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Aim: Due to the continuing increase in life expectancy, the ageing process of the German population in general and the high demands placed on activity levels and quality of life today, the demand for primary and secondary joint replacement surgery continues to increase. To distribute the economic and medical resources properly, while still making technical and surgical innovations available to a broad public, hospitals must be able to adequately finance these procedures with the help of the proper diagnosis related groups., Method: The development of the German DRG-system over the past years, as well as the new calculation for the year 2006 are to be reviewed and analysed in this article with this in mind., Results: An improvement in the degree of differentiation between the individual procedures can be documented., Conclusion: Whether or not these changes will ensure the long-term financial survival of the German health care system will remain to be seen.

The causes of hip pain in adults can vary greatly. We present the case of a 44-year-old woman with recurrent hip pain over a period of years. Medical history and clinical examination did not provide any decisive information. The X-rays revealed a loose body in the cavity of the hip joint. The MRI scan made the following differential diagnosis plausible: osteochondrosis dissecans coxae, osteochondroma and chondromatosis. The final diagnosis of osteochondrosis dissecans coxae was confirmed by surgical dislocation of the hip as modified by Ganz and histological examination of the loose body. This case supports the importance of including rare lesions in the differential diagnostic work-up of joint pain. The advantages of the offset operation as modified by Ganz versus arthroscopy of the hip are outlined.

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 of the Study: Osteoporotic vertebral fractures are an ailment of the aging population of increasing incidence and high socioeconomic impact. Intractable pain causing significant morbidity leads to long-term hospitalisation. Kyphoplasty offers a new minimal invasive operative stabilisation procedure for these vertebral compression fractures. This study is conducted to investigate whether this procedure significantly reduces both pain and the duration of hospital stay in comparison to conservative treatment modalities., Method: From January until July 2002 a total of 22 patients had undergone kyphoplasty in 37 vertebral bodies. Osteoporotic vertebral fractures were treated in 18 cases, while in another 4 cases prophylactic stabilisation for osteolytic lesions was performed. Both the duration of hospital stay and the reduction of pain symptoms were determined and compared to a conservatively treated control group of 20 patients suffering from 35 fractured vertebral bodies. Pre- and postoperative endplate angles were measured to assess the restoration of the sagittal alignment. The effects on pain symptoms were measured on a self-reported Visual Analogue Score Scale., Results: The mean pain relief for the patients undergoing kyphoplasty was 82 %, which was significantly higher (p < 0.0001) compared to the group of the conservatively treated patients (42 %). Reduction of the kyphotic deformity was achieved in 4 cases (average 8.5 degrees ). The average in-patient treatment duration for the surgical treated patients was 10 days as opposed to a significantly longer mean hospitalisation of 20 days (p = 0.003). Cement extravasation was observed in 5 out of 37 treated vertebral bodies without clinical sequelae., Conclusion: Kyphoplasty is a safe minimal invasive procedure for the stabilisation of osteoporotic vertebral fractures leading to a statistically significant reduction both of pain status and duration of hospitalisation.

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.

Objective: The Implementation of a DRG-Variant in Germany - voluntarily since January 1 st, 2003 and obligatory from January 1 st, 2004 - has been leading to uncertainty, particularly in the hospitals, due to fears that currently practised German diagnostic and therapeutic measures will not be financed properly by a DRG-Variant. The G-DRG-Version 1.0 that was drawn up in connection with an executive order law is to a large degree identical to the Australian AR-DRG-Version 4.1. Adjustments to German requirements were made only marginally. Therefore it is necessary for every medical field to investigate by stock-taking to what extent currently practised German diagnostic and therapeutic measures are considered in the G-DRG-Version 1.0 and whether and where modifications and adaptations need to be made. In order to make qualified statements scientific evaluations of possible problems have to be made based German data. Therefore an evaluation was made of the mapping of the medical fields of orthopaedics and trauma surgery. The German Society of Trauma Surgery (DGU), the German Society of Orthopaedy and Orthopaedic Surgery (DGOOC) in cooperation with the DRG-Research-Group of the University Hospital Muenster, the German Hospital Federation (DKG) and the German Medical Association carried out a DRG evaluation project in order to investigate the medical and economical homogeneity of the case groups., Method: 12,645 orthopaedic and trauma surgery cases from 23 hospitals - 11 university hospitals and 12 non-university hospitals - were collected within an period of three months and were scientifically evaluated with regard to their performance homogeneity and length of stay homogeneity., Results: The data formed the basis for the proof of suspected deficiencies of mapping of orthopaedic and trauma surgery cases within the G-DRG-Variant. Based on the data and additionally on conclusions of medical experts when the number of cases were small, 14 suggestions for adaptation were proposed and submitted by the deadline of March 31 st, 2003 to the InEK., Conclusion: The results of the DRG-Evaluation Project demonstrate the problems of mapping the very heterogenous and complex medical performances of orthopaedy and trauma surgery to a flat rate financing system that is not adapted properly to German conditions. The G-DRG-Variant Version 1.0 does not offer the sufficient possibilities of differentiation that are needed to map the various orthopaedical and trauma surgical measures in Germany.

