Cervical external immobilization devices: evaluation of magnetic resonance imaging issues at 3.0 Tesla

External Orthopaedic Implants in the Magnetic Resonance Environment: Current Concepts and Controversies

MRI provides diagnostic three-dimensional imaging and remains extremely important in the diagnosis and management of spinal trauma as well as other acute traumatic injuries, including those of the extremities. The American Society for Testing and Materials has created standards against which all implantable medical devices are tested to ensure safety in an MR environment. Most implantable passive orthopaedic devices can undergo MRI without consequence to the patient. However, the American Society for Testing and Materials has recently updated its terminology resulting in confusion among providers and institutions. Primary safety concerns are radiofrequency-induced heating and magnetically induced torque or displacement. These safety concerns have emerged as a recent source of debate, particularly regarding the imaging of patients with external fixation and cervical immobilization devices in place. Surveys have shown a lack of consensus among radiologists regarding this issue. Having an institutional protocol in place for the imaging of these patients streamlines the diagnosis and early stabilization of certain polytraumatized patients. The purpose of this review is to summarize the pertinent literature as well as the current industry recommendations regarding the safety of commonly used external fixation, cervical immobilization, and traction devices in the MR environment.

Association of postoperative covert stroke and cognitive dysfunction among elderly patients undergoing non-cardiac surgery: protocol for a prospective cohort study (PRECISION study)

INTRODUCTION

The incidence of covert stroke and cognitive dysfunction has gradually increased due to an ageing population. Recently, a prospective cohort study reported perioperative covert stroke was associated with an increased risk of postoperative cognitive dysfunction (POCD) 1 year after non-cardiac surgery. However, the mechanism remains unclear.

METHODS AND ANALYSIS

This is a prospective observational trial aiming to investigate the cumulative incidence of perioperative covert stroke and test the hypothesis that perioperative covert stroke associates with POCD in elderly patients undergoing non-cardiac and non-neurological surgery. Data on risk factors, brain MRI, cognitive function evaluation and serum immune-inflammatory cytokines will be collected and analysed.

ETHICS AND DISSEMINATION

Ethical approval has been granted by the Medical Ethics Committee of Beijing Tiantan Hospital, Capital Medical University (reference number: KY2017-027-02). The results of this study will be disseminated through presentations at scientific conferences and publication in scientific journals.

TRIAL REGISTRATION NUMBER

NCT03081429.

Monitoring the use of halo fixation device through an assessment form

PURPOSE

To compare the use of the halo fixation device in our hospital before and after implementation of a new compliance protocol.

METHODS

From 2003 to 2008, 17 (47%) of 36 patients had dislodgement of their halo fixation device. All rings and vests and some of the pins were reused. Documentation of poundage assessment and change of skull pins before dislodgement was lacking. There was no protocol for assessing superstructure throughout the course of the application. To improve the standard of care, knowledge about the application of the halo fixation device in orthopaedic and orthotic departments was reinforced and compliance documented. From September 2008 to April 2010, 15 patients used the halo fixation device for cervical immobilisation. Patients were reminded to minimise shoulder shrugging and report any discomfort. Poundage checking was strictly observed during and after application. The integrity of the device was regularly checked by orthotists. The conditions of the skull pins, halo ring, and vest were also documented after removal.

RESULTS

Two (13%) of the 15 patients had ring dislodgement. One occurred a day after application owing to malposition of a posterior skull pin, and the other was related to a fall in a toilet at week 4. Both involved reused skull pins. 45% of the skull pins were new, whereas 44% were found defective after removal of rings. Compliance with the new assessment form was satisfactory.

CONCLUSION

Clinical audit improved outcome achieved with the halo fixation device. Reuse of titanium skull pins should be avoided. Re-torquing of the pin should be avoided when the tip is blunted or hooked. The new assessment form enabled compliance with the principle of application by orthotists and patients.