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V Ewerbeck

Publications and source records attributed to V Ewerbeck.

At least 19 recordsLinked to original sources
PubMed2001

[The importance to generate robot-assisted milled cavities for total hip replacement. A comparative experimental study: manual versus robotic preparation].

We present an experimental study to determine the effectiveness of computer assisted robotic bone preparation with regard to primary rotational stability in comparison to hand broaching. 5 different cementless stems were standardized implanted in synthetic femora and measured in a specially designed apparatus (displacement in 6 degrees of freedom). In addition the contact areas of the stems and the bone were visualized. The S-ROM- and ABG-stems were more stable in hand broached femora. The Osteolock-, G2- and Vision-2000-stems were more stable in the robot group. The mode of fixation of each implant could be characterized in relation to its position and its stiffness (primary rotational stability). The contact areas differed in some prosthesis in the way of preparation. The findings highlight the current difficulties in creating a perfect match of robotically milled cavity and stem geometry to achieve enhanced stability.

Arthroplasty, Replacement, Hip↗
PubMed2001

Quantitative evaluation of skeletal tumours with dynamic FDG PET: SUV in comparison to Patlak analysis.

This study was carried out to evaluate bone lesions using fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) and to explore whether dynamic and quantitative PET data may help to differentiate benign lesions from malignant masses. Forty patients with primary bone lesions were studied. The final diagnosis was confirmed by histopathology. A 60-min dynamic FDG PET acquisition was undertaken in all subjects. From the dynamic PET images, indices such as the average and maximal standardised uptake values (SUVs), the tumour SUV-to-muscle SUV ratio (T/M) and the SUV at 60 min-to-SUV at 30 min ratio (averSUV60/30 min and maxSUV60/30 min) were produced. Patlak graphical analysis was used to obtain the influx constant (Ki), and the metabolic rate of FDG (MRFDG) was calculated. Based on the receiver operator characteristic curve, the sensitivity and specificity for each parameter in differentiating between malignant and benign lesions were evaluated. The histological results revealed 21 malignant tumours and 19 benign lesions in this group. The MRFDG and SUV indices in malignant lesions were significantly higher than those in benign lesions. However, each index showed a considerable overlap between benign and malignant lesions. Average SUV correlated positively with MRFDG (r=0.67). When a cut-off of 1.8 average SUV was used, the sensitivity and specificity for discrimination of malignancy from benign disease were 85% and 82.4%, respectively. MRFDG showed a similar sensitivity (82.4%) and a better specificity (92.9%). A combination consisting of a cut-off of average SUV (1.8) and averSUV60/30 min (1.1) resulted in an improvement of specificity to 93.3%, with a small reduction in sensitivity (81.3%) as compared with exclusive use of SUV. The results of this study indicate that a detectable difference in glucose metabolism exists between malignant and benign skeletal lesions. The static FDG uptake indices alone may not enable adequate differentiation between benign and malignant lesions. Quantitative dynamic imaging may provide more helpful information, but will not permit a definite diagnosis. The use of uptake indices may represent an alternative and interesting approach to the evaluation of bone lesions.

Adolescent↗
PubMed2000

Drug-induced apoptosis in osteosarcoma cell lines is mediated by caspase activation independent of CD95-receptor/ligand interaction.

Osteosarcoma is one of the most common primary malignant tumors of bone. Treatment of this tumor with systemic chemotherapy dramatically improves the prognosis, although the molecular mechanisms involved in the drug action are poorly understood. In chemosensitive leukaemic T cells and certain solid tumors, cytotoxic drugs mediate the induction of apoptosis by activation of the CD95/APO-1/Fas system. Triggering of the corresponding signaling pathway may involve CD95-receptor/ligand interaction, activation of caspases, or alterations in mitochondrial function. The purpose of our study was to determine if similar mechanisms are involved in the chemosensitivity of osteosarcomas. We found that cytotoxic drugs induce characteristic biochemical and morphological alterations related to apoptosis in osteosarcoma cell lines, including activation of caspases and disturbance of mitochondrial function. However, drug treatment did not result in activation of CD95-receptor or CD95-ligand mRNA. In addition, drug-induced apoptosis was blocked by caspase inhibitors but not by inhibition of CD95-ligand action, indicating a CD95-receptor/ligand-independent mechanism in osteosarcoma cell lines.

Annexin A5↗
PubMed2000

[Pathological fracture in primary malignant bone tumors].

Retrospective analysis of 30 patients with pathological fracture out of 336 patients with primary malignant bone tumors should demonstrate the influence a pathologic fracture and the form of surgical therapy have on the survival rate. In 25 out of 30 patients a fracture led to diagnosis of the disease. Pathological fractures occurred cumulatively by malignant fibrous histiocytoma of the bone and in tumor stages IIb and III. Surgery was performed on 26 out of 30 patients (12 ablative therapies, 14 reconstructive therapies). The mortality risk for patients with pathological fractures was more than double the risk for patients without pathological fractures (P = 0.0062). When performed correctly, reconstructive therapy does not influence the survival rate.

