The Effect of Waiting for a Primary Total Hip Arthroplasty on the Overall Hip Function and Quality of Life.

BACKGROUND: The primary aim was to determine whether time spent awaiting primary total hip arthroplasty (THA) affects patient-reported outcome measures (PROMs) using the Oxford Hip score, Harris Hip Score, and visual analogue scale (VAS) pain. The secondary aim was to assess whether patients have worsening HRQoL, while awaiting THA using the European Quality of Life Five Dimension (EQ-5D) index and EQ-5D health VAS. METHODS: This was a single center cross-sectional study of 190 patients awaiting THA. Patients were divided into waiting "more than 6 months" and "less than 6 months." Baseline and current scores were compared. Multivariate regression analyses were performed to identify predictors of PROM change. RESULTS: No significant intergroup differences were observed for change in preoperative Oxford Hip score, Harris Hip Score, and VAS pain from index consultation to time of study. The EQ-5D index and EQ-5D health VAS decreased significantly further in patients waiting more than 6 months (P = .043, P = .004). Time awaiting THA was significantly associated with a decrease in EQ-5D index and EQ-5D health VAS in multivariate regression (P = .013, P < .001). CONCLUSIONS: Waiting more than 6 months is not associated with a decrease in hip-specific PROMs and longer waiting times are not associated with changes in hip-specific PROMs. Waiting time was associated with a decrease in health-related quality of life and patients waiting more than 6 months had significantly higher decreases in EQ-5D scores. This suggests that living longer with hip osteoarthritis leads to a decrease in QoL, not necessarily through perceived osteoarthritis progression. LEVEL OF EVIDENCE: Level III cross-sectional study.

Girdlestone resection arthroplasty for femoral neck fractures has poorer outcomes than hemiarthroplasty in frail patients with increased risk for arthroplasty-related complications: a retrospective case study of 21 patients.

BACKGROUND AND PURPOSE: Hemiarthroplasty (HA) is the usual treatment for displaced femoral neck fractures (FNF) in elderly patients. Patients may be unsuitable for HA due to secondary conditions such as systemic infections or severe neurological conditions, which is why Girdlestone resection arthroplasty (GRA) may be an option. We aimed to determine (1) patient survival in matched patient groups treated with either GRA or HA and (2) functional outcomes. PATIENTS AND METHODS: 21 patients treated with GRA for FNF in a German university hospital were retrospectively reviewed (2015-2019). After matching for age and comorbidities, a control group of 42 HA patients was established. Patient survival was determined by a Kaplan-Meier analysis. The mean follow-up (FU) was 1.5 (0-4.4) years. Function at FU was documented using the modified Harris Hip Score (mHHS) and the National Hip Fracture Database (NHFD) mobility score. RESULTS: The 1-month-mortality was 19% in the GRA group and 12% in the HA group; the 1-year mortality was 71% and 49%, respectively (P = 0.01). The mHHS at FU was lower in the GRA group than in the HA group (22 [range 0-50] vs. 46 [11-80]). 82% of patients in the GRA group were bedridden post-surgery as opposed to 19% in the HA group. CONCLUSION: Patients with HA after FNF had higher survival and better functional outcomes when compared with GRA in matched patient groups. Considering this, GRA for FNF should be selected restrictively.

Treatment of Severe Acetabular Defects With an Antiprotrusio Cage and Trabecular Metal Augments - Clinical and Radiographic Results After a Mean Follow-Up of 6.6 Years.

