Aims To investigate metallosis in patients with magnetically controlled growing rods (MCGRs) and characterize the metal particle profile of the tissues surrounding the rod. Methods This was a prospective observational study of patients with early onset scoliosis (EOS) treated with MCGRs and undergoing rod exchange who were consecutively recruited between February 2019 and January 2020. Ten patients were recruited (mean age 12 years (SD 1.3); 2 M:8 F). The configurations of the MCGR were studied to reveal the distraction mechanisms, with crucial rod parts being the distractable piston rod and the magnetically driven rotor inside the barrel of the MCGR. Metal-on-metal contact in the form of ring-like wear marks on the piston was found on the distracted portion of the piston immediately outside the barrel opening (BO) through which the piston rod distracts. Biopsies of paraspinal muscles and control tissue samples were taken over and away from the wear marks, respectively. Spectral analyses of the rod alloy and biopsies were performed to reveal the metal constituents and concentrations. Histological analyses of the biopsies were performed with haematoxylin and eosin staining. Results Titanium (Ti), vanadium (V), and neodymium (Nd) concentrations in the biopsies taken near the wear marks were found to be significantly higher than those in the control tissue samples. Significantly increased Nd concentrations were also found in the tissues near the barrel of the MCGR. Chronic inflammation was revealed by the histological studies with fibrosis and macrophage infiltration. Black particles were present within the macrophages in the fibrotic tissues. Conclusion Ti and V were generated mainly at the BO due to metal-on-metal contact, whereas the Nd from the rotor of the MCGR is likely released from the BO during distraction sessions. Phagocytotic immune cells with black particles inside raise concern regarding the long-term implications of metallosis. Cite this article: Bone Joint J 2020;102-B(10):1375–1383.
3D printing in the context of medical application can allow for visualization of patient-specific anatomy to facilitate surgical planning and execution. Intra-operative usage of models and guides allows for real time feedback but ensuring sterility is essential to prevent infection. The additive manufacturing process restricts options for sterilisation owing to temperature sensitivity of thermoplastics utilised for fabrication. Here, we review one of the largest single cohorts of 3D models and guides constructed from Acrylonitrile butadiene styrene (ABS) and utilized intra-operatively, following terminal sterilization with hydrogen peroxide plasma. We describe our work flow from initial software rendering to printing, sterilization, and on-table application with the objective of demonstrating that our process is safe and can be implemented elsewhere. Overall, 7% (8/114 patients) of patients developed a surgical site infection, which was not elevated in comparison to related studies utilizing traditional surgical methods. Prolonged operation time with an associated increase in surgical complexity was identified to be a risk factor for infection. Low temperature plasma-based sterilization depends upon sufficient permeation and contact with surfaces which are a particular challenge when our 3D-printouts contain diffusion-restricted luminal spaces as well as hollows. Application of printouts as guides for power tools may further expose these regions to sterile bodily tissues and result in generation of debris. With each printout being a bespoke medical device, it is important that the multidisciplinary team involved in production and application understand potential pitfalls to ensuring sterility as to minimize infection risk.
Study Design Systematic review and meta-analysis Objectives The present review aimed to summarize the evidence regarding differences in proprioception between children with and without adolescent idiopathic scoliosis (AIS). Methods Seven electronic databases were searched from their inception to April 10, 2021. Articles were included if they involved: (1) AIS patients aged between 10 and 18 years, (2) measurements of proprioceptive abilities, and (3) comparisons with non-AIS controls. Animal studies, case reports, commentaries, conference proceedings, research protocols, and reviews were excluded. Two reviewers independently conducted literature screening, data extraction, risks of bias assessments, and quality of evidence evaluations. Relevant information was pooled for meta-analyses. Results From 432 identified citations, 11 case-control studies comprising 1121 participants were included. The meta-analyses showed that AIS participants displayed proprioceptive deficits as compared to non-AIS controls. Moderate evidence supported that AIS participants showed significantly larger repositioning errors than healthy controls (pooled mean difference = 1.27 degrees, P < .01). Low evidence substantiated that AIS participants had significantly greater motion detection threshold (pooled mean difference = 1.60 degrees, P < .01) and abnormal somatosensory evoked potentials (pooled mean difference = .36 milliseconds, P = .01) than non-AIS counterparts. Conclusions Consistent findings revealed that proprioceptive deficits occurred in AIS patients. Further investigations on the causal relationship between AIS and proprioception, and the identification of the subgroup of AIS patients with proprioceptive deficit are needed.
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