[Complication profile and revision concepts for megaprosthetic reconstruction following tumour resection at the hip]. / Komplikationsprofil und Revisionsstrategien nach Tumorspezialendoprothetik am Hüftgelenk.

BACKGROUND: Tumourous destruction of the periacetabular region and the proximal femur is a typical consequence of either primary malignant bone tumour manifestation or skeletal metastatic diseases. Pathological fractures of the proximal femur and periacetabular regions due to primary manifestation or metastatic disorders are frequent. OBJECTIVES: Presentation of the most common complications of tumour endoprostheses at the hip and a description of management strategies, including therapeutic recommendations and concepts for complication avoidance. MATERIALS AND METHODS: The current knowledge and our own experience of complication management with the use of megaprostheses around the hip are presented. RESULTS: Compared to elective/primary total hip arthroplasty, megaprosthetic reconstructions following tumour resections have an increased rate of postoperative deep infections, dislocations, incidence of pathological and periprosthetic fractures and of deep vein thrombosis. The postoperative mortality and local tumour recurrence along with deep infections represent the most serious complications. CONCLUSIONS: In comparison to primary arthroplasty, the risk of failure and complications following tumour-endoprosthetic replacement is increased. Precise surgical planning and careful selection and preoperative preparation of suitable patients should be performed in close interdisciplinary cooperation with final decision-making on an interdisciplinary tumour board. Wide resection and advanced reconstruction, as well as complicated palliative stabilization due to malignant bone tumour growth around the hip joint should be performed in musculoskeletal tumour centres with profound expertise in osteosynthetic and endoprosthetic reconstruction and consecutive complication management of the pelvis and the proximal femur.

[Reality of care for musculoskeletal diseases at the population level : Results of the PROCLAIR collaborative project. German version]. / Versorgungswirklichkeit muskuloskeletaler Erkrankungen auf Bevölkerungsebene : Erkenntnisse aus dem Verbundprojekt PROCLAIR.

BACKGROUND: The objective of the research consortium PROCLAIR was to gain population level knowledge on the treatment of patients with rheumatoid arthritis (RA), axial spondylarthritis (axSpA) and osteoarthritis (OA) in Germany. AIMS: A main question of the consortium was whether it is possible to identify groups of people who were exposed to a particular risk of undersupply or oversupply of treatment. In addition, the study investigated the validity of claims data for these diseases as a basis for further studies. PATIENTS AND METHODS: Cross-sectional surveys were carried out among insurees of the BARMER statutory health insurance fund whose claims data included RA, axSpA and OA diagnoses. The questionnaire data were linked with the claims data of the insured persons if they agreed. RESULTS: In all three diseases risk groups for care deficits could be identified. Persons with RA who are not treated by a specialist have less access to drug treatment. Physical therapy is prescribed for all three diagnoses at a low level, even for people undergoing joint replacement surgery. A connection between depressive symptoms and disease activity or function in axSpA was shown. In addition to the results relevant to care, the PROCLAIR network has also made contributions to critically assess the quality of health insurance data. DISCUSSION: The combination of billing data with survey data enables a comprehensive description of the treatment of musculoskeletal diseases. Particularly relevant factors are the specialization of the physician, sociodemographic parameters of the patients and the region of residence. In particular, access to treatment cannot be investigated in randomized clinical trials.

Reality of care for musculoskeletal diseases at the population level : Results of the PROCLAIR collaborative project.

BACKGROUND: The objective of the research consortium PROCLAIR was to gain population level knowledge on the treatment of patients with rheumatoid arthritis (RA), axial spondylarthritis (axSpA) and osteoarthritis (OA) in Germany. AIMS: A main question of the consortium was whether it is possible to identify groups of people who were exposed to a particular risk of undersupply or oversupply of treatment. In addition, the study investigated the validity of claims data for these diseases as a basis for further studies. PATIENTS AND METHODS: Cross-sectional surveys were carried out among insurees of the BARMER statutory health insurance fund whose claims data included RA, axSpA and OA diagnoses. The questionnaire data were linked with the claims data of the insured persons if they agreed. RESULTS: In all three diseases risk groups for care deficits could be identified. Persons with RA who are not treated by a specialist have less access to drug treatment. Physical therapy is prescribed for all three diagnoses at a low level, even for people undergoing joint replacement surgery. A connection between depressive symptoms and disease activity or function in axSpA was shown. In addition to the results relevant to care, the PROCLAIR network has also made contributions to critically assess the quality of health insurance data. DISCUSSION: The combination of billing data with survey data enables a comprehensive description of the treatment of musculoskeletal diseases. Particularly relevant factors are the specialization of the physician, sociodemographic parameters of the patients and the region of residence. In particular, access to treatment cannot be investigated in randomized clinical trials.

