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1.  Prosthetic infection: improvement of diagnostic procedures using 16S ribosomal deoxyribonucleic acid polymerase chain reaction 
International Orthopaedics  2013;37(12):2515-2521.
Prosthetic infection is the worst complication in joint arthroplasty. The diagnostic procedure is time consuming and in many cases unrewarding. The aim of this investigation was to raise the sensitivity of the diagnostic procedure.
Altogether, 229 implants were removed from 229 patients. Complete data from 157 patients could be analysed. On explantation of the respective arthroplasty, tissue was removed, puncture fluid aspirated and biofilm scratched from the implant surface with a surgical knife. Specimens were investigated with conventional culture methods and with 16S ribosomal DNA (rDNA) polymerase chain reaction (PCR) and sequencing.
In 123 cases, no pathogen could be identified by routine culture methods. In three of these culture-negative cases, bacteria could be identified with 16S rDNA sequencing of the removed biofilm. In 34 cases, bacteria could be identified with culture methods. In two of these cases, sequencing detected additional pathogens.
The process of 16S ribosomal deoxyribonucleic acid polymerase chain reaction (rDNA PCR) and sequencing of biofilm removed from the explanted prosthesis is an important addition to conventional culture methods in prosthetic joint infection. Polymerase chain reaction detects additional pathogens and improves diagnostic sensitivity. The examination of tissue, puncture fluid and biofilm should be performed in cases of prosthesis loosening and explantation.
PMCID: PMC3843206  PMID: 23917855
Prosthetic infection; Diagnosis using 16S rDNA PCR; Biofilm
2.  Epigenetic silencing of genes and microRNAs within the imprinted Dlk1-Dio3 region at human chromosome 14.32 in giant cell tumor of bone 
BMC Cancer  2014;14:495.
Growing evidence exists that the neoplastic stromal cell population (GCTSC) within giant cell tumors (GCT) originates from mesenchymal stem cells (MSC). In a previous study we identified a microRNA signature that differentiates between these cell types. Five differentially expressed microRNAs are located within the Dlk1-Dio3 region on chromosome 14. Aberrant regulation within this region is known to influence cell growth, differentiation and the development of cancer. The aim of this study was to elucidate the involvement of deregulations within the Dlk1-Dio3 region in GCT pathogenesis.
Quantitative gene and microRNA expression analyses were performed on GCTSCs and MSCs with or without treatment with epigenetic modifiers. Methylation analysis of differentially methylated regions was performed by bisulfite sequencing.
In addition to microRNA silencing we detected a significant downregulation of Dlk1, Meg3 and Meg8 in GCTSCs compared to MSCs. DNA methylation analyses of the Meg3-DMR and IG-DMR revealed a frequent hypermethylation within the IG-DMR in GCTs. Epigenetic modification could restore expression of some but not all analyzed genes and microRNAs suggesting further regulatory mechanisms.
Epigenetic silencing of genes and microRNAs within the Dlk1-Dio3 region is a common event in GCTSCs, in part mediated by hypermethylation within the IG-DMR. The identified genes, micro RNAs and microRNA target genes might be valuable targets for the development of improved strategies for GCT diagnosis and therapy.
PMCID: PMC4101709  PMID: 25005035
Giant cell tumor; Mesenchymal stem cell; MicroRNA; Epigenetics; Methylation
3.  Excellent local control with IOERT and postoperative EBRT in high grade extremity sarcoma: results from a subgroup analysis of a prospective trial 
BMC Cancer  2014;14:350.
To report the results of a subgroup analysis of a prospective phase II trial focussing on radiation therapy and outcome in patients with extremity soft tissue sarcomas (STS).
Between 2005 and 2010, 50 patients (pts) with high risk STS (size ≥ 5 cm, deep/extracompartimental location, grade II-III (FNCLCC)) were enrolled. The protocol comprised 4 cycles of neoadjuvant chemotherapy with EIA (etoposide, ifosfamide and doxorubicin), definitive surgery with IOERT, postoperative EBRT and 4 adjuvant cycles of EIA. 34 pts, who suffered from extremity tumors and received radiation therapy after limb-sparing surgery, formed the basis of this subgroup analysis.
