Aseptic Failure Research Articles

Sonication of orthopaedic implants: A valuable technique for diagnosis of prosthetic joint infections

IntroductionAccurate and prompt microbiological diagnosis of prosthetic joint infection (PJI) is crucial for successful antimicrobial treatment. Studies have shown the diagnostic utility of sonication of explanted implants in total joint arthroplasty but all did not use consensus statements for defining PJI. We evaluated the diagnostic utility of culture of samples obtained by sonication of explanted implants compared with periprosthetic tissue cultures (PTC) for the diagnosis of PJI using Musculoskeletal Infection Society (MSIS) consensus criteria. We also assessed the utility of culture of sonicate fluid for determining the microbial profile of PJI compared with standard culture methods. Materials and methodsForty consecutive revision arthroplasty cases were enrolled. Three to five periprosthetic tissue samples were obtained during each explant procedure. The 40 explanted implants were collected in sterile containers and sonicated under sterile conditions. MSIS criteria were used for the definition of PJI. ResultsTwenty - seven patients had PJI and thirteen were aseptic failures. Of the PJI cases, there were nine cases of early PJI's, 10 of delayed PJI's and eight of late PJI's. Twenty-five (92.5%) of the twenty-seven patients with PJI, had positive cultures in the sonicate fluid of implants and in 18 (66.7%) of them cultures of the periprosthetic tissues were also positive. Both PTC and SFC cultures of implants were negative in all the 13 cases of aseptic failure. Sensitivity of sonicate fluid culture (SFC) of implants was greater than PTC (92.5% vs. 66.7%), P = .02. The specificity of both was 100%. The incidence of gram-positive and gram-negative bacteria was nearly equal by both methods. However, SFC showed an increased ability to detect Gram-positive pathogens which was evidenced by better recovery of coagulase-negative staphylococci. ConclusionsSonication of explanted implants is a simple and valuable microbiological technique and its routine use improves the diagnostic sensitivity of PJI.

Proinflammatory biomarkers' level and functional genetic polymorphisms in periprosthetic joint infection

ObjectiveThe aims of this study were 1) to identify the level of inflammatory biomarkers interleukin (IL)-1α, IL-1β, IL-6, IL-8, IL-17, C-reactive protein (CRP), granulocyte colony-stimulating factor (GCSF), ferritin, and tumor necrosis factor (TNF)-α in serum and synovial fluid samples of patients who underwent revision arthroplasty surgery; 2) to establish the relationship between serum and synovial fluid levels; 3) to determine if any of the 11 genetic polymorphisms of TNFα, IL-1, IL-6, IL-8, IL-17, and GCSF on the encoding genes was associated with periprosthetic joint infection (PJI). MethodsSynovial fluid and serum was collected from 88 patients who underwent revision arthroplasty surgery. The Musculoskeletal Infection Society definition was used to classify these patients into 2 groups: 36 PJIs and 52 aseptic failures. Synovial fluid and serum samples were tested for 9 biomarkers using a micro enzyme-linked immunosorbent assay. Genetic polymorphisms were evaluated with polymerase chain reaction and restriction endonuclease analysis. ResultsSynovial fluid-derived IL-1α, IL-1β, IL-8, IL-17, CRP, GCSF, TNFα, and serum-derived IL-6, IL-17, ferritin, CRP were found suitable to classify PJI and aseptic failure. In addition, IL-17 and CRP levels demonstrated a positive correlation between synovial fluid and serum. TNFα-238, IL6-174, GCSF3R, and IL1 RN-VNTR genetic polymorphisms occurred more frequently in individuals with septic failure. ConclusionSignificant differences between the two groups were observed in the functional polymorphisms of the genes encoding the cytokines investigated. These differences could be interpreted as indicating that there is an association between PJI and genetic polymorphisms. Level of evidenceLevel III, diagnostic study.