BACKGROUND: Large acetabular bone defects present a serious challenge in revision total hip arthroplasty. The off-label use of antiprotrusio cages in combination with tantalum augments is a promising treatment option in these difficult situations. METHODS: Between 2008 and 2013, 100 consecutive patients underwent acetabular cup revision with a cage-augment combination in Paprosky 2 and 3 defect types (including pelvic discontinuities). There were 59 patients available for follow-up. The primary endpoint was the explantation of the cage-and-augment construct. The secondary endpoint was acetabular cup revision for any reason. Also, radiographic and functional outcomes (Western Ontario and McMaster Universities Osteoarthritis Index, Harris Hip Score) were evaluated. Implant survival rates were determined using a Kaplan-Meier analysis. The significance level was set at P < .05. RESULTS: Explantation-free survivorship of the "Cage-and-Augment" system was 91.9% after a mean follow-up of 6.2 years (range, 0 to 12.8). All 6 explantations were due to periprosthetic joint infection (PJI). The overall revision-free implant survival rate was 85.7%, including 6 additional liner revisions due to instability. In addition, 6 early PJI occurred, which were successfully treated with debridement, irrigation, and implant retention. We did observe one patient who had radiographic loosening of the construct without necessity for treatment. CONCLUSION: The combination of an antiprotrusio cage with tantalum augments is a promising technique in treating large acetabular defects. A major risk of PJI and instability due to large bone and soft tissue defects needs special attention.

Cementation of a dual mobility cup in a well-fixed acetabular component- a reliable option in revision total hip arthroplasty?

BACKGROUND: The "cup-in-cup" technique allows for revision of failed total hip arthroplasty (THA) when the cementless cup is well fixed. Furthermore, it can be used for liner wear or mechanical failure where liner replacement may be impossible or impractical. Recently, the "cup-in-cup" technique in combination with dual mobility cups (DMC) has drawn increased attention. Our aim was to report on the clinical and radiographic outcomes following this surgery. METHODS: From 2015 to 2020, 33 patients treated with the DMC- "cup in cup" technique were retrospectively reviewed. Fourteen patients had died while 19 were available for the final follow-up (FU), of which 15 underwent both a radiograph and a FU visit, 2 underwent a radiograph only and 2 underwent a telephone interview only. Patient-related outcome measures included the HHS and the WOMAC. Radiographs were assessed for implant loosening and positioning. Primary endpoint was revision of any cause and secondary endpoint was loosening of the DMC at the latest FU. The survival analysis was conducted using the Kaplan-Meier method. RESULTS: The mean age at surgery was 78.6 ± 7.1 (63-93) years and the mean surgery duration was 124.4 ± 52.0 (60-245) minutes. Recurrent dislocation (42.4%), periprosthetic fracture (39.4%) and polyethylene wear (6.1%) were the most frequent reasons for surgery. The mean FU duration (n = 19) was 28.5 ± 17.3 (3-64) months. The mean HHS score at FU was 59.4 ± 22.2 (29-91) and the mean WOMAC score was 59.7 ± 25.6 (15.6-93.8). Two cups were revised due to instability and one revision was performed due to periprosthetic joint infection, accounting for an overall cup survival rate of 86.8% after a mean FU of 22.9 ± 18.0 (1.5-64.6) months. The survival rate free of loosening was 90.9% after a mean FU of 22.3 ± 18.5 (1.5-64.7) months. CONCLUSIONS: We found that the cementation of a DMC in a well-fixed cup is a promising short- to mid-term treatment addressing THA instability especially in elderly and frail patients, who benefit from a reduced operation time. Proper cementation technique, adequate cup positioning as well as selection of a sufficiently large DMC are crucial for treatment success. Longer FUs will be needed in the future in order to further prove the benefit of this technique.

Erythropoietin inhibits osteoblast function in myelodysplastic syndromes via the canonical Wnt pathway.

