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Knee arthroplasty is a successful standard procedure in orthopedic surgery; however, approximately 20 % of patients are dissatisfied with the clinical results as they suffer pain and can no longer achieve the presurgery level of activity. According to the literature the reasons are inexact fitting of the prosthesis or too few anatomically formed implants resulting in less physiological kinematics of the knee joint. Reducing the number of dissatisfied patients and the corresponding number of revisions is an important goal considering the increasing need for artificial joints. In this context, patient-specific knee implants are an obvious alternative to conventional implants. For the first time implants are now matched to the individual bone and not vice versa to achieve the best possible individual situation and geometry and more structures (e.g. ligaments and bone) are preserved or only those structures are replaced which were actually destroyed by arthrosis. According to the authors view, this represents an optimal and pioneering addition to conventional implants. Patient-specific implants and the instruments needed for correct alignment and fitting can be manufactured by virtual 3D reconstruction and 3D printing based on computed tomography (CT) scans. The portfolio covers medial as well as lateral unicondylar implants, medial as well as lateral bicompartmental implants (femorotibial and patellofemoral compartments) and cruciate ligament-preserving as well as cruciate ligament-substituting total knee replacements; however, it must be explicitly emphasized that the literature is sparse and no long-term data are available.

Hip resurfacing in young patients has been increasingly performed within the last decade. In comparison to standard total hip arthroplasty the failure rate remains high. Age and implant size have a significant effect on the risk of revision for primary total resurfacing and the risk of revision increases with increasing age. At 7 years the cumulative revision rate for patients is 5% and females have more than twice the cumulative revision rate as males. Even in hip resurfacing arthroplasty which has been performed in a perfect manner, a certain percentage of patients suffer from persistent pain for various reasons, such as neck fracture, iliopsoas tendinopathy, metal hypersensitivity, such as aseptic lymphocytic vasculitis associated lesions (ALVAL) and aseptic loosening. Diagnostic work-up of the painful hip resurfacing is challenging even for experienced surgeons. Recommendations for the diagnostic procedure are described.

The number of total hip replacement (THR) surgeries has increased significantly over the last few years and patients undergoing surgery are of decreasing age. In consequence the question of the influencing factors for the survival of artificial hip joints becomes more and more urgent. The expected survival time of an implant is nowadays 15-20 years and it seems that factors for a shorter lifetime are female gender, overweight, younger age and certain indications which led to surgery, such as rheumatoid arthritis or fractures. In the early phase of rehabilitation, measures against dislocation including training of the abductor muscles are most important. Starting rehabilitation programs early after surgery has positive effects on outcome, especially when strengthening programs are included. There are different opinions concerning the question how the lifetime of a THR is influenced by sports activities. However, it seems to have been demonstrated that suitable sports activities have a positive effect and do not necessarily correlate with higher loosening rates after THR. In general, high-impact sports should be avoided. Recommended activities are cycling, swimming, aquajogging, hiking, rowing and dancing.

Prognosis of cemented total hip replacement seems to be excellent for elderly patients. In younger age the outcome is less favourable and early revision is more common. Thus, different concepts with better prognosis and preservation of bone stock for possible revisions were needed. After more than 30 years of application with excellent short-term and long-term results, uncemented total hip arthroplasty is nowadays generally regarded as the standard procedure for younger patients. New bone-preserving implants, such as surface replacement or short-stemmed femoral shaft prostheses, have been introduced especially for younger patients. Some of these new procedures are still under development, and the long-term results of new implant concepts have to be evaluated over the next decades. Regarding recently published scientific studies an overview about non-cemented total hip arthroplasty is given and current concepts and developments are presented.

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.