Press fit condylar cobalt chrome sigma total knee arthroplasty: No difference to original design at five year point

BackgroundTotal knee arthroplasty (TKA) is an established procedure for relieving pain and improving function. The Press Fit Condylar Cobalt Chrome Sigma (PFCSCC) Total Knee System was introduced by Depuy, Johnson & Johnson in 2006, as an update of their existing PFC Sigma design intended to reduce backside wear. MethodsTo identify any significant early failures following the introduction of this knee system, we prospectively identified all patients undergoing TKA with the PFCSCC over a one-year period. Clinical and demographic patient data, American Knee Society scores, Oxford Knee scores, SF-12 scores and radiographic data were recorded pre-operatively and at three and five years post-operatively. Results233 patients underwent 249 primary TKA's with the PFCSCC. Seventeen patients (19 TKAs) died before the last review and 29 patients (30 knees) were lost to follow up. The mean age was 66.6 (range 34–80) with 47.6% male. Mean five year follow-up was 1836days (range 1530–2307). Five knees (2.2%) were revised for infection with three revised for pain. The 5-year survival rate was 96.6% and 98.6% for aseptic failure. American Knee Society Score (AKSS) was 32.6 (0–86.6) preoperatively and 80.7 (29–95) 5 years post-operatively P<0.001. OKS was 20.9 (7–38) preoperatively and 36.4 (10–48) at 5 years P<0.001. ConclusionWe report the first five year outcome of this design change, which demonstrates a good early survivorship when compared to the previous PFC Sigma design.

Minimising aseptic loosening in extreme bone resections: custom-made tumour endoprostheses with short medullary stems and extra-cortical plates.

Following the resection of an extensive amount of bone in the treatment of a tumour, the residual segment may be insufficient to accept a standard length intramedullary cemented stem. Short-stemmed endoprostheses conceivably have an increased risk of aseptic loosening. Extra-cortical plates have been added to minimise this risk by supplementing fixation. The aim of this study was to investigate the survivorship of short-stemmed endoprostheses and extra-cortical plates. The study involved 37 patients who underwent limb salvage surgery for a primary neoplasm of bone between 1998 and 2013. Endoprosthetic replacement involved the proximal humerus in nine, the proximal femur in nine, the distal femur in 13 and the proximal tibia in six patients. There were 12 primary (32%) and 25 revision procedures (68%). Implant survivorship was compared with matched controls. The amount of bone that was resected was > 70% of its length and statistically greater than the standard control group at each anatomical site. The mean follow-up was seven years (one to 17). The mean length of the stem was 33 mm (20 to 60) in the humerus and 79 mm (34 to 100) in the lower limb. Kaplan-Meier analysis of survival of the implant according to anatomical site confirmed that there was no statistically significant difference between the short-stemmed endoprostheses and the standard stemmed controls at the proximal humeral (p = 0.84), proximal femoral (p = 0.57), distal femoral (p = 0.21) and proximal tibial (p = 0.61) sites. In the short-stemmed group, no implants with extra-cortical plate osseointegration suffered loosening at a mean of 8.5 years (range 2 to 16 years). Three of ten (30%) without osseointegration suffered aseptic loosening at a mean of 7.7 years (range 2 to 11.5 years). When extensive resections of bone are required in the surgical management of tumours, and in revision cases, the addition of extra-cortical plates to short medullary stems has shown non-inferiority to standard length medullary stems and minimises aseptic failure. Cite this article: Bone Joint J 2017;99-B:1689-95.

Evaluation of Surface Finish and Dimensional Control of Tribological Metal-Ultra High Molecular Weight Polyethylene Pair of Commercially Available Hip Implants

