Synovial aspiration and serological testing in two-stage revision arthroplasty for prosthetic joint infection: evaluation before reconstruction with a mean follow-up of twenty seven months.

INTRODUCTION: The two-stage revision protocol is the gold standard for controlling and treating low-grade prosthetic joint infections of total hip and total knee arthroplasty. The antibiotic pause for diagnostic reasons before reconstruction (stage two) is discussed in relation to the persistence of the infection and the development of resistant bacterial strains. Serological markers and a synovial analysis are commonly used to exclude the persistence of infection. Therefore, we asked (1) is the serological testing of C-reactive protein and leucocytes a valuable tool to predict a persistence of infection? and (2) what is the role of synovial aspiration of Plymethylmethacrylat (PMMA) spacers in hip and knee joints? MATERIALS AND METHODS: One hundred twelve patients who were MSIS criteria-positive for a prosthetic joint infection were studied, including 45 total hip arthroplasties (THA) and 67 total knee artrhoplasties (TKA) patients. All patients were treated with a two-stage-protocol using a mobile PMMA spacer after a 14-day antibiotic-free interval, during which we measured serological markers (C-reactive protein and leucocytes) and performed synovial aspiration (white blood cell count, polymorphonuclear cell percentage, and microbiological culture) in these patients and compared the results with those of their long-term-follow-up (mean follow-up 27 months, range 24-36 months). RESULTS: Of the 112 patients, 89 patients (79.5%; 95% CI 72-86.9) exhibited infection control after a two-stage exchange, and we detected most methicillin-resistant, coagulase-negative Staphylococci (CoNS) in cases of a persistent infection. The mean sensitivity of serum C-reactive protein in the patients was 0.43 (range 0.23-0.64), and the mean specificity was 0.73 (range 0.64-0.82). For serum leucocytes, the mean sensitivity was 0.09 (range 0-0.29), and the mean specificity was 0.81 (range 0.7-0.92). The mean sensitivity for the WBC count in the synovial fluid (PMMA spacer aspiration) was 0.1 (range 0-0.29), and the mean specificity was 0.79 (range 0.68-0.92). For the PMN percentage, the mean sensitivity was 0.1 (range 0-0.29), and the mean specificity was 0.79 (range 0.68-0.92). No cut-off values could be established for C-reactive protein, leucocytes, WBC count and PMN percentage due to the low AUC. CONCLUSION: No reliable markers were identified for the long-term persistence of infection. C-reactive protein and leucocytes were often elevated, even when the infection was controlled. In addition, normalized serum markers did not exclude the persistence of infection during follow-up. The synovial analysis of the WBC count and PMN percentage did not predict the persistence of infection. However, microbiological synovial fluid analysis is often misleading due to false positive microbiological cultures, which results in overtreatment.

In vitro Growth Pattern of Primary Human Osteoblasts on Calcium Phosphate- and Polymethylmethacrylate-Based Bone Cement.

BACKGROUND/PURPOSE: Polymethylmethacrylate (PMMA) and calcium phosphate (Ca-P) cements are widely used for arthroplasty surgery and augmentation of bone defects. However, aseptic implant loosening in absence of wear-induced osteolysis indicates an unfavourable interaction between the cement surface and human osteoblasts. Our underlying hypothesis is that cement surfaces directly modify cell viability, proliferation rate, and cell differentiation. METHODS: To test this hypothesis, we examined primary human osteoblasts harvested from six individuals. These cells were pooled and subsequently seeded directly on cement pellets prepared from Palacos® R, Palacos® R+G, and Norian® Drillable cements. After incubation for 24 and 72 h, cell viability, proliferation rate, apoptosis rate, and cell differentiation were analysed. RESULTS: Upon cultivation of human osteoblasts on cement surfaces, we observed a significantly reduced cell viability and DNA content compared to the control. Analysis of the apoptosis rate revealed an increase for cells on Palacos R and Norian Drillable, but a significant decrease on Palacos R+G compared to the control. Regarding osteogenic differentiation, significantly lower values of alkaline phosphatase enzyme activity were identified for all cement surfaces after 24 and 72 h compared to cultivation on tissue culture plastic, serving as control. CONCLUSIONS: In summary, these data suggest a limited biocompatibility of both PMMA and Ca-P cements, necessitating further research to reduce unfavourable cell-cement interactions and consequently extend implant survival.

Glucosamine sulfate suppresses the expression of matrix metalloproteinase-3 in osteosarcoma cells in vitro.

