

Total knee arthroplasty (TKA) has been proven to be the most effective treatment for patients with severe joint disease. Although infection is not a frequent complication, it is certainly one of the most dreaded. The purpose of this study was to identify factors associated with infection after TKA.

METHODS

Between 1995 and 2006, 2,022 primary TKAs in 1,146 patients were evaluated. Flexible Nichidai Knee (FNK) was used as a prothesis in all subjects. Twenty-four patient-specific data items were collected via chart review for each patient. Revision arthroplasty procedures and infected knees were excluded. The medical records were reviewed to extract the following information: age, gender, body mass index (BMI), preoperative C-reactive protein (CRP), preoperative erythrocyte sedimentation rate (ESR), preoperative total protein (TP), duration of surgery, operative blood loss, total blood loss, duration of surgical drain, duration of antibiotic prophylaxis, primary diagnoses, smoking, diabetes mellitus, steroid or disease modifying anti-rheumatic drugs (DMARDs) therapy, previous operation around the knee joint, previous arthroscopic surgery, previous non-arthroscopic surgery, previous high tibial osteotomy (HTO) or open reduction internal fixation (ORIF), remnants of previous internal fixation material, bone graft, patella replacement, and bone cement.

RESULTS

The median age of the patients at the time of primary TKA was 72 (range, 26-91) years. The median follow-up period after primary TKA was 42 (range, 6-145) months. During the study period, 17 infected knee arthroplasties in 17 patients were identified. Previous history of ORIF, male gender, remnants of previous internal fixation material, and BMI showed significant correlation with postoperative infection.

CONCLUSION

This study identified previous history of fracture and remnants of internal fixation as major risk factors of infection after TKA. For clinical relevance, surgeons should be aware of potential infection when performing TKA in patients with these risk factors and patients should be informed of the potential risks.

Infection control rate of irrigation and débridement for periprosthetic joint infection

BACKGROUND

Irrigation and débridement with retention of prosthesis is commonly performed for periprosthetic joint infection. Infection control is reportedly dependent on timing of irrigation and débridement relative to the index procedure.

QUESTIONS/PURPOSES

We therefore (1) compared the ability of irrigation and débridement to control acute postoperative, acute delayed, and chronic infections and (2) determined whether any patient-related factors influenced infection control.

PATIENTS AND METHODS

We retrospectively reviewed the records of 136 patients (138 joints) from two institutional databases treated with irrigation and débridement between 1996 and 2007. Mean age at time of treatment was 64 years (range, 18-89 years); 77 (56%) joints were in women. Three subgroups were extracted: acute postoperative infections, occurring within 4 weeks (52 joints), acute delayed infections occurring after 4 weeks with acute onset of symptoms (50 joints), and chronic infections (36 joints). Minimum followup was 12 months (average, 54 months; range, 12-115 months). Failure to control infection was reported as the need for any subsequent surgical intervention and/or use of long-term suppressive antibiotics.

RESULTS

Infection control was not achieved in 90 joints (65%; 82 requiring return to surgery and eight remaining on long-term suppressive antibiotics). Failure rates were 69% (36 of 52), 56% (28 of 50), and 72% (26 of 36) for acute postoperative, acute delayed, and chronic infections, respectively. Of the 10 variables considered as potential risk factors, only Staphylococcal organisms predicted failure.

CONCLUSIONS

Irrigation and débridement is unlikely to control periprosthetic joint infection, including acute infections. Our data suggest surgeons should be cautious using this procedure as a routine means to address periprosthetic joint infection. For most patients, we recommend irrigation and débridement be reserved for an immunologically optimized host infected acutely with a non-Staphylococcal organism.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Does cyclical loading affect the elution of antibiotics from articulating cement knee spacers?

Two-stage revision surgery for infected total knee replacement offers the highest rate of success for the elimination of infection. The use of articulating antibiotic-laden cement spacers during the first stage to eradicate infection also allows protection of the soft tissues against excessive scarring and stiffness. We have investigated the effect of cyclical loading of cement spacers on the elution of antibiotics. Femoral and tibial spacers containing vancomycin at a constant concentration and tobramycin of varying concentrations were studied in vitro. The specimens were immersed and loaded cyclically to 250 N, with a flexion excursion of 45°, for 35 000 cycles. The buffered solution was sampled at set intervals and the antibiotic concentration was established so that the elution could be calculated. Unloaded samples were used as a control group for statistical comparison.

