Periprosthetic Joint Infections of the Knee-Comparison of Different Treatment Algorithms.

Background: Periprosthetic joint infection (PJI) following total knee arthroplasty is a serious complication lacking evidence-based diagnostic and treatment protocols, particularly in ruling out persisting infection before reimplantation. Methods: This retrospective analysis assessed the mid-term outcomes of 66 patients undergoing septic two-stage knee revision surgeries from 2007 to 2013, diagnosed as per the Musculoskeletal Infection Society criteria. After implant removal and antibiotic treatment, reimplantation decisions were based on either joint aspiration, blood counts, and clinical examination (group A) or an open biopsy (group B). Both groups underwent meticulous debridement and spacer exchange during the interim period. Results: Late re-infection occurred in 12.1% of all patients. In group A, 13.8% experienced late re-infection, with 14.3% in subgroup A1 and 13.3% in subgroup A2. In group B, 10% had a late re-infection. No significant difference in re-infection or complication rates was found between the groups. Conclusions: The study did not demonstrate the superiority of group B's approach of open biopsy over group A's joint aspiration, clinical examination, and blood counts in preventing re-infection or reducing complications.

The effect of a collar on primary stability of standard and undersized cementless hip stems: a biomechanical study.

INTRODUCTION: Aseptic loosening and periprosthetic fractures are main reasons for revision after THA. Quite different from most other stem systems, Corail cementless hip stems show better survival rates than their cemented counterpart, which can possibly be explained by the use of a collar. The study aimed to investigate primary stability with standard and undersized hip stems both collared and collarless. MATERIALS AND METHODS: Primary stability of cementless, collared and collarless, femoral stems was measured in artificial bones using both undersized and standard size. After preconditioning, 3D micromotion was measured under cyclic loading at the bone-implant interface. RESULTS: The use of a collar resulted in higher micromotion within the same stem size but showed no statistically significant difference for both standard and undersized hip stems. The collared and collarless undersized stems showed no significant differences in 3D micromotion at the upper measuring positions compared to the standard stem size. Micromotion was significantly higher in the distal measuring positions, with and without collar, for the undersized stems (vs. standard collarless stem size). CONCLUSION: The key finding is that the collarless and collared Corail hip stems, within one stem size, showed no significant differences in primary stability. Undersized stems showed significantly higher micromotion in the distal area both with and without collar.

Second opinion and time to knee arthroplasty: a prospective cohort study of 142 patients.

OBJECTIVE: The objective of this study was to determine the impact of obtaining a second opinion consultation on time to knee arthroplasty (KA). We further examined the frequency of KA and the determinants of KA following the second opinion. DESIGN: Prospective cohort study. SETTING: The second opinion programme was implemented at the Ludwig Maximilian University Hospital in Munich. PARTICIPANTS: Participants comprised patients with knee osteoarthritis who were insured with one of the largest statutory health insurance Allgemeine Ortskrankenkasse Bayern (mean age 64.3±9.6 years). Patients participated in a second-opinion programme and completed questionnaires on site before and after personal presentation for the second opinion consultation. Follow-up questionnaires were delivered by post at 3 and 12 months after the second opinion consultation. Of the 142 patients included in the study, 47 (33.1%) underwent KA within 12 months after obtaining the second opinion. PRIMARY OUTCOME MEASURES: Primary outcome measure was time until patients received KA. Cox proportional hazard modelling was used to calculate the associations between the selected predictors and time that elapsed between receipt of the second opinion to KA. RESULTS: Mean time until KA was 17 weeks. Kaplan-Meier curves showed significant differences in time to KA according to the recommendation given at second opinion consultation, knee-related quality of life and Kellgren-Lawrence grade. In multivariate Cox proportional hazard modelling, second opinion recommendation (HR 5.33, 95% CI 1.16, 24.41) and knee-related quality of life (HR 1.03, 95% CI 1.01, 1.06) were significant predictors of time from second opinion to KA. CONCLUSIONS: Obtaining a second opinion had significant impact on time to knee replacement. Those who were recommended immediate surgery also underwent surgery more quickly after the second opinion. The effect of knee-related quality of life supports the importance of patient-reported outcome measures in the decision for or against KA.

