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Over the last few years bone resin based vertebral augmentation in the form of vertebro- and kyphoplasty has proved to be a safe therapeutic option in cases of vertebral compression fractures. Nevertheless, rare systemic complications have been seen, i.e., pulmonary embolisms ranging from harmless to lethal.The presence of an anesthesiologist can be especially useful in cases of systemic complications. Whether the form of anesthesia has any influence on the outcome of vertebro- or kyphoplasty is currently unknown. Local anesthesia supplemented by analgosedation is often used as an alternative to general anesthesia. The rationale for one or the other form of anesthesia can be factors like type of augmentation (vertebro- or kyphoplasty), number of vertebral levels to be treated as well as the patient's age, condition, and comorbidities.Single-shot epidural anesthesia is yet another anesthetic option that has been successfully used in our clinic for some years now. It combines the advantages of general and local anesthesia: excellent segmental analgesia even in multilevel cases in awake and responding patients.

Aim: Computer assisted navigation of the acetabular cup in THR requires reliable digitalisation of bony landmarks defining the frontal pelvic plane by user driven palpation. According to the system recommendations the subcutaneous fat should be held aside during epicutaneous digitalization. To improve intraoperative practicability this is often neglected in the symphysis area. In these cases the fat is just compressed and not pushed aside., Method: In this study soft tissue thickness was assessed by ultrasound and pelvic geometry was measured in 72 patients to quantify potential misinterpretation of cup anteversion triggered by the simplified palpation. As reference we employed data of the same patients that had been acquired by recommended palpation., Results: Anteversion misinterpretation averaged at 8.2 degrees with extremes from 2 to 24 degrees. There were no correlations between soft tissue thickness or misinterpretation and body weight, height and pelvic size. Anteversion misinterpretation was highly significant worse compared to the reference data., Conclusion: In 31 % of the patients the anteversion misinterpretation of a navigation system would have been wrong by over 10 degrees and in 81 % over 5 degrees . Therefore the simplified palpation should not be utilized. For epicutaneous digitalization of the bony landmarks it is mandatory to push the subcutaneous fat aside.

In contrast to the present, the diagnosis and treatment of pes cavus was a major subject of research at the beginning of last century. This was due to the high incidence of certain neurological disorders (poliomyelitis, myelodysplasia) which led to the development of this foot deformity. Advances in anaesthetic technique and the establishment of antisepsis contributed largely to the development of the surgical treatment of pes cavus. Ladislaus Leo Freiherr von Lesser performed the first surgically induced ankylosis of the ankle by denuding the joint surfaces of cartilage followed by fixation with a metal nail. This procedure was then introduced as arthrodesis; a word derived from the Greek meaning "binding of the joint". Numerous methods and modifications of arthrodesis have been developed for the correction of foot deformities. With increasing knowledge of the pathogenesis of pes cavus, soft tissue and tendon transfer procedures were added to the surgical treatment. Today, the philosophy of arthrodesis in the treatment of foot deformity is the same, but the development of fixation techniques and implant materials could improve postoperative care and outcome.

The rationale for autogenous osteochondral grafting into necrotic areas of the femoral head is to provide hyaline cartilage for areas of main articular contact pressure. The aim of this study was to present our results of autogenous osteochondral grafting to the femoral head in the treatment of avascular necrosis. The mean follow-up of the five patients was 57 months following autogenous osteochondral grafting to the femoral head using DBCS (diamond bone-cutting system). The number of transplanted cylinders varied between one and three, and the diameter of the cylindrical transplants between 9 and 13 mm. Results were unsatisfactory in four of five hips and these underwent total hip replacement a mean of 49 months following DBCS of the hip. In our hands, osteochondral grafting to the femoral head using DBCS had proven technically possible in restoring the articular surface of the femoral head; however, this operation was associated with unsatisfactory results in four of five cases.

Important criteria for stable cup fixation are the type of anchor system and stabilizers,cup form and the material and surface structure. Different fixation systems are manifest in pressfit and threaded cups. Pressfit implants are oversized and lead to equatorial jamming. For additional fixation, and to improve stability, screws, pegs, rings, fins, spikes or hollow cylinders are used. In threaded cups, thread geometry is decisive for the cup's performance during the screw-in process and positioning. The hemispheric shape of the cups requires less bone resection and the position of the implant can be arbitrarily selected. The conical shape guarantees high tilting stability. Most implants are made of pure titanium or a titanium-aluminum alloy. A rough surface area - produced by corundum blasting, titanium-plasma spray, titanium balls, nets or other grid designs - is essential for osseointegration. The results of second generation pressfit and threaded cups with 10 year survival rates of 93-100% are persuasive.