The elution of tobramycin increased proportionately with its concentration in cement and was significantly higher at all sampling times from five minutes to 1680 minutes in loaded components compared with the control group (p = 0.021 and p = 0.003, respectively). A similar trend was observed with elution of vancomycin, but this failed to reach statistical significance at five, 1320 and 1560 minutes (p = 0.0508, p = 0.067 and p = 0.347, respectively). However, cyclically loaded and control components showed an increased elution of vancomycin with increasing tobramycin concentration in the specimens, despite all components having the same vancomycin concentration. The concentration of tobramycin influences both tobramycin and vancomycin elution from bone cement. Cyclical loading of the cement spacers enhanced the elution of vancomycin and tobramycin.

Failure following revision total knee arthroplasty: infection is the major cause

The objective of this study was to evaluate the survivorship of revision TKA and determine the reasons and predictors for failure. Between January 1999 to December 2005, 499 total knee arthroplasty revisions were performed on 474 patients. There were 292 (61.6%) women and 182 (38.4%) men. The average age at the time of index revision was 63.9 years. Revision was defined as surgery in which at least one component (tibial, patellar, femoral, or polyethylene) required exchange. At an average follow-up of 64.8 months (range, 24.1-111.6), and considering reoperation or re-revision as failure, there were 102 failures (18.3%). Infection was the major cause of failure (44.1%) followed by stiffness (22.6%), patellar or extensor mechanism problems (12.8%), periprosthetic fracture (5.9%), loosening (4.9%), haematoma formation (3.9%), malalignment (2.9%), and instability (2.9%). A total of 83% of failures were early (less than two years). Infection was the most common mechanism of failure of revision TKA. The majority of TKA revision failures tend to occur in the first two years after revision. The mode of failure of revision TKA appears to differ from the failure of primary TKA to some extent. Better understanding of current modes by which TKA revisions fail may enable surgeons to prevent these problems and improve outcomes for revision TKA.

Irrigation and débridement and prosthesis retention for treating acute periprosthetic infections

BACKGROUND

Infections following hip and knee replacements can compromise the function and durability of arthroplasty. When these infections occur during the immediate postoperative period, irrigation and débridement can be attempted to salvage the implant. Prior studies have reported varying results likely due to lack of consistent inclusion criteria, variations in surgical technique, and lack of uniform treatment protocols.

QUESTIONS/PURPOSES

To supplement this literature we determined the rate at which irrigation and débridement and prosthesis retention would control acute periprosthetic infections.

METHODS

We retrospectively reviewed the medical records of 18 patients with acute periprosthetic infections occurring within 28 days after 13 THAs and 5 TKAs. The mean time to reoperation was 19 days (range, 6-28 days) after arthroplasty. Superficial débridements were performed in five cases, and a polyethylene or ball head exchange was performed in the remaining 13 cases when fascial defects were encountered at the time of surgery.

RESULTS

We salvaged the prosthesis in four of five patients with superficial irrigation and débridement group and eight of 13 with deep infections. Intraoperative cultures were positive in 83% of cases (n = 15). Five patients (one superficial and four deep) eventually underwent resection arthroplasty. Three patients underwent repeat irrigation and débridement, and one of these three ultimately had resection arthroplasty. Polymicrobial infections were detected in four cases, all failures. The average time to resection was 62 days (range, 12-134 days).

CONCLUSIONS

Consistent with the literature, success of prosthesis salvage for periprosthetic infections occurring within 28 days after arthroplasty depends on the location, extent, and microbiology of the infection.

LEVEL OF EVIDENCE

Level IV, case series. See the Guidelines for Authors for a complete description of levels of evidence.