[Management of complications following tumor endoprosthetic replacement]. / Komplikationsmanagement nach Tumorendoprothesen.

BACKGROUND: Tumor endoprostheses are available as modular systems with which bone defects can be partially reconstructed, usually close to the joints, or as a total replacement of long tubular bones. As a result of continuously improved survival times, they are used with bone tumors, skeletal metastases and, increasingly, in revision arthroplasty. OBJECTIVES: Presentation of the most common complications of tumor endoprostheses and a description of their management, including treatment recommendations. MATERIALS AND METHODS: The current knowledge and our own experience of complication management with the use of megaprostheses are presented. RESULTS: The number of tumor endoprostheses procedures is limited, so that a limited number of studies and classifications are available. Periprosthetic infections involving the soft tissues represent the most serious failure after perioperative dying and local recurrence of the tumor. Two-stage revision remains the gold standard in periprosthetic infection, even if one-stage revision is justifiable in selective indications. Periprosthetic infection and local recurrence is associated with the risk of secondary amputations. Mechanical failure can be treated more easily. Specific socket systems for proximal femoral replacement and attachment tubing allow for adequate soft tissue reconstruction, restoration of joint function, and minimize the risk of dislocation. CONCLUSIONS: In comparison to primary arthroplasty, the risk of failure following tumor endoprosthetic replacement is increased but is basically controllable by revision surgery.

Factors associated with the orthopaedic surgeon's decision to recommend total joint replacement in hip and knee osteoarthritis: an international cross-sectional study of 1905 patients.

OBJECTIVE: To determine factors associated with orthopaedic surgeons' decision to recommend total joint replacement (TJR) in people with knee and hip osteoarthritis (OA). DESIGN: Cross-sectional study in eleven countries. For consecutive outpatients with definite hip or knee OA consulting an orthopaedic surgeon, the surgeon's indication of TJR was collected, as well as patients' characteristics including comorbidities and social situation, OA symptom duration, pain, stiffness and function (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]), joint-specific quality of life, Osteoarthritis Research Society International (OARSI) joint space narrowing (JSN) radiographic grade (0-4), and surgeons' characteristics. Univariable and multivariable logistic regressions were performed to identify factors associated with the indication of TJR, adjusted by country. RESULTS: In total, 1905 patients were included: mean age was 66.5 (standard deviation [SD], 10.8) years, 1082 (58.0%) were women, mean OA symptom duration was 5.0 (SD 7.0) years. TJR was recommended in 561/1127 (49.8%) knee OA and 542/778 (69.7%) hip OA patients. In multivariable analysis on 516 patients with complete data, the variables associated with TJR indication were radiographic grade (Odds Ratio, OR for one grade increase, for knee and hip OA, respectively: 2.90, 95% confidence interval [1.69-4.97] and 3.30 [2.17-5.03]) and WOMAC total score (OR for 10 points increase: 1.65 [1.32-2.06] and 1.38 [1.15-1.66], respectively). After excluding radiographic grade from the analyses, on 1265 patients, greater WOMAC total score was the main predictor for knee and hip OA; older age was also significant for knee OA. CONCLUSION: Radiographic severity and patient-reported pain and function play a major role in surgeons' recommendation for TJR.

[Periacetabular osteotomy-what influence does age have on patient-relevant results? : A prospective 5­year investigation]. / Periazetabuläre Osteotomie ­ Welchen Einfluss hat das Alter auf patientenrelevante Ergebnisse? : Eine prospektive 5­Jahres-Untersuchung.

