Rapid study assessment in follow-up whole-body computed tomography in patients with multiple myeloma using a dedicated bone subtraction software.

OBJECTIVES: The diagnostic reading of follow-up low-dose whole-body computed tomography (WBCT) examinations in patients with multiple myeloma (MM) is a demanding process. This study aimed to evaluate the diagnostic accuracy and benefit of a novel software program providing rapid-subtraction maps for bone lesion change detection. METHODS: Sixty patients (66 years ± 10 years) receiving 120 WBCT examinations for follow-up evaluation of MM bone disease were identified from our imaging archive. The median follow-up time was 292 days (range 200-641 days). Subtraction maps were calculated from 2-mm CT images using a nonlinear deformation algorithm. Reading time, correctly assessed lesions, and disease classification were compared to a standard reading software program. De novo clinical reading by a senior radiologist served as the reference standard. Statistics included Wilcoxon rank-sum test, Cohen's kappa coefficient, and calculation of sensitivity, specificity, positive/negative predictive value, and accuracy. RESULTS: Calculation time for subtraction maps was 84 s ± 24 s. Both readers reported exams faster using subtraction maps (reader A, 438 s ± 133 s; reader B, 1049 s ± 438 s) compared to PACS software (reader A, 534 s ± 156 s; reader B, 1486 s ± 587 s; p < 0.01). The course of disease was correctly classified by both methods in all patients. Sensitivity for lesion detection in subtraction maps/conventional reading was 92%/80% for reader A and 88%/76% for reader B. Specificity was 98%/100% for reader A and 95%/96% for reader B. CONCLUSION: A software program for the rapid-subtraction map calculation of follow-up WBCT scans has been successfully tested and seems suited for application in clinical routine. Subtraction maps significantly facilitated reading of WBCTs by reducing reading time and increasing sensitivity. KEY POINTS: • A novel algorithm has been successfully applied to generate motion-corrected bone subtraction maps of whole-body low-dose CT scans in less than 2 min. • Motion-corrected bone subtraction maps significantly facilitate the reading of follow-up whole-body low-dose CT scans in multiple myeloma by reducing reading time and increasing sensitivity.

[Revised consensus classification. Histopathological classification of diseases associated with joint endoprostheses]. / Erweiterte Konsensusklassifikation. Histopathologische Klassifikation von Gelenkendoprothesen-assoziierten Erkrankungen.

The revised classification of the periprosthetic membrane (synovial-like interface membrane SLIM) encompasses all pathological alterations which can occur as a result of endoprosthetic replacement of major joints and lead to a reduction in durability of prostheses. This also includes the established consensus classification of SLIM by which aseptic and septic prosthetic loosening can be subdivided into four histological types and histopathological criteria for additional pathologies: endoprosthesis-associated arthrofibrosis, immunological/allergic alterations and osseous pathologies. This revision represents the foundation for the histopathological diagnostics of the total spectrum of diseases associated with joint prostheses, is a suitable basis for a standardized diagnostic procedure and etiological clarification of endoprosthesis failure and also as a data standard for endprosthesis registers, in particular for registers based on routine data (e.g. German endoprosthesis register).

[Joint endoprosthesis pathology. Histopathological diagnostics and classification]. / Gelenkendoprothesenpathologie. Histopathologische Diagnostik und Klassifikation.

Prosthesis durability has steadily increased with high 10-year rates of 88-95%. However, four pathogenetic groups of diseases can decrease prosthesis durability: (1) periprosthetic wear particle disease (aseptic loosening) (2) bacterial infection (septic loosening) (3) periprosthetic ossification, and (4) arthrofibrosis. The histopathological "extended consensus classification of periprosthetic membranes" includes four types of membranes, arthrofibrosis, and osseous diseases of endoprosthetics: The four types of neosynovia are: wear particle-induced type (type I), mean prosthesis durability (MPD) in years 12.0; infectious type (type II), MPD 2.5; combined type (type III) MPD 4.2; and indeterminate type (type IV), MPD 5.5. Arthrofibrosis can be determined in three grades: grade 1 needs clinical information to be differentiated from a type IV membrane, and grades 2 & 3 can be diagnosed histopathologically. Periprosthetic ossification, osteopenia-induced fractures, and aseptic osteonecrosis can be histopathologically diagnosed safely with clinical information. The extended consensus classification of periprosthetic membranes may be a diagnostic groundwork for a future national endoprosthesis register.