Median follow-up from inclusion was 48 months in survivors. Margin status was R0 in 30 pts (88%) and R1 in 4 pts (12%). IOERT was performed as planned in 31 pts (91%) with a median dose of 15 Gy, a median electron energy of 6 MeV and a median cone size of 9 cm. All patients received postoperative EBRT with a median dose of 46 Gy after IOERT or 60 Gy without IOERT. Median time from surgery to EBRT and median EBRT duration was 36 days, respectively. One patient developed a local recurrence while 11 patients showed nodal or distant failures. The estimated 5-year rates of local control, distant control and overall survival were 97%, 66% and 79%, respectively. Postoperative wound complications were found in 7 pts (20%), resulting in delayed EBRT (>60 day interval) in 3 pts. Acute radiation toxicity mainly consisted of radiation dermatitis (grade II: 24%, no grade III reactions). 4 pts developed grade I/II radiation recall dermatitis during adjuvant chemotherapy, which resolved during the following cycles. Severe late toxicity was observed in 6 pts (18%). Long-term limb preservation was achieved in 32 pts (94%) with good functional outcome in 81%.
Multimodal therapy including IOERT and postoperative EBRT resulted in excellent local control and good overall survival in patients with high risk STS of the extremities with acceptable acute and late radiation side effects. Limb preservation with good functional outcome was achieved in the majority of patients.
Trial registration NCT01382030, EudraCT 2004-002501-72, 17.06.2011
PMCID: PMC4032585  PMID: 24885755
Soft tissue sarcoma; Extremity; Neoadjuvant chemotherapy; Intraoperative radiation therapy; Postoperative radiation therapy; Prospective trial
4.  TERT promoter hotspot mutations are recurrent in myxoid liposarcomas but rare in other soft tissue sarcoma entities 
Recently, recurrent point mutations in the telomerase reverse transcriptase (TERT) promoter region have been found in many human cancers, leading to a new transcription factor binding site, increased induction of TERT and subsequently to telomere maintenance. We determined the prevalence of TERT promoter mutations in soft tissue sarcomas of 341 patients comprising 16 entities and in 16 sarcoma cell lines covering 7 different soft tissue sarcoma types.
The sarcoma tissue samples were collected from the archives of the Institute of Pathology, University of Heidelberg and were composed of 39 myxoid liposarcomas (MLS), 61 dedifferentiated liposarcomas, 15 pleomorphic liposarcomas, 27 leiomyosarcomas, 25 synovial sarcomas (SS), 35 malignant peripheral nerve sheath tumors (MPNST), 40 undifferentiated pleomorphic sarcomas, 17 myxofibrosarcomas, 9 low grade fibromyxoid sarcomas, 10 cases of dermatofibrosarcoma protuberans, 31 solitary fibrous tumors (SFT), 8 extraskeletal myxoid chondrosarcomas, 9 angiosarcomas, 6 alveolar soft part sarcomas, 5 clear cell sarcomas and 4 epithelioid sarcomas. Sarcoma cell lines were obtained from the raising laboratories. A 193 bp fragment of the TERT promoter region covering the hot-spot mutations C228T and C250T was amplified, and direct sequencing of the PCR products was performed.
TERT promoter mutations were detected in 36/341 sarcomas. They were highly recurrent in MLS (29/39; 74%) and were in the present MLS series not associated with the phenotype (myxoid vs. round cell variant), tumor grade, tumor site and patients’ median age or gender. In the remaining cases, TERT promoter mutations were found only in 7/302 sarcoma samples and confined to SFTs (4/31; 13%), MPNSTs (2/35; 6%), and SSs (1/25; 4%). Within the collection of sarcoma cell lines examined, TERT promoter mutations were detected in two MLS and in one of three MPNST cell lines.
TERT promoter mutations are frequent in MLSs including their round cell variants, representing the most prevalent mutation identified in this sarcoma entity to date, and in a minor fraction of SFTs, MPNSTs and SSs. The majority of sarcomas are devoid of TERT promoter hotspot mutations. These data suggest that telomere maintenance through increased expression of telomerase plays an important role in the pathogenesis especially of MLS.
