Search

Three cases of pulmonary osteoarthropathy secondary to pulmonary metastases from extrathoracic tumours are described. Analysis of the reported cases shows that most of them were secondary to osteosarcoma, nasopharyngeal tumour, fibrosarcoma, and uterine tumour. Fibrous tumours and tumours with a predominantly fibrous stroma tend to be associated with osteoarthropathy more than others. This suggests that the fibrous stroma may be a factor in the stimulation of the reflex mechanism responsible for osteoarthropathy. [ABSTRACT FROM PUBLISHER]

Background MRSA represents a considerable health threat to orthopaedic patients. Throughout the last decade, livestock-associated MRSA emerged increasingly in livestock all over Europe. LA-MRSA broke the species barrier, colonizing and causing infections in humans. Nevertheless, to date there are no studies concerning livestock-associated MRSA and orthopaedic patients. Therefore, we aimed to investigate the prevalence of LA-MRSA in a regional orthopaedic department localized in an area with high-density livestock. Patients and Methods 1544 persons were enrolled in this prospective study. Nasal swabs and questionnaires were collected in patients admitted to the orthopaedic hospital. Nasal carriage was assessed by using selective MRSA agars. MRSA-positive samples were spa typed. Results Overall, the prevalence of MRSA carriage was 3.3%, nearly all spa types were indicative for LA-MRSA. 91% of all LA-MRSA carriers had contact to livestock during the last 6 months before testing. Conclusion Livestock-associated MRSA emerged rapidly over the last few years and will contribute substantially to MRSA infection rates in orthopaedic hospitals. Livestock-associated patients must be screened before admission in order to control infectious complications., Competing Interests: Interessenkonflikt: Nein., (Georg Thieme Verlag KG Stuttgart · New York.)

Objects: Beta tricalciumphosphate pellets loaded with individualized antibiotics may represent novel options in the treatment of osteomyelitis and infectious bone disease. Here, the in vitro antibiotic elution of vancomycin and gentamicin from the synthetic bone graft substitutes Cerasorb(®) and Cerasorb M(®) was tested., Methods: Antibiotic elution and concentration of gentamcin and vancomycin were measured using photometrically-based measurement and homogeneous particle-enhanced turbidimetric inhibition immunoassays (PETINIA)., Results: Initially both materials showed a high release of the loaded antibiotics, with Cerasorb M(®) showing lower release levels for gentamicin and vancomycin than Cerasorb(®). Gentamicin concentrations of Cerasorb M granules and Cerasorb were below the minimum detectiontreshold until day four and six of the experiment respectively. The vancomycin release-level followed a similar pattern, although the vancomycin concentration eluted by Cerasorb M(®) granules stayed above the detection threshold during the experimental time., Conclusions: Cerasorb(®) and Cersorb M(®) may represent a new treatment option in osteomyelitis and infectious bone disease.

Aim: Before clinical implementation of an approved electromagnetic tracking system (CAPPA IRAD EMT) an experimental trial was performed to investigate the accuracy of the system and its safety in application for transpedicular vertebral punctures in comparison to the classical fluoroscopic method., Material and Methods: A total of 110 transpedicular punctures were performed bilaterally using 11 vertebrae of 5 realistic artificial phantoms and 1 pedicle was punctured with the conventional technique using c-arm fluoroscopy and the other with the electromagnetic tracking system. As a target a radiopaque non-ferromagnetic marker was implanted bilaterally in the anterior wall of the vertebrae. For evaluation of the precision the distance from the end of the puncture to the target and the gradual deviation of the actual channel from the ideal trajectory were assessed in three-dimensional computer tomography. Calculations and statistical analysis were performed according to the Wilcoxon test by means of SPSS 16.0.1 for Windows., Results: The mean distance from the target was 6.6 mm (± 3.9 mm standard deviation SD) with electromagnetic navigation compared to 3.2 mm (± 2.8 mm SD) with fluoroscopic assistance and the mean aberration from the ideal trajectory was 18.4° (± 4.6° SD) compared to 6.5° (± 3.5° SD), respectively. The difference of accuracy was highly significant regarding both parameters (p < 0.001)., Conclusions: The minimum requirement for accuracy of transpedicular punctures could not be achieved with electromagnetic navigation. Unless proven otherwise, the lack of accuracy is attributed to unstable referencing. Despite evidence of successful employment for soft tissue punctures the system cannot currently be recommended for osseous applications of the spine.