BackgroundDimensional control and surface finish of the femoral head and acetabular liner are critical factors in the manufacturing process due to the risk of increased polyethylene wear, which is the primary cause of aseptic failure of a metal/polymer hip prosthesis. The aim of this study is to perform a dimensional and surface finish analysis to evaluate the reproduction and accuracy of the manufacturing processes of metal femoral heads and ultra high molecular weight polyethylene acetabular liners. MethodsFour femoral heads and acetabular liners from 5 manufacturers were evaluated. The methods of evaluation followed the standards ISO 7206-2:2011 and ISO 21535:2010. ResultsThe diameter, sphericity, and roughness of the femoral heads from all the manufacturers were in accordance with the standard requirements. Only the sphericity showed a lack of repeatability among the manufacturers. The variability in sphericity was high among some manufacturers and low in others. The diameters of the acetabular liners of 2 manufacturers were not in accordance with the standard requirements. The repeatability of sphericity, thickness, and roughness of the acetabular liners were heterogeneous among the manufacturers, which means that some manufacturers need to improve quality control. ConclusionOur results showed a good dimensional and surface finish control of the manufacturing processes of the femoral heads. However, the same control was not shown during the manufacturing of the acetabular liners although all samples had a thickness and sphericity in accordance with the standard. A better quality control of the manufacturing process of ultra high molecular weight polyethylene acetabular liners should be made to improve the dimensional parameters of the acetabular liners and the tribological pair.

Total knee arthroplasty in young patients: Factors predictive of aseptic failure in the 2nd–4th decade

ObjectiveIn a recently published article we reviewed our long term outcomes of TKA in young patients (<55) with end stage OA. The purpose of this study was to identify what additional factors may predict aseptic failure in these young patients. MethodsA retrospective review of all patients in our young TKA database was performed, and included failure only for mechanical wear and loosening. ResultsThe IB-II prosthesis, a thin polyethylene (<9mm), and higher Knee Society functional class at midterm follow-up was associated with higher failure rate. ConclusionThis study helps better identify the etiology of failed young patient TKA.

Diagnostic accuracy of synovial fluid, blood markers, and microbiological testing in chronic knee prosthetic infections.

This retrospective study was undertaken to define cut-off values for synovial fluid (SF) leukocyte count and neutrophil percentage for differentiating aseptic failure and periprosthetic joint infection (PJI) and to evaluate the diagnostic accuracy of blood inflammatory markers, and microbiological testing according to the criteria proposed by the International Consensus Meeting (ICM) of Philadelphia. All patients who underwent revision total knee arthroplasty from January 2010 to July 2015 were included: we identified and classified 31 PJIs and 136 aseptic joints. The diagnostic performance of single test was assessed by receiver operating characteristic curve analyses. The sensitivity and specificity were calculated for each of the cut-off values and the area under the curve (AUC) was calculated. The median SF leukocyte count as well as the neutrophil percentage and inflammatory markers were significantly higher in patients with PJI than in those with aseptic failure (p<0.001). A leukocyte count of>2.8×103/μL had a sensitivity of 83.8% and a specificity of 89.7% whereas a neutrophil percentage of>72% yielded a marginally higher sensitivity of 84% and a specificity of 91%. Applying the ICM criteria we found a significant correlation between all these diagnostic measures and PJI (p<0.001) except for a single positive culture. The most accurate criterion of the ICM was the synovial neutrophil differential (AUC=0.89; 95% CI 0.81-0.97), followed by SF leukocyte count (AUC=0.86; 95% CI 0.78-0.94), increased inflammatory markers (AUC=0.85; 95% CI 0.76-0.93), and two positive periprosthetic cultures (AUC=0.84; 95% CI 0.73-0.94). The presence of sinus tract communicating with the joint and a single positive culture showed unfavourable diagnostic accuracy (AUC=0.60, 95% CI 0.47-0.72; AUC=0.49, 95% CI 0.38-0.61, respectively) CONCLUSIONS: The present study highlights the adequate ability of fluid cell count and neutrophil differential to distinguish between PJI and aseptic loosening. The clinical utility of fluid analysis in diagnosing infection can be improved by evaluation of other diagnostic criteria. Level I Diagnostic Study.

