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The present manuscript provides an overview of current evidence-based data and new clinically relevant developments in the field of hip arthroplasty. A multitude of current clinical trials have focussed on tribology with special interest on metal-on-metal implants. Large trials from implant registries have defined specific risk factors for early implant failure and pseudotumors in surface replacement. Furthermore, new ceramic liners and femoral head implants have been investigated in randomized trials. Apart from other very interesting studies, the results of large meta-analyses are now available for laboratory values in periprosthetic infection, antibiotic prophylaxis, regional anesthesia, prevention of thromboembolism, implant fixation, navigation and clinical pathways to prevent complications.

Extensive bone loss, as encountered in both revision arthroplasty of the hip and after resection of malignant tumors of the pelvis, is a major challenge for the surgeon as well as for the revision implant. The aims are, despite extensive acetabular defects, to achieve a primary and load-stable fixation of the revision prosthesis in the pelvic bone as well as restoring the physiological joint biomechanics. At present, a large number of different alloarthroplastic revision implants and complex techniques are available for reconstruction of acetabular deficiencies. According to D'Antonio's classification of acetabular defects, particularly high-grade defects with loss of the posterior column or a pelvic discontinuity require special attention regarding implant selection and surgical planning. The object of this paper is to highlight the most important tools and techniques of endoprosthetic reconstruction for grade III and IV defects (D'Antonio) of the acetabulum by means of a classification-oriented therapeutic concept and to discuss the pros and cons of the particular implant.

The number of periprosthetic fractures following hip replacement is increasing due to longer life expectancy and the rising number of joint replacements. The main causes of periprosthetic fractures include trauma, implant specific factors or loosening of the endoprosthesis. When planning therapy, surgeons should consider specific and general implant- and patient-related risk factors to ensure the best possible treatment. Established classification systems can facilitate preoperative planning. At present, the Vancouver classification system probably comes closest to the ideal, as it considers fracture configuration, stability of the implant and quality of the bone stock. Depending on these factors, therapeutic options include conservative treatment, fracture stabilisation or replacement of the endoprosthesis. The problems associated with periprosthetic fractures of varying etiology and the available treatment options are discussed against the background of the established classification systems.

A number of drugs can have "side effects" on bone metabolism and formation, causing bone atrophy, impaired mineralisation, as well as osteonecrosis. In both clinical and general practitioner settings, these forms of bone damage have been hitherto considered as adverse drug side effects and have received insufficient attention; moreover, they have not been the subject of patient information. Preventive measures are not instigated prior to initiation of medication and even after onset of bone damage, therapeutic strategies are poorly implemented. Even fracture healing with its complex, staged course can be both positively and negatively influenced by a number of drugs and these effects require monitoring. Recommendations regarding practical screening and therapy of drug-induced osteopathies are presented.

Osteoporosis is one of the 10 most important and widespread global diseases. In Germany alone the cost of osteoporosis runs into many billions of Euros. However, it should be noted that in the past 15 years great progress has been made both in diagnosis and in the development of new medications, and this has changed the general perception of and attitude to osteoporosis. It is now taken very seriously and recognised as a national and global disorder which is both preventable and treatable. In spite of this progress, in Europe and especially in Germany, osteoporosis remains an underdiagnosed and undertreated disease. In Germany, only about 10%-15% of patients with manifest osteoporosis are properly treated. However, in addition to national guidelines, there is now a new edition of the "European Position Paper for the Diagnosis and Management of Osteoporosis". This provides physicians treating osteoporosis patients with additional information and therefore more confidence.

Over the past three decades, the members of the substance group called bisphosphonates (BP) have been employed with growing success to manage osteopathies caused by increased osteoclastic activity. The following developments in BP are responsible: Modern BP are now already 20,000 times more potent than the first preparation approved for use. Their biochemical and cellular mechanisms of action have meanwhile been elucidated. They have no effect on hormones so that they are open for all patients. They are well tolerated and can be administered orally or intravenously. They have admirably been thoroughly studied in multinational trials. They are the "gold standard" in the treatment of osteoporosis, a widespread disease. Rare but serious side effects such as osteonecrosis of the jaw or acute renal insufficiency can be avoided to a large extent. BP also have tumoricidal properties and are used to suppress tumor growth in bones. Their anti-inflammatory activity is also successfully used in the treatment of bone marrow edema and bone pain.

