FeMn with Phases of a Degradable Ag Alloy for Residue-Free and Adapted Bioresorbability.

The development of bioresorbable materials for temporary implantation enables progress in medical technology. Iron (Fe)-based degradable materials are biocompatible and exhibit good mechanical properties, but their degradation rate is low. Aside from alloying with Manganese (Mn), the creation of phases with high electrochemical potential such as silver (Ag) phases to cause the anodic dissolution of FeMn is promising. However, to enable residue-free dissolution, the Ag needs to be modified. This concern is addressed, as FeMn modified with a degradable Ag-Calcium-Lanthanum (AgCaLa) alloy is investigated. The electrochemical properties and the degradation behavior are determined via a static immersion test. The local differences in electrochemical potential increase the degradation rate (low pH values), and the formation of gaps around the Ag phases (neutral pH values) demonstrates the benefit of the strategy. Nevertheless, the formation of corrosion-inhibiting layers avoids an increased degradation rate under a neutral pH value. The complete bioresorption of the material is possible since the phases of the degradable AgCaLa alloy dissolve after the FeMn matrix. Cell viability tests reveal biocompatibility, and the antibacterial activity of the degradation supernatant is observed. Thus, FeMn modified with degradable AgCaLa phases is promising as a bioresorbable material if corrosion-inhibiting layers can be diminished.

Heat Treatments of Metastable ß Titanium Alloy Ti-24Nb-4Zr-8Sn Processed by Laser Powder Bed Fusion.

Titanium alloys, especially ß alloys, are favorable as implant materials due to their promising combination of low Young's modulus, high strength, corrosion resistance, and biocompatibility. In particular, the low Young's moduli reduce the risk of stress shielding and implant loosening. The processing of Ti-24Nb-4Zr-8Sn through laser powder bed fusion is presented. The specimens were heat-treated, and the microstructure was investigated using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The mechanical properties were determined by hardness and tensile tests. The microstructures reveal a mainly ß microstructure with α″ formation for high cooling rates and α precipitates after moderate cooling rates or aging. The as-built and α″ phase containing conditions exhibit a hardness around 225 HV5, yield strengths (YS) from 340 to 490 MPa, ultimate tensile strengths (UTS) around 706 MPa, fracture elongations around 20%, and Young's moduli about 50 GPa. The α precipitates containing conditions reveal a hardness around 297 HV5, YS around 812 MPa, UTS from 871 to 931 MPa, fracture elongations around 12%, and Young's moduli about 75 GPa. Ti-24Nb-4Zr-8Sn exhibits, depending on the heat treatment, promising properties regarding the material behavior and the opportunity to tailor the mechanical performance as a low modulus, high strength implant material.

LPBF Manufactured Functionally Graded Lattice Structures Obtained by Graded Density and Hybrid Poisson's Ratio.

The additive manufacturing (AM) of innovative lattice structures with unique mechanical properties has received widespread attention due to the capability of AM processes to fabricate freeform and intricate structures. The most common way to characterize the additively manufactured lattice structures is via the uniaxial compression test. However, although there are many applications for which lattice structures are designed for bending (e.g., sandwich panels cores and some medical implants), limited attention has been paid toward investigating the flexural behavior of metallic AM lattice structures with tunable internal architectures. The purpose of this study was to experimentally investigate the flexural behavior of AM Ti-6Al-4V lattice structures with graded density and hybrid Poisson's ratio (PR). Four configurations of lattice structure beams with positive, negative, hybrid PR, and a novel hybrid PR with graded density were manufactured via the laser powder bed fusion (LPBF) AM process and tested under four-point bending. The manufacturability, microstructure, micro-hardness, and flexural properties of the lattices were evaluated. During the bending tests, different failure mechanisms were observed, which were highly dependent on the type of lattice geometry. The best response in terms of absorbed energy was obtained for the functionally graded hybrid PR (FGHPR) structure. Both the FGHPR and hybrid PR (HPR) structured showed a 78.7% and 62.9% increase in the absorbed energy, respectively, compared to the positive PR (PPR) structure. This highlights the great potential for FGHPR lattices to be used in protective devices, load-bearing medical implants, and energy-absorbing applications.