Background: The osseointegration of actually rarely implanted cobalt-chromium implants can be critical in an elderly population. The aim of our study was to evaluate the effect of preoperative testosterone treatment on the osseointegration of cobalt-chromium implants., Materials and Methods: Press-fit implantation of 1.6 mm-diameter cobalt-chromium-molybdenum (CoCrMo) implants was performed in rats without pre-treatment in one group (n = 10) and after pre-treatment with 1 mg dihydrotestosterone (DHT) 2 days before surgery in the other group (n = 10). After 14 days, the specimens were examined by a pull-out test, histology and histomorphometry., Results: The biomechanical testing delivered inconsistent data leading to no significant difference (6.45 ± 6.94 N vs. 4.66 ± 3.77 N). Histology showed closed contact between surrounding tissue and the implants in both groups. The bone/implant contact area was significantly enhanced after treatment with DHT (42.23 % ± 9.25 vs. 57.57 % ± 16.71, p < 0.05), while the ratio of osteoid was reduced (38.68 % ± 16.7 vs. 27.38 % ± 13.02, not significant)., Conclusions: Pre-treatment with DHT enhances osseointegration of cobalt-chromium implants through enhanced mineralisation of peri-implant tissue. The treatment might additionally shorten postoperative rehabilitation due to its positive effects on musculature., (Georg Thieme Verlag KG Stuttgart · New York.)

A clinically evident radiculopathy without correlation in the imaging studies represents a serious problem regarding the indication, planning and execution of an operative procedure for its treatment. Both the diagnosis and treatment of such cases are deemed to be difficult without clear morphological correlation. Moreover, the surgeon lacks an important basis for the adequate planning and above all the justification of surgical treatment. Although discography with post-discographic computer tomography (CT discography) is still controversially discussed as an invasive diagnostic measure, the literature shows that this method is not only useful but also indispensable in certain cases. Based on these findings and our own empirical data, we recommend CT discography to be considered for imaging in patients suffering from lumbar radiculopathy with equivocal or insufficient MRI findings. The technique allows an accurate diagnosis and precise planning of a targeted surgical intervention such as endoscopic sequestrotomy or decompression., (© Georg Thieme Verlag KG Stuttgart · New York.)

Aim of the Study: Total disc arthroplasty is reported to maintain segmental motion. From finite element studies a rather posterior and central implantation of the prosthesis is recommended. However, there is yet no in vitro study with cadaveric specimens investigating the topic of implant positioning., Methods: Ten human lumbar spines were subjected to biomechanical testing. Flexion/extension and side-bending moments were applied from 2.5-7.5 Nm on a spine load simulator. First, the intact specimens were tested in 3 load cycles while motion was monitored with regard to the facet joints under different loads by an ultrasound-based system. An unconstrained total disc prosthesis was then implanted in a central position and the different load cycles were repeated. Finally the implant was positioned in a decentral position with an average offset of 6.2 mm for repetitive data acquisition., Results: Comparison of the facet joint motion in central and eccentric prosthesis positions resulted in the following averaged differences. During flexion of the lumbar spine an average difference of the reference point excursions of 0.38 mm was recorded on the ipsilateral facet joint with reference to the decentral position. For extension, the difference was 0.33 mm on average, for right side bending a difference of 0.63 mm was recorded while left side bending resulted in an average difference of 0.24 mm. The deviation of the reference markers on the contralateral facet joint showed the following average differences: for flexion 0.23 mm and for extension 0.54 mm, respectively. For side bending right/left the differences amounted to 0.18 mm and 0.39 mm. With regard to segmental motion there was no statistically significant difference for both the ipsilateral (p = 0.0564) and the contralateral (p = 0.2593) reference marker., Conclusions: The comparison of the segmental motion after central and decentral implantation of a lumbar total disc prosthesis reveals differences that have, nevertheless, no statistical significance. However, for clinical use it is recommended to strive for a central position of the implant.