Aim: Osteochondral grafting procedures have developed into one of the preferred methods of treatment for focal osteochondral lesions, although the management of the donor site remains problematic. In this animal study, an attempt at sealing the donor site with a fully-resorbable tricalcium phosphate bone cement was evaluated., Method: Autologous osteochondral transplantation of the medial and lateral condyle was performed on the ovine knee using a standard operative protocol. The ensuing defect was filled with the original beta-TCP cement laterally, while medially the cement was augmented with 50 micro g BMP-2. Two groups, consisting of 10 sheep each, were evaluated after three and 6 months, respectively., Results: The clinical evaluation of the specimens revealed an improved reconstruction of the joint surface following the application of the augmented biomaterial. Macroscopically, the superficial border of the original donor site could easily be outlined at both time periods in both groups. Solid osteointegration of the bone cement could be documented radiographically as early as three months following implantation., Conclusion: The beta-TCP bone cement represents a promising resorbable filler for osteochondral defects. The augmentation with BMP-2 seems to expedite the remodelling process and improve the surface reconstruction.

Aim: The increased demands placed on the Achilles tendon in recreational and professional sports have led to a rise in pathological changes in this anatomic region. Magnetic resonance evaluations of the tendon have proven to be a valid but expensive and stationary diagnostic tool. In this study, a new mobile NMR sensor was to be tested in the evaluation of the Achilles tendon., Method: The technical development of the so-called NMR-MOUSE ( Mobile Universal Surface Explorer) represents a novelty with an open and portable sensor. To appraise its diagnostic efficacy, healthy athletes (professional soccer players, track and field, as well as aquatic athletes), healthy controls and patients with Achilles tendon lesions were evaluated. As an accessible, sensitive and reproducible parameter for the study the transverse relaxation time T2 with its angular dependency was chosen. As part of the examination, the relaxation times of the skin, the tendon and the surrounding soft tissue were determined., Results: During the evaluation with the NMR-MOUSE, the skin and peritendineous tissue exhibited relatively long T2 relaxation times, while the tendon itself had significantly shorter T2 times, allowing for a clear differentiation of the structures. The T2 relaxation time of the Achilles tendon in the control group averaged 5.8 ms. The MRI-MOUSE was able to demonstrate an increase in the T2 relaxation times in patients with pathological lesions of the tendon due to the increased water retention of the tissue., Conclusion: The novel NMR-MOUSE represents a cost efficient and portable sensor, which allows for a reliable evaluation of surface structures, such as the Achilles tendon. The anisotropic structure of the tendon and the surrounding soft tissue can be reliably differentiated with the help of the NMR-MOUSE.

Aim: An investigation into the objective criteria of shoulder mobility possesses special meaning for diagnostic documentation, the evaluation of therapy and the effects of rehabilitation in the treatment of diseases of the shoulder. In order to ascertain the criteria which characterise shoulder mobility, it is necessary to have a tool available that is objective, comparable and allows the complexity, variability and range of motion to be recorded. Motion analysis represents one such standard procedure used to measure joint movement., Method: Accordingly, a marker- based motion analysis of the wrist and elbow, a marker-based three-dimensional motion analysis system for the upper extremities was developed. We evaluated 10 healthy subjects without shoulder conditions and 8 patients with impingement syndrome (7 operative, 1 conservative therapy)., Results: The healthy subjects revealed a reproducible motion curve for the specific motion tested. The curves were defined as the normal standard and we used them for comparative purposes. In the treatment group, an improvement of the 3D range of motion could be documented for the affected shoulder following rehabilitation., Conclusion: It can be stated that this newly developed marker-based procedure for the three-dimensional motion analysis is suitable for recording complex unconstrained movements. This was found to be more relevant for the assessment of the ability of patients to manage the physical demands of daily living than traditional clinical tests. Furthermore, the information gained from motion analysis of the upper extremities will play a valuable role in the future for quality control during diagnosis and treatment, as well as for the design of shoulder rehabilitation programs.

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.

Aim: Extraskeletal chondromas in the region of the knee joint are very rare tumors which may cause diagnostic problems and have concomitant therapeutic consequences., Method: In a case report we present the clinical, radiological and histological features of an a extraskeletal chondroma., Results: A 47-year-old female patient presented with an infrapatellar, painless tumor of the knee joint. The clinical features were unspecific. On plain X-ray images, calcifications were visabled within Hoffa's fat pad. An important preoperative imaging procedure was MRI, which showed a well defined mass of 2.5 cm in diameter with a hyperintense signal on fat suppressed images. Subsequent operative therapy involved marginal resection of the tumor., Conclusion: The differentiation of this entity especially from myxoid chondrosacroma and synovial chondroamatosis was crucial with respect to an adequate therapy. Further differential diagnoses included heterotopic ossifications, synovial sarcoma, mesenchymoma and soft-tissue osteosarcoma.