Synovial fluid multiplex PCR is superior to culture for detection of low-virulent pathogens causing periprosthetic joint infection

IntroductionAnalysis of joint aspirate is the standard preoperative investigation for diagnosis of periprosthetic joint infection (PJI). We compared the diagnostic performance of culture and multiplex polymerase chain reaction (PCR) of synovial fluid for diagnosis of PJI. Patients and MethodsPatients in whom aspiration of the prosthetic hip or knee joint was performed before revision arthroplasty were prospectively included. The performance of synovial fluid culture and multiplex PCR was compared by McNemar's chi-squared test. ResultsA total of 142 patients were included, 82 with knee and 60 with hip prosthesis. PJI was diagnosed in 77 patients (54%) and aseptic failure in 65 patients (46%). The sensitivity of synovial fluid culture and PCR was 52% and 60%, respectively, showing concordant results in 116 patients (82%). In patients with PJI, PCR missed 6 high-virulent pathogens (S. aureus, streptococci, E. faecalis, E. coli) which grew in synovial fluid culture, whereas synovial fluid culture missed 12 pathogens detected by multiplex PCR, predominantly low-virulent pathogens (Cutibacterium acnes and coagulase-negative staphylococci). In patients with aseptic failure, PCR detected 6 low-virulent organisms (predominantly C. acnes). ConclusionWhile the overall performance of synovial fluid PCR was comparable to culture, PCR was superior for detection of low-virulent bacteria such as Cutibacterium spp. and coagulase-negative staphylococci. In addition, synovial fluid culture required several days for growth, whereas multiplex PCR provided results within 5hours in an automated manner.

Cementless Total Knee Arthroplasty in Knee Osteonecrosis Demonstrated Excellent Survivorship and Outcomes at Three-Year Minimum Follow-Up

BackgroundLack of consensus exists on the use of cementless total knee arthroplasty (TKA) in patients with knee osteonecrosis. Therefore, this study was conducted to evaluate (1) implant survivorship; (2) clinical outcomes and complications; and (3) radiographic outcomes of primary cementless TKA in knee osteonecrosis. MethodsThis study included 46 patients (49 knees) who had knee osteonecrosis and underwent primary cementless TKA and had a mean follow-up of 44 months (range 36-96). Kaplan-Meier analysis was used to evaluate implant survivorship. Follow-up was performed post-operatively at 6 weeks, 3 months, and annually thereafter. Clinical outcomes including the Knee Society Scores (KSS) for pain and function, changes in range-of-motion, complications, and radiographic outcomes were analyzed. ResultsAseptic implant survivorship was 97.9% (95% confidence interval 1.01-0.93) and all-cause implant survivorship was 95.9% (95% confidence interval 1.01-0.9), with 1 septic and 1 aseptic failures. The mean KSS for pain was 93 points (range 85-100) and the mean KSS for function was 84 points (range 70-90). Additionally, 1 patient had superficial wound necrosis and was treated with local wound care with no further sequela. Otherwise, no evidence of loosening, subsidence, or progressive radiolucencies were noted on radiological evaluation. ConclusionExcellent implant survivorship, clinical, and radiographic outcomes of primary cementless TKA in the setting of knee osteonecrosis was demonstrated. Although further long-term study is needed to validate survivorship, new generation cementless TKA implants provide promising results in this subset of patients.

Performance of automated multiplex PCR using sonication fluid for diagnosis of periprosthetic joint infection: a prospective cohort

Sonication of explanted prostheses improved the microbiological diagnosis of periprosthetic joint infections (PJI). We evaluated the performance of automated multiplexpolymerase chain reaction (PCR) using sonication fluid for the microbiological diagnosis of PJI. In a prospective cohort using uniform definition criteria for PJI, explanted joint prostheses were investigated by sonication and the resulting sonication fluid was analyzed by culture and multiplex PCR. McNemar's Chi-squared test was used to compare the performance of diagnostic tests. Among 111 patients, PJI was diagnosed in 78 (70%) and aseptic failure in 33 (30%). For the diagnosis of PJI, the sensitivity and specificity of periprosthetic tissue culture was 51 and 100%, of sonication fluid culture 58 and 100%, and of sonication fluid PCR 51 and 94%, respectively. Among 70 microorganisms, periprosthetic tissue culture grew 52 (74%), sonication fluid culture grew 50 (71%) and sonication fluid PCR detected 37 pathogens (53%). If only organisms are considered, for which primers are included in the test panel, PCR detected 37 of 58 pathogens (64%). The sonication fluid PCR missed 19 pathogens (predominantly oral streptococci and anaerobes), whereas 7 additional microorganisms were detected only by PCR (including Cutibacterium spp. and coagulase-negative staphylococci). The performance of multiplex PCR using sonication fluid is comparable to culture of periprosthetic tissue or sonication fluid. The advantages of PCR areshort processing time (<5h) and fully automated procedure. However, culture technique is still needed due to the low sensitivity and the need of comprehensive susceptibility testing. Modification of primers or inclusion of additional ones may improve the performance of PCR, especially of low-virulent organisms.