[Registration procedure for incidents with implants]. / Meldeverfahren bei Vorkommnissen mit Implantaten.

Incidents involving implants, whether there is a break in the osteosynthesis plate or a synthetic inlay of an endoprosthesis, are incidents with mostly severe repercussions for the patient with immediate and delayed effects for the clinic involved and the manufacturer.

Efficacy of autograft and freeze-dried allograft to enhance fixation of porous coated implants in the presence of interface gaps.

Autogenous cancellous bone and freeze-dried allogeneic cancellous bone were tested in a total of 41 adult male mongrel dogs. In each humerus, an implant with a commercially pure titanium fiber metal porous coating was placed in an overreamed cavity so that a uniform 3-mm gap was present between the implant and host cancellous bone. Graft material was placed in the gap of one humerus while the gap of the other humerus was left empty and served as a paired negative control. Histologically, both autograft and allograft appeared to aid repair of the defect, but quantitatively only autograft enhanced new bone formation within the defect. Treatment with autograft significantly increased the amount of bone ingrowth within the implants by nearly three-fold at 4 weeks and eight-fold at 8 weeks. The enhancing effect was recognizable as early as 2 weeks. The strength of fixation was increased by nearly seven-fold at 4 weeks and two-fold at 8 weeks in the autograft group, but this was only statistically significant at 4 weeks. Treatment with allograft did not enhance bone ingrowth at any time period, but had a small positive effect on strength of fixation at 4 weeks.

Effects of radiation on fixation of non-cemented porous-coated implants in a canine model.

A non-weight-bearing porous-coated rod was implanted bilaterally in the proximal part of the humerus in thirty-five adult male mongrel dogs. In all of the animals, one limb was treated with radiation and the opposite limb served as the control. In twenty-one animals, the dose was 1000 centigrays (rads) and in fourteen, it was 500 centigrays. The strength of fixation and the volume fraction of ingrowth of bone were determined two, four, and eight weeks after the operation in the group that received 1000 centigrays and two and four weeks after the operation in the group that received 500 centigrays. Treatment with 500 centigrays had no significant effect on the strength of fixation or the amount of ingrowth of bone. In contrast, at two weeks, treatment with 1000 centigrays had reduced the strength of fixation to 50 per cent of the control value (p less than 0.01), although, at four and eight weeks, the strength of fixation was not significantly different than that in the control limb. The amount of ingrowth of bone in the irradiated limb was significantly reduced at two weeks (30 per cent of the control value) (p less than 0.01), four weeks (70 per cent of the control value) (p less than 0.05), and eight weeks (56 per cent of the control value) (p less than 0.05).

Human bone marrow cell culture: a sensitive method for determination of the biocompatibility of implant materials.

The objective of this study was to develop a test method for determining the cytotoxicity and biocompatibility of various biomaterials that are used in orthopaedic surgery. This method is based on the use of a human bone marrow cell culture and was developed as an alternative to animal experiments. Human bone marrow cell culture has certain advantages over other cell culture models, as its results show a greater conformity with animal experimental results and clinical studies. Primary cell adherence, cell number, cell proliferation, production of extracellular matrix, cell viability and cell differentiation were used as indicative parameters of biocompatibility. After 2 weeks in culture, differences could be observed between the biomaterials with respect to these parameters. Cell numbers were greatest on the hydroxyapatite ceramic specimens, but were decreased on the titanium alloy specimens. Extracellular matrix hydroxyapatite production was high for ceramics, but reduced for titanium specimens. The polymers allowed only a few cells to adhere, and there were no signs of extracellular matrix production. The influence of biomaterials on differentiation of large numbers of cells was analysed by using flow cytophotometry. There were similar populations of T cells and monocytes on all specimens. However, extended B cell and granulocyte populations were observed with titanium and polyethylene.

[A scale for measuring symptoms related to degenerative diseases of the cervical spine. A reference in determining indications and evaluating surgical outcome]. / Eine Skala zur Messung von Beschwerden bei degenerativen Veränderungen der Halswirbelsäule (HWS). Hilfe zur Indikationsstellung und zur Evaluation des Operationserfolgs.