Linear correlation between patellar positioning and rotation of the lower limb in radiographic imaging: a 3D simulation study.

PURPOSE: The purpose of this study was to quantify changes in rotation of the lower limb between image pairs based on patellar position. Additionally, we investigated the differences in alignment between centralized patellar and orthograde-positioned condyles. METHODS: Three-dimensional models of 30 paired legs were aligned in neutral position with condyles orthogonal to the sagittal axis and then rotated internally and externally in 1° increments up to 15°. For each rotation, the deviation of the patella and the subsequent changes in alignment parameters were calculated and plotted using a linear regression model. Differences between neutral position and patellar centralization were analysed qualitatively. RESULTS: A linear relationship between lower limb rotation and patellar position can be postulated. The regression model (R2 = 0.99) calculated a change of the patellar position of - 0.9 mm per degree rotation and alignment parameters showed small changes due to rotation. The physiological lateralization of the patella at neutral position was on average - 8.3 mm (SD: ± 5.4 mm). From neutral position, internal rotation that led to a centralized patella was on average - 9.8° (SD: ± 5.2°). CONCLUSION: The approximately linear dependence of the patellar position on rotation allows an inverse estimation of the rotation during image acquisition and its influence on the alignment parameters. As there is still no absolute consensus about lower limb positioning during image acquisition, data about the impact of a centralized patella compared to an orthograde condyle positioning on alignment parameters was provided. LEVEL OF EVIDENCE: IV.

[Postoperative imaging of the hip]. / Postoperative Bildgebung des Hüftgelenks.

CLINICAL ISSUE: To assess postoperative imaging of the hip joint regarding possible complications, it is indispensable to have in-depth knowledge of commonly used surgical techniques, access routes, and the implanted materials. STANDARD RADIOLOGICAL METHODS: While radiography is used to evaluate the position of foreign material and to rule out periprosthetic fractures that have occurred intraoperatively, follow-up examinations might show signs of material failure, aseptic loosening, prosthesis infections, or the occurrence of heterotopic ossifications. If radiographic findings are ambiguous, computed tomography (CT) may be used to clarify findings, whereas magnetic resonance imaging (MRI) is helpful to identify intra- and periarticular soft tissue pathologies such as surgery-associated cartilage and ligament damage, muscle insufficiency, or metallosis. METHODOLOGICAL INNOVATION AND EVALUATION: To guide clinical decision making in common postoperative complications, various classification systems are available, e.g., for periprosthetic fractures, aseptic loosening, or heterotopic ossification. However, the differentiation between aseptic material loosening and septic endoprosthesis infection remains challenging if based on imaging alone. PRACTICAL RECOMMENDATIONS: The assessment of postoperative hip imaging should be closely linked to the respective surgical technique and the implanted foreign material, whereby different probabilities of specific complications can be derived.

Lumbar spinal stenosis - surgical outcome and the odds of revision-surgery: Is it all due to the surgeon?

BACKGROUND: Surgical decompression is the intervention of choice for lumbar spinal stenosis (LSS) when non-operative treatment has failed. Apart from acute complications such as hematoma and infections, same-level recurrent lumbar stenosis and adjacent-segment disease (ASD) are factors that can occur after index lumbar spine surgery. OBJECTIVE: The aim of this retrospective case series was to evaluate the outcome of surgery and the odds of necessary revisions. METHODS: Patients who had undergone either decompressive lumbar laminotomy or laminotomy and spinal fusion due to lumbar spinal stenosis (LSS) between 2000 and 2011 were included in this analysis. Demographic, perioperative and radiographic data were collected. Clinical outcome was evaluated using numeric rating scale (NRS), the symptom subscale of the adapted version of the german Spinal Stenosis Measure (SSM) and patient-sreported ability to walk. RESULTS: Within the LSS- cohort of 438 patients, 338 patients underwent decompression surgery only, while instrumentation in addition to decompression was performed in 100 cases (22.3%). 38 patients had prior spinal operations (decompression, disc herniation, fusion) either at our hospital or elsewhere. Thirty-five intraoperative complications were documented with dural tear with CSF leak being the most common (33/35; 94.3%). Postoperative complications were defined as complications that needed surgery and differentiated between immediate postoperative complications (⩽ 3 weeks post operation) and complications that needed revisions surgery at a later date. Within all patients 51 revisions were classified as immediate complications of the index operation with infections, neurological deficits and hematoma being the most common. Within this group only 22 patients had fusion surgery in the first place, while 29 were treated by decompression. Revision surgery was indicated by 53 patients at a later date. While 4 patients decided against surgery, 49 revision surgeries were planned. 28 were performed at the same level, 10 at the same level plus an adjacent level, and 10 were executed at index level with indications of adjacent level spinal stenosis, adjacent level spinal stenosis plus instability and stand-alone instability. Pre- operative VAS score and ability to walk improved significantly in all patients. CONCLUSIONS: While looking for predictors of revision surgery due to re-stenosis, instability or same/adjacent segment disease none of these were found. Within our cohort no significant differences concerning demographic, peri-operative and radiographic data of patients with or without revision wer noted. Patients, who needed revision surgery were older but slightly healthier while more likely to be male and smoking. Surprisingly, significant differences were noted regarding the distribution of intraoperative and early postoperative complications among the 6 main surgeons while these weren't obious within the intial index group of late revisions.