Serum D-Dimer Test Is Promising for the Diagnosis of Periprosthetic Joint Infection and Timing of Reimplantation.

Despite the availability of a battery of tests, the diagnosis of periprosthetic joint infection (PJI) continues to be challenging. Serum D-dimer assessment is a widely available test that detects fibrinolytic activities that occur during infection. We hypothesized that patients with PJI may have a high level of circulating D-dimer and that the presence of a high level of serum D-dimer may be a sign of persistent infection in patients awaiting reimplantation. This prospective study was initiated to enroll patients undergoing primary and revision arthroplasty. Our cohort consisted of 245 patients undergoing primary arthroplasty (n = 23), revision for aseptic failure (n = 86), revision for PJI (n = 57), or reimplantation (n = 29) or who had infection in a site other than a joint (n = 50). PJI was defined using the Musculoskeletal Infection Society criteria. In all patients, serum D-dimer level, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) level were measured preoperatively. The median D-dimer level was significantly higher (p < 0.0001) for the patients with PJI (1,110 ng/mL [range, 243 to 8,487 ng/mL]) than for the patients with aseptic failure (299 ng/mL [range, 106 to 2,571 ng/mL). Using the Youden index, 850 ng/mL was determined as the optimal threshold value for serum D-dimer for the diagnosis of PJI. Serum D-dimer outperformed both ESR and serum CRP, with a sensitivity of 89% and a specificity of 93%. ESR and CRP had a sensitivity of 73% and 79% and a specificity of 78% and 80%, respectively. The sensitivity and specificity of ESR and CRP combined was 84% (95% confidence interval [CI], 76% to 90%) and 47% (95% CI, 36% to 58%), respectively. It appears that serum D-dimer is a promising marker for the diagnosis of PJI. This test may also have a great utility for determining the optimal timing of reimplantation. Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Excellent Diagnostic Characteristics for Ultrafast Gene Profiling of DEFA1-IL1B-LTF in Detection of Prosthetic Joint Infections.

ABSTRACTThe timely and exact diagnosis of prosthetic joint infection (PJI) is crucial for surgical decision-making. Intraoperatively, delivery of the result within an hour is required. Alpha-defensin lateral immunoassay of joint fluid (JF) is precise for the intraoperative exclusion of PJI; however, for patients with a limited amount of JF and/or in cases where the JF is bloody, this test is unhelpful. Important information is hidden in periprosthetic tissues that may much better reflect the current status of implant pathology. We therefore investigated the utility of the gene expression patterns of 12 candidate genes (TLR1, -2, -4, -6, and 10, DEFA1, LTF, IL1B, BPI, CRP, IFNG, and DEFB4A) previously associated with infection for detection of PJI in periprosthetic tissues of patients with total joint arthroplasty (TJA) (n = 76) reoperated for PJI (n = 38) or aseptic failure (n = 38), using the ultrafast quantitative reverse transcription-PCR (RT-PCR) Xxpress system (BJS Biotechnologies Ltd.). Advanced data-mining algorithms were applied for data analysis. For PJI, we detected elevated mRNA expression levels of DEFA1 (P < 0.0001), IL1B (P < 0.0001), LTF (P < 0.0001), TLR1 (P = 0.02), and BPI (P = 0.01) in comparison to those in tissues from aseptic cases. A feature selection algorithm revealed that the DEFA1-IL1B-LTF pattern was the most appropriate for detection/exclusion of PJI, achieving 94.5% sensitivity and 95.7% specificity, with likelihood ratios (LRs) for positive and negative results of 16.3 and 0.06, respectively. Taken together, the results show that DEFA1-IL1B-LTF gene expression detection by use of ultrafast qRT-PCR linked to an electronic calculator allows detection of patients with a high probability of PJI within 45 min after sampling. Further testing on a larger cohort of patients is needed.