PMCID: PMC4022359  PMID: 24726063
TERT; Promoter; Mutation; Soft tissue; Sarcoma; Myxoid liposarcoma; Solitary fibrous tumor
5.  On the inflammatory response in metal-on-metal implants 
Metal-on-metal implants are a special form of hip endoprostheses that despite many advantages can entail serious complications due to release of wear particles from the implanted material. Metal wear particles presumably activate local host defence mechanisms, which causes a persistent inflammatory response with destruction of bone followed by a loosening of the implant. To better characterize this inflammatory response and to link inflammation to bone degradation, the local generation of proinflammatory and osteoclast-inducing cytokines was analysed, as was systemic T cell activation.
By quantitative RT-PCR, gene expression of cytokines and markers for T lymphocytes, monocytes/macrophages and osteoclasts, respectively, was analysed in tissue samples obtained intraoperatively during exchange surgery of the loosened implant. Peripheral T cells were characterized by cytofluorometry before surgery and 7 to 10 days thereafter.
At sites of osteolysis, gene expression of cathepsin K, CD14 and CD3 was seen, indicating the generation of osteoclasts, and the presence of monocytes and of T cells, respectively. Also cytokines were highly expressed, including CXCL8, IL-1ß, CXCL2, MRP-14 and CXCL-10. The latter suggest T cell activation, a notion that could be confirmed by detecting a small, though conspicuous population of activated CD4+ cells in the peripheral blood T cells prior to surgery.
Our data support the concept that metallosis is the result of a local inflammatory response, which according to histomorphology and the composition of the cellular infiltrate classifies as an acute phase of a chronic inflammatory disease. The proinflammatory environment, particularly the generation of the osteoclast-inducing cytokines CXCL8 and IL1-ß, promotes bone resorption. Loss of bone results in implant loosening, which then causes the major symptoms of metallosis, pain and reduced range of motion.
PMCID: PMC3994416  PMID: 24650243
Metal-on-metal implants; Metal wear particles; Innate immune response; T-cell response; Cytokines; Osteolysis
6.  Osteosarcoma Microenvironment: Whole-Slide Imaging and Optimized Antigen Detection Overcome Major Limitations in Immunohistochemical Quantification 
PLoS ONE  2014;9(3):e90727.
In osteosarcoma survival rates could not be improved over the last 30 years. Novel biomarkers are warranted to allow risk stratification of patients for more individual treatment following initial diagnosis. Although previous studies of the tumor microenvironment have identified promising candidates, novel biomarkers have not been translated into routine histopathology. Substantial difficulties regarding immunohistochemical detection and quantification of antigens in decalcified and heterogeneous osteosarcoma might largely explain this translational short-coming. Furthermore, we hypothesized that conventional hot spot analysis is often not representative for the whole section when applied to heterogeneous tissues like osteosarcoma. We aimed to overcome these difficulties for major biomarkers of the immunovascular microenvironment.
Immunohistochemistry was systematically optimized for cell surface (CD31, CD8) and intracellular antigens (FOXP3) including evaluation of 200 different antigen retrieval conditions. Distribution patterns of these antigens were analyzed in formalin-fixed and paraffin-embedded samples from 120 high-grade central osteosarcoma biopsies and computer-assisted whole-slide analysis was compared with conventional quantification methods including hot spot analysis.
More than 96% of osteosarcoma samples were positive for all antigens after optimization of immunohistochemistry. In contrast, standard immunohistochemistry retrieved false negative results in 35–65% of decalcified osteosarcoma specimens. Standard hot spot analysis was applicable for homogeneous distributed FOXP3+ and CD8+ cells. However, heterogeneous distribution of vascular CD31 did not allow reliable quantification with hot spot analysis in 85% of all samples. Computer-assisted whole-slide analysis of total CD31- immunoreactive area proved as the most appropriate quantification method.
Standard staining and quantification procedures are not applicable in decalcified formalin-fixed and paraffin-embedded samples for major parameters of the immunovascular microenvironment in osteosarcoma. Whole-slide imaging and optimized antigen retrieval overcome these limitations.
PMCID: PMC3940945  PMID: 24594971
7.  Integrative DNA methylation and gene expression analysis in high-grade soft tissue sarcomas 
Genome Biology  2013;14(12):r137.
