Jaiben George

Are Frozen Sections and MSIS Criteria Reliable at the Time of Reimplantation of Two-stage Revision Arthroplasty?

BackgroundFrozen section histology is widely used to aid in the diagnosis of periprosthetic joint infection at the second stage of revision arthroplasty, although there are limited data regarding its utility. Moreover, there is no definitive method to assess control of infection at the time of reimplantation. Because failure of a two-stage revision can have serious consequences, it is important to identify the cases that might fail and defer reimplantation if necessary. Thus, a reliable test providing information about the control of infection and risk of subsequent failure is necessary.Questions/purposes(1) At second-stage reimplantation surgery, what is the diagnostic accuracy of frozen sections as compared with the Musculoskeletal Infection Society (MSIS) as the gold standard? (2) What are the diagnostic accuracy parameters for the MSIS criteria and frozen sections in predicting failure of reimplantation? (3) Do positive MSIS criteria or frozen section at the time of reimplantation increase the risk of subsequent failure?MethodsA total of 97 patients undergoing the second stage of revision total hip arthroplasty or total knee arthroplasty in 2013 for a diagnosis of periprosthetic joint infection (PJI) were considered eligible for the study. Of these, 11 had incomplete MSIS criteria and seven lacked 1-year followup, leaving 79 patients (38 knees and 41 hips) available for analysis. At the time of reimplantation, frozen section results were compared with modified MSIS criteria as the gold standard in detecting infection. Subsequently, success or failure of reimplantation was defined by (1) control of infection, as characterized by a healed wound without fistula, drainage, or pain; (2) no subsequent surgical intervention for infection after reimplantation surgery; and (3) no occurrence of PJI-related mortality; and diagnostic parameters in predicting treatment failure were calculated for both the modified MSIS criteria and frozen sections.ResultsAt the time of second-stage reimplantation surgery, frozen section is useful in ruling in infection, where the specificity is 94% (95% confidence interval [CI], 89%–99%); however, there is less utility in ruling out infection, because sensitivity is only 50% (CI, 13%–88%). Both the MSIS criteria and frozen sections have high specificity for ruling in failure of reimplantation (MSIS criteria specificity: 96% [CI, 91%–100%]; frozen section: 95% [CI, 88%–100%]), but screening capabilities are limited (MSIS sensitivity: 26% [CI, 9%–44%]; frozen section: 22% [CI, 9%–29%]). Positive MSIS criteria at the time of reimplantation were a risk factor for subsequent failure (hazard ratio [HR], 5.22 [1.64–16.62], p = 0.005), whereas positive frozen section was not (HR, 1.16 [0.15–8.86], p = 0.883).ConclusionsOn the basis of our results, both frozen section and MSIS are recommended at the time of the second stage of revision arthroplasty. Both frozen section and modified MSIS criteria had limited screening capabilities to identify failure, although both demonstrated high specificity. MSIS criteria should be evaluated at the second stage of revision arthroplasty because performing reimplantation in a joint that is positive for infection significantly increases the risk for subsequent failure.Level of EvidenceLevel III, diagnostic study.

Administrative Databases Can Yield False Conclusions—An Example of Obesity in Total Joint Arthroplasty

BACKGROUND Research using large administrative databases has substantially increased in recent years. Accuracy with which comorbidities are represented in these databases has been questioned. The purpose of this study was to evaluate the extent of errors in obesity coding and its impact on arthroplasty research. METHODS Eighteen thousand thirty primary total knee arthroplasties (TKAs) and 10,475 total hip arthroplasties (THAs) performed at a single healthcare system from 2004-2014 were included. Patients were classified as obese or nonobese using 2 methods: (1) body mass index (BMI) ≥30 kg/m2 and (2) international classification of disease, 9th edition codes. Length of stay, operative time, and 90-day complications were collected. Effect of obesity on various outcomes was analyzed separately for both BMI- and coding-based obesity. RESULTS From 2004 to 2014, the prevalence of BMI-based obesity increased from 54% to 63% and 40% to 45% in TKA and THA, respectively. The prevalence of coding-based obesity increased from 15% to 28% and 8% to 17% in TKA and THA, respectively. Coding overestimated the growth of obesity in TKA and THA by 5.6 and 8.4 times, respectively. When obesity was defined by coding, obesity was falsely shown to be a significant risk factor for deep vein thrombosis (TKA), pulmonary embolism (THA), and longer hospital stay (TKA and THA). CONCLUSION The growth in obesity observed in administrative databases may be an artifact because of improvements in coding over the years. Obesity defined by coding can overestimate the actual effect of obesity on complications after arthroplasty. Therefore, studies using large databases should be interpreted with caution, especially when variables prone to coding errors are involved.