Behavioural and patient-individual determinants of quality of life, functioning and physical activity in older adults (MobilE-TRA 2): study protocol of an observational cohort study in a tertiary care setting.

INTRODUCTION: Vertigo, dizziness and balance problems (VDB) as well as osteoarthritis (OA) are among the health conditions with the greatest impact on mobility and social participation in older adults. Patients with VDB and OA were shown to benefit from specialised care such as vestibular rehabilitation therapy or joint replacement. However, these effects are not permanent and seem to disappear over time. One important reason might be a decreasing adherence to therapy recommendations. Findings from behavioural economics (BE) can help to shed light on individual effects on adherence behaviour and long-term outcomes of VDB and OA. OBJECTIVE: Based on insights from BE concepts (ie, self-efficacy, intention, and time and risk preferences), MobilE-TRA 2 investigates the determinants of functioning and health-related quality of life (HRQoL) 3 and 12 months after discharge from total hip replacement (THR)/total knee replacement (TKR) in patients with OA and after interdisciplinary evaluation for VDB. METHODS AND ANALYSIS: MobilE-TRA 2 is a longitudinal observational study with data collection in two specialised tertiary care centres at the university hospital in Munich, Germany between 2020 and 2023. Patients aged 60 and older presenting for their first THR/TKR or interdisciplinary evaluation of VDB at Ludwig Maximilians University (LMU) hospital will be recruited for study participation. Three and twelve months after baseline assessment, all patients will receive a follow-up questionnaire. Mixed-effect regression models will be used to examine BE concepts as determinants of adherence, HRQoL and functioning. ETHICS AND DISSEMINATION: The study was approved by the ethics committee at the medical faculty of the LMU Munich under the number 20-727. Results will be published in scientific, peer-reviewed journals and at national and international conferences. Findings will also be disseminated via newsletters, the project website and a regional conference for representatives of local and national authorities.

The Expression Levels of Toll-like Receptors after Metallic Particle and Ion Exposition in the Synovium of a Murine Model.

To date, the exact role of specific Toll-like receptors (TLRs) in regulating immune reactivity to metallic byproducts of orthopedic implants has not been fully clarified. In light of the situation, our objective in this investigation was to assess the expression levels of surface TLRs after metallic particle and ion exposure in an established animal model. Ten female BALB/c mice in each group received intra-articular injections of phosphate buffer (PBS) (control), metallic particles (MP), and metallic ions (MI), respectively. Seven days later, immunohistochemical staining was undertaken in the synovial layer of the murine knee joints using anti-TLR 1, 2, 4, 5, and 6 polyclonal antibodies. In addition to increased cellular infiltrates and a hyperplastic synovial membrane, the MP group showed significantly elevated TLR expression compared to the control group and had higher TLR 1-, 4-, and 6-positive cells than the MI group (p < 0.0167). TLR 4- and TLR 6-positive cells were significantly augmented for the MI group compared to the control group (p < 0.0167). Additionally, greenish corrosion particles found in the necrotic tissue suggested that metallic particles might release a certain level of locally toxic metallic ions in vivo.