High-grade soft tissue sarcomas are a heterogeneous, complex group of aggressive malignant tumors showing mesenchymal differentiation. Recently, soft tissue sarcomas have increasingly been classified on the basis of underlying genetic alterations; however, the role of aberrant DNA methylation in these tumors is not well understood and, consequently, the usefulness of methylation-based classification is unclear.
We used the Infinium HumanMethylation27 platform to profile DNA methylation in 80 primary, untreated high-grade soft tissue sarcomas, representing eight relevant subtypes, two non-neoplastic fat samples and 14 representative sarcoma cell lines. The primary samples were partitioned into seven stable clusters. A classification algorithm identified 216 CpG sites, mapping to 246 genes, showing different degrees of DNA methylation between these seven groups. The differences between the clusters were best represented by a set of eight CpG sites located in the genes SPEG, NNAT, FBLN2, PYROXD2, ZNF217, COL14A1, DMRT2 and CDKN2A. By integrating DNA methylation and mRNA expression data, we identified 27 genes showing negative and three genes showing positive correlation. Compared with non-neoplastic fat, NNAT showed DNA hypomethylation and inverse gene expression in myxoid liposarcomas, and DNA hypermethylation and inverse gene expression in dedifferentiated and pleomorphic liposarcomas. Recovery of NNAT in a hypermethylated myxoid liposarcoma cell line decreased cell migration and viability.
Our analysis represents the first comprehensive integration of DNA methylation and transcriptional data in primary high-grade soft tissue sarcomas. We propose novel biomarkers and genes relevant for pathogenesis, including NNAT as a potential tumor suppressor in myxoid liposarcomas.
PMCID: PMC4054884  PMID: 24345474
8.  BMP and TGFbeta pathways in human central chondrosarcoma: enhanced endoglin and Smad 1 signaling in high grade tumors 
BMC Cancer  2012;12:488.
As major regulators of normal chondrogenesis, the bone morphogenic protein (BMP) and transforming growth factor β (TGFB) signaling pathways may be involved in the development and progression of central chondrosarcoma. In order to uncover their possible implication, the aim of this study was to perform a systematic quantitative study of the expression of BMPs, TGFBs and their receptors and to assess activity of the corresponding pathways in central chondrosarcoma.
Gene expression analysis was performed by quantitative RT-PCR in 26 central chondrosarcoma and 6 healthy articular cartilage samples. Expression of endoglin and nuclear localization of phosphorylated Smad1/5/8 and Smad2 was assessed by immunohistochemical analysis.
The expression of TGFB3 and of the activin receptor-like kinase ALK2 was found to be significantly higher in grade III compared to grade I chondrosarcoma. Nuclear phosphorylated Smad1/5/8 and Smad2 were found in all tumors analyzed and the activity of both signaling pathways was confirmed by functional reporter assays in 2 chondrosarcoma cell lines. Immunohistochemical analysis furthermore revealed that phosphorylated Smad1/5/8 and endoglin expression were significantly higher in high-grade compared to low-grade chondrosarcoma and correlated to each other.
The BMP and TGFβ signaling pathways were found to be active in central chondrosarcoma cells. The correlation of Smad1/5/8 activity to endoglin expression suggests that, as described in other cell types, endoglin could enhance Smad1/5/8 signaling in high-grade chondrosarcoma cells. Endoglin expression coupled to Smad1/5/8 activation could thus represent a functionally important signaling axis for the progression of chondrosarcoma and a regulator of the undifferentiated phenotype of high-grade tumor cells.
PMCID: PMC3495847  PMID: 23088614
Conventional central chondrosarcoma; Bone tumor; Chondrogenic differentiation; Bone morphogenic proteins; Transforming growth factor β
9.  First experiences with negative pressure wound therapy and instillation in the treatment of infected orthopaedic implants: a clinical observational study 
International Orthopaedics  2011;35(9):1415-1420.
Infections associated with orthopaedic implants remain a serious complication. The main objective in acute infection control is component retention, whereas this option is usually not considered for chronic infections.
This multi-centre prospective, non-randomised observational study investigated one possible treatment option for implant retention in combination with negative pressure wound therapy with instillation (NPWTi). Thirty-two patients with an infected orthopaedic implant were analysed. Twenty-two patients had an acute infection (< 8 weeks after implantation) and ten patients had a chronic infection (> 8 weeks and < 36 weeks after implant placement). Polyhexanide was used as the instillation solution in 31 of the 32 cases.