Obesity Epidemic: Is Its Impact on Total Joint Arthroplasty Underestimated? An Analysis of National Trends

BackgroundObesity is a well-established risk factor for total joint arthroplasty (TJA) and a number of complications including prosthetic joint infection. The annual changes in the prevalence of obesity among primary, revision, and infected TJA has not been studied at a national level. Given the higher costs of complications of TJA, it is important to understand the association of obesity with the annual trends of revision and infected TJA.Questions/purposes(1) Is the prevalence of obesity increasing among patients undergoing THA/TKA? (2) Is the prevalence of obesity increasing among patients undergoing revision THA/TKA? (3) Is the prevalence of obesity increasing among patients with infected THA/TKA?MethodsAnnual volumes of primary, revision, and infected THA and TKA from 1998 to 2011 were obtained from the Nationwide Inpatient Sample. Using mathematical equations, the prevalence of obesity was estimated from relative risks and national obesity prevalence. National obesity prevalence was obtained from public health sources and the relative risk estimates were obtained from previously published meta-analyses and population-based studies. Annual prevalence of obesity was obtained by dividing the number of obese primary/revision/infected procedures in each year by the total number of corresponding procedures in that year. Annual changes in the prevalence of obesity were analyzed using linear regression.ResultsThe prevalence of obesity is increasing among patients undergoing THA (1998: 60,264 of 154,337 [39%], 2011: 160,241 of 305,755 [52%], increase of 1.05%/year [confidence interval {CI}, 0.95%–1.15%], p < 0.001) and TKA (1998: 143,681 of 251,309 [57%], 2011: 448,712 of 644,243 [70%], increase of 0.97%/year [CI, 0.87%–1.07%], p < 0.001). There was an increasing prevalence of obesity with THA revisions (1998: 16,322 of 34,139 [48%], 2011: 33,304 of 54,453 [61%], increase of 1.04%/year [CI, 0.94%–1.15%], p < 0.001) and in TKA revisions (1998: 16,837 of 26,539 [63%], 2011: 52,151 of 69,632 [75%], increase of 0.89%/year [CI, 0.79%–0.99%], p < 0.001). There was an increasing prevalence of obesity with THA infections (1998: 2068 of 3018 [69%], 2011: 6856 of 8687 [79%], increase of 0.80%/year [CI, 0.71%-0.89%], p < 0.001) and in TKA infections (1998: 3563 of 4684 [76%], 2011: 14,178 of 16,774 [85%], increase of 0.65%/year [CI, 0.57%–0.73%], p < 0.001).ConclusionsThe prevalence of obesity has increased in patients undergoing primary, revision, and infected TJA in United States. The obesity epidemic appears to be related to the growing trends of revision and infection after TJA. With the obesity rates expected to grow further, the revision and infection burden associated with obesity may increase in the future.Level of EvidenceLevel II, prognostic study.

