A Conserved Histidine in the RNA Sensor RIG-I Controls Immune Tolerance to N1-2'O-Methylated Self RNA.

The cytosolic helicase retinoic acid-inducible gene-I (RIG-I) initiates immune responses to most RNA viruses by detecting viral 5'-triphosphorylated RNA (pppRNA). Although endogenous mRNA is also 5'-triphosphorylated, backbone modifications and the 5'-ppp-linked methylguanosine ((m7)G) cap prevent immunorecognition. Here we show that the methylation status of endogenous capped mRNA at the 5'-terminal nucleotide (N1) was crucial to prevent RIG-I activation. Moreover, we identified a single conserved amino acid (H830) in the RIG-I RNA binding pocket as the mediator of steric exclusion of N1-2'O-methylated RNA. H830A alteration (RIG-I(H830A)) restored binding of N1-2'O-methylated pppRNA. Consequently, endogenous mRNA activated the RIG-I(H830A) mutant but not wild-type RIG-I. Similarly, knockdown of the endogenous N1-2'O-methyltransferase led to considerable RIG-I stimulation in the absence of exogenous stimuli. Studies involving yellow-fever-virus-encoded 2'O-methyltransferase and RIG-I(H830A) revealed that viruses exploit this mechanism to escape RIG-I. Our data reveal a new role for cap N1-2'O-methylation in RIG-I tolerance of self-RNA.

Preoperative dental screening can reduce periprosthetic infections of hip and knee endoprostheses in the first month after surgery: results of a cohort study.

PURPOSE: The oral cavity and, in particular, potential oral foci might pose a risk of periprosthetic joint infection (PJI). The aim of this cohort study was to determine whether practical preoperative dental screening would reduce the prevalence of early PJI in the first month after surgery. METHODS: Patients attending a specialized endoprosthesis implantation clinic between 2018 and 2022 were recruited. Two groups were examined. The test group consisted of patients attending the clinic between 2020 and 2022 and who were referred to their family dentist using a standardized form. The comparison group consisted of patients who were treated in the clinic between 2018 and 2020. They were not referred to their family dentist. The two groups were compared for the prevalence of PJI. Univariate analysis followed by multiple logistic regression was performed to confirm risk factors for PJI in this cohort. RESULTS: 2560 individuals (test group: 1227, comparison group: 1333) were included. The prevalence of PJI was significantly lower in the test group (0.8% vs. 1.8%, p = 0.04). Multiple logistic regression with PJI as the dependent variable showed that a dental referral was a strong predictor of a lower prevalence of PJI (OR: 0.43, CI95 0.205-0.917, p = 0.03). Male gender was also strongly associated with a higher frequency of PJI (OR: 2.68, CI95 1.32-5.42, p = 0.01). Age (OR: 1.06, CI95 1.01-1.10, p = 0.01) and BMI (OR: 1.11, CI95 1.05-1.17, p < 0.01) had little effect on the risk of PJI. CONCLUSION: Dental referral using a standardized form can reduce the prevalence of early PJI. Accordingly, orthopedists and dentists should collaborate in this practical way.

CHIP and hips: clonal hematopoiesis is common in patients undergoing hip arthroplasty and is associated with autoimmune disease.

Clonal hematopoiesis (CH) is an age-related condition predisposing to blood cancer and cardiovascular disease (CVD). Murine models demonstrate CH-mediated altered immune function and proinflammation. Low-grade inflammation has been implicated in the pathogenesis of osteoarthritis (OA), the main indication for total hip arthroplasty (THA). THA-derived hip bones serve as a major source of healthy hematopoietic cells in experimental hematology. We prospectively investigated frequency and clinical associations of CH in 200 patients without known hematologic disease who were undergoing THA. Prevalence of CH was 50%, including 77 patients with CH of indeterminate potential (CHIP, defined as somatic variant allele frequencies [VAFs] ≥2%), and 23 patients harboring CH with lower mutation burden (VAF, 1% to 2%). Most commonly mutated genes were DNMT3A (29.5%), TET2 (15.0%), and ASXL1 (3.5%). CHIP is significantly associated with lower hemoglobin, higher mean corpuscular volume, previous or present malignant disease, and CVD. Strikingly, we observed a previously unreported association of CHIP with autoimmune diseases (AIDs; multivariable adjusted odds ratio, 6.6; 95% confidence interval, 1.7-30; P = .0081). These findings underscore the association between CH and inflammatory diseases. Our results have considerable relevance for managing patients with OA and AIDs or mild anemia and question the use of hip bone-derived cells as healthy experimental controls.