Tuberculosis constitutes an important clinical entity with 90 million new infections worldwide during the last decade. 10 % of these infections affect osseous structures based on haematogenous spread. Therefore, tuberculous spondylodiscitis remains a major illness in orthopaedics which needs to be considered in cases of unspecific back pain. Pathognomonic characteristics are absent and clinical, chemical and radiological parameters are not reliable. The consequences of a delayed surgical intervention are discussed based on a case report with 5 year follow-up. Both adequate early CT and MRI scans and identification of the pathogen are essential in order to plan the therapy. Final re-evaluation of a conservative treatment regime needs to be done no later than six to eight weeks depending on the clinical constellation. Persistent or progressive spondylodiscitis with osseous destructions or neurological deficits demands a radical surgical intervention.

The main objective of orthoMIT is to develop an integrated platform for "gentle" surgery in orthopedics and traumatology with particular emphasis on hip, knee and spinal column surgery. The goal of the 24 partners of the orthoMIT consortium and further associated industrial partners is an integrated approach to reduce the cost of orthopedic interventions: full workflow integration in the operating room, full treatment integration extending through to rehabilitation, and full integration of the typical value chain of medical product development, from the laboratory to production and commercialization by the firms and industrial partners involved in the project including education and training. Development, therefore, focuses on new strategies in minimally invasive surgery and improved, knowledge-based planning and navigation systems. Other topics include the development of improved methods of interventional imaging using ultrasound and computed tomography (flat panel detectors) and new, miniaturized instruments with integrated sensors and a modular integration of various applications and components into an integrated surgical workstation.

We report on the case of an 81-year-old woman who was hospitalised because of severe pain at the sacro-iliacal joint radiating into the left leg without any accompanying neurological defect. X-rays demonstrated a step in the left massa lateralis of the sacrum, thus CT scans and MRI were performed, and multiple perineural cysts (Tarlov's cysts) were found. The patient underwent microsurgical treatment by fenestration of the cyst wall and evacuation of the fluid content in order to avoid further expansion of the cysts. Under consequent treatment with pain killers, complete mobilisation of the patient could be achieved. Ambulant follow-up by clinical controls and X-rays demonstrated a substantial resolution of the patient's preoperative symptoms. Symptomatic perineural cysts should be included into differential diagnosis of severe low back pain, thus CT or MRI scans should be performed in case of long-lasting or intrackable pain.

Aim: The diagnosis of spondylodiscitis is often prolonged, but it is an important differential diagnosis of backache. The discrimination between a bacterial infection and an aseptic inflammation with laboratory examinations like ESG, CRP or leukocytes is not possible. The aim of the present study was to determine the value of procalcitonin (PCT) as a diagnostic tool and monitoring parameter for spondylodiscitis and for the discrimination between bacterial infection and aseptic inflammation of the spine., Method: A total of 17 patients with spondylodiscitis and 18 patients with disc herniation as control were included in this study and ESG, CRP, leukocytes, fibrinogen, PNM elastase und PCT were examined for 50 days. The median age was 65 (17-78) years and the ratio of males to females was 8 : 9 in patients with spondylodiscitis and 62 (32-87) years and 7 : 11 in patients with disc herniation. For microbiological examination, CT-guided punctures were performed in patients with spondylodiscitis., Results: In 64 % of the 17 patients with spondylodiscitis a microbiological agent was detected, in 73 % of these cases staphylococcus aureus was isolated. The laboratory parameters indicating an infection were increased except for two cases in patients with spondylodiscitis, the mean value of CRP was 115 mg/dL. Influenced by the therapy these parameters decreased during the observation period. Except for one patient with an infection of a cardiac pacemaker, the PCT concentration was not elevated in both groups (< 0.5 ng/mL). In the group with disc herniation there were no elevated laboratory parameters during the entire observation period., Conclusion: PCT is not useful as diagnostic tool or monitoring parameter for spondylodiscitis. Furthermore, it is not useful for the discrimination between a bacterial infection and an aseptic inflammation of the spine.