Requirements for Processing High-Strength AlZnMgCu Alloys with PBF-LB/M to Achieve Crack-Free and Dense Parts.

Processing aluminum alloys employing powder bed fusion of metals (PBF-LB/M) is becoming more attractive for the industry, especially if lightweight applications are needed. Unfortunately, high-strength aluminum alloys such as AA7075 are prone to hot cracking during PBF-LB/M, as well as welding. Both a large solidification range promoted by the alloying elements zinc and copper and a high thermal gradient accompanied with the manufacturing process conditions lead to or favor hot cracking. In the present study, a simple method for modifying the powder surface with titanium carbide nanoparticles (NPs) as a nucleating agent is aimed. The effect on the microstructure with different amounts of the nucleating agent is shown. For the aluminum alloy 7075 with 2.5 ma% titanium carbide nanoparticles, manufactured via PBF-LB/M, crack-free samples with a refined microstructure having no discernible melt pool boundaries and columnar grains are observed. After using a two-step ageing heat treatment, ultimate tensile strengths up to 465 MPa and an 8.9% elongation at break are achieved. Furthermore, it is demonstrated that not all nanoparticles used remain in the melt pool during PBF-LB/M.

Is Preoperative Identification of the Infecting Organism Essential Before Single-Stage Revision Hip Arthroplasty for Periprosthetic Infection?

BACKGROUND: It is commonly stated that identification of the infecting organism is a prerequisite to single-stage revision arthroplasty of the hip for deep infection. We have performed single-stage revision in a series of patients where the organism was not identified preoperatively. The aim of this study is to investigate whether the rate of infection eradication following single-stage revision was affected by preoperative knowledge of the infecting organism. METHODS: We identified all patients who had undergone a single-stage revision for a deep infection at our hospital between 2006 and 2015. One hundred five patients were assigned into 2 groups based upon whether the infecting organism had been identified preoperatively (group A = 28) or not (group B = 77). RESULTS: The reinfection rates were 3.6% in group A and 9.1% for group B (P = .679). Re-revision rates were 7.1% and 9.1%, respectively (P = 1.00). Overall, the implant survival rate at 6 years was 87.9% (95% confidence interval, 97.4-78.4). In group B, preoperative aspiration was performed in 36.4% (28/77) of cases. Staphylococci species were the predominant causative organisms, with gram-negative involvement in 19.0% (20/105) of cases. CONCLUSION: The rate of infection eradication and overall survivorship with single-stage revision was similar in our series to that reported in the literature. While desirable, we did not find identification of the infecting organism before surgery influenced the outcome. Given the functional and economic benefits of single-stage revision, we suggest that failure to identify an organism is not an absolute contraindication to this approach.

Fractured Femoral Stems in Primary and Revision Hip Arthroplasties Revisited: Wrightington Experience.

BACKGROUND: The aim of this study is to present our experience in managing fractured femoral stems over the last 10 years for both primary and revision stems at our tertiary unit focusing on modes of failure and operative techniques. METHODS: This is a retrospective consecutive study of all patients with fractured femoral stems that were operatively managed in our unit between 2008 and 2018. Detailed radiographic evaluation (Paprosky classification) was undertaken and data collected on operative techniques used to extract distal fractured stem fragments. RESULTS: Thirty-five patients (35 hips) were included (25 men/10 women) with average age at time of presentation of 68 years (range, 29-93). Average body mass index was 30 (standard deviation, 3.8; range, 22.5-39). There were variety of stems both contemporary and historical, primary and revision cases (15 hips polished tapered cemented stems, 10 hips composite beam and miscellaneous stems, and 10 revision hip stems). The predominant mechanism of failure was fatigue due to cantilever bending in distally fixed stems. Surgical techniques used to extract distal fragment were drilling technique in 2 hips, cortical window in 13 hips, extended trochanteric osteotomy (ETO) in 5 hips, and proximal extraction in 15 hips. CONCLUSION: When faced with a contemporary fractured stem, drilling techniques into the distal fragment are unlikely to succeed. If a trochanteric osteotomy had been used at time of index surgery, this could be used again to aid proximal extraction with conventional revision instrumentations. The cortical window technique is useful but surgically demanding technique that is most successful in extracting polished tapered fractured stems particularly when an ETO is not planned for femoral reconstruction. Use of trephines can be useful for removal of longer, uncemented stems. Finally, an ETO might be necessary when other techniques have failed.