Active Akt signaling triggers CLL toward Richter transformation via overactivation of Notch1.

Richter's transformation (RT) is an aggressive lymphoma that occurs upon progression from chronic lymphocytic leukemia (CLL). Transformation has been associated with genetic aberrations in the CLL phase involving TP53, CDKN2A, MYC, and NOTCH1; however, a significant proportion of RT cases lack CLL phase-associated events. Here, we report that high levels of AKT phosphorylation occur both in high-risk CLL patients harboring TP53 and NOTCH1 mutations as well as in patients with RT. Genetic overactivation of Akt in the murine Eµ-TCL1 CLL mouse model resulted in CLL transformation to RT with significantly reduced survival and an aggressive lymphoma phenotype. In the absence of recurrent mutations, we identified a profile of genomic aberrations intermediate between CLL and diffuse large B-cell lymphoma. Multiomics assessment by phosphoproteomic/proteomic and single-cell transcriptomic profiles of this Akt-induced murine RT revealed an S100 protein-defined subcluster of highly aggressive lymphoma cells that developed from CLL cells, through activation of Notch via Notch ligand expressed by T cells. Constitutively active Notch1 similarly induced RT of murine CLL. We identify Akt activation as an initiator of CLL transformation toward aggressive lymphoma by inducing Notch signaling between RT cells and microenvironmental T cells.

Cell-free DNA extraction from urine of lung cancer patients and healthy individuals: Evaluation of a simple method using sample volume up-scaling.

BACKGROUND: Urine holds promise as a source for cell-free DNA (cfDNA) analysis of cancer genetics due to its nature as a self-collectable biospecimen available in large quantities. However, pre-analytical variables such as preservation of cfDNA or efficiency of up-scaling specimen volume need to be better explored to increase analysis sensitivity. PATIENTS AND METHODS: Initially effects of pH levels on cfDNA stability of urine preserved with EDTA were investigated in three healthy probands. Furthermore, the efficiency of urine volume up-scaling was examined using a simple DNA extraction method and cfDNA in urine of 32 individuals. Quantification was performed by PCR detection of three relevant targets used for EGFR and KRAS gene mutational analysis. RESULTS: Only samples preserved with EDTA at alkaline pH levels showed cfDNA stability of up to 10 days at room temperature. Moreover, it was found that increasing the volume up to 100 mL was highly efficient. A similar amount of copies was detected in three different gene sites in all specimens indicating both a good availability and a non-random distribution pattern across genes. Since the median cfDNA copy number was 1642 copies/mL, abundance of cfDNA in this type of liquid biopsy is low. CONCLUSION: Predictable sensitivities with different urine volumes on the ground of detectable cfDNA in our study population revealed that up-scaling (>5 mL) is mandatory if the mutation allele frequency is less than 1%.

BMP-2 (and partially GDF-5) coating significantly accelerates and augments bone formation close to hydroxyapatite/tricalcium-phosphate/brushite implant cylinders for tibial bone defects in senile, osteopenic sheep.