Effects of a medical second opinion programme on patients' decision for or against knee arthroplasty and their satisfaction with the programme.

BACKGROUND: German social legislation gives patients the right to obtain a second opinion before elective surgery and defines quality criteria for reimbursement by statutory health insurances. However, the effects of second opinions before elective surgery are largely unknown. The aim of this study was to evaluate the effects of a second opinion programme in patients recommended for knee arthroplasty. METHODS: The largest statutory health insurance funds in Bavaria offered patients who had been recommended to have knee arthroplasty the opportunity to partake in a second opinion programme which consisted of an in person presentation to an experienced knee surgeon. In this cohort study, consecutive patients from this second opinion programme who signed informed consent were included from 07/10/2016 to 14/02/2020. Data were collected before and after the second opinion visit. RESULTS: A total of 141 (66%) of 215 patients who presented for a second opinion participated in the evaluation study. The second opinion physician recommended knee arthroplasty to 40% of the patients, later knee arthroplasty if the conditions worsened to 40%, and no knee arthroplasty to 20%. After receiving the second opinion 28 of 56 (41%) undecided patients preferred knee arthroplasty, 14 no knee arthroplasty, 14 remained undecided. Four of 46 patients with a preference for "arthroplasty" changed their decision to "no arthroplasty", five of 35 patients from "no arthroplasty" to "arthroplasty". The patients were more confident in their decision according to the decision confidence scale (before: 5.4 ± 3.0; after: 7.8 ± 2.5; p < 0.001). They rated their satisfaction with the second opinion programme with a mean grade of 1.35 (± 0.60) (best:1; worst:6). Logistic regression analyses showed that the recommendation of the second opinion physician for joint arthroplasty was associated with the guideline criteria radiological severity of osteoarthritis (p = 0.001) and knee-joint-specific quality of life (p = 0.041). CONCLUSION: The second opinion of an experienced knee surgeon frequently deviates from the initial recommendation for knee arthroplasty. The association of guideline criteria to the second recommendation suggests a high quality of the second opinion. From the patient perspective, the second opinion reduces uncertainties in their treatment decision.

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.

Functional testing of tranexamic acid effects in patients undergoing elective orthopaedic surgery.

Tranexamic acid (TXA) can reduce blood loss and transfusion rates in orthopaedic surgery. In this regard, a new viscoelastometric test (TPA-test, ClotPro), enables the monitoring of TXA effects. This prospective observational study evaluated and correlated TXA plasma concentrations (cTXA) following intravenous and oral administration in patients undergoing elective orthopaedic surgery with lysis variables of TPA-test. Blood samples of 42 patients were evaluated before TXA application and 2, 6, 12, 24 and 48 h afterwards. TPA-test was used to determine lysis time (LT) as well as maximum lysis (ML) and cTXA was measured using Ultra-High-Performance-Liquid-Chromatography/Mass-Spectrometry. Data are presented as median (min-max). LTTPA-test and MLTPA-test correlated with cTXA (r = 0.9456/r = 0.5362; p < 0.0001). 2 h after intravenous TXA administration all samples showed complete lysis inhibition (LTTPA-test prolongation: T1: 217 s (161-529) vs. T2: 4500 s (4500-4500);p < 0.0001), whereas after oral application high intraindividual variability was observed as some samples showed only moderate changes in LTTPA-test (T1: 236 s (180-360) vs. T2: 4500 s (460-4500); p < 0.0001). Nevertheless, statistically LTTPA-test did not differ between groups. MLTPA-test differed 2 h after application (i.v.: 9.0% (5-14) vs. oral: 31% (8-97); p = 0.0081). In 17/21 samples after oral and 0/21 samples after intravenous administration cTXA was < 10 µg ml-1 2 h after application. TPA-test correlated with cTXA. MLTPA-test differed between intravenous and oral application 2 h after application. Most patients with oral application had TXA plasma concentration < 10 µg ml-1. The duration of action did not differ between intravenous and oral application. Additional studies evaluating clinical outcomes and side-effects based on individualized TXA prophylaxis/therapy are required.

High conservation combined with high plasticity: genomics and evolution of Borrelia bavariensis.