Slipped capital femoral epiphysis (SCFE) leads to an unphysiologic function in adolescent hips. Evaluation of the slippage as well planning of corrective osteotomies is a major three-dimensional (3D) problem. Therefore, the current clinical evaluation, which is based on biplanar plain radiographs, cannot be satisfying. More is needed than simply measuring the femoral geometry to evaluate the impact of a slippage onto the physiologic hip function. We have developed a computer-based system for planning and evaluation of reorienting osteotomies in severe cases of SCFE. In our system, CT-based 3D computer models of the hip are used to simulate the range of motion within physiologic cartilage-to-cartilage contact. This helps to visualize and quantify the early impingement due to the slippage. In addition, 3D techniques allow to simulate and plan the corrective osteotomy in an intuitive way on the computer screen. Using the same range of motion system mentioned above, the projected result can be evaluated quantitatively and compared to other approaches. The motion simulation is based on the surface geometry of the joint partners rather than on a predefined, fixed rotation center. The presented system allows a much more intuitive and appropriate system for indicating and planning corrective osteotomies than conventional methods.

Objective: Affecting as it does the geometry of adolescent hips, slipped capital femoral epiphysis (SCFE) and its evaluation represent a major three-dimensional problem. The current methods of clinical assessment-geometric measurements of the femur on plain radiographs or on axial computed tomographic (CT) cross-sections-address only one of the two joint components., Materials and Methods: We have developed a system to simulate motion of hip joints with physiologic joint contact. In our system, CT-based computer models of the femur, pelvis, etc., are fitted with oriented bounding boxes (OBBs) and manipulated. Collision detection algorithms control the hip motion, which, in this virtual joint, is based on the surface geometry of the joint partners rather than on a predefined fixed rotation center., Results: An illustrative case is presented to show the advantages of the new biomechanical evaluation method over conventional radiological assessments for SCFE. The proposed system provides remarkably high speed, and the necessary data can be prepared in a reasonable time., Conclusion: The range-of-motion assessment provides the surgeon with information about the site and the impact of nonphysiologic contact in the hip joint. The information thus obtained can be valuable for indication and planning of corrective surgery in cases of SCFE., (Copyright 1999 Wiley-Liss, Inc.)

To date no satisfactory method has been available for the quantitative in vivo measurement of the complex hepatic blood flow. In this study two modelling approaches are proposed for the analysis of liver blood flow using positron emission tomography (PET). Five experiments were performed on three foxhounds. The anaesthetised dogs were each given an intravenous bolus injection of oxygen-15 labelled water, and their livers were then scanned using PET. Radioactivity in the blood from the aorta and portal vein was measured directly and simultaneously using closed external circuits. Time-activity curves were constructed from sequential PET data. Data analysis was performed by assuming that water behaves as a freely diffusible tracer and adapting the standard one-compartment blood flow model to describe the dual blood supply of the liver. Two particular modelling approaches were investigated: the dual-input model used both directly measured input functions (i.e. using the hepatic artery and the portal vein input, determined from the radioactivity detected in the aorta and portal vein respectively) whereas the single-input model used only the measured arterial curve and predicted the corresponding portal input function. Hepatic arterial flow, portal flow and blood volume were fitted from the PET data in several regions of the liver. The resulting estimates were then compared with reference blood flow measurements, obtained using a standard microsphere technique. The microspheres were injected in a separate experiment on the same dogs immediately prior to PET scanning. Whilst neither the single- nor the dual-input models accurately reproduced the arterial reference flow values, the flow values from the single-input model were closer to the microsphere flow values. The proposed single-input model would be a good approximation for liver blood flow measurements in man. The observed discrepancies between the PET and microsphere flow values may be due to the inherent temporal and spatial heterogeneity of liver blood flow. The results presented suggest that adaptation of the standard one-compartment blood flow model to describe the dual blood supply of the liver is limited and other flow tracers have to be considered for quantitative PET measurements in the liver.