A scale for measuring symptoms related to degenerative diseases of the cervical spine is presented. Twenty typical symptoms are listed, e. g., neck pain, dysesthesia, and reduced mobility. Responses are assessed via a 6-point scaling ("did not have symptom" - "had symptom and suffered very strongly".) The cervical spine scale was tested in three samples: patients having undergone cervical spine surgery (n = 70), patients with other orthopedic diagnoses (n = 104), and healthy students (n = 100). The single items of the scale were aggregated into four scores: total number of symptoms, degree of overall symptom distress, functional disability, and pain/psychological distress. Statistical analyses proved the high reliability (Cronbach's alpha = 0.85 to 0.95) and validity (content, convergent, discriminant) of all scores. The scale differs clearly between cervical spine patients, other orthopedic patients and healthy individuals, and between cervical spine patients with different subjective operative outcomes. For applied clinical purposes the cervical spine scale can be included in a quality of life profile (QL-profile); this allows for a readily understandable graphic depiction of individual patients' QL-status.

[Morphological and numerical studies of the stress compatibility of patella implants]. / Morphologische und numerische Untersuchungen zur Stresskompatibilität von Patellaimplantaten.

Failure of total knee arthroplasty is relatively often caused by problems of the patellofemoral replacement. The purpose of this study was to analyze the distribution of stresses within an anatomical patella and the changes in stress distribution after patellar resurfacing with a Miller-Galante I patellar implant using two- and three dimensional finite element models (FEM). To assess validity, FEM results were compared with morphological findings from contact radiographs and densitographs. Internal orientation of bone trabeculae is in good agreement with the orientation of theoretically calculated principal stresses. Almost unchanged principal tensile stresses after implantation, together with the lack of extreme stress peaks within the cancellous bone ensure stress compatibility of the implant. In the case of a firmly seated implant with good bone ingrowth, increased von Mises stresses are found near the fixation peg/plate junction. Their relevance for improved bone ingrowth near this part of the interface is emphasized. At the same time, material failure at the peg/plate junction can be better understood. An analysis of the early postoperative period assuming nonlinear interface conditions failed to demonstrate an uniform distribution of normal and tangential interface forces.

Revised histopathological consensus classification of joint implant related pathology.

This extended classification of joint implant related pathology is a practical histopathologic classification based on defined morphological criteria covering the complete spectrum of pathohistologic changes in periprosthetic tissues. These changes may occur as a consequence of endoprosthetic replacement of large joints and may lead to a reduction in the prosthesis survival rate. We describe the established consensus classification of the periprosthetic membrane, in which aseptic and septic prosthetic loosening can be subdivided into four histological types, as well as histopathological criteria for additional significant pathologies including endoprosthetic-associated arthrofibrosis, particle-induced immunological, inflammatory and toxic mechanisms (adverse reactions), and bone tissue pathologies. These characteristic tissue alterations and their relationships are summarized in the extended classification. Since particle heterogeneity in periprosthetic tissue is high and particle identification is a necessary part of diagnosis, the identification of different types of particles is described in the histopathological particle algorithm. The morphological qualities of prosthetic material particles and the demarcation between abrasion and non-abrasion endogenous particles are also summarized. This feasible classification which is based on low cost standard tissue processing and examination and on well-defined diagnostic criteria is a solid platform for the histological diagnosis of implant associated pathologies providing a stable and reproducible tool for the surgical pathologist. Since this classification is suitable for standardized histopathological diagnostics, it might also provide a useful data set for joint arthroplasty registers, particularly for registers based on so-called routine data.

[DRG based development of revenues in orthopaedic surgery. A comparison on the development of cost weights and average lengths of hospital stay in Germany (G-DRG V1.0) and in Australian teaching hospitals (AR-DRG 4.1)]. / DRG-basierte Erlösentwicklung in der Orthopädischen Chirurgie. Die vergleichende Entwicklung der Relativgewichte und Patientenverweildauern in Deutschland (aktueller G-DRG V1.0) und in australischen Lehrkrankenhäusern (AR-DRG 4.1) am Beispiel Endoprothetik, Wirbelsäulen-, Schulter- und Fusschirurgie.