The effects of erythropoietin on osteoblasts and bone formation are controversial. Since patients with myelodysplastic syndromes often display excessively high erythropoietin levels, we aimed to analyze the effect of erythropoietin on osteoblast function in myelodysplastic syndromes and define the role of Wnt signaling in this process. Expression of osteoblast-specific genes and subsequent osteoblast mineralization was increased in mesenchymal stromal cells from healthy young donors by in vitro erythropoietin treatment. However, erythropoietin failed to increase osteoblast mineralization in old healthy donors and in patients with myelodysplasia, whereas the basal differentiation potential of the latter was already significantly reduced compared to that of age-matched controls (P<0.01). This was accompanied by a significantly reduced expression of genes of the canonical Wnt pathway. Treatment of these cells with erythropoietin further inhibited the canonical Wnt pathway. Exposure of murine cells (C2C12) to erythropoietin also produced a dose-dependent inhibition of TCF/LEF promoter activity (maximum at 500 IU/mL, -2.8-fold; P<0.01). The decreased differentiation capacity of erythropoietin-pretreated mesenchymal stromal cells from patients with myelodysplasia could be restored by activating the Wnt pathway using lithium chloride or parathyroid hormone. Its hematopoiesis-supporting capacity was reduced, while reactivation of the canonical Wnt pathway in mesenchymal stromal cells could reverse this effect. Thus, these data demonstrate that erythropoietin modulates components of the osteo-hematopoietic niche in a context-dependent manner being anabolic in young, but catabolic in mature bone cells. Targeting the Wnt pathway in patients with myelodysplastic syndromes may be an appealing strategy to promote the functional capacity of the osteo-hematopoietic niche.

Icariin promotes angiogenic differentiation and prevents oxidative stress-induced autophagy in endothelial progenitor cells.

Reduced tissue levels of endothelial progenitor cells (EPCs) and functional impairment of endothelium are frequently observed in patients with diabetes and cardiovascular disease. The vascular endothelium is specifically sensitive to oxidative stress, and this is one of the mechanisms that causes widespread endothelial dysfunction in most cardiovascular diseases and disorders. Hence attention has increasingly been paid to enhance mobilization and differentiation of EPCs for therapeutic purposes. The aim of this study was to investigate whether Icariin, a natural bioactive component known from traditional Chinese Medicine, can induce angiogenic differentiation and inhibit oxidative stress-induced cell dysfunction in bone marrow-derived EPCs (BM-EPCs), and, if so, through what mechanisms. We observed that treatment of BM-EPCs with Icariin significantly promoted cell migration and capillary tube formation, substantially abrogated hydrogen peroxide (H2 O2 )-induced apoptotic and autophagic programmed cell death that was linked to the reduced intracellular reactive oxygen species levels and restored mitochondrial membrane potential. Icariin downregulated endothelial nitric oxide synthase 3, as well as nicotinamide-adenine dinucleotide phosphate-oxidase expression upon H2 O2 induction. These antiapoptotic and antiautophagic effects of Icariin are possibly mediated by restoring the loss of mammalian target of rapamycin /p70S6K/4EBP1 phosphorylation as well as attenuation of ATF2 and ERK1/2 protein levels after H2 O2 treatment. In summary, favorable modulation of the angiogenesis and redox states in BM-EPCs make Icariin a promising proangiogenic agent both enhancing vasculogenesis and protecting against endothelial dysfunction.

Breast carcinoma cells modulate the chemoattractive activity of human bone marrow-derived mesenchymal stromal cells by interfering with CXCL12.

We investigated whether breast tumor cells can modulate the function of mesenchymal stromal cells (MSCs) with a special emphasis on their chemoattractive activity towards hematopoietic stem and progenitor cells (HSPCs). Primary MSCs as well as a MSC line (SCP-1) were cocultured with primary breast cancer cells, MCF-7, MDA-MB231 breast carcinoma or MCF-10A non-malignant breast epithelial cells or their conditioned medium. In addition, the frequency of circulating clonogenic hematopoietic progenitors was determined in 78 patients with breast cancer and compared with healthy controls. Gene expression analysis of SCP-1 cells cultured with MCF-7 medium revealed CXCL12 (SDF-1) as one of the most significantly downregulated genes. Supernatant from both MCF-7 and MDA-MB231 reduced the CXCL12 promoter activity in SCP-1 cells to 77% and 47%, respectively. Moreover, the CXCL12 mRNA and protein levels were significantly reduced. As functional consequence of lower CXCL12 levels, we detected a decreased trans-well migration of HSPCs towards MSC/tumor cell cocultures or conditioned medium. The specificity of this effect was confirmed by blocking studies with the CXCR4 antagonist AMD3100. Downregulation of SP1 and increased miR-23a levels in MSCs after contact with tumor cell medium as well as enhanced TGFß1 expression were identified as potential molecular regulators of CXCL12 activity in MSCs. Moreover, we observed a significantly higher frequency of circulating colony-forming hematopoietic progenitors in patients with breast cancer compared with healthy controls. Our in vitro results propose a potential new mechanism by which disseminated tumor cells in the bone marrow may interfere with hematopoiesis by modulating CXCL12 in protected niches.