BACKGROUND: Borrelia bavariensis is one of the agents of Lyme Borreliosis (or Lyme disease) in Eurasia. The genome of the Borrelia burgdorferi sensu lato species complex, that includes B. bavariensis, is known to be very complex and fragmented making the assembly of whole genomes with next-generation sequencing data a challenge. RESULTS: We present a genome reconstruction for 33 B. bavariensis isolates from Eurasia based on long-read (Pacific Bioscience, for three isolates) and short-read (Illumina) data. We show that the combination of both sequencing techniques allows proper genome reconstruction of all plasmids in most cases but use of a very close reference is necessary when only short-read sequencing data is available. B. bavariensis genomes combine a high degree of genetic conservation with high plasticity: all isolates share the main chromosome and five plasmids, but the repertoire of other plasmids is highly variable. In addition to plasmid losses and gains through horizontal transfer, we also observe several fusions between plasmids. Although European isolates of B. bavariensis have little diversity in genome content, there is some geographic structure to this variation. In contrast, each Asian isolate has a unique plasmid repertoire and we observe no geographically based differences between Japanese and Russian isolates. Comparing the genomes of Asian and European populations of B. bavariensis suggests that some genes which are markedly different between the two populations may be good candidates for adaptation to the tick vector, (Ixodes ricinus in Europe and I. persulcatus in Asia). CONCLUSIONS: We present the characterization of genomes of a large sample of B. bavariensis isolates and show that their plasmid content is highly variable. This study opens the way for genomic studies seeking to understand host and vector adaptation as well as human pathogenicity in Eurasian Lyme Borreliosis agents.

Surgical intra- and extra-articular anterior cruciate ligament reconstruction: a meta-analysis.

BACKGROUND: It is still controversial whether the combination of anterior cruciate ligament (ACL) reconstruction and extra-articular reconstruction (EAR) have good clinical efficacy. This meta-analysis aims systematically to compare the clinical effectiveness of ACL reconstruction and combined reconstruction. METHODS: Electronic databases, including Medline/PubMed, Embase and the Cochrane Library, were systematically searched to identify targeted studies. A meta-analysis were performed to pool the outcome estimates of interest, such as the Lysholm, International Knee Documentation Committee (IKDC) and Tegner scores and the results from the KT-1000/2000 arthrometer test, the Lachman test and the pivot shift test. RESULTS: Twelve studies involving 1146 knees were identified. Compared with single ACL reconstruction, combined reconstruction had better results for a pivot shift of grade 1 (relative ratio [RR] = 0.88, 95% CI: 0.83-0.94) and grade 2 (RR = 0.95, 95% CI: 0.91-0.99) rather than grade 3 (RR = 0.98, 95% CI: 0.90-1.06) and no statistically significant difference for both Lachman grade 1 (RR = 0.96, 95% CI: 0.89-1.05) and grade 2 (RR = 0.96, 95% CI: 0.90-1.03). Combined reconstruction resulted in significant improvements on the instrumented joint laxity test when considering a failure standard of more than 5 mm (a side-to-side arthrometric difference) (RR = 0.94, 95% CI: 0.89-0.98) rather than 3 mm (RR = 0.94, 95% CI: 0.86-1.03). Moreover, combined reconstruction increased the IKDC score at the 12-month (weighted mean difference [WMD] = - 6.38, 95% CI: - 9.66 to - 3.10), 24-month (WMD = - 5.60, 95% CI: - 8.54 to - 2.66) and 36-month follow-ups (WMD = - 4.71, 95% CI: - 7.59 to - 1.83) and the Tegner score at the 36-month follow-up (WMD = - 0.53, 95% CI: - 0.97 to - 0.09), but it did not increase the Lysholm score at the 36-month follow-up (WMD = - 0.84, 95% CI: - 2.02 to 0.34). CONCLUSION: With the advances in reconstruction techniques, combined reconstructions were found to be effective in improving rotational stability and to lead to good functional scores. However, obviously, the combined reconstruction technique is more time-consuming and requires an additional incision, which is not suitable for all ACL-deficient patients. Therefore, programs should be personalized and customized for the specific situation of each patient.

Biological Reactions to Metal Particles and Ions in the Synovial Layer of Mice.