Oscillatory device for use with linear tribometer, for tribological evaluation of biomaterials.

Orthopedic implants still have limitations regarding their durability, despite being in use for over fifty years. Particles arising from wear due to the relative motion of their surfaces remain responsible for aseptic failure. This paper presents a device to be coupled with a reciprocal linear tribometer to reproduce the ex vivo wear of biomaterials, allowing the measurement of force and coefficient of friction. The device consists of a structure connected to the tribometer that transforms its reciprocal linear motion into one that is oscillatory for the mechanical assembly that contains the samples to test the desired biomaterials. The tribological pair used for testing consisted of Ultra High Molecular Weight Polyethylene (UHMWPE) in conjunction with the austenitic stainless steel AISI 316L in dry lubrication. The results showed that the values of the coefficient of friction in the linear mode and oscillatory mode and the UHMWPE life curve in the oscillatory mode were consistent with those cited in the literature for tests in a dry lubrication environment. Moreover, the UHMWPE sample life curve showed a reduction in the wear rate that can be explained by the preponderance of a wear mechanism over the others. The volumetric wear showed an increase with the number of cycles.

The Leukocyte Esterase Strip Test has Practical Value for Diagnosing Periprosthetic Joint Infection After Total Knee Arthroplasty: A Multicenter Study

BackgroundLeukocyte esterase (LE) was recently reported to be an accurate marker for diagnosing periprosthetic joint infection (PJI) as defined by the Musculoskeletal Infection Society (MSIS) criteria. However, the diagnostic value of the LE test for PJI after total knee arthroplasty (TKA), the reliability of the subjective visual interpretation of the LE test, and the correlation between the LE test results and the current MSIS criteria remain unclear. MethodsThis study prospectively enrolled 60 patients undergoing revision TKA for either PJI or aseptic failure. Serological marker, synovial fluid, and histological analyses were performed in all cases. The PJI group comprised 38 cases that met the MSIS criteria and the other 22 cases formed the aseptic group. All the LE tests were interpreted using both visual judgment and automated colorimetric reader. ResultsWhen “++” results were considered to indicate a positive PJI, the sensitivity, specificity, positive and negative predictive value, and diagnostic accuracy were 84, 100, 100, 79, and 90%, respectively. The visual interpretation agreed with the automated colorimetric reader in 90% of cases (Cronbach α = 0.894). The grade of the LE test was strongly correlated with the synovial white blood cell count (ρ = 0.695) and polymorphonuclear leukocyte percentage (ρ = 0.638) and moderately correlated with the serum C-reactive protein and erythrocyte sedimentation rate. ConclusionThe LE test has high diagnostic value for diagnosing PJI after TKA. Subjective visual interpretation of the LE test was reliable and valid for the current battery of PJI diagnostic tests according to the MSIS criteria.

Unusually High Rate of Early Failure of Tibial Component in ATTUNE Total Knee Arthroplasty System at Implant-Cement Interface.

AbstractA novel design total knee arthroplasty (TKA) system has been introduced to improve patient outcomes and increase longevity. However, we have encountered a high rate of debonding of tibial implant–cement interface. In addition, multiple reports have been filed in Manufacturer and User Facility Device Experience database (MAUDE) with the same mechanism of failure. Therefore, we evaluated: clinical, radiographic, and intraoperative findings of patients who received this system and required a revision surgery, and findings from MAUDE database compiled to this date. We reviewed three hospital databases for patients who had revision TKA for tibial loosening at the implant–cement interface. This yielded 15 cases with a mean age of 61 years (range, 47–84). All patients received a novel knee system at another institution. Radiographic analysis was performed by treating orthopaedist. The MAUDE database was reviewed for reports of aseptic failure. Patients presented with pain on weight bearing, effusion, and decreased range of motion (ROM) within 2 years after surgery. Radiographic evaluation demonstrated loosening of the tibial components in 2 of 15 knees. This included cruciate retaining, posterior stabilized, fixed bearing, and rotating platform bearing designs. Intraoperative findings demonstrated gross loosening of the tibial component at the implant–cement interface. Femoral and patellar components were well fixed. There were 21 reports of tibial loosening at the implant–cement interface in MAUDE database in the past 2 months alone. Numerous other tibial failures were reported; however, the mechanisms of failures were not specified. Tibial component loosening is a rare complication of cemented TKA at short-term follow-up. Several possible reasons include increased constraint, reduced cement pockets, and reduced keel rotational stabilizers. The tibial component, which has greater torsional loads, has lower surface roughness than femoral component. We believe that this complication is underreported due to failure of radiographs to assess loosening. In addition, MAUDE database reporting is not consistent and competing companies cannot provide data on the revised components. In patients who have negative workup for a painful joint, one must consider the diagnosis of debonding.