Aim: Autologous grafting has developed into one of the preferred methods of treatment for focal osteochondral lesions, although basic research on this topic remains sparse. In an animal study, questions regarding the healing of such osteochondral transplants are clarified., Method: An autologous osteochondral transplantation was performed on the ovine knee using the standard operative protocol. Two groups, consisting of 10 sheep each, were evaluated after 3 and 6 months, respectively., Results: During the clinical evaluation of the specimens, neither osteophytes nor synovial changes were observed. The consistency of the cartilaginous tissue began to reach a level equivalent to the surrounding tissue only after 6 months. Macroscopically, the superficial border of the transplanted osteochondral plug could easily be outlined at both time points. Radiographically, a solid osteointegration of the graft could already be documented at 3 months. In contrast, integration of the chondral surface of the OAT was not seen macro- or microscopically at any point in time. A firm physical interdigitation of the reconstructed joint surface could not be demonstrated., Conclusions: The lack of integration of the cartilaginous portion of the transplanted plugs into the reconstructed joint surface leads to questions regarding the long-term survival of the joint itself.

Aim: Low back pain ranks high among the reasons for physician office visits and is costly in terms of medical treatment. A number of studies have shown that low back pain patients have significantly lower trunk strength when compared with healthy controls. The working hypothesis at the beginning of the 1990's was that low back pain patients could be treated effectively using lumbar extension exercise., Method: 21 papers and abstracts reporting on lumbar extension training are rated. Validation was performed for each paper according to the internationally accepted system of the American Association of Spine Surgery in types A-E., Results: 1100 cases from 21 publications and abstracts dealing with lumbar extension training were evaluated. We did not find a single type A study in our search. The clinical outcome of the studies was a reduction of pain, improvement of range of motion, improvement of spinal condition and of the lumbar extension strength., Conclusion: Prospective, randomized, controlled studies with long-term results should help to delineate further the role of isolated lumbar extension exercise for the treatment of low back pain and to test the efficacy compared to other methods of care.

Aim: In the study we evaluated the effectiveness of intraarticular injected hyaluronic acid (Hyalart) with regard to the changes in the parameters maximal isokinetic muscle strength, total work, pain at rest, and pain under toad., Method: We examined 43 patients with osteoarthritis in both knee joints (Kellgren II or II according to X-ray) in right/left comparison. We used the isokinetic system Cybex 600 for measuring the maximal isokinetic muscle strength and the total work. We used the visual analog scale for the pain. The evaluated parameters were measured before and after a 5-week treatment phase with 5 intraarticular injections (one injection per week with 20 mg hyaluronic acid)., Results: In knees treated with hyaluronic acid the mean peak torque of the knee extensor was 57 +/- 26.15/32 +/- 19.63 Nm vs. 77.17 +/- 32.54/47.83 +/- 21.43 Nm after (p < 0.01), the mean peak torque of the knee flexor was 40.44 +/- 21.58/22.89 +/- 16.64 Nm vs. 53.55 +/- 24.26/34.05 +/- 17.37 Nm after treatment (p < 0.01) at the angular velocities of 60 degrees/s and 180 degrees/s. Significant differences (p > 0.01) between treated and untreated knee were found for total work of the extensor and flexor of the knee. The pain at rest decreased from 3.83 +/- 1.72 cm to 1.36 +/- 1.42 cm and the pain under load decreased from 7.57 +/- 1.34 cm to 3.75 +/- 1.32 cm in the treated knee group (p < 0.01)., Conclusion: The intraarticular injection of hyaluronic acid is effective and safe in the treatment of patients with gonarthrosis. The treatment resulted in a functional improvement of the knee joint and had a good pain lowering effect in patients suffering from gonarthrosis.

Purpose: As part of a retrospective analysis of posttraumatic malunions of the lower extremity, the causes for deformity, as well as indications and methods for corrective osteotomies are reviewed., Methods: From January 1992 until December 1996, a total of 115 patients underwent corrective osteotomies of the lower extremity secondary to posttraumatic deformities. The 89 adult patients with tibial (n = 54) or femoral (n = 35) malunion were analyzed as part of this study., Results: The primary fracture treatment consisted of an intramedullary stabilization in 19 instances, a plate osteosynthesis in 22 and an external fixateur in 14 cases. Other forms of treatment were choosen in the remaining (n = 34) instances. Torsional deformities were seen after primary intramedullary nailings, while plate osteosynthesis lead to angulation in the frontal plane in the majority of the treated patients. In 43 instances uniplanar and in 46 cases multiplanar deformities had to be corrected. The correction was carried out with the help of an Ilisarow-ring fixator in 37 instances. As an internal stabilizer, 9 nails, 2 dynamic compression screws and 38 AO-plates were used. A bone graft was carried out primarily 33 times., Conclusions: The review of the literature, as well as of our own results, shows that deformities in the frontal plane should be corrected if they exceed 10 degrees of varus or 15 degrees of valgus. Malunions of more than 15 degrees in the sagittal and 15-20 degrees in the transverse plane should also be considered for correction, while a shortening of more than 3 cm represents an indication for corrective osteotomy. Callus distraction techniques have proven valuable in the correction of posttraumatic malunions of the lower leg, especially when soft tissue compromise is evident.