Metal particles and ions released from implants not only have a fundamental effect on the longevity of total joint replacements, but can also be disseminated to remote organs. Periprosthetic tissues harvested during revision surgeries mainly reflect end-stage failure but may not adequately reveal initial biological reactions and systemic side effects. Therefore, primary reactions caused by metal particles and ions were investigated in an established murine model. Left knee joints in three groups, each consisting of ten female BALB/c mice, received injections of metal ions (MI), metal particles (MP) and phosphate-buffered saline (PBS) (control). Seven days after the injection, immunohistochemical analyses of the synovial layer were performed with respect to some biological markers including Tumor necrosis factor -α (TNF-α), Interleukin-6 (IL-6), Interleukin-1ß (IL-1ß), Cluster of Differentiation 45 (CD45), Cluster of Differentiation 68 (CD68) and Cluster of Differentiation 3(CD3). The MP group showed significantly enhanced proinflammatory cytokine expression (TNF-α, IL-6 and IL-1ß) compared with the other groups (p < 0.05). Interestingly, CD3, as a marker for T lymphocytes, did not increase in any of the groups. The MI group showed a significantly increased expression of CD45 compared with the control group (p < 0.05). Therefore, during the primary process, metal particles have stronger pro-inflammatory potential than metal ions, and T lymphocytes did not seem to be activated in our murine model. Systemic reactions caused by metal particles and ions were found by observing the untreated right knees.

Optimisation of the drill-in behaviour of the EcoFit® SC threaded cup.

Threaded cups show good clinical results when implanted correctly. In clinical use, multiple cases with an incomplete placement of the EcoFit threaded cup (implantcast) were observed. This behaviour could not be explained intra- and postoperatively. The aim of this study was to compare and optimise the drill-in-behaviour of the EcoFit cup in a biomechanical investigation. EcoFit cup sizes 46, 50 and 54 mm were compared with the SC cup (Aesculap) size 50 mm. Foam blocks (Sawbones) of density 0.16 g/ml (pcf 10), 0.32 g/ml (pcf 20) and 0.48 g/ml (pcf 30) were used. After standardised placement using a universal testing system (n = 8 per group), the primary stability, the overhang of the cups and the drill-in behaviour were measured. Overreamings of 1 and 2 mm were performed (pcf 20, n = 8) for the EcoFit cup size 50 and the primary stability as well as the overhang measurements were examined. Measurements of the cup diameter, thread depth and thread pitch were performed on three-dimensional (3D) images of the cup size 50 mm. The drill-in behaviour was different between the EcoFit and the SC cups. Even with maximum torque, the EcoFit cup could not be positioned as deep as the SC cup in standard reaming conditions (overhang of 1.1 ± 0.4 mm for the EcoFit size 50 in pcf 20 and of -0.01 ± 0.2 mm for the SC cup). The primary stability was lower for the EcoFit cup in comparison to the SC cup (128.8 ± 3.2 Nm vs. 138.6 ± 9.1 Nm, p = 0.0291). With overreaming to 51 mm, a deeper positioning of the EcoFit was possible (overlap of -0.3 ± 0.1, comparable to the SC cup). The overreaming of the cavity also led to a significantly higher primary stability of 143.4 ± 3.7 Nm (p < 0.001) comparable to the unaltered condition (128.8 ± 3.2 Nm). Overreaming to 52 mm had no further advantage in terms of primary stability or overhang. The geometric measurements showed significant differences as well. The previously clinically observed difficulties in inserting the cup were confirmed by this study. By overreaming to 51 mm, the drill-in behaviour, the primary stability and the measured overhang were comparable to the reference cup. The obtained results suggest that the extension of the acetabulum cavity to 51 mm while using the implantcast EcoFit size 50 should be implemented in clinical applications.

Varus or valgus positioning of the tibial component of a unicompartmental fixed-bearing knee arthroplasty does not increase wear.