What is the Diagnostic Accuracy of Aspirations Performed on Hips With Antibiotic Cement Spacers

BackgroundPeriprosthetic joint infection is a serious complication after THA and commonly is treated with a two-stage revision. Antibiotic-eluting cement spacers are placed for local delivery of antibiotics. Aspirations may be performed before the second-stage reimplantation for identification of persistent infection. However, limited data exist regarding the diagnostic parameters of synovial fluid aspiration with or without saline lavage from a hip with an antibiotic-loaded cement spacer.Questions/purposesWe asked: (1) For hips with antibiotic cement spacers, does saline lavage influence the diagnostic validity of aspirations? (2) What is the diagnostic accuracy of preoperative aspirations performed on hips with antibiotic cement spacers using the Musculoskeletal Infection Society (MSIS) criteria, stratified by saline and nonlavage? (3) For hips with antibiotic spacers, what are the optimal thresholds for synovial fluid white blood cell (WBC) count and polymorphonuclear neutrophil (PMN) percentage for diagnosing infections?MethodsOne hundred seventy-four hips (155 patients) with antibiotic-eluting cement spacers inserted between October 2012 and July 2015 were reviewed. Of these, 98 hips (80 patients) met the inclusion criteria and were included in the analysis (77 nonlavage, 21 saline lavage aspirations). Laboratory data from the aspiration and preoperative workup and intraoperative details were collected. Infection status of each hip procedure was determined based on a modified MSIS criteria using serologic, histologic, and intraoperative findings (sinus tract communicating with the joint at surgery or two positive intraoperative periprosthetic cultures with the same organism or two of the three following criteria: elevated erythrocyte sedimentation rate [ESR] [> 30 mm/hour] and C-reactive protein [CRP] [> 10 mg/L], a single positive intraoperative periprosthetic tissue culture, or a positive histologic analysis of periprosthetic tissue [> 5 neutrophils per high power field]). The diagnostic parameters were calculated for the MSIS criteria thresholds for synovial fluid (ie, WBC count > 3000 cells/µL and PMN percentage > 80%). Optimal thresholds were calculated for the corrected synovial WBC count and PMN percentage with a receiver operating characteristic curve. Separate analyses were performed for the hips with successful aspirations (nonlavage group) and those with saline lavage aspirations.ResultsThe WBC count and PMN percentage were higher in hips with infection than in hips without infection when nonlavage aspirations were done (WBC count, 6680 cells/µL ± 6980 cells/µL vs 2001 ± 4825; mean difference, 4679; 95% CI, 923-8436; p = 0.015; PMN percentage, 83% ± 13% vs 44% ± 30%; mean difference, 39%; 95% CI, 39%–49%; p < 0.001) and the findings between infected and noninfected aspirations were not different when saline lavage aspirations were done (WBC count, 782 cells/µL ± 696 vs 307 cells/µL ± 343; mean difference, 475; 95% CI, −253 to 1203; p = 0.161; PMN percentage, 67% ± 15% vs 58% ± 28%; mean difference, 10%; 95% CI, −11% to 30%; p = 0.331). Aspirations performed without lavage yielded good diagnostic accuracy in all parameters (WBC count, 78% [95% CI, 70%–86%]; PMN percentage. 79% [95% CI, 70%–88%]; positive culture: 84% [95% CI, 81%–90%]; at least one of the above: 79% [95% CI, 70%–88%]); but in the saline lavage group, none had WBC counts above the threshold (diagnostic accuracies for WBC count, 0%; PMN percentage, 71% [95% CI, 62%–86%]; positive culture, 76% [95% CI, 76%–86%]; at least one: 71% [95% CI, 57%–91%]). Because saline lavage did not result in differences between aspirations from infected and noninfected hips, we calculated the optimal thresholds in the nonlavage group only; the optimal threshold for synovial WBC count was 1166 cells/µL and for synovial PMN the percentage was 68%, which corresponds to WBC count diagnostic accuracy of 78% (95% CI, 69%–87%) and PMN percentage accuracy of 78% (95% CI, 69%–87%).ConclusionsBecause the MSIS criteria thresholds resulted in suboptimal sensitivities owing to a higher number of false negatives, we recommend considering lower WBC count and PMN percentage thresholds for hip-spacer aspirations. Furthermore, the WBC count and PMN percentage results from aspirations performed with saline lavage are not reliable for treatment decisions.Level of EvidenceLevel III, diagnostic study.