Aim of the Study: Maintaining segmental motion is one of the most reported theoretical advantages of total disc replacement (TDR). Several inlay sizes are available for reconstruction of the physiological disc height. The influence of the implant height on the range of motion (ROM) was investigated in a biomechanical study., Methods: A total of 10 human lumbar cadaver spines were subjected to biomechanical testing. Flexion/extension and side-bending moments were applied from 2.5-7.5 Nm on a spine load simulator allowing for all 6 degrees of freedom. Motion under different loads was monitored by the Zebris system in 3 dimensions. Initially intact specimens were tested in 3 load cycles. Then a total disc prothesis was implanted with an 8.5 mm inlay and the cycles were repeated. Finally in 5 cases a 1-mm larger inlay was inserted while in the remaining 5 cases the inlay was exchanged with a 2-mm larger implant. Neutral zone (NZ) and ROM were recorded under the different loads., Results: The average motion for the various loads showed no significant difference when the intact motion segment was compared to the specimen containing the 8.5-mm inlay. After the larger inlay had been mounted the average reduction of the ROM in flexion/extension was 25% under the load of 7.5 Nm, 26% under a torque of 5.0 Nm and 30% when 2.5 Nm were applied. The NZ was reduced by 37%. For side-bending the ROM was reduced by 21% under a load of 7.5 Nm, by 26% under 5.0 Nm and by 35% under a torque of 2.5 Nm. The NZ was decreased by 27%. The reduction of the ROM was significant (p=0.0057)., Conclusion: Segmental lumbar motion is maintained after TDR. The size of the inlay can significantly change the ROM in lumbar spine segments treated by TDR.

Echinococcosis of human pathogenetic relevance is a very rare disease in Europe. The vertebral manifestation of the latter zoonosis constitutes one percent of all cases. Intraspinal echinococcosis appears worldwide just sporadically, whereas extradurally located cysts are identified more often than intradurally located ones. The diagnostic and specific therapeutic consequences of this very seldom entity are discussed based on a case report.

Aim: The treatment of slipped capital femoral epiphysis (SCFE) is usually treated operatively, but there is still no consensus about the method to be used. Up to a 30 degrees degree of slipping, the epiphysis is normally fixed in situ. The aim of our study was to compare the intermediate results after fixation in situ by K-wires versus cannulated titanium screws (Königsee-Implantate, Königsee-Aschau, Germany)., Methods: In this study 46 patients with SCFE grade I and II and mostly chronic slipping of the epiphysis were included. After fixation in situ and, if necessary, careful, closed reposition, the patients were clinically and radiologically followed-up for one year. The clinical results were documented by the score adapted from Heyman and Herndon. Furthermore, MRI scans were done to evaluate the vitality of the epiphysis pre- and postoperatively, when titanium screws were used., Results: Clinical follow-up showed comparable results in the clinical scores after fixation by K-wires or cannulated titanium screws (3.13 +/- 1.02 vs. 3.10 +/- 1.01). After the treatment with titanium screws we saw a higher rate of abnormal gait (33.3 % vs. 19 %), a decreased rate of the positive Drehmann sign (10 % vs. 38 %) and a lower rate of revisions (16 % vs. 50 %) in comparison to K-wire fixation. After displacement of the K-wires we saw chondrolysis and prearthrosis in one case. Removal of the K-wires was done without any complications, while the removal of the cannulated titanium screws failed in 4 of 10 cases., Conclusion: The treatment of SCFE with K-wires and cannulated titanium screws showed comparable results in the clinical follow-up. The treatment with cannulated titanium screws reduces the number of necessary revisions, but the removal of the material is hindered. Because of the lower rate of complications we prefer in the meantime the use of cannulated steel screws.

Aim: Androgens have proliferative effects on osteoblasts and increase fracture healing by systemic and local stimulation of bone formation. The aim of the present study was to evaluate if the systemic stimulation by androgens leads to increased bone-defect healing., Methods: 1.5-mm trepanation defects were created in the femoral diaphysis of 30 Sprague-Dawley rats. 10 animals were used as untreated controls and 10 animals per group were treated by intramuscular injection of 1 or 10 mg dihydrotestosterone two days prior to surgery. After 14 days the samples were explanted and examined by macroscopy, histology and histomorphometry., Results: All animals were included into the study and were analysed. Clinical observation showed no complications. Macroscopic examination and histology showed no significant differences. All defects were filled with trabecular bone in direct contact to the surrounding bone. Histomorphometry showed a significantly decreased bone content in the controls in comparison to both therapy groups, while the therapy groups showed no significant differences between each other., Conclusion: The stimulation of healing of bone defects with androgens leads to a significantly higher bone content inside the defects. In clinical application, androgens may be a possibility to increase bone formation, especially in elderly patients. Furthermore, it may be possible to shorten postoperative rehabilitation because of the effects of androgens on muscles.