Bilateral defects (diameter 8 mm) in the medial tibial head of senile, osteopenic female sheep (n = 48; 9.63 ± 0.10 years; mean ± SEM) were treated with hydroxyapatite (HA)/beta-tricalcium phosphate (ß-TCP)/dicalcium phosphate dihydrate (DCPD; brushite) cylinders coated with BMP-2 (25 or 250 micrograms) or growth differentiation factor (GDF)-5 (125 or 1250 micrograms; left side); cylinders without BMP served as controls (right side). Three, 6, and 9 months post-operation (n = 6 each group), bone structure and formation were analyzed in vivo by X-ray and ex vivo by osteodensitometry, histomorphometry, and micro-computed tomography (micro-CT) at 3 and 9 months. Semi-quantitative X-ray evaluation showed significantly increasing bone densities around all implant cylinders over time. High-dose BMP-2-coated cylinders (3 and 9 months) and low-dose GDF-5-coated cylinders (3 and 6 months) demonstrated significantly higher densities than controls (dose-dependent for BMP-2 at 3 months). This was confirmed by osteodensitometry at 9 months for high-dose BMP-2-coated cylinders (and selected GDF-5 groups), and was again dose-dependent for BMP-2. Osteoinduction by BMP-2 was most pronounced in the adjacent bone marrow (dynamic histomorphometry/micro-CT). BMP-2 (and partially GDF-5) significantly increased the bone formation in the vicinity of HA/TCP/DCPD cylinders used to fill tibial bone defects in senile osteopenic sheep and may be suitable for surgical therapy of critical size, non-load-bearing bone defects in cases of failed tibial head fracture or defect healing.

Lack of oral health awareness and interdisciplinary dental care: a survey in patients prior to endoprosthesis and orthopaedic centres in Germany.

OBJECTIVES: This cross-sectional survey aimed to evaluate the oral health behaviour of patients prior to endoprosthesis (EP), as well as the handling of oral health topics by German orthopaedic surgeons. MATERIALS AND METHODS: Consecutive patients prior to EP answered a questionnaire regarding oral health behaviour, oral hygiene, oral complaints and information on the relationship between EP and oral health. Another questionnaire was digitally mailed to orthopaedic centres throughout Germany. This questionnaire included the importance of oral health for EP and issues on dental referrals/consultations prior to EP. RESULTS: A total of 172 patients were included in the study, of whom 35.5% of patients reported that they were informed about oral health and EP. Half of the individuals reported regular professional tooth cleaning, and less than one-third (29.1%) reported of the performance of interdental cleaning. Information on oral health and EP was associated with regular professional tooth cleaning (yes: 59.8% vs. no: 35.6%, p = 0.01). A total of 221 orthopaedic clinics were included in the study, of which only a few had dental contact (14%), although the majority (92.8%) of the clinics were familiar with causal relationships between oral health and EP infections. Less than half of the centres reported of either verbal (48%) or written (43.9%) referrals for their patients to the dentist. University Medical Centres reported of more frequent dental contacts (p < 0.01). CONCLUSION: Prior to EP, patients exhibited deficits in oral health behaviour, and orthopaedic clinics exhibited a lack of dental collaboration. Improvements in interdisciplinary care, especially regarding practical concepts for patient referral and education on oral health, appear to be necessary.

The use of acetabular screws in total hip arthroplasty and its influence on wear and periacetabular osteolysis in the long-term follow-up.

PURPOSE: The cementless implantation of hip replacement cups may be performed with and without the additional use of acetabular screws. If the surgeon uses screws or not depends on variable factors. In general, the use of screws is intended to increase the primary stability of the cup. Whether screws increase the initial stability of the cup construct, or even reduce it in part, is the subject of considerable debate in the literature. It is also unclear whether the additional screws lead to increased wear or increased periacetabular osteolysis over the long-term course. METHODS: Two hundred eleven patients from a previous study with a minimum follow-up of 10.7 years were included. Of these, 68 patients with 82 total hip arthroplasties (THA) were given clinical and radiological follow-up examinations. Of these, 52 had been fitted without screws and 30 with screws. On the basis of radiographs, annual wear and osteolysis were quantified. The clinical results were recorded by means of VAS, HHS, and WOMAC scores. RESULTS: Significantly more periacetabular osteolysis was found if additive acetabular screws had been used. No difference was found in relation to the volumetric wear per year. Likewise, no difference was found with regard to the clinical scores. CONCLUSIONS: The use of additive acetabular screws leads to increased osteolysis in the periacetabular bone stock. Insofar as the primary stability of the cementless cup construct allows it, no additional acetabular screws should be used.

Simultaneous 18F-FDG-PET/MRI for the detection of periprosthetic joint infections after knee or hip arthroplasty: a prospective feasibility study.