Adolescent↗
PubMed2000

[Anchoring principles in hip endoprostheses. I: Prosthesis stem].

Total hip replacement is one of the most successful procedures in surgery. In Germany there is a great variety of cemented and uncemented implants with different principles of fixation. We reviewed the different principles, with particular reference to long-term clinical outcome, and discuss the most popular systems available in Germany. Despite many new developments which have been made in the field of cementless hip replacement, cemented total hip arthroplasty will remain the "gold standard" until prospective long-term data (> 15 years) of cementless systems become available.

Arthroplasty, Replacement, Hip↗
PubMed2000

[Anchoring principles in hip prosthesis implantation. II: Acetabulum components].

In this review the different anchorage concepts of cemented and cementless acetabular components are presented and clinical long-term results--if available--are discussed. Despite numerous design improvements and modifications the long-term durability of acetabular components remains a major concern with results being clearly inferior than achieved with femoral components. Until valid, prospective long-term success is proven for cementless designs cemented acetabular fixation using modern cementing technique must be regarded as standard treatment. However, successful fixation over 15-20 years very much depends on the quality of operative and cementing technique. Some cementless systems appear easier to use and have been documented to offer reliable mid-term survival rates. In young patients cementless devices have been well established and for some systems promising 10-year results have been published.

Acetabulum↗
PubMed2000

[Effects of the cementing technique on cementing results concerning the coxal end of the femur].

The purpose of this study was to determine the influence of jet-lavage and cement pressurising techniques upon cement penetration into proximal femoral cancellous bone. In a cadaver study 60 left human cadaver femora were used for implantation of cemented stem components. Four different groups of cementing techniques were generated, the allocation to the groups was randomized. Bone lavage was carried out either using jet-lavage or manual syringe lavage, cement application differed with regard to the amount of pressurisation used. Five different stem designs were used. Radiographs were taken and horizontal sections were obtained at predefined levels (2 cm) using a diamond saw. Microradiographs were taken and analysed using image analysis to assess cement penetration into cancellous bone. In an additional study the influence of jet-lavage (1000 ml) versus syringe lavage (1000 ml) was studied in 11 paired human cadaver femora. The specimens were imbedded in specially designed pots. Bone cement was applied in a retrograde manner and subjected to a standard pressure protocol with a constant force of 3000 N. The analysis protocol was identical to the main experiment. Both jet-lavage and pressurisation of bone cement significantly improved the penetration of cement into cancellous bone (p = 0.027 and p = 0.003, respectively). In the presence of strong, dense cancellous bone the findings were more pronounced. In the additional comparative study cement intrusion was significantly better (p < 0.001) in the jet-lavage group. We did not observe an influence of the stem type upon outcome (penetration). The use of jet-lavage yields significantly improved cement penetration and should be regarded mandatory in cemented total hip arthroplasty. High pressurising techniques are effective means to improve the interdigitation between cancellous bone and cement, but should only be administered in combination with jet-lavage to reduce the risk of thrombo-embolic complications.

Arthroplasty, Replacement, Hip↗
PubMed2000

[Cemented hip prosthesis implantation--decreasing the rate of fat embolism with pulsed pressure lavage].

Intraoperative fat embolism associated with cemented total hip arthroplasty is a well recognized complication. In a new sheep model allowing for standardized bilateral, simultaneous cement pressurization we studied the effectiveness of both pulsatile and syringe lavage of equal volume with regard to their cleansing capabilities as measured by fat and bone marrow intravasation. The operative procedure involved bilateral placement of intravenous catheters into the external iliac veins via retroperitoneal approach. After femoral neck osteotomies both femoral cavities were prepared for retrograde cement application. After randomization one side was lavaged with 250 ml irrigation using a bladder syringe, the contralateral femur with the identical volume but using a pulsatile lavage. A specially designed apparatus was used to allow for bilateral simultaneous cement pressurization. Venous blood from both iliac catheters was then collected, anticoagulated and a quantitative and qualitative fat analysis was performed. Despite equal volume manual lavage produced significantly higher fat and bone marrow intravasation (P < 0.001) than pulsatile lavage thus suggesting that not only the volume but also the quality of bone lavage is an essential factor influencing the risk of fat embolism and adverse cardiorespiratory effects. Our findings further emphasize the important role of pulsatile lavage in preventing fat and bone marrow embolisation during cemented total hip arthroplasty.

Animals↗
PubMed2000

Influence of extracorporeal irradiation on the reintegration of autologous grafts of bone and joint. Study in a canine model.