An epidemiological investigation of training and injury patterns in triathletes.

Associated with the trend towards increased health consciousness and fitness, triathlon has established itself as a sport for masses. The goals of this study were to evaluate injury risk factors of non-professional triathletes and to compare prospective and retrospective evaluation methods. Using an online survey, 212 triathletes retrospectively answered a questionnaire about their training habits and injuries during the past 12 months. Forty-nine of these triathletes participated in a 12-month prospective trial. Injuries were classified with regard to the anatomical location, type of injury, incidence and associated risk factors. Most injuries occurred during running (50%) followed by cycling (43%) and swimming (7%). Fifty-four per cent (retrospective) and 22% (prospective) of the injuries were contusions and abrasions, 38% (retrospective) and 46% (prospective) were ligament and capsular injuries, 7% (retrospective) and 32% (prospective) were muscle and tendon injuries and 1% (retrospective) and 0% (prospective) were fractures. The incidence of an injury per 1000 training hours was 0.69 (retrospective) and 1.39 (prospective) during training and 9.24 (retrospective) and 18.45 (prospective) during competition. The main risk factor for injury in non-professional triathlon is participation in a competitive triathlon event. A retrospective design may underestimate the rate of overuse injuries.

Mesenchymal stromal cells from patients with myelodyplastic syndrome display distinct functional alterations that are modulated by lenalidomide.

The contribution of the bone marrow microenvironment in myelodysplastic syndrome is controversial. We therefore analyzed the functional properties of primary mesenchymal stromal cells from patients with myelodysplastic syndrome in the presence or absence of lenalidomide. Compared to healthy controls, clonality and growth were reduced across all disease stages. Furthermore, differentiation defects and particular expression of adhesion and cell surface molecules (e.g. CD166, CD29, CD146) were detected. Interestingly, the levels of stromal derived factor 1-alpha in patients' cells culture supernatants were almost 2-fold lower (P<0.01) than those in controls and this was paralleled by a reduced induction of migration of CD34(+) hematopoietic cells. Co-cultures of mesenchymal stromal cells from patients with CD34(+) cells from healthy donors resulted in reduced numbers of cobblestone area-forming cells and fewer colony-forming units. Exposure of stromal cells from patients and controls to lenalidomide led to a further reduction of stromal derived factor 1-alpha secretion and cobblestone area formation, respectively. Moreover, lenalidomide pretreatment of mesenchymal stromal cells from patients with low but not high-risk myelodysplastic syndrome was able to rescue impaired erythroid and myeloid colony formation of early hematopoietic progenitors. In conclusion, our analyses support the notion that the stromal microenvironment is involved in the pathophysiology of myelodysplastic syndrome thus representing a potential target for therapeutic interventions.

Establishment of a femoral critical-size bone defect model in immunodeficient mice.

BACKGROUND: The development of innovative therapies for bone regeneration requires the use of advanced site-specific bone defect small-animal models. The achievement of proper fixation with a murine model is challenging due to the small dimensions of the murine femur. The aim of this investigation was to find the optimal defect size for a murine critical-size bone defect model using external fixation method. METHODS: An external fixation device was attached to the right femur of 30 mice. Femoral bone defects of 1 mm (n = 10), 2 mm (n = 10), and 3 mm (n = 10) were created. Wounds were closed without any additional treatment. To investigate bone healing during the 12-wk observation period, x-ray analysis, histomorphology, immunohistochemistry, and µCT scans were performed. RESULTS: MicroCT analyses after 12 wk showed that 3/8 1-mm defects, 5/8 2-mm defects, and 8/8 3-mm defects remained as nonunions. The defect volumes were 0.36 ± 0.42 mm³ (1-mm group), 1.40 ± 0.88 mm³ (2-mm group), and 2.88 ± 0.28 mm³ (3-mm group; P < 0.001, between all groups). CONCLUSION: Using external fixation, a defect size of 3 mm is necessary to reliably create a persisting femoral bone defect in nude mice.