The estimated magnitude and direct hospital costs of prosthetic joint infections in the United States, 1997 to 2004

To estimate the number and cost of prosthetic joint infection hospitalizations in civilian US hospitals, we analyzed the 1997 to 2004 National Hospital Discharge Survey for the 996.66 International Classification of Diseases discharge code (infection or inflammatory reaction secondary to internal joint prosthesis). The annual number of such hospitalizations averaged 17 589 from 1997 to 2000 and 29 225 from 2001 to 2004. The annual adjusted diagnostic-related group cost for such infection increased from $195 million to $283 million (1997-2004). The mean diagnostic-related group reimbursement ($9034 per hospitalization) did not vary over time or by comorbidity. The nearly doubled number of prosthetic joint infection-related hospitalizations may have been caused by an increased implant rate, changes in patient population, implant procedures, or causative organisms.

Acupuncture needle-associated prosthetic knee infection after total knee arthroplasty

The case of a patient who previously had permanent acupuncture needles placed in the knee joint and had been doing well, with no evidence of infection, but who eventually underwent a revision total knee arthroplasty due to acupuncture needle-associated prosthetic infection is presented. The microorganism responsible for the infection was Enterococcus faecalis, a bacterium which rarely causes infection following arthroplasty. This case should be highlighted to increase the awareness of healthcare providers to acupuncture-associated subclinical infection that may be exacerbated by surgical manipulation.

Developing an engineered antimicrobial/prophylactic system using electrically activated bactericidal metals

The increased use of Residual Hardware Devices (RHDs) in medicine combined with antimicrobial resistant-bacteria make it critical to reduce the number of RHD associated osteomyelitic infections. This paper proposes a surface treatment based on ionic emission to create an antibiotic environment that can significantly reduce RHD associated infections. The Kirby-Bauer agar gel diffusion technique was adopted to examine the antimicrobial efficacy of eight metals and their ionic forms against seven microbes commonly associated with osteomyelitis. Silver ions (Ag(+)) showed the most significant bactericidal efficacy. A second set of experiments, designed to identify the best configuration and operational parameters for Ag(+) based RHDs addressed current and ionic concentrations by identifying and optimizing parameters including amperage, cathode and anode length, separation between anode and cathode, and surface charge density. The system demonstrated an unparalleled efficacy. The concept was then implemented during in vitro testing of an antimicrobial hip implant, RHD.

The salvage of knee-exposed prosthesis using neurofasciocutaneous sural flap

Prosthetic exposure is a severe complication of total knee arthroplasty. Many factors are responsible for failed wound healing, and successful salvage of total knee arthroplasty requires early identification of infection, antecedent events related with wound healing failure, aggressive surgical debridement and early appropriate soft-tissue coverage with local skin, fasciocutaneous, muscle, neurocutaneous or perforator flaps. In this report, we present 15 cases of exposed knee prosthesis treated with island sural neurocutaneous flap. Follow-up showed favorable clinical outcomes: all flaps survived and only two cases of hematoma and one of aseptic phystula occurred. According to our results, the island neurofasciocutaneous sural flap represents a sensate reconstructive alternative for providing fine and dependable soft tissue for covering skin defects around the knee.

Incidence of prosthetic joint infections after primary knee arthroplasty

We report the 1-year incidence of postoperative infections in an unselected series of 2647 consecutive primary knee arthroplasties (3137 knees) performed in a modern specialized hospital dedicated solely to joint arthroplasty surgery in 2002 to 2006. The rates of superficial and prosthetic joint infections were 2.9% and 0.80%, respectively. Prospective surveillance by hospital infection register failed to detect 6 of the 24 prosthetic joint infections. Increased rate of prosthetic joint infections was associated with complex surgery and with several patient-related factors, for example, comorbidity, obesity, and poor preoperative clinical state. The rate of prosthetic joint infections in contemporary knee arthroplasty is low and mainly related to patient-related factors, of which patient comorbidity has the most profound effect on the infection rate.

Organic-inorganic composites for bone drug delivery

This review paper attempts to provide an overview in the fabrication and application of organic-inorganic based composites in the field of local drug delivery for bone. The concept of local drug delivery exists for a few decades. However, local drug delivery in bone and specially application of composites for delivery of drugs to bone is an area for potential research interest in the recent time. The advantages attained by an organic-inorganic composite when compared to its individual components include their ability to release drug, adopting to the natural environment and supporting local area until complete bone regeneration, which make them carriers of interest for local drug delivery for bone.