Resurfacing arthroplasty is regarded as an attractive method, especially for the young patient who needs a hip replacement. However, the high expectations regarding this new technique in THR must first be met. Earlier experiences with similar forms of surface replacement have led to high revision rates with early aseptic wear induced component loosening and neck fractures. Technical progresses in production techniques for metal-on-metal articulations with minimized wear have enabled the introduction of new surface replacements for the hip joint. Long-term results of these resurfacing arthroplasties are still due. Femoral neck fractures and femoro-acetabular impingement are possible early complications which require revision. The implantation of these systems requires a high degree of operative skill and experience on the part of the surgeon. Approach dependent trauma to the musculature and endangering of the blood supply to the femoral head is balanced with the positive effect of the preservation of femoral bone stock and better options in case of revision. Whether the younger patient with a higher activity profile and an increased chance of implant loosening actually profits from the resurfacing arthroplasty will be determined in the future.

The treatment of soft tissue sarcoma requires an individually tailored, multimodal therapy due to the high variability in the clinical situation. Resection is the usual treatment for patients with superficial, low grade tumors with a diameter of <5 cm. For intermediate grade, differentiated lesions, resection with negative resection edges combined with radiotherapy attains an almost 80% total survival rate. For patients with high grade sarcoma of >5 cm, local control can be attained by resection and radiotherapy, however every second patient will develop metastases. Patients with a local recurrence should consider a new resection. Radiotherapy is the more effective the lower the remaining postoperative tumor burden.

Arthrofibrosis is one of the most common complications after total knee arthroplasty with an overall incidence of approximately 10%. Nevertheless, published data are rare and clinical trials mostly include small and heterogeneous patient series resulting in controversial conclusions. Clinically, arthrofibrosis after knee arthroplasty is defined as (painful) stiffness with scarring and soft tissue proliferation. Differentiation between local (peripatellar) and generalized fibrosis is therapeutically relevant. Histopathology typically shows subsynovial fibrosis with synovial hyperplasia, chronic inflammatory infiltration, and excessive and unregulated proliferation of collagen and fibroblasts. Diagnostic strategies are based on the exclusion of differential causes for painful knee stiffness, and especially the exclusion of low-grade infections represents a diagnostic challenge. Early and intensive physiotherapy combined with sufficient analgesia should be initiated as a basic therapy. The next therapeutic steps for persisting arthrofibrosis include closed manipulation and open arthrolysis. Arthroscopic interventions should be limited to local fibrosis. Revision arthroplasty represents a rescue surgery, often associated with recurrence of fibrosis. Prevention of arthrofibrosis by sufficient analgesia and early physiotherapy remains the best treatment option for painful stiffness after knee arthroplasty.

Background: Arthrotic deformities with changes in knee geometry can produce difficulties in implanting long stem knee prosthesis systems using intramedullary alignment. They can result in incorrect lower limb axis and prosthesis positioning. The aim of the presented study was to measure knee geometry in patients with varus and valgus gonarthrosis in order to define diagnosis related differences., Methods: A total of 75 patients with indication for total knee arthroplasty were divided in two groups using the weight bearing lower limb axis: patients with varus gonarthrosis (n=43) and with valgus gonarthrosis (n=32). Angles and extensions, important for knee prosthesis implantation, were measured, digitalized and analyzed. The results were investigated for diagnosis specific differences., Results: After regulation of the measured extension in mean femur/tibia lengths, significant diagnosis specific differences were found: femur condyles were widened towards pathologic weight bearing (P<0.044), and the mechanical tibia axis of the varus gonarthrosis group is transferred to the lateral side (P<0.046) and in projection over the lateral internal cortical substance., Conclusion: The significant differences in deformed arthrotic knees indicate that for an optimal postoperative result the use of standard implants is not always sufficient. Modular knee prosthesis systems can provide adequately for individual demands.

Background: Despite great advances in hip alloarthroplasty there are still numerous indications for joint-saving procedures such as correction osteotomies. Often these procedures include complex 3D rearrangements of the proximal femur, which are for the surgeon technically very demanding. The project aim was to develop a precise intraoperative virtual 3D planning tool including a detailed biomechanical analysis and enable the surgeon to realize exactly this plan by using computer-assisted techniques., Methods: Using only two different angled fluoro frames a simplified femoral model was inversely constructed. For navigation a passive optical system was used with a C-arm calibration kit and PC-based software. For in vitro evaluation complex osteotomies were performed on ten femora under simulated OR conditions., Results: The mean difference between the planning and real surgical outcome for the wedge size was less then 2 degrees and for the femur head center position less then 4 mm. No implant penetrated the femur neck isthmus., Conclusion: Without changing the standard operative procedure the method can be of high clinical importance to improve planning accuracy and consecutive operative realization for precise fragment positioning and plate location without penetrating the isthmus of the femoral neck. And -- besides precision -- it can potentially help to reduce intraoperative complications such as implant penetration and minimize X-ray use.