PURPOSE: This study investigated the diagnostic value of simultaneous 18F-fluordeoxyglucose positron emission tomography/magnetic resonance imaging (PET/MRI) in suspected periprosthetic joint infection (PJI) of the hip and knee. METHODS: Sixteen prostheses from 13 patients with suspected PJI were prospectively examined using PET/MRI. Image datasets were evaluated in consensus by a radiologist and a nuclear physician for the overall diagnosis of 'PJI' (yes/no) and its anatomical involvement, such as the periprosthetic bone margin, bone marrow, and soft tissue. The imaging results were compared with the reference standard obtained from surgical or biopsy specimens and subjected to statistical analysis. RESULTS: Using the reference standard, ten out of the 13 prostheses (ten hips, threes knees) were diagnosed with PJI. Using PET/MRI, every patient with PJI was correctly diagnosed (sensitivity, 100%; specificity, 100%). Considering the anatomical regions, the sensitivity and specificity were 57% and 50% in the periprosthetic bone margin, 75% and 33% in the bone marrow, and 100% and 100% in the soft tissue. CONCLUSION: PET/MRI can be reliably used for the diagnosis of PJI. However, assessment of the periprosthetic bone remains difficult due to the presence of artefacts. Thus, currently, this modality is unlikely to be recommended in clinical practice.

Atraumatic femoral head necrosis: a biomechanical, histological and radiological examination compared to primary hip osteoarthritis.

INTRODUCTION: Atraumatic necrosis of the femoral head (AFHN) is a common disease with an incidence of 5000-7000 middle-aged adults in Germany. There is no uniform consensus in the literature regarding the configuration of the bone in AFHN. The clinical picture of our patients varies from very hard bone, especially in idiopathic findings, and rather soft bone in cortisone-induced necrosis. A better understanding of the underlying process could be decisive for establishing a morphology-dependent approach. The aim of this study is the closer examination of the condition of the bone in the AFHN compared to the primary hip osteo arthritis (PHOA). MATERIALS AND METHODS: The preparations were obtained as part of elective endoprosthetic treatment of the hip joint. Immediately after sample collection, thin-slice CT of the preserved femoral heads was performed to determine the exact density of the bone in the necrosis zone. Reconstruction was done in 0.8-1 mm layers in two directions, coronary and axial, starting from the femoral neck axis. Density of the femoral heads was determined by grey value analysis. The value in Hounsfield units per sample head was averaged from three individual measurements to minimize fluctuations. For biomechanical and histomorphological evaluation, the samples were extracted in the load bearing zone perpendicular to the surface of the femoral head. Group-dependent statistical evaluation was performed using single factor variance analysis (ANOVA). RESULTS: A total of 41 patients with a mean age of 64.44 years were included. The mean bone density of the AFHN samples, at 1.432 g/cm3, was about 7% higher than in the PHOA group with a mean value of 1.350 g/cm3 (p = 0.040). The biomechanical testing in the AFHN group showed a 22% higher-but not significant-mean compressive strength (20.397 MPa) than in the PHOA group (16.733 MPa). On the basis of histological analysis, no differentiation between AFHN and PHOA samples was possible. CONCLUSIONS: The present study (NCT, evidence level II) shows that AFHN has a very well detectable higher bone density compared to PHOA. However, neither biomechanical stress tests nor histomorphological evaluation did show any significant difference between the groups. The results allow the conclusion that there is no "soft" necrosis at all in the AFHN group.

Association between oral health and oral health-related quality of life in patients before hip and knee endoprosthesis surgery: a cross-sectional study.