Background: Idiopathic tumorous calcinosis is a rare benign disease of the periarticular tissue near large joints. Deposits of hydroxyapatite in single or multiple pseudocysts lead to consecutive pain or complaints by attaching the surrounding tissues. The etiology of this disease is not definitively clear., Case Report: We describe the case of an 11-year-old turkish girl with a well known chronic recurrent multifocal osteomyelitis (CRMO) and hyperphosphataemia. Furthermore, she developed a tumorous calcinosis around the left hip, which recurred after surgery, and around the ankle joint., Conclusions: CRMO and tumorous calcinosis can be associated diseases. The development of tumorous calcinosis in patients with CRMO and hyperphosphataemia should be excluded.

Aim of the Study: Multiple instrument systems are currently available for the reduction of spondylolisthesis, where posteriorly oriented tensile forces are directly acting on the slipped vertebra. The aim of this clinical study was to evaluate the clinical efficacy of a new indirect reduction manoeuvre applied to the lumbar spine., Method: A total number of 32 patients (14 female, 18 male) suffering of spondylolisthesis were reduced by transpedicular instrumentation during June 2001 until October 2003. The cranial adjacent vertebra was temporarily instrumented and the reduction of the slipped vertebra was facilitated by the application of traction on the instrumentation leading to tension of the longitudinal ligaments. Posterior transforaminal lumbar interbody fusion (TLIF) or anterior lumbar interbody fusion (ALIF) was then carried out according to the degree of degenerative shortening of the anterior long. spinal ligament. On the last follow up (average 32 month postoperatively; min.: 22 month) both the reduction of the spondylolisthesis and the ossification of the interbody fusion was evaluated radiologically. Physical function and patients satisfaction was measured by means of the SF 36 questionnaire., Results: The dislocation was reduced in all cases (81% on average). At the time of the last follow up bony fusion was depicted on the radiographs in all 32 patients. A distinct improvement in all categories of the SF 36 (in 5 out of 8 categories statistic significant) could be demonstrated., Conclusion: Temporary intraoperative instrumentation of the cranial adjacent segment proofs to be a simple an effective method for the sufficient reduction of spondylolisthesis.

Aim: Due to the initial disappointing experience with minimally invasive knee arthroplasty, many surgeons still prefer the conventional technique. Sharing technical details, personal insights and results may help abbreviate the individual learning curve towards successful MIS., Method: Based on the experience of over 250 minimally invasive knee arthroplasties an operative algorithm was developed and evaluated to assure optimal realization of a gentle joint replacement using a mini-mid-vastus incision. Short-term results were compared to those of the conventional technique with particular regard to pain, use of analgesic medication, flexion of the knee and achievements at physiotherapy., Results: In comparison to the conventional procedure, MIS produced significantly better results regarding pain and function during early rehabilitation and did not affect the perfect positioning of the implants. The morphine-equivalent dose was less than a half on day 2 after operation. Flexion on days 1 and 3 was 70 degrees and 75 degrees respectively. 80 degrees were obtained after 4 days and after 6 weeks flexion was at an average of 115 degrees . In contrast, results of the conventional control group were notably worse, with 50 degrees and 65 degrees on days 1 and 3, 80 degrees being obtained on day 6 only and a mean flexion of 100 degrees after 6 weeks., Conclusion: The special surgical technique of minimally invasive knee arthroplasty accelerates and facilitates the rehabilitation of the patient and thereby defines a new quality standard.

