Metal-on-metal hip arthroplasty: indications for continued use in light of adverse reaction to metal debris

Adverse reaction to metal debris (ARMD) represents a recently recognised mode of failure of metal-on-metal (MoM) hip resurfacings (HRs) and total hip replacements (THRs). ARMD often requires revision surgery which can have poor outcomes, therefore questioning the future role of MoM hip bearings. The 14-year survival of 447 HRs implanted by a designing surgeon was 94.1% (95% CI 84.9%-97.3%) with the best outcomes in males with primary osteoarthritis. The 8-year survival of 578 MoM THRs was 88.9% (95% CI 78.5%-93.4%) with 44% (17 of 39) of revisions performed for ARMD. A systematic review identified six studies reporting short-term outcomes following 216 ARMD revisions with variable complication (4%-68%) and re-revision (3%-38%) rates. Analysis of outcomes following 64 ARMD revisions demonstrated comparable complication (20.3%) and re-revision (12.5%) rates at a mean 4.5 year follow-up. The 5-year survival following ARMD revision was 87.9% (95% CI 78.9%-98.0%) with revision to another MoM bearing having significantly higher re-revision rates (p=0.046). Male patients with primary osteoarthritis may undergo HR in the future, however designing surgeons may also consider females for HR. There is no future role for MoM THR. Limited evidence exists regarding outcomes following ARMD revision, though exchange to a non-MoM bearing surface is advised

On rheological, mechanical, thermal, wear and morphological properties of melamine formaldehyde reinforced recycled ABS for sustainable manufacturing

This study outline the procedure of filament fabrication for fused deposition modelling (FDM), based upon rheological, mechanical, thermal, wear and morphological characterization as a case study of acrylonitrile butadiene styrene (ABS) - melamine formaldehyde (MF) composite. It has been ascertained that with increase in proportion of MF in ABS, viscosity is improved and melt flow index (MFI) is reduced significantly. As regards to the wear behavior is concerned it has been observed that ABS-MF (12.5 wt.%) composite has shown minimum weight loss and porosity. For the mechanical properties of the composite, experimental results show increased brittleness of the samples with addition of MF reinforcement. The thermal stability analysis was performed using differential scanning calorimetry (DSC) for virgin ABS and samples having 12.5% MF in ABS and results show the increased heat capacity of the material with increase in MF percentage. Further for sustainability analysis (based upon thermal stability), matrix of ABS-MF12.5% was subjected to three repeated thermal (heating-cooling) cycles and it has been ascertained that no significant loss was noticed in heat capacity of recycled composite matrix. The results are also supported by Fourier transform infrared spectroscopy (FTIR) analysis. Overall the results of the rheological, mechanical, wear, morphological and thermal properties suggested that 12.5% proportion of MF can be reinforced into selected grade of ABS thermoplastic for 3D printing as a sustainable solution