Use of Chlorhexidine Preparations in Total Joint Arthroplasty

Prosthetic joint infection (PJI) is a serious complication after total joint arthroplasty (TJA). Chlorhexidine is a widely used antiseptic because of its rapid and persistent action. It is well tolerated and available in different formulations at various concentrations. Chlorhexidine can be used for pre-operative skin cleansing, surgical site preparation, hand antisepsis of the surgical team and intra-articular irrigation of infected joints. The optimal intra-articular concentration of chlorhexidine gluconate in irrigation solution is 2%, to provide a persistent decrease in biofilm formation, though cytotoxicity might be an issue. Although chlorhexidine is relatively cheap, routine use of chlorhexidine without evidence of clear benefits can lead to unnecessary costs, adverse effects and even emergence of resistance. This review focuses on the current applications of various chlorhexidine formulations in TJA. As the treatment of PJI is challenging and expensive, effective preparations of chlorhexidine could help in the prevention and control of PJI.

Early Surgery Confers 1-year Mortality Benefit in Hip-fracture Patients

Background: To evaluate the relationship between surgical timing and 1-year mortality in patients requiring hip fracture repair. Methods: We analyzed all 720 patients (>65 years) who had hip fracture surgery between March 2005 and February 2015, identifying patients by ICD-9 diagnosis and procedure codes using electronic data query. Mortality data were obtained from the institutional database, state and Social Security Death Indices. The relationship between surgical timing (defined as the interval from admission to the start of surgery) and 1-year mortality was assessed using a multivariable logistic regression, adjusting for baseline clinical status and surgical factors. Results: Among the 720 patients, 159 patients (22%) died within 1 year. The median time from admission to surgery was 30 hours. A linear relationship between the surgical timing and 1-year mortality was demonstrated. Delaying surgery was significantly associated with increased 1-year mortality, odds ratio 1.05 (95% CI: 1.02–1.08) per 10-hour delay (P = 0.001). Conclusions: A linear relationship was observed between surgical timing and 1-year mortality. Each 10-hour delay from admission to surgery was associated with an estimated 5% higher odds of 1-year mortality. Therefore, we suggest that hip fractures should be treated urgently similar to other time-sensitive pathology such as stroke and myocardial ischemia. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Have the annual trends of total hip arthroplasty in rheumatoid arthritis patients decreased

Background Rheumatoid arthritis (RA) is characterized by chronic systemic and synovial inflammation, resulting in damage to both cartilage and bone. Medical treatment, which has increasingly relied upon disease modifying anti-rheumatic drugs (DMARDs), may fail to slow disease progression and limit joint damage, ultimately warranting surgical intervention. Up to 25% of RA patients will require lower extremity total joint arthroplasty. Though total hip arthroplasty (THA) is known to improve quality of life and functional measures, clarification is still required with respect to the impact of increased DMARD use on annual rates of THA. Thus, the purpose of this study was to evaluate: (I) the annual trends of THAs due to RA in the United States population; (II) the annual trends in the proportion of THAs due to RA in the United States. Methods This study utilized the Nationwide Inpatient Sample (NIS) to identify all patients who underwent THA between 2002 and 2013 (n=3,135,904). Then, THA patients who had a diagnosis of RA, which was defined by the International Classification of Disease 9th revision diagnosis code 714.0, were identified. The incidence of THAs with a diagnosis of RA in the United States was calculated using the United States population as the denominator. Regression models were used to analyze the annual trends of RA in patients who underwent THA. Results Review of the database identified 90,487 patients who had a diagnosis of RA and underwent THA from 2002 to 2013. The annual prevalence of RA in those who underwent THA slightly decreased over the specified time period, with 28.7 per 1,000 THAs in 2002 and 28.6 per 1,000 THAs in 2013; however, this change was not statistically significant (R2=0.158, P=0.200). Conclusions The annual rates of THA among RA patients did not show any significant change between 2002 and 2013. DMARD use has decreased both disease progression and joint destruction, and DMARDs are now often utilized as primary treatment. The increase in population of the country during the study period may have overestimated THA trends. Moreover, patients may be more likely to opt for surgical management, given the advances in operative techniques as well as peri- and post-operative course.