BACKGROUND: Glucosamine, a common dietary supplement, has a possible anti-sarcoma effect. However, an understanding of the underlying mechanism of such an effect is limited. For this study we hypothesized that glucosamine suppresses the basal level of matrix metalloproteinase expression in human osteosarcoma cell lines. METHODS: We examined the osteosarcoma cell lines, MG-63 and SaOS-2. Cells were exposed to 0, 10, 50 and 100 µg/ml glucosamine sulfate for 48 h and treatment toxicity was determined through measurement of cell viability and proliferation. Relative gene expression of matrix metalloproteinase (MMP)-2, -3 and -9 was quantified by real-time polymerase chain reaction. Protein levels of MMP-2 and -9 were assessed by ELISA. RESULTS: Administration of 10, 50 or 100 µg/ml glucosamine sulfate had no effect on the cell viability of MG-63 and SaOS-2 cells. A significant reduction of MMP expression in both cell lines was observed only for MMP-3, while a decrease in MMP-9 was seen in SaOS-2 cells. The expression of MMP-2 was not significantly affected in either cell line. Protein level of MMP-3 was reduced in both cell lines upon stimulation with 10 µg/ml glucosamine sulfate whereas for MMP-9 a decrease could only be observed in SaOS-2 cells. CONCLUSION: In this study, we found a pronounced suppressive effect of glucosamine sulfate particularly on MMP-3 and also MMP-9 mRNA and protein levels in osteosarcoma cell lines in vitro. The data warrants further investigations into the potential anti-tumor efficacy of glucosamine sulfate in osteosarcoma.

Autologous Chondrocyte Transplantation in Femoroacetabular Impingement Syndrome: Growth and Redifferentiation Potential of Chondrocytes Harvested from the Femur in Cam-Type Deformities.

OBJECTIVE: Cam-type femoroacetabular impingement (FAI) syndrome is one of the most frequent reasons for cartilage damage in the hip. Autologous chondrocyte transplantation has proven high success rates in the treatment of focal chondral defects; however, harvesting of chondrocytes in the hip has been reported but not specifically from the region of femoral cam lesions. Therefore, the goal of this study was to analyze the growth and redifferentiation potential of cartilage samples harvested from the cam deformities in patients with FAI. DESIGN: Cartilage samples were gained from 15 patients with cam-type FAI undergoing arthroscopic femoral cam resection. Healthy (hyaline cartilage of the hip and knee joint, n = 12) and arthritic control groups (degenerative changes in cartilage of the hip joint, n = 8) were also analyzed. Chondrocytes were initially cultured under monolayer, and subsequently under pellet conditions. A comparative representation of the groups was performed by Mankin score classification, immunohistochemistry (IHC) (Col1, Col2, aggrecan), and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) (Col1, Col2, Col10, Sox9, RunX2). RESULTS: Mankin score of FAI-samples (4.1±3.1, Range 0-10) showed a wide variation but was significant lower (P = 0.0244) when compared with the arthritic control (7.5 ± 2.7, range 4-12). IHC showed an increased deposition of Col2 (P = 0.0002) and aggrecan (P = 0.0261) after pellet culture compared with deposition after monolayer culture in all groups. In qRT-PCR, FAI samples showed after pellet culture increased Col2 (P = 0.0050) and Col10 expression (P = 0.0006) and also Mankin score correlated increasing gene-expression of Col10 (r = 0.8108, P = 0.0341) and RunX2 (r = 0.8829, P = 0.123). CONCLUSIONS: Cartilage samples of patients with cam-type FAI showed sufficient but heterogeneous composition relating to histological quality and chondrogenic potential. However, harvesting of chondrocytes from the cam lesion might be a valid option especially if a cartilage lesion is noted in a diagnostic arthroscopy and individual preexisting stage of cartilage degeneration and appropriate pellet-culturing conditions are considered.

High hydrostatic pressure, a novel approach in orthopedic surgical oncology to disinfect bone, tendons and cartilage.