Nano-architectural complexity of zinc oxide nanowall hollow microspheres and their structural properties.

Zinc oxide (ZnO) hollow spheres with defined morphology and micro-/nanostructure are prepared by a hydrothermal synthesis approach. The materials possess fine-leaved structures at their particle surface (nanowall hollow micro spheres). Morphology control is achieved by citric acid used as an additive in variable relative quantities during the synthesis. The structure formation is studied by various time-dependent ex situ methods, such as scanning electron microscopy, x-ray diffraction, and Raman spectroscopy. The fine-leaved surface structure is characterized by high-resolution transmission electron microscopy techniques (HRTEM, STEM), using a high-angle annular dark field detector, as well as by differential phase contrast analysis. In-depth structural characterization of the nanowalls by drop-by-drop ex situ FE-SEM analysis provides insight into possible structure formation mechanisms. Further investigation addresses the thermal stability of the particle morphology and the enhancement of the surface-to-volume ratio by heat treatment (examined by N2 physisorption).

Developing a national musculoskeletal core capabilities framework for first point of contact practitioners.

OBJECTIVE: We aimed to support service transformation by developing a core capabilities framework for first contact practitioners working with people who have musculoskeletal conditions. METHODS: We conducted a modified three-round Delphi study with a multi-professional panel of 41 experts nominated through 18 national professional and patient organizations. Qualitative data from an open-ended question in round one were analysed using a thematic approach and combined with existing literature to shape a draft framework. Participants rated their agreement with each of the proposed 142 outcomes within 14 capabilities on a 10-point Likert scale in round two. The final round combined round two results with a wider online survey. RESULTS: Rounds two and three of the Delphi survey were completed by 37 and 27 participants, respectively. Ninety practitioners responded to the wider online survey. The final framework contains 105 outcomes within 14 capabilities, separated into four domains (person-centred approaches; assessment, investigation and diagnosis; condition management, intervention and prevention; and service and professional development). The median agreement for all 105 outcomes was at least nine on the 10-point Likert scale in the final round. CONCLUSION: The framework outlines the core capabilities required for practitioners working as the first point of contact for people with musculoskeletal conditions. It provides a standard structure and language across professions, with greater consistency and portability of musculoskeletal core capabilities. Agreement on each of the 105 outcomes was universally high amongst the expert panel, and the framework is now being disseminated by Health Education England, NHS England and Skills for Health.

Conversion of Failed Hip Hemiarthroplasty to Low Friction Arthroplasty (LFA).