OBJECTIVES: Aim of this cross-sectional study was the assessment of oral health-related quality of life (OHRQoL) health-related quality of life (HRQoL), oral health behaviour and oral health status in patients before hip and knee endoprosthesis (EP) surgery. Moreover, associations between OHRQoL, HRQoL and oral health should be examined. METHODS: Consecutive patients before hip and/or knee EP implantation were recruited and referred to the dental clinic for oral examination including: number of remaining teeth, dental findings (DMF-T-Index), periodontal condition (periodontal treatment need, Staging/Grading) and temporomandibular joint screening. OHRQoL was assessed by the German short form of oral health impact profile (OHIP G14), HRQoL by short-form 36 survey. RESULTS: Hundred and sixty two patients with a mean age of 66.80 ± 11.10 years were included, which had on average 18.22 ± 8.57 remaining teeth and a periodontal treatment need of 84.5%. The OHIP G14 sum score revealed a median of 1 (mean: 2.7 ± 4.4, 25-75th percentile: 0-4) and its dimension oral function of 0 (mean: 0.8 ± 1.8, 25-75th percentile: 0-1), what was also found for psychosocial impact (median: 0, mean: 1.4 ± 2.6, 25-75th percentile: 0-2). The OHIP G14 sum score and both dimensions were significantly associated with mental component summary (p < 0.01). A higher number of remaining teeth as well as remaining molars/premolars were associated with lower OHIP G14 sum score (p = 0.02). This was also found for the dimension oral function (p < 0.01). CONCLUSION: Patients prior to hip and knee EP had an unaffected OHRQoL, although they had an insufficient oral health. Individuals before EP implantation need increased attention in dental care, fostering information, sensibilization and motivation of the patients.

[Cavernous Nontuberculous Mycobacterial Lung Infection in an HIV-positive Patient]. / Kavernöse nichttuberkulöse Mykobakteriose der Lunge durch M. heckeshornense bei einem HIV-infizierten Patienten.

Since we first described Mycobacterium heckeshornense, a rare species of mycobacteria in 2000, only 21 cases of infection with this mycobacterium have been described in humans. We relate the diagnosis and therapy of another case of this uncommon nontuberculous mycobacterium in an immune-suppressed patient.

Metaphyseal sleeves in arthroplasty of the knee : A suitable tool in management of major metaphyseal bone loss.

BACKGROUND: This study examined the clinical outcome following revision arthroplasty of the knee joint and severe arthrosis with metaphyseal bone defects and instability using metaphyseal sleeves. We analyzed the results based on established scores and recorded the complications occurring on revision arthroplasty. MATERIAL AND METHODS: Patients with revision arthroplasty of the knee and metaphyseal bone defects grade III according to the Anderson Orthopedic Research Institute (AORI) classification were included (16 patients, 9 females and 7 males). In all cases, surgery was performed using an endoprosthesis COMPLETE™ revision knee system with metaphyseal sleeves. RESULTS: All patients had a significant reduction in pain level after revision surgery. The median HSS score in the cohort with primary arthroplasty was 84 and in the cohort with revision arthroplasty 73 and the KSS was 83 and 55, respectively. According to the HSS an excellent result was achieved by 50% of the patients in the primary arthroplasty group and 25% in the revision group. Only three patients were considered to have an insufficient result. Postoperative pain was significantly reduced in both groups. The median ROM was 112° flexion in the primary arthroplasty group and 95° in the revision group. An extension deficit was observed in three patients and four patients showed prolonged wound healing postoperatively (25%), which was treated conservatively and did not lead to septic changes. CONCLUSION: The use of metaphyseal sleeves in patients with bone defects is a suitable instrument with no negative impact on the outcome both in primary and revision arthroplasty. Further studies with larger study groups and analysis of long-term results after use of such endoprosthetic components should be conducted.

Podcasts as a teaching tool in orthopaedic surgery : Is it beneficial or more an exemption card from attending lectures?

OBJECTIVE: The aim of this study was to evaluate the influence of the introduction of online podcasts as part of the main lecture series in orthopaedics on the number of lecture attendees, the examination results and the assessment of teaching by the students. Additionally, we evaluated the use of other media for examination preparation. METHODOLOGY: At the beginning and end of the lecture series questionnaires were handed out to the students to evaluate their attitudes towards attending lectures, the use of video podcasts and examination preparation. In addition, the number of lecture attendees and podcast usage during the semester were counted and the statements of the students in the evaluation assessments of orthopaedic teaching were evaluated. The examination results were correlated in a statistical analysis with the learning materials provided by the students for examination preparation. RESULTS: At the end of the lecture series, 284 students stated that they used the lecture podcast about twice as often as attending lectures; however, for the majority of the students the provision of a video podcast was no reason not to attend the lecture. For example, 37.2% stated that they never and 26.8% stated that they rarely had not attended the lecture by providing the podcasts. Of the students 91-95% considered the availability of lecture podcasts to be a rather meaningful or very meaningful supplement to the lecture visit. Students increasingly used digital media to prepare for examinations instead of using traditional analogue methods. None of the learning methods or materials examined showed a statistically significant advantage in examination results. CONCLUSION: Students in the age of digitalization use a variety of learning materials and are no longer bound to classical analog teaching methods. The use of online podcasts had no negative impact on examination performance. Most students perceived lecture podcasts as a useful supplement to lecture attendance. The students praised the expansion of the teaching curriculum to include additional digital offers with positive comments in the evaluations, but without achieving an improvement in these student evaluations.