Nineteen patients (86.4%) with an acute infection and eight patients (80%) with a chronic infection retained their implant at 4–6 months follow-up after treatment.
Our study showed that NPWTi can be used as adjunctive therapy for salvage of acutely infected orthopaedic implants and may even be considered for early chronically infected implants.
PMCID: PMC3167463  PMID: 21584643
10.  Mid- and long-term clinical results of surgical therapy in unicameral bone cysts 
Unicameral (or simple) bone cysts (UBC) are benign tumours most often located in long bones of children and adolescents. Pathological fractures are common, and due to high recurrence rates, these lesions remain a challenge to treat. Numerous surgical procedures have been proposed, but there is no general consensus of the ideal treatment. The aim of this investigation therefore was to study the long-term outcome after surgical treatment in UBC.
A retrospective analysis of 46 patients surgically treated for UBC was performed for short and mid-term outcome. Clinical and radiological outcome parameters were studied according to a modified Neer classification system. Long-term clinical information was retrieved via a questionnaire at a minimum follow-up of 10 years after surgery.
Forty-six patients (17 female, 29 male) with a mean age of 10.0 ± 4.8 years and with histopathologically confirmed diagnosis of UBC were included. Pathological fractures were observed in 21 cases (46%). All patients underwent surgery for UBC (35 patients underwent curettage and bone grafting as a primary therapy, 4 curettage alone, 3 received corticoid instillation and 4 decompression by cannulated screws). Overall recurrence rate after the first surgical treatment was 39% (18/46), second (17.4% of all patients) and third recurrence (4.3%) were frequently observed and were addressed by revision surgery. Recurrence was significantly higher in young and in male patients as well as in active cysts. After a mean of 52 months, 40 out of 46 cysts were considered healed. Prognosis was significantly better when recurrence was observed later than 30 months after therapy. After a mean follow-up of 15.5 ± 6.2 years, 40 patients acknowledged clinically excellent results, while five reported mild and casual pain. Only one patient reported a mild limitation of range of motion.
Our results suggest satisfactory overall long-term outcome for the surgical treatment of UBC, although short-and mid-term observation show a considerable rate of recurrence independent of the surgical technique.
PMCID: PMC3258224  PMID: 22165900
Solitary bone cyst; Unicameral bone cyst; Simple bone cyst; Juvenile bone cyst; Curettage; Bone graft; Steroid injection
11.  A phase II study evaluating neo-/adjuvant EIA chemotherapy, surgical resection and radiotherapy in high-risk soft tissue sarcoma 
BMC Cancer  2011;11:510.
The role of chemotherapy in high-risk soft tissue sarcoma is controversial. Though many patients undergo initial curative resection, distant metastasis is a frequent event, resulting in 5-year overall survival rates of only 50-60%. Neo-adjuvant and adjuvant chemotherapy (CTX) has been applied to achieve pre-operative cytoreduction, assess chemosensitivity, and to eliminate occult metastasis. Here we report on the results of our non-randomized phase II study on neo-adjuvant treatment for high-risk STS.
Patients with potentially curative high-risk STS (size ≥ 5 cm, deep/extracompartimental localization, tumor grades II-III [FNCLCC]) were included. The protocol comprised 4 cycles of neo-adjuvant chemotherapy (EIA, etoposide 125 mg/m2 iv days 1 and 4, ifosfamide 1500 mg/m2 iv days 1 - 4, doxorubicin 50 mg/m2 day 1, pegfilgrastim 6 mg sc day 5), definitive surgery with intra-operative radiotherapy, adjuvant radiotherapy and 4 adjuvant cycles of EIA.
Between 06/2005 and 03/2010 a total of 50 subjects (male = 33, female = 17, median age 50.1 years) were enrolled. Median follow-up was 30.5 months. The majority of primary tumors were located in the extremities or trunk (92%), 6% originated in the abdomen/retroperitoneum. Response by RECIST criteria to neo-adjuvant CTX was 6% CR (n = 3), 24% PR (n = 12), 62% SD (n = 31) and 8% PD (n = 4). Local recurrence occurred in 3 subjects (6%). Distant metastasis was observed in 12 patients (24%). Overall survival (OS) and disease-free survival (DFS) at 2 years was 83% and 68%, respectively. Multivariate analysis failed to prove influence of resection status or grade of histological necrosis on OS or DFS. Severe toxicities included neutropenic fever (4/50), cardiac toxicity (2/50), and CNS toxicity (4/50) leading to CTX dose reductions in 4 subjects. No cases of secondary leukemias were observed so far.