The First SICOT Oral Presentation Award 2011: imageless computer-assisted femoral component positioning in hip resurfacing: a prospective randomised trial.

PURPOSE: The aim of the study was to evaluate the effects of imageless computer-assisted surgery (CAS) on the accuracy of positioning of the femoral component and on the short-term clinical outcome in hip resurfacing (HR) using a randomised prospective design. METHODS: A total of 75 consecutive patients undergoing HR were randomly allocated to CAS and conventional implantation, respectively. Preoperatively and six months post-operatively standardised pelvic anteroposterior X-ray images, the total Western Ontario and McMaster Universities Osteoarthritis Index, the Harris Hip Score and the EQ-5D utility index were evaluated in a blinded manner. The primary end point of the study was a post-operative femoral component malpositioning in five degrees or more either varus or valgus absolute deviation from the planned stem shaft angle. RESULTS: Patient demographics and algofunctional scores did not differ between the CAS and conventional implantation samples. Using CAS fewer femoral components were positioned in five or more degrees absolute deviation (4/37 vs 12/38, Fisher's exact p = 0.047; 95 % confidence interval for the primary end point's incidence difference: +3 %; +39 %); the respective incidences of five or more degrees of varus deviation were 0/37 vs 5/38. One conversion to a stemmed prosthesis (CAS group) was performed for periprosthetic femoral neck fracture. Radiological signs of superolateral femoral neck/implant impingement were observed in two cases (one CAS-based and one conventional implantation). CONCLUSIONS: The accuracy of femoral HR component positioning was significantly improved using CAS. However, one major complication necessitated early revision in the CAS group at six months of observation. Apart from that adverse event no inter-group differences were observed for the short-term clinical outcome. Future studies need to address the clinical long-term relevance of CAS in HR.

[Strategies for cup revision]. / Strategien für die Pfannenrevision.

Hip arthroplasty revision management can range from simple procedures using standard implants to complex surgical interventions requiring the combined use of revision cups, metal augments, bone grafts, and antiprotrusio cages. The adequate restoration of biomechanics and function of the hip joint with reconstruction of the original center of rotation can be challenging. We present an overview of various available techniques with the associated implant and anchoring strategies and the respective clinical results depending on the acetabular defect situation.

Ultrasonic bone cement removal efficiency in total joint arthroplasty revision: A computer tomographic-based cadaver study.

Polymethylmethacrylate (PMMA) removal during septic total joint arthroplasty revision is associated with a high fracture and perforation risk. Ultrasonic cement removal is considered a bone-preserving technique. Currently, there is still a lack of sound data on efficacy as it is difficult to detect smaller residues with reasonable technical effort. However, incomplete removal is associated with the risk of biofilm coverage of the residue. Therefore, the study aimed to investigate the efficiency of ultrasonic-based PMMA removal in a human cadaver model. The femoral components of a total hip and a total knee prosthesis were implanted in two cadaver femoral canals by 3rd generation cement fixation technique. Implants were then removed. Cement mantle extraction was performed with the OSCAR-3-System ultrasonic system (Orthofix®). Quantitative analysis of cement residues was carried out with dual-energy and microcomputer tomography. With a 20 µm resolution, in vitro microcomputer tomography visualized tiniest PMMA residues. For clinical use, dual-energy computer tomography tissue decomposition with 0.75 mm resolution is suitable. With ultrasound, more than 99% of PMMA was removed. Seven hundred thirty-four residues with a mean volume of 0.40 ± 4.95 mm3 were identified with only 4 exceeding 1 cm in length in at least one axis. Ultrasonic cement removal of PMMA was almost complete and can therefore be considered a highly effective technique. For the first time, PMMA residues in the sub-millimetre range were detected by computer tomography. Clinical implications of the small remaining PMMA fraction on the eradication rate of periprosthetic joint infection warrants further investigations.