Purpose: We aimed to study clinical and radiological outcomes of conversion from hemiarthroplasty to Charnley hip replacement (CHR) with a particular concern over reported increased dislocation rate and literature review. Conversion of hip hemiarthroplasty to total hip replacement (THR) is a procedure reported to have high rates of complications. In the literature, there is no specific study on small head conversion. The purpose of this study was to evaluate the conversion of failed hip hemiarthroplasty to CHR with the use of modern implants. Methods: The study included 42 patients, who underwent the above procedure. The operations were carried out using a modern Charnley-type THR with a 22-mm diameter of femoral head and a trans-trochanteric approach. The mean follow-up was 75.7 months (range 25-171). Radiographs from the last follow up were evaluated for loosening and other reasons of failure. Clinical outcome was assessed using postoperative pain, function scores, complications and implant survivorship as well as radiological evaluation. Charnley's modified pain and mobility scoring system were used for clinical and Hodgkinson and Harris' criteria were used for radiological assessment. Results: Functionally, all of the patients showed improvement. Mean improvement in the pain level was by average of 2.4. On mobility assessment, 38 patients (90.4%) improved. Three patients (7.1%) had recurrent infections and three (4.8%) cases were treated with revision surgery and pseudarthrosis. Further complications occurred in 19.1%, not requiring operative treatment. On radiological evaluation, one (2.4%) case showed cup demarcation without bone loss, two (4.8%) cup migration, and one (2.4%) stem demarcation. Kaplan Meier survival analysis showed a survival of 90% at 96 months of follow up (95% CI (confidence interval), 60-90). Conclusion: Larger head might not be the answer to decrease the dislocation rate. Complication rates during revision of hip hemiarthroplasty to modern CHR with 22.225-mm head diameter were comparable to first-time THR revision despite having a smaller head.

One- and two-stage surgical revision of peri-prosthetic joint infection of the hip: a pooled individual participant data analysis of 44 cohort studies.

One-stage and two-stage revision strategies are the two main options for treating established chronic peri-prosthetic joint infection (PJI) of the hip; however, there is uncertainty regarding which is the best treatment option. We aimed to compare the risk of re-infection between the two revision strategies using pooled individual participant data (IPD). Observational cohort studies with PJI of the hip treated exclusively by one- or two-stage revision and reporting re-infection outcomes were retrieved by searching MEDLINE, EMBASE, Web of Science, The Cochrane Library, and the WHO International Clinical Trials Registry Platform; as well as email contact with investigators. We analysed IPD of 1856 participants with PJI of the hip from 44 cohorts across four continents. The primary outcome was re-infection (recurrence of infection by the same organism(s) and/or re-infection with a new organism(s)). Hazard ratios (HRs) for re-infection were calculated using Cox proportional frailty hazards models. After a median follow-up of 3.7 years, 222 re-infections were recorded. Re-infection rates per 1000 person-years of follow-up were 16.8 (95% CI 13.6-20.7) and 32.3 (95% CI 27.3-38.3) for one-stage and two-stage strategies respectively. The age- and sex-adjusted HR of re-infection for two-stage revision was 1.70 (0.58-5.00) when compared with one-stage revision. The association remained consistently absent after further adjustment for potential confounders. The HRs did not vary importantly in clinically relevant subgroups. Analysis of pooled individual patient data suggest that a one-stage revision strategy may be as effective as a two-stage revision strategy in treating PJI of the hip.

Acetabular revision with bone grafting and cementation for aseptic loosening after primary Charnley low-friction hip arthroplasty with structural bulk autografts.

PURPOSE: To review the outcome of acetabular revision with bone grafting and cementation for aseptic loosening after primary Charnley low-friction hip arthroplasty with structural bulk autografts in 15 patients. METHODS: Records were reviewed for 3 men and 12 women aged 31 to 72 (mean, 53) years who underwent acetabular revision with bone grafting and cementation for aseptic loosening at a mean of 12.4 (range, 6.6-20.3) years after primary Charnley low-friction hip arthroplasty with superolateral structural bulk autografts from the femoral head for dysplastic hip (n=14) or bone loss secondary to acetabular fracture (n=1). RESULTS: After a mean follow-up of 6.7 (range, 1.1-14.5) years, the mean Merle d'Aubigné and Postel score improved from 8.55 to 16.5. Bridging trabeculae was noted in 10 hips and graft remodelling in 5 hips. Five hips had ectopic ossification of Brooker grade 1 to 2. The mean hip centre of rotation was 21.6 (range, 16.2-30.6) mm. Two women required re-revision for aseptic loosening of the acetabulum after 8.5 and 6.6 years. The first one underwent re-revision with solid allograft for superolateral deficiency of the acetabulum. The second one underwent re-revision with solid and morselised bone allografts for loosened acetabulum. One patient had superior migrationof the acetabulum for 9 mm at year 2, but it was asymptomatic. One patient had a dislocation that was reduced with manipulation under anaesthesia. Threepatients had trochanteric non-union and presented with lateral thigh pain and tenderness, but no further surgery was performed. CONCLUSION: The medium-term outcome of acetabular revision with bone grafting and cementation is satisfactory. Repeat bone grafting is required to restore the anatomic acetabular position and bone loss secondary to acetabular loosening.