INTRODUCTION: Periacetabular osteotomy (PAO) is an effective procedure in treatment of symptomatic hip dysplasia. To achieve a good outcome a strict patient selection has to be applied. The aim of this study was to evaluate the influence of patient age at surgery on clinical outcome. METHODS: In a prospective study 86 patients (106 hips) underwent clinical and radiographic follow-up at a mean time of 5 years (2.5-8.5 years) after PAO. Patient-related outcome measurements (PROMs: EQ-5D, WOMAC, OHS, GTO) were applied preoperatively as well as postoperatively and the deformity correction as well as development of osteoarthritis were evaluated. In order to analyze the influence of patient age at surgery on clinical outcome, we subdivided the patient cohort into four different age groups (<20 years, 20-29 years, 30-39 years, >40 years). RESULTS: Of the patients 90% were very satisfied or satisfied with the results 5 years after surgery, and in all age groups PROMs significantly increased. Even though preoperative as well as postoperative algofunction declined in cohorts with increasing age, the overall benefit as measured in WOMAC and EQ-5D scores was equal in all age groups. Increasing age is associated with a progression in osteoarthritis as well as a higher conversion rate to total arthroplasty. DISCUSSION: Age is an important influencing factor on the long-term outcome after PAO. A certain age as cut off for indications could not be identified in this study. Even patients in the age groups 30-39 years and > 40 years showed PROM improvement and satisfaction with outcome at medium-term follow-up. The expected success rate has to be discussed preoperatively with the patient; however, as a higher conversion rate to hip arthroplasty as well as progressive osteoarthritis is associated with higher age, not only patient age alone but also morphological characteristics of the hip joint have to be taken into consideration.

[The S2k guideline: Indications for knee endoprosthesis : Evidence and consent-based indications for total knee arthroplasty]. / S2k-Leitlinie: Indikation Knieendoprothese : Evidenz- und konsensbasierte Indikationsstellung in der Knie-Endoprothetik (EKIT-Knie).

Total knee arthroplasty (TKA) is one of the most frequent surgical procedures in orthopaedic surgery. Until now there have not been any standardized indication criteria, which might contribute to the large geographical differences in the frequency of TKA. This guideline aims to consent minimal requirements (main criteria), additional important aspects (minor criteria), as well as relative and absolute contraindications for TKA. The following main criteria have been consented: knee pain, radiological confirmation of osteoarthritis or osteonecrosis, inadequate response to conservative treatment, adverse impact of knee disease on the patient's quality of life and the burden of suffering due to the knee disease. Relative contraindications have been consented as severe general disease with reduced life expectancy and a BMI ≥40; absolute contraindications are an active infection and if the patient is not able to undergo major surgery.

A new responder criterion (relative effect per patient (REPP) > 0.2) externally validated in a large total hip replacement multicenter cohort (EUROHIP).

OBJECTIVE: To validate a new method to identify responders (relative effect per patient (REPP) >0.2) using the OMERACT-OARSI criteria as gold standard in a large multicentre sample. METHOD: The REPP ([score before - after treatment]/score before treatment) was calculated for 845 patients of a large multicenter European cohort study for THR. The patients with a REPP >0.2 were defined as responders. The responder rate was compared to the gold standard (OMERACT-OARSI criteria) using receiver operator characteristic (ROC) curve analysis for sensitivity, specificity and percentage of appropriately classified patients. RESULTS: With the criterion REPP>0.2 85.4% of the patients were classified as responders, applying the OARSI-OMERACT criteria 85.7%. The new method had 98.8% sensitivity, 94.2% specificity and 98.1% of the patients were correctly classified compared to the gold standard. CONCLUSION: The external validation showed a high sensitivity and also specificity of a new criterion to identify a responder compared to the gold standard method. It is simple and has no uncertainties due to a single classification criterion.

Characterization of primary chondrocytes harvested from hips with femoroacetabular impingement.

OBJECTIVE: Acetabular chondral lesions are common in patients with femoroacetabular impingement (FAI) syndrome. The aim of this study was (1) to evaluate the proliferation potential of primary human chondrocytes (hC) derived from both acetabular and femoral site and (2) to validate cellular differentiation during three-dimensional (3D) cultivation as a prerequisite for autologous matrix-assisted cartilage regeneration of the hip joint. METHODS: hC were isolated from cartilage samples obtained from N = 6 patients during offset reconstruction. Proteoglycan content was assessed by Safranin-O staining. Proliferation and cell viability were quantified by microscopic cell counting and Trypan Blue exclusion. Messenger ribonucleic acid (mRNA) expression levels of collagen type 1 and 2, aggrecan (ACAN), and interleukin-1ß (IL-1ß) genes were assessed upon monolayer cultivation, after 48 h/4-10°C - transport simulation and after 14 days of 3D hydrogel cultivation. RESULTS: Primary hC from acetabular and femoral damaged sites were viable. No significant intergroup differences were observed concerning cell viability (>95%) after monolayer cultivation and transport simulation. Harvest yields from acetabular and femoral cartilage samples were comparable to that known from knee joints (mean ± standard deviation (SD), 13.4 × 10(6) ± 5 × 10(6) cells per culture vs 20 × 10(6) cells). Redifferentiation was induced during 3D hydrogel cultivation as observed by increased levels of collagen II (1000-fold) and ACAN (10-fold) gene vs monolayer cultivation (P < 0.001). CONCLUSION: hC derived from damaged acetabular and femoral site are qualified for autologous matrix-assisted cartilage transplantation paving the way for cell-based cartilage regeneration in FAI patients.