Knee arthrodesis as last resort for persistent knee joint infections : Comparison of extramedullary and intramedullary treatment.

BACKGROUND: Knee joint arthrodesis is an established treatment for periprosthetic infections (PPI) providing stability and pain relief. In this study the outcome after arthrodesis of the knee joint for persistent infections was compared and evaluated depending on the surgical procedure (intramedullary vs. extramedullary). MATERIAL AND METHODS: In a retrospective case analysis, all patients who underwent knee joint arthrodesis between 1 January 2010 and 31 December 2016 were identified and divided into two groups: IMA and EMA. All patients were examined clinically and radiologically and the patient files were evaluated. In addition, the FIM score, the LEFS, the WHOQOL-BREF and NRS were evaluated. RESULTS: The median LEFS score for the IMA group was 26 points and in the EMA group 2 points (p = 0.03). The IMA patients showed a median pain scale at rest of 0 and during exercise of 2. The EMA group recorded a pain scale of 3 at rest and 5 during exercise (p = 0.28 at rest; p = 0.43 during exercise). In the IMA group the median postsurgical leg length difference was -2.0 cm and -2.5 cm in the EMA group (p = 0.31). At the end of the follow-up examinations, the FIM score of patients in the IMA group was 74.5 points and 22 points in the EMA group (p = 0.07). CONCLUSION: The study showed that no arthrodesis procedure is obviously superior with respect to the postoperative outcome. The IMA combines advantages especially in the early phase after surgery in terms of function as well as patient comfort and is therefore currently the procedure of choice. The attending physician should be familiar with the advantages and disadvantages of the various procedures in order to be able to make an individual decision and thus maximize the chance of treatment success.

Significance of nutritional status in the development of periprosthetic infections : A retrospective analysis of 194 patients.

BACKGROUND: Malnutrition caused by protein and vitamin deficiencies is a significant negative prognostic factor in surgical wound healing disorders and infections. Particularly in elective surgery, preoperative compensation of deficiencies is advisable to avoid negative postoperative consequences. This study examined the nutritional and protein balance of patients with periprosthetic hip and knee joint infections. MATERIAL AND METHODS: Patients with periprosthetic hip or knee joint infections constituted the study group (SG). Control group I (CG I) included patients with primary implants and CG II included patients who required revision surgery because of aseptic loosening. Relevant nutritional and protein parameters were determined via analysis of peripheral venous blood samples. In addition, a questionnaire was used to evaluate the nutritional and eating patterns of all patients. The nutritional risk screening (NRS) 2002 score and body mass index (BMI) were also calculated for all participants. RESULTS: Differences were found in the albumin level (SG: 36.23 ± 7.34, CG I: 44.37 ± 3.32, p < 0.001, CG II: 44.06 ± 4.24, p < 0.001) and total protein in serum (SG: 65.42 ± 8.66, CG I: 70.80 ± 5.33, p = 0.004, CG II: 71.22 ± 5.21, p = 0.004). The number of patients with lowered albumin levels (SG 19/61, CG I 1/78, CG II 2/55) and total protein in serum (SG: 12/61, CG I 5/78, CG II 2/55) also showed considerable variation. The number of patients with a NRS 2002 score ≥3 differed significantly between SG and both CGs (SG: 5/61, CG I 1/78, CG II 0/55); however, these differences could not be confirmed using BMI. CONCLUSION: As expected, lowered albumin and total protein levels were observed in PJI due to the acute phase reaction. The NRS can be performed to exclude nutritional deficiency, which cannot be excluded based on BMI. In cases of periprosthetic joint infection it is reasonable to compensate the nutritional deficiency with dietary supplements.