Genetic variation in inflammatory and bone turnover pathways and risk of osteolytic responses to prosthetic materials.

Wear particle-induced inflammatory bone loss (osteolysis) is the leading cause of total hip arthroplasty (THA) failure. Individual susceptibility to osteolysis is modulated by genetic variation. In this 2-stage case-control association study we examined whether variation within candidate genes in inflammatory and bone turnover signaling pathways associates with susceptibility to osteolysis and time to prosthesis failure. We examined two cohorts, comprising 758 (347 male) Caucasian subjects who had undergone THA with a metal on polyethylene bearing couple; 315 of whom had developed osteolysis. Key genes within inflammatory, bone resorption, and bone formation pathways were screened for common variants by pairwise-SNP tagging using a 2-stage association analysis approach. In the discovery cohort four SNPs within RANK, and one each within KREMEN2, OPG, SFRP1, and TIRAP (p < 0.05) were associated with osteolysis susceptibility. Two SNPs within LRP6, and one each within LRP5, NOD2, SOST, SQSTM1, TIRAP, and TRAM associated with time to implant failure (p < 0.05). Meta-analysis of the two cohorts identified four SNPs within RANK, and one each within KREMEN2, OPG, SFRP1, and TIRAP associated with osteolysis susceptibility (p < 0.05). Genetic variation within inflammatory signaling and bone turnover pathways may play a role in susceptibility to osteolysis.

The C-stem in clinical practice: fifteen-year follow-up of a triple tapered polished cemented stem.

The triple tapered polished cemented stem, C-Stem, introduced in 1993 was based on the original Charnley concept of the "flat back" polished stem. We present our continuing experience with the C-Stem in 621 consecutive primary arthroplasties implanted into 575 patients between 1993 and 1997. Four hundred and eighteen arthroplasties had a clinical and radiological follow-up past 10 years with a mean follow-up of 13 years (10-15). There were no revisions for stem loosening but 2 stems were revised for fracture - both with a defective cement mantle proximally. The stem design and the surgical technique support the original Charnley concept of limited stem subsidence within the cement mantle and the encouraging results continue to stand as a credit to Sir John Charnley's original philosophy.

[Ernst von Metternich (1656-1727). A patient-focused view of the medical marketplace around 1720]. / Ernst von Metternich (1656-1727). Ein patientenzentrierter Einblick in den medizinischen Markt um 1720.

In his medical diary the physician Johann Christoph Götz from Nuremberg recorded his visits as well as his consiliary correspondence. The case of Count Ernst of Metternich who dwelled in Ratisbon and suffered from a bladder stone is particularly well documented. Thus, the source which is focusing the doctor permits to take a look at a section of the medical market managed by the patient around 1720. Besides the Medicus ordinarius Metternich's specific network, the patient's network, comprised quite a number of local or transmigratory doctors, surgeons or lay healers as well as (former) invalids, whom he consulted in direct interviews or--in the case of Götz--by letter. The example reveals in which way the medical market was determined by the ego-network. Analyzing this section of the market, which becomes visible through the interaction between Metternich and Götz, one can profit from Pierre Bourdieu's conception of different forms of capital. Financial capital, the exchange of goods or services against money, seems of minor importance. In lieu thereof, different cohesions become obvious, in which social, cultural and symbolical capital could become decisive for the doctor's as well as for the patient's actions and assertive for the market.