[Total hip arthroplasty in overweight osteoarthritis patients]. / Die endoprothetische Versorgung beim übergewichtigen Koxarthrosepatienten.

BACKGROUND: An increasing number of patients scheduled for total hip arthroplasty (THA) are obese and exhibit a different risk profile from that of patients of normal weight. OBJECTIVES: To provide an overview of the impact of obesity on the outcome of primary THA. MATERIALS AND METHODS: Literature review and discussion of own epidemiological data. RESULTS: Obese patients can expect as much functional improvement as non-obese patients after THA. However, peri- and postoperative complication (e.g., periprosthetic infection and dislocation) rates are reported to be increased in obese THA patients. CONCLUSIONS: The knowledge of obesity-associated risks is the prerequiste for successful THA in obese patients.

[Hip endoprosthetics in osteoarthritis after acetabular fractures]. / Hüftendoprothetik bei Arthrose nach Azetabulumfrakturen.

BACKGROUND: The incidence of post-traumatic osteoarthritis after acetabular fractures is between 26 and 57%. With total hip arthroplasty (THA), affected patients can achieve a clear functional improvement and pain reduction if specific conditions are heeded. OBJECTIVE: Depending on the degree and localisation of bone defects and deformities, scarring and the presence of remaining osteosynthesis material, different treatment strategies are available. This review gives an overview of current treatment strategies. MATERIALS AND METHODS: Review of relevant clinical studies, meta-analyses and presentation of our own approach. RESULTS: The best results regarding to implant survival and clinical outcome, comparable with THA in primary osteoarthritis, can be achieved, when cementless acetabular reconstruction with anatomical restoration of the hip's rotational center and sufficient mechanical support is obtained. Pre-operative planing based on a thorough radiographic examination is essential. CONCLUSION: Althoug the postoperative complication rate is elevated after THA for posttraumatic arthritis after acetabular fractures compared with primary osteoarthritis, the overall functional results and implant survival are comparable.

[Ipsilateral THA after stemmed TKA: Risk of interprosthetic fracture?]. / Ipsilaterale Hüftendoprothese nach stielgeführter Knieendoprothese: Risiko einer interprothetischen Fraktur?

BACKGROUND: There is an increasing number of patients who have undergone stemmed total knee arthroplasty and total hip arthroplasty in the same leg. These patients may be at increased risk of periprosthetic and interprostethic fracture. Etiology and the potential therapy strategies are not well represented in the current literature. OBJECTIVES: Determination of the risk factors for interprosthetic fractures and possible prevention. MATERIALS AND METHODS: We performed a review of the literature and additionally a survey among experts (members of the German Association for Arthroplasty [AE]) to investigate the risk and the necessity for a preventive internal fixation. RESULTS: There are only a few biomechanical studies. The interprosthetic distance seems to have little influence on the fracture risk, but the thickness of the cortex and the cortical area at the diaphysis seems to be important. The value of a bridging osteosynthesis remains uncertain. Ninety experts took part in the survey. The risk of fracture risk was estimated to be only slight to medium. Opinions regarding the necessity of preventive internal fixation were heterogeneous. CONCLUSIONS: The indication for preventive internal fixation could be derived neither from the literature nor from the survey of experts. The thickness of the cortex and co-morbidities (osteoporosis, tendency to fall, and medication) seem to be more important than the interprosthetic distance.

[Arthroplasty for osteoarthritis secondary to hip dysplasia: Problem-oriented treatment strategies]. / Endoprothese bei Dysplasiecoxarthrose: Problemorientierte Versorgungsstrategien.