PURPOSE: Higher revision rates were shown in varus- or valgus-positioned tibias in unicompartmental knee arthroplasty (UKA), but more than 15% of UKA prostheses are implanted with more than 5° of varus or valgus. This study aimed to analyze the wear rate in UKA when implanting the tibial component in either varus or valgus position versus a neutral placement at 90° to the tibial anatomical axis. The study hypothesized that a 5° varus or valgus positioning of the tibial plateau will generate less wear compared to a neutral alignment. METHODS: Wear was experimentally analyzed on a medial anatomical fixed-bearing unicompartmental knee prosthesis (Univation, Aesculap, Germany) in vitro with a customized, four-station, servohydraulic knee wear simulator, reproducing the walking cycle. The forces, loading and range of motion were applied as specified in the ISO 14243-1:2002, 5 million cycles were analyzed. The tibial components of the medial prostheses were inserted in a neutral position, with 5° varus, and 5° valgus (n = 3, each group). RESULTS: The wear rate decreased significantly with a 5° varus positioning (6.30 ± 1.38 mg/million cycles) and a 5° valgus positioning (4.96 ± 2.47 mg/million cycles) compared to the neutral position (12.16 ± 1.26 mg/million cycles) (p < 0.01 for the varus and the valgus position). The wear area on the inlay was slightly reduced in the varus and valgus group. CONCLUSION: A varus or valgus "malpositioning" up to 5° will not lead to an increased wear. Wear was even less because of the reduced articulating contact area between the inlay and the femur. A slight varus positioning of the tibial component (parallel to the anatomical joint line) positioning can be advocated from a point of wear. LEVEL OF EVIDENCE: Experimental study.

Local Biological Reactions and Pseudotumor-Like Tissue Formation in relation to Metal Wear in a Murine In Vivo Model.

Metal wear debris and released ions (CoCrMo), which are widely generated in metal-on-metal bearings of hip implants, are also found in patients with metal-on-polyethylene bearings due to the mechanically assisted crevice corrosion of modular taper junctions, including head-neck and neck-stem taper interfaces. The resulting adverse reactions to metal debris and metal ions frequently lead to early arthroplasty revision surgery. National guidelines have since been published where the blood metal ion concentration of patients must consistently be monitored after joint replacement to prevent serious complications from developing after surgery. However, to date, the effect of metal particles and metal ions on local biological reactions is complex and still not understood in detail; the present study sought to elucidate the complex mechanism of metal wear-associated inflammation reactions. The knee joints in 4 groups each consisting of 10 female BALB/c mice received injections with cobalt chrome ions, cobalt chrome particles, and ultra-high-molecular-weight polyethylene (UHMWPE) particles or PBS (control). Seven days after injection, the synovial microcirculation and knee joint diameter were assessed via intravital fluorescence microscopy followed by histological evaluation of the synovial layer. Enlarged knee diameter, enhanced leukocyte to endothelial cell interactions, and an increase in functional capillary density within cobalt chrome particle-treated animals were significantly greater than those in the other treatment groups. Subsequently, pseudotumor-like tissue formations were observed only in the synovial tissue layer of the cobalt chrome particle-treated animals. Therefore, these findings strongly suggest that the cobalt chrome particles and not metal ions are the cause for in vivo postsurgery implantation inflammation.

Radiographic changes and clinical outcomes after open and closed wedge high tibial osteotomy: a systematic review and meta-analysis.

BACKGROUND: The purpose of this meta-analysis is to examine changes in radiological variables and clinical outcomes between open and closed wedge high tibial osteotomy (OWHTO and CWHTO, respectively), which have ongoing controversial issues in numerous quantitative clinical studies. METHODS: PubMed, Embase, and the Cochrane Library were systematically searched for suitable controlled trials between Jan 1, 1999, and Feb 2, 2018. The inclusion criteria included studies written in English, studies with a level of evidence of I-IV, and studies presenting comparisons between OWHTO and CWHTO. The main clinical and radiographic results were extracted and pooled using Stata 12.0. RESULTS: After searching for and screening trials, 28 trials involving 2840 knees were eligible for the meta-analysis. After OWHTO or CWHTO, clinical scores, including the American Knee Society Score, Hospital for Special Surgery Knee Score, Lysholm score, and Visual Analog Scale pain score, improved (p < 0.05), but the range of motion was unchanged (p > 0.05). The anatomical femorotibial angle (SMD 0.04, 95% CI - 0.66 to 0.74) and hip-knee-ankle angle (SMD 0.11, 95% CI - 0.11 to 0.33) data suggested that the OWHTO and CWHTO groups were similar in function of correction. Posterior tibial slope increased (SMD - 0.71, 95% CI - 1.04 to - 0.37) after OWHTO but decreased (SMD 0.72, 95% CI 0.35 to 1.08) after CWHTO. OWHTO decreased patellar height (p < 0.05), while patellar height did not change significantly after CWHTO (p > 0.05). CONCLUSION: This meta-analysis indicates that compared with CWHTO, OWHTO increases the posterior slope, decreases the patellar height, and provides a similar accuracy of correction; however, CWHTO leads to a decreased posterior slope and an unchanged patellar height. Therefore, programs should be personalized and customized for the specific situation of each patient.