Unlabelled: In primary knee replacement, posterior-stabilized prostheses often are used but we wondered if by balancing the flexion and extension spaces satisfactory coronal and AP stability could be achieved without a more constrained implant. We retrospectively reviewed 61 patients who had a unilateral revision knee replacement 58 of whom had a posterior stabilized implant. The initial indication for the revision had been coronal instability in 42% and a loose tibial component in 44%. All patients were followed up for at least 4 years after the revision operation. Fifty two of 58 patients have fewer than 5 mm of anteroposterior instability. Fifty three of 58 patients had 0 degrees to 5 degrees of coronal instability. Patients who had either coronal or anteroposterior instability had evidence of instability usually by the 1-year followup. It did not progress in severity during the subsequent 3 years. In many patients satisfactory stability can be achieved in revision TKA with a posterior constrained implant and without implants with greater constraint., Level of Evidence: Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Aim: Optoelectronic navigation for computer-assisted orthopaedic surgery (CAOS) is based on a firm connection of bone with passive reflectors or active light-emitting diodes in a specific three-dimensional pattern. Even a so-called "minimally-invasive" dynamic reference base (DRB) requires fixation with screws or clamps via incision of the skin. Consequently an originally percutaneous intervention would unnecessarily be extended to an open procedure. Thus, computer-assisted navigation is rarely applied. Due to their tree-like design most DRB's interfere with the surgeon's actions and therefore are at permanent risk to be accidentally dislocated. Accordingly, the optic communication between the camera and the operative site may repeatedly be interrupted. The aim of the research was the development of a less bulky, more comfortable, stable and safely trackable device that can be fixed truly percutaneously., Method: With engineering support of the industrial partner the radiolucent epiDRB was developed. It can be fixed with two or more pins and gains additional stability from its epicutaneous position. The intraoperative applicability and reliability was experimentally tested., Results: Its low centre of gravity and its flat design allow the device to be located directly in the area of interest. Thanks to its epicutaneous position and its particular shape the epiDRB may perpetually be tracked by the navigation system without hindering the surgeon's actions. Hence, the risk of being displaced by accident is minimised and the line of sight remains unaffected., Conclusion: With the newly developed epiDRB computer-assisted navigation becomes easier and safer to handle even in punctures and other percutaneous procedures at the spine as much as at the extremities without an unproportionate amount of additional trauma. Due to the special design referencing of more than one vertebral body is possible at one time, thus decreasing radiation exposure and increasing efficiency.

Aim: The transpedicular placement of a hollow needle into vertebral bodies for kyphoplasty requires utmost accuracy and thereby permanent multiplanar X-ray control. Facing the increasing number of vertebral compression fractures, the aim of this work was the implementation of computer-assistance to optimise the issue. Prior to clinical implementation, experimental trials were undertaken to analyse the quality-improving options of the technique., Method: The virtual image of the planning and the puncture were correlated with the postoperative X-ray image of the needle. The real canal in the bone was then correlated with the preoperative planning in a CT-based 3D model and differences were calculated. As a measure of accuracy the deviation of the needle from the ideal intruding vector and the distance between its top and the centre of a predefined target were scrutinised and related to the indications of the navigation system. Operating time, radiation exposure and general applicability were additionally assessed. All data were compared with those of a conventional control group., Results: Planning and navigation could be executed with high accuracy. With an exactly transpedicular approach, neural structures were safely circumnavigated without once missing the target. In the control group the distance fault was up to 9 mm. The navigated drilling differed from the ideal trajectory by 1 degrees to max. 4 degrees. Conventional C-arm control led to a divergence of 4 degrees to 8 degrees . Radiation exposure could be reduced through computer assistance by 76 % to a fourth of the conventionally resulting amount and the pure operating time thereby decreased by 40 %. The inconvenient course of repeated positioning of the C-arm was overcome., Conclusion: In challenging cases of deteriorated anatomy and difficult radiomorphologic orientation, especially of the lower thoracic spine, the CAOS-procedure succeeds in finding the optimal pedicular approach to the vertebral body, helps to avoid collateral damage and minimises the overall risk of the procedure. High accuracy and reduced radiation exposure justify the clinical use of fluoroscopic navigation for transpedicular instrumentation.