BACKGROUND: Because of anatomical variations total hip arthroplasty (THA) can be demanding in patients with osteoarthritis secondary to hip dysplasia. OBJECTIVES: Depending on the degree of bony deformation, hip dislocation and soft tissue alteration numerous treatment strategies are available. This review describes current approaches that address frequent deformities. MATERIALS AND METHODS: Review of relevant clinical studies, meta-analyses, and presentation of our own approach. RESULTS: Pre-operative planning (based on a thorough clinical and radiographic examination) is essential. Acetabular reconstruction close to the primary acetabulum should always be intended. Roof augmentation and/or cup medialization can support stable bony implant fixation. Subtrochanteric shortening osteotomy of the femur is a demanding but reliable technique that avoids nerve damage in cases where inappropriate lengthening would be necessary (i.e., high riding dislocation). CONCLUSIONS: Although the post-operative complication rate is elevated after THA for dysplastic hips compared with primary osteoarthritis, the overall functional results and implant survival are comparable.

[Objectifying results in total knee arthroplasty: Is "patient satisfaction" adequate]. / Ergebnisobjektivierung bei Knietotalendoprothesen : Reicht die "Patientenzufriedenheit"?

BACKGROUND: Arthroplasty is an effective treatment for end-stage osteoarthritis of the knee and is one of Germany's most frequently performed orthopedic procedures. DISCUSSION: However, a considerable number of patient are not satisfied with the results after knee arthroplasty. The patient's perspective is particularly important for shared decision making. "Patient satisfaction" with the surgery is an expression of the patient's perspective, but might not be sufficient as the only outcome measure. There is no international consensus which outcome measures should be used after knee arthroplasty. CONCLUSION: Therefore, different measurement tools are used for the acquisition of a variety of outcome measures in order to quantify the results of knee arthroplasty. These tools should be used according to their reliability, validity, and responsiveness. This article provides an overview about available measurement tools.

[Personality and comorbidity: are there "difficult patients" in hip arthroplasty?]. / Persönlichkeitsprofil und Komorbidität: Gibt es den "schwierigen Patienten" in der primären Hüftendoprothetik?

BACKGROUND: Concomitant disorders at the time of surgery in addition to psychological and socioeconomic patient characteristics may influence treatment outcomes in hip arthroplasty. OBJECTIVES: To describe the impact of these factors on perioperative complications and postoperative results in terms of function, quality of life, and patient satisfaction. MATERIALS AND METHODS: Review of relevant clinical studies, meta-analyses, and presentation of our own results. RESULTS: Comorbidities in general, especially in combination, increase the perioperative risk profile. Socioeconomic factors (education, professional qualifications, social deprivation) in addition to psychological variables (depression, distressed personality) can have a major impact on postoperative functional outcomes and patient satisfaction. CONCLUSIONS: It is of crucial importance to avoid inequalities in the provision of joint replacement for patients with hip osteoarthritis and co-existing risk factors. Preventive strategies should be implemented to reduce the negative impact of comorbidities on treatment outcome. Personalized communication and education may be helpful in avoiding unrealistic patient expectations before hip replacement.

Prevalence of low back pain in adolescent athletes - an epidemiological investigation.

Low back pain (LBP) is a common symptom in the populations of western countries, and adolescent athletes seem to be prone to LBP. The main objective of this study was to analyze the point (LBP within the last 48 h), 1-year (LBP within the last 12 months) and lifetime (LBP within the entire life) prevalence rates of LBP in adolescent athletes participating in various sports. We also assessed the characteristics of LBP and its association with potential risk factors. To this end, 272 competitive adolescent athletes involved in 31 different sports (158 males, 113 females, 15.4 ± 2.0 years, body mass index [BMI] 20.3 ± 2.4 kg/m(2)) were enrolled in a 10-month prospective clinical trial that included a questionnaire and physical examination. We found a point prevalence of 14%, a 1-year prevalence of 57%, and a lifetime prevalence of 66% for LBP. The mean age of first appearance of LBP was 13.1 ± 2.0 years. The lifetime prevalence was significantly higher in volleyball than in biathletes (74.3 vs. 45.7%, p = 0.015). Our findings confirm that LBP is a common symptom in adolescent athletes; LBP prevalence correlates with sports participation and individual competitive level. Adolescent athletes with LBP should receive a thorough diagnostic work-up and adapt training and technique correspondingly when indicated.

[Endoprosthetic treatment of osteoporosis-related coxarthrosis : aspects of safe patient treatment]. / Endoprothetische Versorgung bei osteoporoseassoziierter Koxarthrose : Aspekte zur sicheren Patientenversorgung.