Relationship between perioperative urinary tract infection and deep infection after joint arthroplasty

Surgical wound infection is a serious and potentially catastrophic complication after joint arthroplasty. Urinary tract infection is a common infection that creates a potential reservoir of resistant pathogens and increases patient morbidity. We asked whether treated preoperative and postoperative urinary tract infections are risk factors for deep joint infection. We examined the medical records of 19,735 patients. The minimum had joint infections develop. Of these, three had preoperative and four had postoperative urinary tract infections. The majority of bacteria were not enteric. The bacteria in the two types of infections were not identical. Control subjects were randomly selected from a list of patients matched with patients having infections. Of these, eight had preoperative and one had postoperative urinary tract infections. We found no association between the preoperative urinary tract infection (odds ratio, 0.341; 95% confidence interval, 0.086-1.357) or postoperative urinary tract infection (odds ratio, 4.222; 95% confidence interval, 0.457-38.9) and wound infection. Only one of the 58 patients with wound infections had a urinary tract infection with the same bacteria in both infections. Given the infection rate was very low (0.29%), the power of the study was only 25%. Although limited, the data suggest patients with urinary tract infections had no more likelihood of postoperative infection. We believe treated urinary tract infection should not be a reason to delay or postpone surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Surgical treatment of early wound complications following primary total knee arthroplasty

BACKGROUND

Wound-healing problems are a known complication after primary total knee arthroplasty. However, little is known about the clinical outcomes for patients who require surgical treatment of these early wound-healing problems. The purpose of the present study was to determine the incidence, risk factors, and long-term sequelae of early wound complications requiring surgical treatment.

METHODS

The total joint registry at our institution was reviewed for the period from 1981 to 2004. All knees with early wound complications necessitating surgical treatment within thirty days after the index total knee arthroplasty were identified. The cumulative probabilities for the later development of deep infection and major subsequent surgery were determined. A case-control study in which these patients were matched with an equal number of controls was performed to attempt to identify risk factors for the development of early superficial wound complications requiring surgical intervention.

RESULTS

From 1981 to 2004, 17,784 primary total knee arthroplasties were performed at our institution. Fifty-nine knees were identified as having early wound complications necessitating surgical treatment within thirty days after the index arthroplasty, for a rate of return to surgery of 0.33%. For knees with early surgical treatment of wound complications, the two-year cumulative probabilities of major subsequent surgery (component resection, muscle flap coverage, or amputation) and deep infection were 5.3% and 6.0%, respectively. In contrast, for knees without early surgical intervention for the treatment of wound complications, the two-year cumulative probabilities were 0.6% and 0.8%, respectively (p < 0.001 for both comparisons). A history of diabetes mellitus was identified as being significantly associated with the development of early wound complications requiring surgical intervention.

CONCLUSIONS

Patients requiring early surgical treatment for wound-healing problems after primary total knee arthroplasty are at significantly increased risk for further complications, including deep infection and/or major subsequent surgery, specifically, resection arthroplasty, amputation, or muscle flap coverage. These results emphasize the importance of obtaining primary wound-healing after total knee arthroplasty.

Infection after knee arthroplasty a prospective study of 1509 cases

We report a prospective study of 1509 consecutive total knee arthroplasties looking at risk factors for infection in modern surgical practice. The overall deep infection rate was 1%. A further 51 patients had a superficial infection (3.3%). Statistical analysis revealed no correlation between risk of infection and age and sex. Those who had poor health as assessed by the American Society of Anesthesiologists score had no increased risk of infection. Neither did patients undergoing arthroplasty for rheumatoid arthritis. Diabetic patients and those with morbid obesity (body mass index, >40 kg/m(2)) had an increased odds ratio for deep and superficial infection, but these results did not reach statistical significance.

Quality of life after infection in total joint replacement

PURPOSE

To compare the health-related quality of life and functional outcomes of patients with and without periprosthetic infection after total joint replacement (TJR).