STUDY GOAL: In September 2002 the Federal Ministry of Health (BMG) has passed a decree in respect to the diagnosis related group system (G-DRG) for German hospitals (KFPV). From 2003 on the basis of this decree German hospitals were offered for the first time to use the G-DRG system optionally according to the " Section 17b Abs.4 of the Hospital Financing Law (Krankenhausfinanzierungsgesetz-KHG)". In addition the preliminary calculation data for the German DRG-System were published. The goal of this study was to compare the development of the cost weights and the average lengths of hospital stay in Australian teaching hospitals between 1998 and 2001 with the cost weights and average lengths of hospital stay in German hospitals according to the data published in the first German calculation (G-DRG V1.0). METHODS: An analysis was performed using the publically accessible reports on the national hospital cost data collections from 1998 until 2001 as they were published by the Commonwealth Department of Health and Aged Care in Australia. These data were compared with the cost weight calculation and average lengths of hospital stay calculation of the Institute for the Assessment of Cost Weights (InEK GmbH) published in the G-DRG V1.0 version. RESULTS: From 1998 until 2001 the cost weights of medical procedures such as spine fusion operations and joint arthroplasty revision operations on the hip and on the knee with severe complications and co-morbidities increased continuously. This development was not seen in DRG's without complications and co-morbidities, in food and ankle procedures and in shoulder procedures. The average length of hospital stay decreased continuously with very few exceptions. The average length of stay for so called C-DRG's (I09, I12, I13, I68, I69, I71, I75, I76) and in particular so called Z-DRG's (I16-I27) are in general longer by a factor of at least 2 in German hospitals when compared to Australian hospitals. CONCLUSION: A high quality of right-coding of ICD and ICPM Codes is a prerequisite to reach the correct revenue-relevant DRG. In Germany the average length of hospital stay is significantly longer than in Australia. In general the MDC-8-DRG's have demonstrated a smaller range when compared with the first calculated German DRG's in respect to the complexity of the procedures. Future management of the expected reductions in hospital stay will be based on a continuous co-operative efforts to improve the structural-, process- and (clinical guidelines and clinical pathways) and outcome quality of our medical procedures. The central objective of this effort is the well-being of our patients.

Three- to five-year results with the cementless Harris-Galante acetabular component used in hybrid total hip arthroplasty.

In this paper we present our 3- to 5-year results after hybrid total hip replacement using the cementless porous coated Harris-Galante acetabular component and the cemented Griss femoral component in 39 patients with 40 implantations. Postoperatively, mild to moderate pain was experienced by 16.1% of patients, mostly following hard activity. A slight to moderate limp occurred in 24.2%. All patients were able to walk more than 1000 m. Full-time use of support was required by 2.8%. The postoperative range of motion was increased in 93.9%. Radiographically, none of the acetabular or femoral components had to be classified as unstable. Only one acetabular component displayed complete (i.e., along all interface zones) radiolucency and was therefore classified as possibly unstable.

Cementless Gustilo-Kyle and BIAS total hip arthroplasty: 2- to 5-year results.

We conducted extensive radiographic and clinical examination of 58 cementless total hip arthroplasties. Forty BIAS femoral stems had heads made of Co-base F 75 alloy and 18 Gustilo-Kyle femoral stems had Ti6A14V alloy heads. The cross-sectional geometry and location of the porous coating pads of the two stem types was identical, the BIAS component being slightly shorter. At the last follow-up, 27.8% of the Gustilo-Kyle femoral components and 2.5% of the BIAS femoral components were unstable. None of the acetabular components in the BIAS group as against 38.9% of the acetabular components in the Gustilo-Kyle group demonstrated wear of more than 1 mm. All unstable components which did not suffer intraoperative fracture had also acetabular wear of more than 1 mm. The only case with endosteal erosion was seen in a patient with an unstable implant displaying the most extensive wear. Nonparametric statistical analysis showed that the patients with Ti6A14V/polyethylene bearing surfaces had a statistically significantly higher extent of wear and a statistically significant higher incidence of femoral component loosening than patients with CrCoMo/polyethylene bearing surfaces.

Cell differentiation under the influence of rh-BMP-2.

Bioactive bone growth factors will likely play an important role in the regeneration of bone. BMP-2 is known to promote osteoblastic cell differentiation and osteogenesis. Whether the BMPs act on human osteoblastic cells by increasing immature cell growth and/or differentiation is unknown. The goal of this study was to analyse possible effects of rhBMP-2 on cell differentiation using a human bone marrow cell culture. rhBMP-2 was added to the culture medium once. Fourteen days after addition of rhBMP-2 the cells were incubated with monoclonal antibodies. The cells were counted and analysed in a fluorescence-activating cell sorter (FACS). Compared to the controls there was an increasing effect on granulocytes, B cells and stem cells. The T-cells and monocytes show no increase or decrease after rhBMP-2 treatment.