BACKGROUND: With increasing life expectancy the prevalence of osteoarthritis is also substantially rising. Patients aged between 65 and 75 years scheduled for total joint arthroplasty suffer from undetected osteoporosis in 20-25% of cases. OBJECTIVES: How to determine osteoporosis during preoperative workup? Which conclusions can be drawn for the operation treatment and the postoperative course? METHODS: The literature dealing with the prevalence of osteoporosis, perioperative complications of total hip arthroplasty, selected register informations, guidelines for diagnostics and treatment of osteoporosis and for the postoperative treatment are summarized and discussed. RESULTS: The fracture risk is determined according to the guidelines of the Dachverband Osteologie (DVO, Governing Body on Osteology). The implant and the anchorage are selected based on the risk of suffering from osteoporosis. An intraoperative fracture and early aseptic loosening are the main operative risk factors. For the postoperative course in addition to education about arthroplasty, adequate support for prevention of falls is mandatory. Continuous physiotherapy with muscular strengthening is advisable. The long-term medication should be checked for risks in the PRISCUS list of potentially inappropriate medication in the elderly and non-steroidal anti-inflammatory drugs (NSAIDs) should not be prescribed in patients with cardiac comorbidities. Patients with confirmed osteoporosis should be treated with antiresorptive agents.

[Complications of metal-on-metal tribological pairing]. / Komplikationen bei Metall-Metall-Gleitpaarungen.

BACKGROUND: Metal-on-metal (MoM) tribological pairing results in less volumetric abrasion than pairing with the conventionally used polyethylene and is associated with a lower risk of material failure compared to other hard-hard pairings. An increased frequency of problem cases in recent years has led to a great increase in uncertainty. Against this background in this article the current aspects of epidemiology, etiology, diagnostics and treatment of complications in MoM hip joint endoprostheses will be discussed. EPIDEMIOLOGY AND ETIOLOGY: Based on the results from national endoprosthesis registers and selected clinical studies an evaluation of the rate of local complications from MoM tribological pairings was undertaken. A differentiation was made between MoM pairings in pedicled small head prostheses (≤ 32 mm), large head (> 32 mm) and surface replacement (OFE) endoprostheses. Each year MoM endoprostheses release on average 10(12)-10(14) cobalt (Co) and chromium (Cr) nanoparticles per patient. This release of metal ions and particles can lead to a variety of tissue reactions. DIAGNOSTICS: A differentiation must be made between regular routine diagnostics within the framework of implant follow-up screening and specific investigations due to the occurrence of complaints. The diagnostics for patients treated with MoM hip endoprostheses consists of a standardized step-wise approach considering possible differential diagnoses and the utilization of modern laboratory chemical and radiological methods. When problems occur, a differentiation should preferentially be made between complaints not caused by metal and mechanical problems (e.g. prosthesis loosening and impingement) and symptoms due to periprosthetic infections. THERAPY OF COMPLICATIONS: The normal standards for hip endoprosthetics are also valid for periprosthetic infections, fractures and other general complications. Specific measures are, however, necessary for complications due to metal-specific risks.

Trends and geographical variation of primary hip and knee joint replacement in Germany.

OBJECTIVE: Considerable variation in total hip replacement and total knee replacement (THR/TKR) between regions has been described. The aim of this study was to explore geographical variation in THR and TKR in Germany and to analyse potentially explanatory variables. METHOD: We used data of Germany's largest statutory health insurer. Between 2005 and 2009 451,108 THR and 335,022 TKR were performed. Age-standardised joint replacement rates were calculated for 16 federal states and 407 counties. We performed cluster (Moran's I) and spatial error regression analyses including regional deprivation, osteoarthritis rate, urbanity and number of orthopaedic specialists as dependent variables on county level. RESULTS: In 2009 the overall age-standardised and crude rates were 148.9 (95% CI (confidence interval) 147.6-151.1) and 290.2 for THR, and 132.5 (95% CI 131.3-133.6) and 232.7 for TKR. Between counties THR rates differed by factor 2 (106.1-215.8) and showed significant clusters with high utilisation in South and Northwest Germany. TKR rates differed by factor 3.2 (69.1-219.5) and were also high in South Germany whereas almost all areas in East Germany showed low replacement rates. Differences were pronounced when restricting the analysis to cases with an indication of osteoarthritis. All tested predictors could be identified as significant explanatory variables (each P < 0.001). CONCLUSION: This study proofed considerable and consistent geographic variation of THR and TKR in Germany. Thereby relevant explanatory factors were identified. These results may foster the discussion and future research in health services which should include areas of patients' and doctors' expectation, financial aspects and an outcome-based definition of appropriate supply.