High hydrostatic pressure (HHP) is widely used in the food processing industry, for example to inactivate vegetative microorganisms in meat products, milk and juice, thereby avoiding the addition of any chemical preservatives. Besides this, HHP is also an attractive novel approach to effectively kill vegetative microorganisms or tumor cells in bone, cartilage and tendon ex vivo while leaving the tissues' mechanical properties unimpaired, thus allowing reimplantation of the resected tissue explants. In contrast, sterilization by gamma irradiation and thermal or chemical inactivation of potentially infected autografts, allografts and other biomaterials considered for tissue regeneration and reconstruction is often associated with deterioration of the mechanical, physical and biological properties of the implant. HHP technology is now in preclinical testing with the aim of disinfecting/devitalizing grafts in order to inactivate both vegetative microorganisms and tumor cells in resected bone tissue segments, eventually allowing reimplantation of resected bone segments initially afflicted with osteomyelitis or tumors. The technical advantages, state-of-the-art, and potential application of HHP in orthopedic surgery are reviewed.

Quantitative analysis of the impact of short-time high hydrostatic pressure on bone tumor-associated proteases.

In orthopedic surgery, sterilization of bone used for reconstruction of osteoarticular defects caused by malignant tumors is carried out in various ways. At present, to devitalize tumor-bearing osteochondral segments, extracorporeal irradiation or autoclaving is mainly used, although both methods have substantial disadvantages, leading to a significant loss of biomechanical and biological integrity of the bone. As an alternative approach, a new technology to achieve bone sterilization, the high hydrostatic pressure (HHP) treatment of bone, has been suggested, which is currently being preclinically tested. This novel technique leads to the inactivation of tumor cells without impairing biomechanical properties of the bone, cartilage, or tendons. HHP may not only exert an effect on tumor and normal cells present in the bone but also on tumor-associated proteases released by these cells, which are conductive to tumor bone turnover. In order to investigate this, proteolytic key enzymes, e.g. MMP-9, uPA, t-PA, plasmin, trypsin, and thrombin were subjected to HHP

How to address ischiofemoral impingement? Treatment algorithm and review of the literature.

Ischiofemoral impingement (IFI) is a rare cause of hip pain defined by a narrowing of the space between the lateral aspect of the os ischium and the lesser trochanter of the femur. Several underlying anatomic, functional and iatrogenic pathologies have been identified for symptomatic IFI in native hip joints and after total hip arthroplasty. Clinical symptoms vary but most commonly consist of pain of the lower buttock and groin including the inner thigh, and a snapping or clunking phenomenon is often reported. Symptoms may be provoked by a combined extension, adduction and external rotation during physical examination and during long-stride walking. Radiographs of the pelvis and an axial or false-profile-view of the hip as well as magnetic resonance imaging (MRI)-scans should be obtained to strengthen the diagnosis. On MRI, the quadratus femoris muscle signal and the space confined by the anatomic structures surrounding the muscle, the quadratus femoris space, are to be assessed. Targeted infiltration of the muscle can be helpful both diagnostically and therapeutically. The literature on differential diagnoses and treatment options for IFI is limited; therapeutic suggestions are offered only in case reports and series. With this work, we aim to give a systematic approach to the non-surgical and surgical treatment options for IFI based upon the current literature and the authors' personal experience.

Prosthetic joint infection development of an evidence-based diagnostic algorithm.

BACKGROUND: Increasing rates of prosthetic joint infection (PJI) have presented challenges for general practitioners, orthopedic surgeons and the health care system in the recent years. The diagnosis of PJI is complex; multiple diagnostic tools are used in the attempt to correctly diagnose PJI. Evidence-based algorithms can help to identify PJI using standardized diagnostic steps. METHODS: We reviewed relevant publications between 1990 and 2015 using a systematic literature search in MEDLINE and PUBMED. The selected search results were then classified into levels of evidence. The keywords were prosthetic joint infection, biofilm, diagnosis, sonication, antibiotic treatment, implant-associated infection, Staph. aureus, rifampicin, implant retention, pcr, maldi-tof, serology, synovial fluid, c-reactive protein level, total hip arthroplasty (THA), total knee arthroplasty (TKA) and combinations of these terms. RESULTS: From an initial 768 publications, 156 publications were stringently reviewed. Publications with class I-III recommendations (EAST) were considered. We developed an algorithm for the diagnostic approach to display the complex diagnosis of PJI in a clear and logically structured process according to ISO 5807. CONCLUSIONS: The evidence-based standardized algorithm combines modern clinical requirements and evidence-based treatment principles. The algorithm provides a detailed transparent standard operating procedure (SOP) for diagnosing PJI. Thus, consistently high, examiner-independent process quality is assured to meet the demands of modern quality management in PJI diagnosis.

Diagnostic accuracy of arthroscopic biopsy in periprosthetic infections of the hip.