Microbiological pathogen analysis in native versus periprosthetic joint infections: a retrospective study.

BACKGROUND: The presence or absence of an implant has a major impact on the type of joint infection therapy. Thus, the aim of this study was the examination of potential differences in the spectrum of pathogens in patients with periprosthetic joint infections (PJI) as compared to patients with native joint infections (NJI). METHODS: In this retrospective study, we evaluated culture-positive synovial fluid samples of 192 consecutive patients obtained from January 2018 to January 2020 in a tertiary care university hospital. For metrically distributed parameters, Mann-Whitney U was used for comparison between groups. In case of nominal data, crosstabs and Chi-squared tests were implemented. RESULTS: Overall, 132 patients suffered from periprosthetic joint infections and 60 patients had infections of native joints. The most commonly isolated bacteria were coagulase-negative Staphylococci (CNS, 28%), followed by Staphylococcus aureus (S. aureus, 26.7%), and other bacteria, such as Streptococci (26.3%). We observed a significant dependence between the types of bacteria and the presence of a joint replacement (p < 0.05). Accordingly, detections of CNS occurred 2.5-fold more frequently in prosthetic as compared to native joint infections (33.9% vs. 13.4% p < 0.05). In contrast, S. aureus was observed 3.2-fold more often in NJIs as compared to PJIs (52.2% vs. 16.4%, p < 0.05). CONCLUSION: The pathogen spectra of periprosthetic and native joint infections differ considerably. However, CNS and S. aureus are the predominant microorganisms in both, PJIs and NJIs, which may guide antimicrobial therapy until microbiologic specification of the causative pathogen.

Large Soft-tissue Mass Formation After Revision Total Knee Arthroplasty: An Unusual Case of Adverse Reaction to Metal Debris and Review of the Literature.

We report about the rare case of a patient who developed large soft-tissue mass formations related with revision total knee arthroplasty which was implanted 4 years prior. Owing to suspected periprosthetic joint infection, the prosthesis was removed and the lesions were resected, resulting in severe soft-tissue loss and temporary arthrodesis using a poly(methyl methacrylate) spacer. Histological analysis revealed a type VI periprosthetic membrane. The situation was further complicated by wound infection requiring multiple revision surgeries. After discussion and evaluation of the available treatment options, the decision for an above-the-knee amputation was made. The tissue reaction resulting in these soft-tissue lesions is referred to as an "adverse local tissue reaction." Wear-induced lesions after total knee arthroplasty, especially of this magnitude, are very rare and difficult to treat.

Plastic-Reconstructive Treatment Algorithm for Dead Space Management Following Septic Total Hip Arthroplasty Removal: AV Loop and Two-Stage Free Myocutaneous Latissimus Dorsi Flap. / Plastisch-rekonstruktiver Behandlungsalgorithmus des Totraummanagements nach septischer Hüft-TEP-Explantation: der AV-Loop und der zweizeitige freie myokutane Latissimus-dorsi-Lappen.

BACKGROUND: A 61-year-old patient presented with a right Girdlestone hip and wound dehiscence due to extensive dead space after radical debridement and septic arthroplasty removal. A two-stage reconstruction with the application of a subcutaneous autologous arterio-venous (AV) loop using an autologous vena saphena magna (VSM) interposition graft followed by a free latissimus dorsi flap was performed. METHOD: We decided to perform a two-stage procedure with AV loop creation in the first step and free flap transplantation seven days after it. In the first step, an AV vascular loop was prepared by transplanting the contralateral VSM interposition graft to the inguinal femoral vessels with subcutaneous passage of the venous loop. In the second step after 7 days, the wound was closed by a two-team approach. One surgical team completed the wound debridement, while the other team harvested the flap by microsurgical preparation of the thoracodorsal pedicle in the right axilla. Upon completed harvest, the flap was placed into the wound to fill the periosseous dead space, and the anastomosis was performed in an end-to-end fashion. RESULT: The patient remained free of infection with a well-healed flap. He was mobilized on crutches with partial weight bearing on the operated leg. A lower extremity prosthesis with pelvic support was customized.