Aim: Computer-assisted cement removal out of the femoral medullary canal requires the exact definition of the plug's shape within a 3D coordination system. Aiming at a sufficiently precise reconstruction based on segmentation of just a few 2D X-ray images a special mathematic procedure is needed for automatic surface interpolation. The geometric specification of the resulting virtual model should take into account the characteristic geometry of the navigated tools in order to achieve the best possible removal., Method: Studies were performed on anatomic specimens of entire human femora, that underwent cemented THA before being cut every 5 mm. The cross-sections were scanned at the high resolution of 600 dpi. Segmentation of the cement was performed with the help of a virtual deformable template and was both used for simulation of X-ray projections from various points of view and for validation of the reconstructed 3D model. By this means systematic errors such as those possible during X-ray acquisition, tracking or segmentation could be avoided and the precision of the procedure could be measured exclusively., Results: With increasing number of X-rays the distance from the reconstructed 3D model to the original could continuously be reduced. Using only two x-rays a maximum error was measured with 6.5 mm, whereas 5 pictures taken from different angles showed to be enough to ensure an error below 1 mm in the distal part of the femur. By the use of 6 or more pictures no significant improvement could be attained., Conclusion: The innovative procedure is essential for future 2D image-based fluoroscopic navigation of PMMA removal and bears the options of computer-controlled and robotic material working, respectively.

Aim: Due to the narrow access to the talar dome and the proximity of osteochondritic lesions to the joint surface, the therapeutic retrograde drilling often requires multiple attempts and repeated intraoperative X-ray-control. The advantages of a fluoroscopy-based computer-assisted navigation system regarding efficient planning and easy performance of the ideal drill path are evaluated in respect to accuracy and radiation exposure, as well as to time requirements., Method: A 5 mm spherical target was subcortically implanted in the medial aspect of the talar dome of 16 human cadaver specimens. Free-hand drilling was performed using the FluoroNav TM system in one group and conventional repetitive C-arm control in the other. The computed evaluation of the operative results was realized in a CT-generated 3D-model with the help of the DISOS planning and calculation program. The distance of the tip of the drill to the center of the lesion was measured, as well as X-ray exposure and total operating time., Results: The CAS procedure missed the lesion only once. The mean deviation of the computer-guided drill path was measured to be 2 mm, whereas the conventional method led to a mean distance of 5 mm from the target. Conventional drilling failed to reach the target in 5 cases, violating the articular cartilage twice. Navigation reduced the traditionally required multiple attempts of the intervention to just one drill canal and reduced radiation time to 25 %. Despite the increased technical preparation required, the navigated procedure only exceeded the conventional operating time by 2 minutes., Conclusion: Thanks to the significantly increased accuracy, fluoroscopic navigation offers a high degree of safety and efficacy for this minimally invasive procedure. The operation can easily be performed successfully causing only minimal collateral damage to the bone, preserving the joint surface. The inherent risks of the retrograde drilling of osteochondritic lesions are lower with navigation, while the radiation exposure of the patient and the staff is significantly reduced.

Aim: Many orthopaedic procedures require an accurate drilling in bone. The outcome is frequently dependent on the geometric accuracy of this surgical step. The precision of such a procedure can be improved with the help of fluoroscopic navigation. Reliability, accuracy and benefit of this new method for the patient, as well as for the surgical staff, need to be analysed., Method: In a standardised in vitro trial, the drilling of a 5 mm spherical lesion implanted in an artificial femoral head was performed using a navigated drill-guide and a navigated drill. In groups A and B, the distance of the tip of the drill to the center of the lesion was analysed in a 3D CT-generated model and in macroscopic cross section. Additionally, in group B the actual direction of the drill canal was measured., Results: The mean distance in group A was measured to be 1 mm, with all results ranging between 0 and 2.5 mm. In group B the planned direction of the canal was reproduced with a deviation of 0 degrees to 7 degrees, the target only being missed by a mean distance of 2.5 mm and a maximum of 3.5 mm. Compared to the macroscopic and 3D-CT findings, the correlation of the data calculated by the navigation system was accurate up to a difference of 4 degrees or 2 mm., Conclusion: The fluoroscopically assisted freehand navigation used during the drilling of bone led to a high accuracy of three-dimensional tip placement while reducing radiation exposure to a minimum. It represents a promising and efficient application for a variety of procedures in orthopaedic surgery.