Can Salter osteotomy correct late diagnosed hip dysplasia: A retrospective evaluation of 49 hips after 6.7 years?

BACKGROUND: Surgical treatment of late diagnosed development dysplasia of the hip (DDH) remains challenging with several methods being described. We therefore retrospectively evaluated the outcome of Salter innominate osteotomy (SIO) in patients with fully-grown bone, to evaluate whether this surgical procedure allows sufficient acetabular correction. MATERIAL AND METHODS: Between 2004-2012 SIO had been performed in 45 patients (49 hips) with late diagnosed DDH. The evaluation included pre- and postoperative radiographs (n=49), the complication rate (n=49) and the clinical outcome (WOMAC, HHS, UCLA) (n=34). RESULTS: Mean age at surgery was 27.6 (16-51) with a follow-up of 6.7±2.7 (0.9-11.0) years. Radiologically, a good acetabular correction with a significant improvement of the Center Edge angle (15.4° to 34.9°), sharps angle (45.7° to 32.0°) and migration percentage (33.2% to 14.4%) (p<0.001) was found. Clinical results revealed a WOMAC of 13.9±13.3, UCLA of 7.8±2.1 and HHS of 85.0±11.8. Complications were noted for 10 patients (20%) with 7 (14%) requiring revision. CONCLUSION: The results demonstrated that SIO achieved a satisfying acetabular correction and good clinical results in late diagnosed DDH. It therefore might be an option in some cases, although periacetabular osteotomy techniques are currently preferable used as they allow a wider range of acetabular correction. LEVEL OF EVIDENCE: IV, retrospective observational study.

The impact of continuous non-invasive arterial blood pressure monitoring on blood pressure stability during general anaesthesia in orthopaedic patients: A randomised trial.

BACKGROUND: In patients undergoing general anaesthesia, intraoperative hypotension occurs frequently and is associated with adverse outcomes such as postoperative acute kidney failure, myocardial infarction or stroke. A history of chronic hypertension renders patients more susceptible to a decrease in blood pressure (BP) after induction of general anaesthesia. As a patient's BP is generally monitored intermittently via an upper arm cuff, there may be a delay in the detection of hypotension by the anaesthetist. OBJECTIVE: The current study investigates whether the presence of continuous BP monitoring leads to improved BP stability. DESIGN: Randomised, controlled and single-centre study. PATIENTS: A total of 160 orthopaedic patients undergoing general anaesthesia with a history of chronic hypertension. INTERVENTION: The patients were randomised to either a study group (n = 77) that received continuous non-invasive BP monitoring in addition to oscillometric intermittent monitoring, or a control group (n = 83) whose BP was monitored intermittently only. The interval for oscillometric measurements in both groups was set to 3 min. After induction of general anaesthesia, oscillometric BP values of the two groups were compared for the first hour of the procedure. Anaesthetists were blinded to the purpose of the study. MAIN OUTCOME MEASURE: BP stability and hypotensive events. RESULTS: There was no difference in baseline BP between the groups. After adjustment for multiple testing, mean arterial BP in the study group was significantly higher than in the control group at 12 and 15 min. Mean ±â€ŠSD for study and control group, respectively were: 12 min, 102 ±â€Š24 vs. 90 ±â€Š26 mmHg (P = 0.039) and 15 min, 102 ±â€Š21 vs. 90 ±â€Š23 mmHg (P = 0.023). Hypotensive readings below a mean pressure of 55 mmHg occurred more often in the control group (25 vs. 7, P = 0.047). CONCLUSION: Continuous monitoring contributes to BP stability in the studied population. TRIAL REGISTRATION: NCT02519101.