The current protocol is feasible for achieving local control rates, as well as OS and DFS comparable to previously published data on neo-/adjuvant chemotherapy in this setting. However, the definitive role of chemotherapy remains unclear in the absence of large, randomized trials. Therefore, the current regimen can only be recommended within a clinical study, and a possibly increased risk of secondary leukemias has to be taken into account.
Trial registration NCT01382030, EudraCT 2004-002501-72
PMCID: PMC3248452  PMID: 22152120
12.  The impact of pathological fractures on therapy outcome in patients with primary malignant bone tumours 
International Orthopaedics  2009;34(7):1017-1023.
The primary objective of this study was to investigate the implications of pathological fractures on therapy outcome in patients with primary malignant bone tumours and to determine whether limb salvage can be safely performed. A retrospective analysis of 447 patients with primary malignant bone tumours, treated between 1985 and 2005, was performed. Multivariate Cox regression analysis was used to investigate the influence of pathological fractures and further independent variables on survival rate. In 52 of the 447 patients, the primary malignant bone tumour was complicated by a pathological fracture. These fractures were more common in malignant fibrous histiocytoma (MFH) of the bone and in the tumour stages IIa/b and III. Ablative surgery was performed in ten patients and limb salvage surgery in 42 patients. The mortality risk for patients with pathological fractures was significantly increased by a factor of 1.82 (p = 0.015), and overall duration of survival was significantly lower in the fracture group, with a median of 6.2 years (p < 0.00001). In univariate and multivariate analysis, fracture, higher tumour stages and resection margins remained a significant predictor of worse survival. Overall survival, rate of local recurrence and distant metastases were not affected by the type of surgical treatment selected; there was no difference between the patients who underwent limb salvage and those who underwent an amputation. Pathological fracture in patients with primary malignant bone tumours is a predictor of worse survival and significantly increases mortality risk. Reconstructive surgery did not influence the survival rate, showing that limb salvage therapy is safe when adequate resection margins are achieved.
PMCID: PMC2989037  PMID: 20012861
13.  Trochanteric fractures in the elderly: the influence of primary hip arthroplasty on 1-year mortality 
The aim of the study was to compare the mortality risk and complication rate after operative treatment of pertrochanteric fractures with primary arthroplasty, dynamic hip screw (DHS) or proximal femoral nail (PFN).
Patients and methods
Clinical records including X-rays of all patients with trochanteric femoral fractures, except pathologic fractures and a minimum age of 60 years, which were treated between 1992 and 2005 were entered in this retrospective study. Of these 283 patients, 132 were treated by primary arthroplasty, 109 with a DHS and 42 with a PFN. Survival after 1 year and complications, which had to be treated within this period were our main outcome measurement. Influencing cofactors such as age, gender and comorbidities were reduced by multivariate logistic regression analysis.
Mortality was significantly influenced by age, gender and amount of comorbidities but not by fracture classification. Primary hip arthroplasty did not bear a higher 1-year mortality risk than osteosynthesis in a multiple regression analysis. The main complication with DHS and PFN were cutting out of the hip screw and non-union with a revision rate of 12.8%. With the introduction of hemiarthroplasty, the postoperative dislocation rate decreased from 12 to 0%.
For stable fractures a dynamic hip screw (DHS) and for unstable fractures a short proximal femoral nail (PFN) can be recommended. The mortality risk of primary cemented arthroplasty did not differ significantly from the other treatment groups and because of its low complication rate it is a viable treatment option for trochanteric fractures if osteoporosis prevents from full weight bearing or if osteoarthritis makes further operations likely. Primary total hip replacement should be handled with care due to its significantly higher dislocation rate compared with hemiarthroplasty especially in unstable fractures.
PMCID: PMC2111040  PMID: 17899138
Mortality risk; Trochanteric femoral fractures; Total hip replacement

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