We studied the effects of irradiation on the reintegration of autologous osteoarticular grafts over a period of 24 weeks in a canine model. In 16 foxhounds the medial femoral condyle was resected, irradiated and immediately replanted. In the control group resection and replantation were performed without irradiation. Reintegration was assessed by macroscopic analysis, histology, radiography and gait analysis. Reintegration was equal at 12 weeks, but significantly inferior in the irradiated group after 24 weeks with delayed bone remodelling. The articular cartilage showed modest degeneration. Conventional radiography and histology showed corresponding changes. Limb function was adequate but the gait was inferior in the treated group.

Animals↗
PubMed1999

[Intraoperative extracorporeal irradiation and replantation (EIR) in the treatment of primary malignant bone tumors].

In 6 patients with primary malignant bone tumors (4 Ewing, 1 recurrent Adamantinoma, 1 maligne Haemangioperizytoma) the local therapy was performed as intraoperative extracorporeal irradiation and replantation. During the follow-up 10 (6-24) months no local recurrence in the replanted segment occurred. One recurrence occurred in the host bed; in two cases the replanted segment had to be removed because of severe infection. The other cases showed good functional and radiological results. These clinical findings and the reports in the literature seem to allow the application of the intraoperative extracorporeal irradiation and replantation procedure for defect reconstruction in cases of chemo- and radiotherapy-sensitive bone tumors.

Adolescent↗
PubMed1999

External fixation in proximal tibial osteotomy: a comparison of three methods.

During a period of 6 years (1990-1996), 154 patients with unilateral gonarthrosis underwent proximal tibial osteotomy using 3 different methods of external fixation: (1) closing wedge osteotomy and bilateral fixation; (2) closing wedge osteotomy with unilateral fixation, and (3) opening wedge osteotomy with unilateral fixation. The most common complications were pin-tract infection (25%), temporary nerve palsy (10%), and loss of alignment (17%). At least one complication developed in 33% of patients in this study, indicating that the use and technique of external fixation in proximal tibial osteotomy can be problematic.

Adult↗
PubMed1999

Shock-wave therapy is effective for chronic calcifying tendinitis of the shoulder.

We report a prospective study of the effects of extracorporeal shock-wave therapy in 195 patients with chronic calcifying tendinitis. In part A 80 patients with chronic symptoms were randomly assigned to a control and three subgroups which had different treatment by low-energy and high-energy shock waves. In part B 115 patients had either one or two high-energy sessions. We recorded subjective, functional and radiological findings at six months after treatment. The results showed energy-dependent success, with relief of pain ranging from 5% in our control group up to 58% after two high-energy sessions. The Constant scores and the radiological disintegration of calcification were also dose-dependent. Shockwave therapy should be considered for chronic pain due to calcific tendinitis which is resistant to conservative treatment.

Adult↗
PubMed1998

Periprosthetic mineralization around cementless total hip endoprosthesis: longitudinal study and cross-sectional study on titanium threaded acetabular cup and cementless Spotorno stem with DEXA.

In a prospective longitudinal study over 2 years and a separate cross-sectional study more than 5 years after operation, we analyzed periprosthetic bone mineral density (BMD) after cementless total hip arthroplasty (THA) (press-fit cementless Spotorno stem, Mecron threaded acetabular cup) by dual-energy X-ray absorptiometry (DEXA). BMD was analyzed in a longitudinal prospective study (n = 53 patients: 29 women, 24 men) and in a separate cross-sectional study (n = 23 patients: 13 women, 10 men) with good clinical outcome (Merle d' Aubigne score > 12). Regions of interest were defined according to Gruen (ROI 1-7) and as netto average ROI (NETAVG I) for the periprosthetic femur, and according to De Lee and Charnley (ROI I-III) and as NETAVG II for the periprosthetic acetabulum. BMD during follow-up was compared with immediate postoperative values of the affected limb. Mean precision error (CV%) was 2.6 +/- 0.5% for ROI 1-7 and 1.3 +/- 0.9% for ROI I-III. BMD significantly decreased in the periprosthetic femur and acetabulum during the first 3 months after operation. At the femur, BMD (NETAVG I) for women and men, respectively, was 92.4% and 87.5% at 6 months, then 89.4% and 96.2% at 2 years. ROIs around the proximal stem showed the lowest absolute values and decreased most during follow-up (to 79.9% ROI 1 and 68.2% ROI 7, respectively). Mineralization around the cup (NETAVG II), respectively, amounted to 81.1%, 82.6% at 6 months, then 80.1% and 93.8% at 2 years. The medially placed ROI II demineralized most (respectively, 72.1% and 76.7%). More than 5 years after THA, BMD in the femur showed little change, but decreased significantly to 76.4% and 79.1%, respectively, around the cup (NETAVG II). DEXA is a useful method for analyzing changes of mineralization around cup and stem of cementless THA. The results reflect the different stress on the periprosthetic bone after implantation of THA in defined ROIs, supporting earlier reported good clinical results of the Spotorno stem and increased loosening rate of threaded acetabular cups after 5 years.

Absorptiometry, Photon↗