METHODS

62 uncomplicated TJRs and 34 TJRs complicated with deep infection were compared using a visual analogue scale for satisfaction, the Western Ontario and McMaster Universities Osteoarthritis Index, Assessment of Quality of Life, and Short Form-36.

RESULTS

Patients with complicated TJR had significantly poorer satisfaction in outcome (p<0.0001) and disease-specific functional outcomes (p<0.0001). Six of the 8 health-related quality-of-life scores were also significantly poorer (p<0.05). These results persisted after controlling for age, sex, and follow-up period in a multiple regression analysis.

CONCLUSION

Infection following TJR reduces patient satisfaction and seriously impairs functional health status and health-related quality of life. When hospitals are balancing the costs of preventative measures with the costs of treating infection in TJR, the effect on patients' quality of life must be considered. Our findings argue strongly for allocation of health care resources to minimise the occurrence of infection after TJR.

Incidence and risk factors for surgical infection after total knee replacement

Surgical site infection (SSI) after total knee replacement (TKR) is a devastating complication. We performed a retrospective study of all consecutive TKRs performed during a 2-y period. Surgical site infection (SSI) was defined by standard criteria. All patients were examined 1 y following surgery. Of 180 patients undergoing TKR, 10 (5.6%) developed a superficial (3, 1.7%) or deep (7, 3.9%) SSI. Two independent risk factors for SSI were detected: left knees became infected more often (9/ 92, 9.8%) than right knees (1/88, 1.1%) (Relative Risk 6.7 +/- 95% CI 1.7-26.8); and 7/72 (9.7%) patients receiving a type-1 prosthesis developed infection versus 3/104 (3.1%) receiving a type-2 prosthesis (RR 4.7, 95% CI 1.18-18.4). Investigation of the operating room revealed 3 problems: there was significant traffic through the door on the left of the patient; a nonstandard horizontal-flow air conditioner had been installed above that door; a tool-washing sink was in use on the other side of that door. Infection control guidelines were rehearsed: the sink was removed, the air conditioner was disconnected, and the door was locked. In a prospective survey performed 2 y later only 1/45 patients (2.2%) undergoing TKR developed a superficial SSI (p = 0.5). Correction of independent risk factors for infection following TKR led to a decrease in SSI rate.

Risk factors associated with acute hip prosthetic joint infections and outcome of treatment with a rifampinbased regimen

BACKGROUND AND PURPOSE

Acute prosthetic infection is a serious problem. We report factors related to the incidence of acute infection and results of combined joint debridement and prolonged rifampicin-based antibiotic therapy.

PATIENTS AND METHODS

Between 1998 and 2004, 14 acute infections occurred after 819 primary hip arthroplasties. The association between patient-related and surgical factors and the risk of infection were analyzed. Infections were treated with multiple joint lavage, debridement, 2 weeks of antibiotic therapy, and then oral antibiotics for a minimum of 6 months.

RESULTS

There was a correlation between having a body mass index (BMI) of >or=30, and also more than 2 co-morbidities, and an increased risk of infection. Diabetes was a potential risk factor. Following our regime of treatment, 11 of 14 patients retained their prosthesis. 2 of 3 who required resection arthroplasty underwent successful staged revision, while the third patient had no further surgery because of being deemed unfit.

INTERPRETATION

Primary joint replacement was salvaged in 11 of 14 patients. When successful re-implantation was included, 13 of 14 patients had a mobile prosthetic joint without further infection.

Functional advantage of articulating versus static spacers in 2-stage revision for total knee arthroplasty infection

Infection is an unfortunate complication of total knee arthroplasty. Current literature supports 2-stage reimplantation as the gold standard. Controversy exists whether static or articulating spacers are the best interim treatment method. Seventy-six 2-stage reimplantation procedures met the study inclusion criteria. There were 28 static spacers and 48 articulating spacers. The eradication rate was 94.7% in the articulating group compared with 92.1% in the static group (P = 0.7). There were no significant differences in postoperative Knee Society Scores pain scores. There were 28 (58%) good to excellent function scores in the articulating group and 10 (36%) in the static group (P = .05). Interim use of an articulating spacer maintains excellent infection eradication rates and may improve function over the use of static spacers.