BACKGROUND: Diagnosis of a low-grade periprosthetic joint infection (PJI) prior to revision surgery can be challenging, despite paramount importance for further treatment. Arthroscopic biopsy of synovial and periprosthetic tissue with subsequent microbiological and histological examination can be beneficial but its specific diagnostic value has not been clearly defined. METHODS: 20 consecutive patients who underwent percutaneous synovial fluid aspiration as well as arthroscopic biopsy due to suspected PJI of the hip and subsequent one- or two-stage revision surgery at our institution between January 2012 and May 2015 were enrolled. Indication was based on the criteria (1) history of PJI and increased levels of erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), (2) suspicious cell count and differential but negative bacterial culture in synovial aspirate, (3) early loosening (

IT-based Psychosocial Distress Screening in Patients with Sarcoma and Parental Caregivers via Disease-specific Online Social Media Communities.

BACKGROUND: Psychosocial distress can be frequently observed in patients with sarcoma, depicting a relevant clinical problem. However, prospective data collection on psychosocial distress in patients with rare tumors is often time-consuming. In this context, social media such as Facebook can serve as a potential platform to expand research. The aim of this study was to assess the feasibility of psychosocial distress screening in patients with osteosarcoma and Ewing's sarcoma via social media. MATERIALS AND METHODS: For this study an online questionnaire including general information and self-assessment distress measurement tools for patients and parents was created. The link to the questionnaire was then posted on the main page of the two largest disease-specific Facebook communities on osteosarcoma and Ewing's sarcoma. RESULTS: Within 2 months, 28 patients and 58 parents of patients were enrolled. All patients with osteosarcoma and Ewing's sarcoma, as well as the majority of parental caregivers of such patients, showed relevant psychosocial distress levels. CONCLUSION: Crowdsourcing via disease-specific patient communities on Facebook is feasible and provides great potential for acquisition of medical data of rare diseases.

Prospective Analysis of a Sterile, Semi-automated Tissue Biopsy Homogenization Method in the Diagnosis of Prosthetic Joint Infections.

BACKGROUND/AIM: Prosthetic joint infection (PJI) remains a serious complication of total joint arthroplasty. To effectively treat PJI, it is essential to identify the microorganism causing it and be able to combine correct surgical and anti-infective treatments. This cannot always be achieved with the currently employed diagnostic methods. The aim of this study was to evaluate a semi-automated tissue biopsy bead milling method (Ultra-TurrAX, Axonlab AG; Reichenbach, Germany) based on the hypothesis that the results are more sensitive for microbe detection and less prone to contamination. MATERIALS AND METHODS: We included 35 consecutive patients undergoing 38 hip or knee arthroplasty revisions in this study. In addition to manually processed biopsies, we processed tissue specimens harvested intraoperatively using a semi-automated method. The sensitivity and specificity of both methods were calculated using MSIS criteria and sonication results as gold standards. RESULTS: For total hip arthroplasty samples were evaluated separately based on MSIS criteria as the reference standard, Ultra-TurrAX processing yielded 81% (62-100%) sensitivity and 100% specificity. Using sonication as the gold standard, a sensitivity of 80% (60-100%) and specificity of 80% (45-100%) were calculated. In total knee arthroplasty, Ultra-TurrAX processing yielded 27% (1-54%) sensitivity and 57% (20-94%) specificity when using MSIS criteria as the gold standard. Using sonication as the gold standard, a sensitivity of 60% (17-100%) and specificity of 77% (54-100%) were calculated. CONCLUSION: This is the first study to analyze bead mill processing in total hip and knee arthroplasty revisions in a consecutive patient series. The method's sensitivity was comparable to and its specificity superior to regular sample processing results reported in the literature with respect to hip arthroplasties and to both hip and knee arthroplasties collectively. With respect to total knee arthroplasties, the method fared worse in our collective, most likely due to the small number of patients in the sample. Integrating the method into the clinical workflow allowed for speedier and more efficient sample handling and processing. The theoretical advantage of a lower risk of contamination because of fewer manual processing steps is, in our opinion, valid.

Increased Resistance of Skin Flora to Antimicrobial Prophylaxis in Patients Undergoing Hip Revision Arthroplasty.