Surgical workflow simulation for the design and assessment of operating room setups in orthopedic surgery.

BACKGROUND: The design and internal layout of modern operating rooms (OR) are influencing the surgical team's collaboration and communication, ergonomics, as well as intraoperative hygiene substantially. Yet, there is no objective method for the assessment and design of operating room setups for different surgical disciplines and intervention types available. The aim of this work is to establish an improved OR setup for common procedures in arthroplasty. METHODS: With the help of computer simulation, a method for the design and assessment of enhanced OR setups was developed. New OR setups were designed, analyzed in a computer simulation environment and evaluated in the actual intraoperative setting. Thereby, a 3D graphical simulation representation enabled the strong involvement of clinical stakeholders in all phases of the design and decision-making process of the new setup alternatives. RESULTS: The implementation of improved OR setups reduces the instrument handover time between the surgeon and the scrub nurse, the travel paths of the OR team as well as shortens the procedure duration. Additionally, the ergonomics of the OR staff were improved. CONCLUSION: The developed simulation method was evaluated in the actual intraoperative setting and proved its benefit for the design and optimization of OR setups for different surgical intervention types. As a clinical result, enhanced setups for total knee arthroplasty and total hip arthroplasty surgeries were established in daily clinical routine and the OR efficiency was improved.

Acetabular defect classification and management : Revision arthroplasty of the acetabular cup based on 3-point fixation.

BACKGROUND: The purpose of this study was to provide a practicable and contemporary classification system that is reliable and pragmatic with respect to perioperative evaluation, planning, scientific comparison and analysis. MATERIAL AND METHODS: This was a retrospective study of 160 patients who underwent acetabular revision surgery after THR due to loosening of the acetabular cup. The assessment of the acetabular defect was based on intraoperative description of the bony configuration of the acetabulum as well as on standardized preoperative planning images (pelvic overview and axial view of the hip joint). Preoperative computed tomography (CT) was carried out in individual cases. RESULTS: Acetabular bone defects were classified into 4 types based on whether or not a 3-point fixation of the acetabular cup within the boundaries of the acetabular cavity was possible. Minor segmental defects or cup loosening without bone loss can be treated with standard hemispherical acetabular components. Bone loss can be filled with bone grafts and/or treated by the appropriate acetabular component in order to ensure stable anchorage. When conventional revision cups are no longer suitable a custom made partial pelvic replacement can be used. CONCLUSION: The proposed classification mainly relies on intraoperative findings which were confirmed by preoperative imaging in 154 cases out of 160 (96.25%); however, meticulous preoperative planning based on X­ray radiographs must be carried out. In addition, a CT scan must be performed whenever type III or type IV defects are anticipated. Compared to the existing classification systems, we can state that our classification system is practicable and pragmatic and simplifies the assessment of bone defects.

[Bilateral idiopathic chondrolysis of the hips - A case report of an adolescent patient]. / Idiopathische Chondrolyse beider Hüftgelenke ­ Fallbericht bei einer adoleszenten Patientin.

The diagnosis and treatment of idiopathic chondrolysis of the hips are described in the case of a 12-year-old girl. The patient presented with intermittent pain and extreme dysfunction of both hips. After clinical examination and pelvic X­ray, MRI showed the typical changes of idiopathic chondrolysis. Purely conservative treatment with systematic physiotherapy and regular application of a non-steroidal anti-inflammatory drug produced a good clinical result.

Process optimization in total knee arthoplasty procedures : Impact of size-specific instrument sets on costs and revenue.

Total knee arthroplasty (TKA) is a frequent operation in Germany and in 2017 a total of 191,272 interventions were carried out. These interventions are associated with high costs and involve complex clinical workflow organization and time-consuming instrument logistics. With this in mind, the aim of this study was to identify the economic potential of the instrument configuration in order to optimize the entire process in TKA. Changing the composition of the set of instruments used in the operating theater for TKA resulted in time and cost saving for the complete TKA procedure, including all personnel and off-shoot procedures. In addition, the operating time saved by the introduction of a patient-specific instrumentation set meant that the operating theater could be used for more or other surgical procedures, also generating additional revenue.