Carbon fiber-reinforced plastics have been used clinically as an implant material for different applications for over 20 years.A review of technical basics of the composite materials (carbon fibers and matrix systems), fields of application,advantages (e.g., postoperative visualization without distortion in computed and magnetic resonance tomography), and disadvantages with use as an implant material is given. The question of the biocompatibility of carbon fiber-reinforced plastics is discussed on the basis of experimental and clinical studies. Selected implant systems made of carbon composite materials for treatments in orthopedic surgery such as joint replacement, tumor surgery, and spinal operations are presented and assessed. Present applications for carbon fiber reinforced plastics are seen in the field of spinal surgery, both as cages for interbody fusion and vertebral body replacement.

In addition to autogenous or allogeneic bone grafts, fusion cages composed of metal or plastic are being used increasingly as spacers for interbody fusion of spinal segments. The goal of this study was the mechanical testing of carbon fiber reinforced plastic (CFRP) fusion cages used for anterior lumbar interbody fusion. With a special testing device according to American Society for Testing and Materials (ASTM) standards, the mechanical properties of the implants were determined under four different loading conditions. The implants (UNION cages, Medtronic Sofamor Danek) provide sufficient axial compression, shear, and torsional strength of the implant body. Ultimate axial compression load of the fins is less than the physiological compression loads at the lumbar spine. Therefore by means of an appropriate surgical technique parallel grooves have to be reamed into the endplates of the vertebral bodies according to the fin geometry. Thereby axial compression forces affect the implants body and the fins are protected from damaging loading. Using a supplementary anterior or posterior instrumentation, in vivo failure of the fins as a result of physiological shear and torsional spinal loads is unlikely. Due to specific complications related to autogenous or allogeneic bone grafts, fusion cages made of metal or carbon fiber reinforced plastic are an important alternative implant in interbody fusion.

Due to a rise in life expectancy as well as improved adjuvant and diagnostic measures the incidence of clinically symptomatic metastases has significantly increased. In terms of indication and operative technique in the treatment of these lesions the biologic age, general condition, diagnosis, stage and activity of the disease and the patient's prognosis are highly important. Different techniques of joint replacement have been described to treat patients suffering from metastatic disease of the periacetabular region, being resistant to any kind of adjuvant therapy. From 1977-1996 21 patients with a periacetabular lesion received a tumor prosthesis following internal hemipelvectomy (average age 60 years; average survival 23.1 months). Perioperative complication rate was 42%, functional results were good (n =), fair (n = 9) and poor (n = 2). Mobilisation and analgesia are the most important therapeutic goals. The quality of the patient's life postop is the major point.

X-ray or CT images allows only a limited three-dimensional orientation in presurgical planning. Especially for the planning of internal hemipelvectomies with custom-made endoprosthesis and for peri-acetabular osteotomies a high-grade orientation is necessary. This orientation is improved by a 3D CT-controlled manufactured 1:1 model of the pelvis. This enables and exact classification of defect and deformity, planning of resection planes, design of the suitable custom-made implant and simulation of the operation technique as preoperative quality control.

While the principle of enlarging the surface area has been recognized and used in different ways for some time, there is often no schematic, detailed description or fundamental research. Taking a surface structure consisting of trabecular three-dimensional connecting elements, essential parameters are shown, making it clear that the flexible dynamic reaction of the effective "anchoring space" with a suitable specified shape (construction height, alignment, network) can be reproducibly shaped and used. This has led to a hip endoprosthesis with a graduated surface structure. The construction height of the trabecular structure varies, decreasing from proximal to distal.

Twenty-five patients underwent an internal hemipelvectomy with endoprosthetic reconstruction of the pelvis for primary bone tumor (n = 17) or bone metastasis in the pelvis (n = 8). According to the Enneking tumor classification system, there were 9 stage II B tumors and 16 stage III. Conventional metal or polyacetal prostheses were used in 5 cases, and in 20 anatomically adaptable modular prostheses with intramedullary anchorage were implanted. In the last 11 cases a 3D CT-controlled manufactured model of the pelvis was used. The functional results according to Enneking were good in 5 cases, fair in 11, and poor in 7. The last endoprosthetic system showed better results, because it is easier to implant and the possibility failure is reduced. The learning curve of the surgeon is important, too.