Definition of periprosthetic joint infection of the hip and new tools for diagnosis

A diagnosis of periprosthetic joint infection after total hip arthroplasty remains a challenge without a simple solution. It can be difficult to distinguish from aseptic failure of a total hip but is a significantly worse complication. Recent research has gone into attempting to find a cost-effective laboratory test or imaging modality that can assist in definitive diagnosis of periprosthetic joint infection, but there is no single most effective test as of yet. There are several promising possibilities arising from a variety of serum and synovial laboratory values, including alpha-defensin and leukocyte esterase tests. This review provides information on the most recent advances in the literature with regards to diagnosis of periprosthetic joint infection after total hip arthroplasty.

What is the Long-term Economic Societal Effect of Periprosthetic Infections After THA? A Markov Analysis.

Current estimates for the direct costs of a single episode of care for periprosthetic joint infection (PJI) after THA are approximately USD 100,000. These estimates do not account for the costs of failed treatments and do not include indirect costs such as lost wages. The goal of this study was to estimate the long-term economic effect to society (direct and indirect costs) of a PJI after THA treated with contemporary standards of care in a hypothetical patient of working age (three scenarios, age 55, 60, and 65 years). We created a state-transition Markov model with health states defined by surgical treatment options including irrigation and débridement with modular exchange, single-stage revision, and two-stage revision. Reoperation rates attributable to septic and aseptic failure modes and indirect and direct costs were calculated estimates garnered via multiple systematic reviews of peer-reviewed orthopaedic and infectious disease journals and Medicare reimbursement data. We conducted an analysis over a hypothetical patient's lifetime from the societal perspective with costs discounted by 3% annually. We conducted sensitivity analysis to delineate the effects of uncertainty attributable to input variables. The model found a base case cost of USD 390,806 per 65-year-old patient with an infected THA. One-way sensitivity analysis gives a range of USD 389,307 (65-year-old with a 3% reinfection rate) and USD 474,004 (55-year-old with a 12% reinfection rate). Indirect costs such as lost wages make up a considerable portion of the costs and increase considerably as age at the time of infection decreases. The results of this study show that the overall treatment of a periprosthetic infection after a THA is markedly more expensive to society than previously estimated when accounting for the considerable failure rates of current treatment options and including indirect costs. These overall costs, combined with a large projected increase in THAs and a steady state of septic failures, should be taken into account when considering the total cost of THA. Further research is needed to adequately compare the clinical and economic effectiveness of alternative treatment pathways. Level II, economic and decision analysis.

Midterm Outcomes of Revision Total Hip Arthroplasty With the Use of a Multihole Highly-Porous Titanium Shell