Does preoperative antibiotic prophylaxis affect sonication-based diagnosis in implant-associated infection?

As culture-negative implant-associated infection denote a diagnostic challenge, sonicate fluid cultures of the explanted endoprosthesis and osteosynthesis components are frequently used. However, the effect of antibiotic treatment on pathogen detection by sonication fluid cultures in implant-associated infection has not been investigated. Thus, the aim of this study was to evaluate the influence of preoperative antibiotic prophylaxis (PAP) and antibiotic therapy (AT) on sonicate fluid cultures in patients with implant-associated infection. In this retrospective study three groups were compared: (i) standard PAP, (ii) AT for at least one day, and (iii) no antibiotics before surgery. For the inclusion criteria, an established diagnostic protocol for implant-associated infection was used. Sonicate fluid cultures were validated by corresponding microbiological and histopathological samples. In 90 patients with single and multiple infections, 114 pathogens were detected. The detection rate by sonicate fluid cultures in patients receiving PAP (n = 27, 29 pathogens), AT before surgery (n = 33, 48 pathogens) and no antibiotics before surgery (n = 30, 37 pathogens) were 86.2%, 81.3%, and 86.5% (p = .778), respectively. Eleven of 114 infectious agents were detected exclusively by sonicate fluid cultures, while conventional tissue culture failed in these cases. PAP and AT do not affect intraoperative cultures in implant-associated infection. It is therefore not recommended to omit antibiotic prophylaxis in patients with implant-associated infection. Algorithms including both sonicate fluid cultures and tissue samples should be used for appropriate microbiological diagnosis of implant-associated infections.

Cancellous bone allograft seeded with human mesenchymal stromal cells: a potential good manufacturing practice-grade tool for the regeneration of bone defects.

BACKGROUND AIMS: Combining autologous bone precursor cells with cancellous bone allograft (CBA) offers an appealing strategy for skeletal regeneration. In this context, multipotent mesenchymal stromal cells (MSC) provide an excellent cell source because they are readily harvested from donors, expanded and differentiated in vitro. The aim of this study was to evaluate the proliferation, morphology, osteogenic differentiation and stem cell-related gene expression during static long-term ex vivo cultivation using human MSC and CBA under good manufacturing practice (GMP)-conforming conditions. METHODS: MSC were isolated from healthy donors (n = 5) and cultivated on peracetic acid-sterilized CBA in the presence of 10% human platelet-rich plasma without osteogenic supplements. Total protein content, cell-specific alkaline phosphatase (ALP) activity and osteogenic marker gene expression levels were assessed. Stem cell-related gene expression was compared with MSC monolayer cultivation using microarray analysis. Furthermore, cellular distribution and morphology within the porous CBA were visualized by histology and scanning electron microscopy. RESULTS: Effective adhesion, spreading, proliferation and intercellular contact of human MSC within the pores of CBA were observed during the study (< or = 42 days). Cell-specific ALP activity peaked after 3 weeks of cultivation. Gene expression of early, intermediate and late osteogenic marker genes was detectable during long-term cultivation. Microarray-based annotation and biologic interaction network data analysis indicated that expression levels of genes encoding crucial differentiation-regulating proteins and extracellular matrix components involved in the process of osteogenesis were induced in CBA-cultivated MSC. CONCLUSIONS: MSC-vitalized CBA offers an attractive GMP-grade bone-filling material. Further research is warranted to evaluate its bone-healing potential in vivo.