In the framework of the EC-Project VOEU ("Virtual Orthopaedic European University"), authoring tools have been developed to support the implementation of online interactive courses for multimedia orthopaedic educational modules. Based on the pedagogical concept of case-based, problem-oriented learning, different user-interaction scenarios and Learning Objects (LOs) were analyzed and developed. Each LO acts as an interactive dialogue presenting one kind of question with certain rules and interactions. The multimedia course content entailing anamnesis, diagnosis and therapy is managed in a database and can be adaptively generated as certain LO with the help of Active Server Pages (ASPs). As an example, an interactive course on Developmental Dislocation of Hip has been implemented.

The main objective of the MINARO project (Minimal Invasive NAvigation and RObotics) is the development of a modular intraoperative planning system for fluoroscopy based total hip revision surgery. Especially the distal cement removal can be a challenging problem. To avoid exhaustive x-ray imaging a navigation system should be used, nevertheless, the three-dimensional shape of the bone cement remains unclear. Our approach in the MINARO-project is to reconstruct the real shape of the bone cement by using just a few x-ray projections. First results show, that the reconstruction has an RMS-Error smaller than 0.5 mm using 6 x-ray projections.

In this study we investigate the use of an A-Mode ultrasound probe tracked by a mechanical localizer system (MicroScribe 3D) for non-invasive transcutaneous palpation and registration of bone surface points. A CT of a femur-model has been scanned and subsequently processed by segmentation and 3D-reconstruction. During the ultrasound registration, a computer based assistance tool helped guiding the alignment of the ultrasound probe. Three different modes of registration have been compared. Process times for registration have been recorded and compared. The results for using an A-Mode ultrasound system demonstrate a translation RMS accuracy of 0.58 mm. Mean ultrasound registration time has been measured to 108 sec. for palpation of 10 bone surface points of distal part of femur.

The uppermost monolayers of a metal implant are far more important for the corrosion resistance than the alloy itself. Using electron spectroscopy for chemical analysis (ESCA) technique these oxide layers on Vitallium specimens were investigated regarding thickness, elemental composition, and valence state of the elements. The oxide layers on metal implants are not very strong, as they can be easily damaged mechanically. According to environmental conditions, oxide layers of different elemental composition can be grown on the same specimen.

Instrumental neutron activation analysis with Gamma-spectroscopy is a very sensitive method for testing trace elements. Specimens of contact tissue around 5 Blount's vitallium clamps were, after preparation at the Nuclear Research Institute Jülich irradiated with thermic neutrons and their element-specific gamma spectra were measured after 33 and 125 days. In contact tissue a significant rise in concentration of the alloy-specific elements cobalt and chromium was found. The unspecific elements silver, caesium, iron, rubidium, antimon, scandium and zink were either within or very close to the normal. The metallosis of contact tissue is due to corrosion of the surfaces of cobalt-chromium implants.

The passive layer of a metal implant is responsible for its tolerance in a biological environment. A report is given on ESCA-investigations on the passive layer on Vitallium implants which consists largely of Cr-oxide and is only approx. 3-5 micrometer thick. This passive layer can easily be damaged with OP-instruments. The oxide layers rebuilt on exposure to air or on sterilization in boiling water were also investigated by ESCA. Oxide layers normally formed are very similar to the original passive layer. Accumulations of Co- and Mo-oxides are also observed, however. Some short implantation experiments show that the thin Cr-oxide layer is indeed effective as a passive layer. The analytical findings indicate that the formation or re-formation of the passive layer is due to a selective dissolution process. This accords with results obtained by the neutron activation analysis of the serum.

The principals of the ESCA technique are described in details. Oxide layers on pure metals are investigated regarding composition and growth velocity. The valence state of a metal and the thickness of its oxid layer at the time of implantation into human body tissue are highly responsible for the corrosion resistance of this metal. Compared with Iron, Cobalt and Nickel and oxid layers of pure Titanium, Chromium and Molybdenum did not show further growth of thickness after several days in air. Immediately after removal of the passive layer only the stable and not the reactive oxids of the metal were restored.