Serum biomarkers in periprosthetic joint infections

Objectives The diagnosis of periprosthetic joint infection (PJI) is difficult and requires a battery of tests and clinical findings. The purpose of this review is to summarize all current evidence for common and new serum biomarkers utilized in the diagnosis of PJI. Methods We searched two literature databases, using terms that encompass all hip and knee arthroplasty procedures, as well as PJI and statistical terms reflecting diagnostic parameters. The findings are summarized as a narrative review. Results Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were the two most commonly published serum biomarkers. Most evidence did not identify other serum biomarkers that are clearly superior to ESR and CRP. Other serum biomarkers have not demonstrated superior sensitivity and have failed to replace CRP and ESR as first-line screening tests. D-dimer appears to be a promising biomarker, but more research is necessary. Factors that influence serum biomarkers include temporal trends, stage of revision, and implant-related factors (metallosis). Conclusion Our review helped to identify factors that can influence serum biomarkers’ level changes; the recognition of such factors can help improve their diagnostic utility. As such, we cannot rely on ESR and CRP alone for the diagnosis of PJI prior to second-stage reimplantation, or in metal-on-metal or corrosion cases. The future of serum biomarkers will likely shift towards using genomics and proteomics to identify proteins transcribed via messenger RNA in response to infection and sepsis. Cite this article: A. Saleh, J. George, M. Faour, A. K. Klika, C. A. Higuera. Serum biomarkers in periprosthetic joint infections. Bone Joint Res 2018;7:85–93. DOI: 10.1302/2046-3758.71.BJR-2017-0323.

Magnetic Glycol Chitin-Based Hydrogel Nanocomposite for Combined Thermal and d-Amino-Acid-Assisted Biofilm Disruption

Bacterial biofilms are highly antibiotic resistant microbial cell associations that lead to chronic infections. Unlike free-floating planktonic bacterial cells, the biofilms are encapsulated in a hardly penetrable extracellular polymeric matrix and, thus, demand innovative approaches for treatment. Recent advancements on the development of gel-nanocomposite systems with tailored therapeutic properties provide promising routes to develop novel antimicrobial agents that can be designed to disrupt and completely eradicate preformed biofilms. In our study, we developed a unique thermoresponsive magnetic glycol chitin-based nanocomposite containing d-amino acids and iron oxide nanoparticles, which can be delivered and undergoes transformation from a solution to a gel state at physiological temperature for sustained release of d-amino acids and magnetic field actuated thermal treatment of targeted infection sites. The d-amino acids in the hydrogel nanocomposite have been previously reported to inhibit biofilm formation and also disrupt existing biofilms. In addition, loading the hydrogel nanocomposite with magnetic nanoparticles allows for combination thermal treatment following magnetic field (magnetic hyperthermia) stimulation. Using this novel two-step approach to utilize an externally actuated gel-nanocomposite system for thermal treatment, following initial disruption with d-amino acids, we were able to demonstrate in vitro the total eradication of Staphylococcus aureus biofilms, which were resistant to conventional antibiotics and were not completely eradicated by separate d-amino acid or magnetic hyperthermia treatments.

Vitamin D Supplementation and Progression of Knee Osteoarthritis

To the Editor The article by Dr Bellani and colleagues1 did not describe the role of the clinicians treating patients with ARDS in the study, in particular whether they knew if their skills diagnosing ARDS were being tested. This is relevant to a conclusion drawn by authors in the discussion section. If clinicians were aware of the study purpose (based on the fact that they were asked about ARDS at 2 separate times in the study), then the conclusion that ARDS might have been underrecognized in the study may not be correct. If physicians were conscious of being evaluated for their diagnostic skills, they would be less likely to miss the diagnosis and instead would overdiagnose it. Thus, clinician recognition of ARDS in the study might have occurred more frequently than it would in real-world clinical practice.