Implant fixation by bone ingrowth.

The term osseointegration referred originally to an intimate contact of bone tissue with the surface of a titanium implant; the term bone ingrowth refers to bone formation within an irregular (beads, wire mesh, casting voids, cut grooves) surface of an implant. The section dealing with the historical background describes the development of macroporous, microporous, and textured surfaces with an emphasis on the evolution of porous and textured metal surfaces. The principal requirements for osseointegration and bone ingrowth are systematically reviewed as follows: i) the physiology of osseointegration and bone ingrowth, including biomaterial biocompatibility with respect to cellular and matrix response at the interface; ii) the implant surface geometry characteristics; iii) implant micromotion and fixation modes; and iv) the implant-bone interface distances. Based on current methods of bone ingrowth assessment, this article comparatively reviews and discusses the results of experimental studies with the objective of determining local and systemic factors that enhance bone ingrowth fixation.

Missing osteoconductive effect of a resorbable PEO/PBT copolymer in human bone defects: a clinically relevant pilot study with contrary results to previous animal studies.

PEO/PBT 70/30 (POLYACTIVE(R) 70/30), a degradable porous copolymer with elastic properties, was found to be osteoconductive in many animal studies. The aim of this study was to determine the osteoconductive effect in a human paired control iliac defect model. In seven patients undergoing anterior spinal interbody fusion surgery, two bicortical iliac defects for autograft harvesting were created. The defect size was identical for both defects measuring about 40 x 15 mm (group I). One defect was filled with the degradable implants, whereas the remaining one was left untreated as a control. The defect site for treatment was chosen randomly. In three further patients, only one defect measuring about 40 x 35 mm was created (group II). All patients were examined clinically and radiologically by spiral-CT after 1, 6, 12, 24, and 52 weeks. Three-dimensional reconstructions as well as CT-volumetric measurements using 1 mm sections were used as evaluation methods. In group I, a two-tailed paired t-test showed that the treated defects had significantly less formation of new bone than the untreated ones (p < 0.05 after 12 weeks, p < 0.01 after 52 weeks). Also, in group II, not much bone ingrowth could be observed. The histological evaluation of one patient in group I revealed no bone within the pores, and a fibrous layer between bone and implant was always present. Therefore, PEO/PBT 70/30 cannot be recommended as a bone substitute for clinical use. Differences in bone regeneration between humans and certain animal species as well as inapplicable defect models in previous animal studies are discussed as possible reasons for the failure.

Ultrasound examination for the early determination of dysplasia and congenital dislocation of neonatal hips.

Hip sonography enables an accurate and clinically relevant evaluation of hip maturation during the first days of human life. Experience has shown that an integration of hip sonography into neonatal screening programs is useful and necessary because clinical and even roentgenographic examination does not always establish a confirmed diagnosis of dysplasia.

[2- to 5-year follow-up of cementless implantable knee joint prosthesis of the Miller-Galante type]. / Zwei- bis Fünfjahresergebnisse mit der zementfrei einsetzbaren Kniegelenkprothese vom Typ Miller-Galante.

Based on a prospective study protocol, the two- to five-year results of the Miller-Galante cementless total knee arthroplasty are presented. Sixty-four implants were placed in 59 patients: 60 implantations were cementless and 4 cemented. Clinically, the scores for pain, range of motion, walking and stair climbing improved significantly. Radiographically, the uncemented components displayed no signs of definite or possible loosening, whereas one of the cemented components was found to be definitely loose. On histological evaluation of the retrieved implants, all components had bone ingrowth.

[Human bone marrow cell culture--a sensitive method for the evaluation of the biocompatibility of materials used in orthopedics]. / Die humane Knochenmarkszellkultur--Eine sensitive Methode zur Beurteilung der Biokompatibilität von Materialien, die in der Orthopädie verwendet werden.

The objective of the study was to develop a test system to determine the cytotoxicity and biocompatibility of different biomaterials used in orthopedic surgery. This system was based on the use of a human bone marrow cell culture and the purpose was to find a screening method as a alternative to early animal experimental methods. The established human bone marrow cell culture has certain advantages when compared with other cell culture models. The result demonstrated a high conformity with animal experimental results.