BackgroundWe are reporting on the minimum 5-year outcomes of patients who underwent revision total hip arthroplasty (THA) using a specific highly-porous titanium shell. We assessed (1) aseptic and all-cause survivorship; (2) functional outcomes; (3) complications; and (4) radiographic outcomes. MethodsTwo hospital databases were evaluated for patients who underwent revision THA due to component instability or aseptic loosening using a cementless highly-porous titanium shell between September 2006 and December 2011. This yielded 35 patients who had a mean age of 61 years (range 14-88 years). Patients had a mean follow-up of 6 years (minimum 5 years). All-cause and aseptic survivorship of the shell was calculated. Functional outcomes were assessed using the Harris Hip Score. We determined the incidence of postoperative complications and performed radiographic evaluation of pelvic radiographs from regular office visits. ResultThe aseptic survivorship of the acetabular component was 97% (95% confidence interval; 8.1-9.5). The all-cause survivorship of the acetabular component was 91% (95% confidence interval; 7.3-8.1). One patient had an aseptic failure and 2 patients had septic failures. The mean postoperative Harris Hip Score was 76 points (range, 61-91 points). Excluding the aseptic and septic failures, there was no osteolysis or progressive radiolucencies present on radiographic evaluation at final follow-up. ConclusionAt a minimum of 5-year follow-up, the highly-porous titanium acetabular revision shell has excellent survivorship and functional outcomes. Although long-term follow-up is needed to further monitor these implants, the results are promising and demonstrate that this prosthesis may be an excellent option for patients undergoing revision THA.

Total hip arthroplasty in patients 55 years or younger: Risk factors for poor midterm outcomes

BackgroundTotal hip arthroplasty (THA) is increasingly performed in younger patients. The purpose of this study is to report on the midterm outcomes of primary cementless THA in patients 55 years and younger; and specifically to examine the risk factors for aseptic failure, all-cause revision, and mortality in this patient population. MethodsFour hundred and twenty-six consecutive patients with minimum 5-year follow-up were retrospectively reviewed. Multivariate analyses were conducted to control for potential confounding factors identified by univariate analyses. ResultsMean follow-up was 92.12±30.9months. The overall 5-year implant survival rate was 90.8% and the aseptic survival rate was 92.6%. Among the potential risk factors, only bearing surface had a significant relationship with aseptic revision (P=0.041). Aseptic revisions occurred more frequently with metal-on-polyethylene articulation (P=0.012). Higher Charlson comorbidity index (CCI) was a significant risk factor for all-cause complications (P=0.04) while higher CCI and lower body mass index were significant risk factors for mortality (P=0.001 and 0.006 respectively). ConclusionBearing type was the only risk factor for revision surgery, particularly metal-on-polyethylene bearing. Patients with higher comorbidities were at increased risk for postoperative complications and mortality, while higher body weight appeared to have a protective effect against mortality. These findings should be considered before surgery for risk modification and management of patient expectations. While it appears that bearing couples other than metal-on-polyethylene are especially suitable for young patients, more studies are needed to determine the best bearing couple and to reduce the rates of postoperative complications in this patient population.

Synovial fluid white cell count and histopathological examination of periprosthetic tissue samples (frozen and permanent sections) in the diagnosis of prosthetic knee infection

Abstract The aim of the study was to determine prospectively the importance of synovial fluid white cell count and intraoperative frozen and permanent sections analysis (number of polymorphonuclear leukocytes per high-power field) in the diagnosis of septic total knee arthroplasty. There were studied prospectively 72 patients who needed a revision total knee arthroplasty between 2013-2015. 30 patients were diagnosed with prosthetic joint infection due to high rates of ESR (93%) and CRP (90%) and preoperative positive culture from aspirated synovial fluid and 42 patients were considered to have aseptic failure according to negative preoperative culture from joint aspirate. For all the patients was analysed synovial fluid white cell count and histopathological aspect of intraoperative frozen and permanent sections of periprosthetic tissue. The results showed a median value of 13800 of sinovial white cells count for infected knee and 92 for noninfected knee. 90% of the patients with joint infection had more than 5 polymorphonuclear leukocytes per high power field on intraoperative frozen sections and 83% on permanent sections. None of the patients from aseptic group had more than 5 polymorphonuclear leukocytes per field on permanent sections. The erythrocyte sedimentation rate and C-reactive protein level can be supplemented with cultures of aspirated joint fluid and fluid white cell count to confirm the diagnosis of periprosthetic infection. When the preoperative diagnosis remain unclear, the histological examination of frozen or permanent sections of periprosthetic tissue with at least 5 polymorphonuclear leukocytes per high power field, is predictive for the presence of infection.