BACKGROUND/AIM: Prosthetic joint infection (PJI) remains a major complication after total joint replacement and is the primary indication for revision arthroplasty. Specifically, coagulase-negative Staphylococci (CNS) can cause low-grade infections. Despite the use of cephalosporin-based antimicrobial prophylaxis (AMP) and antiseptic treatment at the surgical site, evidence suggests that a significant number of cases of dermal CNS results in low-grade PJI. Thus, this study examined the bacterial colonization and resistance patterns at the surgical site. We hypothesized that the bacteria developed resistance to antibiotics that are frequently used in primary and revision total hip arthroplasty (THA) procedures. PATIENTS AND METHODS: Ninety patients, including 63 primary and 27 revision THA patients, were enrolled in this study. For each patient, a single swab of the skin at the surgical site was subjected to clinical microbiology to assess bacterial colonization. Furthermore, resistance to a sentinel panel of antibiotics (benzylpenicillin, erythromycin, tetracycline, oxacillin, fusidic acid, clindamycin, gentamicin, levofloxacin/moxifloxacin, rifampicin, linezolid and vancomycin) was tested. RESULTS: In 96.7% of the patients, at least one bacterial strain was identified at the surgical site, with CNS strains comprising 93.1% of the total. The sentinel panel showed that 30.7% of the CNS strains exhibited maximal resistance to oxacillin, a commonly used cephalosporin. Additionally, oxacillin resistance increased 1.9-fold (p=0.042) between primary and revision THA. Notably, 8.1% of the CNS stains found on patients undergoing primary THA were resistant to gentamicin, an aminoglycoside, and this rate increased 4.7-fold (p=0.001) for patients undergoing revision THA. CONCLUSION: CNS strains have significant resistance to standard AMP, particularly in individuals undergoing revision THA.

Implementation of an Algorithm for Prosthetic Joint Infection: Deviations and Problems.

BACKGROUND: The outcome of revision surgery in arthroplasty is based on a precise diagnosis. In addition, the treatment varies based on whether the prosthetic failure is caused by aseptic or septic loosening. Algorithms can help to identify periprosthetic joint infections (PJI) and standardize diagnostic steps, however, algorithms tend to oversimplify the treatment of complex cases. We conducted a process analysis during the implementation of a PJI algorithm to determine problems and deviations associated with the implementation of this algorithm. PATIENTS AND METHODS: Fifty patients who were treated after implementing a standardized algorithm were monitored retrospectively. Their treatment plans and diagnostic cascades were analyzed for deviations from the implemented algorithm. Each diagnostic procedure was recorded, compared with the algorithm, and evaluated statistically. RESULTS: We detected 52 deviations while treating 50 patients. In 25 cases, no discrepancy was observed. Synovial fluid aspiration was not performed in 31.8% of patients (95% confidence interval [CI], 18.1%-45.6%), while white blood cell counts (WBCs) and neutrophil differentiation were assessed in 54.5% of patients (95% CI, 39.8%-69.3%). We also observed that the prolonged incubation of cultures was not requested in 13.6% of patients (95% CI, 3.5%-23.8%). In seven of 13 cases (63.6%; 95% CI, 35.2%-92.1%), arthroscopic biopsy was performed; 6 arthroscopies were performed in discordance with the algorithm (12%; 95% CI, 3%-21%). CONCLUSION: Self-critical analysis of diagnostic processes and monitoring of deviations using algorithms are important and could increase the quality of treatment by revealing recurring faults.

Growth promoting in vitro effect of synthetic cyclic RGD-peptides on human osteoblast-like cells attached to cancellous bone.

In tissue engineering, the application of biofunctional compounds on biomaterials such as integrin binding RGD-peptides has gained growing interest. Anchorage-dependent cells like osteoblasts bind to these peptides thus ameliorating the integration of a synthetic implant. In case sterilized bone grafts are used as substitutes for reconstruction of bone defects, the ingrowth of the implanted bone is often disturbed because of severe pretreatment such as irradiation or autoclaving, impairing the biological and mechanical properties of the bone. We report for the first time on the in vitro coating of the surface of freshly resected, cleaned bone discs with synthetic, cyclic RGD-peptides. For this approach, two different RGD-peptides were used, one containing two phosphonate anchors, the other peptide four of these binding moieties to allow efficient association of these reactive RGD-peptides to the inorganic bone matrix. Human osteoblast-like cells were cultured on RGD-coated bone discs and the adherence and growth of the cells were analyzed. Coating of bone discs with RGD-peptides did not improve the adhesion rate of osteoblast-like cells to the discs but significantly (up to 40%) accelerated growth of these cells within 8 days after attachment. This effect points to pretreatment of bone implants, especially at the critical interface area between the implanted bone and the non-resected residual bone structure, before re-implantation in order to stimulate and enhance osteointegration of a bone implant.