Bending yield strengths just exceeded loads expected in vivo. Multiaxial designs had lower static bending yield strength than fixed screw designs. Five out of six multiaxial screw designs achieved one million cycles at 200 N in compression bending. "Ball-in-cup" multiaxial locking mechanisms were vulnerable to fatigue failure. Smooth surfaces and thicker material appeared to be protective against fatigue failure.

Lumbar spine fusion is a common procedure associated with a high cost burden and risk of serious complications. We aimed to summarise systematic reviews on the effectiveness of lumbar spine fusion for most diagnoses. We found no high‐quality systematic reviews and the risk of bias of the randomised controlled trials in the reviews was generally high. The available evidence does not support a benefit from spine fusion compared to non‐operative alternatives for back pain associated with degeneration. The available evidence does not support a clinical benefit from spine fusion compared to non‐operative treatment or stabilisation without fusion for thoracolumbar burst fractures. Benefits of spine fusion compared to non‐operative treatment for isthmic spondylolisthesis are unclear (one trial at high risk of bias). Surgical intervention for metastatic carcinoma of the spine associated with spinal cord compromise improves mobility and neurological outcome (based on a single trial). Better evidence is required to determine more accurately the effectiveness of spine fusion surgery for all indications. Patients contemplating spinal fusion should be fully informed about the evidence base for their particular problem, including the relative potential benefits and harms of fusion compared with non‐operative treatments.

Study Design: Retrospective analysis of acute spinal cord injuries (ASCI). Objectives: Determine incidence of ASCI due to suicide attempt from 1970 to 2000. Describe demographics, injuries, mental illness, functional outcomes and nature of subsequent deaths. Setting: State spinal cord injury services, New South Wales, Australia. Methods: Retrospective record review and follow-up interview. Results: Of 2752 ASCI admissions, 56 were because of attempted suicide (55 falls, one gunshot wound). Thirty-six males and 20 females. Median age 30 years (15-74). Most common levels of vertebral injury were C5 and L1. Twenty-three had complete spinal cord injury. Thirtytwo had an Injury Severity Score of 415. Forty had more than one major injury. There was a significant rise in the incidence of ASCI following self-harm over time (Poisson regression, P ¼ 0.004). There was a significant change in scene of injury away from hospitals over time (w 2 test, df ¼ 1, P ¼ 0.0001). Psychiatric diagnoses were personality disorder 27; schizophrenia 16; depression 14; chronic alcohol abuse 10; mood disorder 10; chronic substance abuse 10; other four. Follow-up was available in 47 cases (84%) at an average of 8 years. Four subsequent deaths were by suicide. Domiciliary arrangements were: home 28; hospital five; nursing home three; group home/hostel four. Conclusions: Community placement outcomes for survivors were good. Subsequent death by suicide was high. There was a significant rise in cases and a change in injury scene away from hospitals over time.

IntroductionCentral lumbar spinal stenosis (LSS) is a common cause of pain, reduced function and quality of life in older adults. Current management of LSS includes surgery to decompress the spinal canal and alleviate symptoms. However, evidence supporting surgical decompression derives from unblinded randomised trials with high cross-over rates or cohort studies showing modest benefits. This protocol describes the design of the SUrgery for Spinal Stenosis (SUcceSS) trial —the first randomised placebo-controlled trial of decompressive surgery for symptomatic LSS.Methods and analysisSUcceSS will be a prospectively registered, randomised placebo-controlled trial of decompressive spinal surgery. 160 eligible participants (80 participants/group) with symptomatic LSS will be randomised to either surgical spinal decompression or placebo surgical intervention. The placebo surgical intervention is identical to surgical decompression in all other ways with the exception of the removal of any bone or ligament. All participants and assessors will be blinded to treatment allocation. Outcomes will be assessed at baseline and at 3, 6, 12 and 24 months. The coprimary outcomes will be function measured with the Oswestry Disability Index and the proportion of participants who have meaningfully improved their walking capacity at 3 months postrandomisation. Secondary outcomes include back pain intensity, lower limb pain intensity, disability, quality of life, anxiety and depression, neurogenic claudication score, perceived recovery, treatment satisfaction, adverse events, reoperation rate and rehospitalisation rate. Those who decline to be randomised will be invited to participate in a parallel observational cohort. Data analysis will be blinded and by intention to treat. A trial-based cost-effectiveness analysis will determine the potential incremental cost per quality-adjusted life year gained.Ethics and disseminationEthics approval has been granted by the NSW Health (reference:17/247/POWH/601) and the Monash University (reference: 12371) Human Research Ethics Committees. Dissemination of results will be via journal articles and presentations at national and international conferences.Trial registration numberACTRN12617000884303; Pre-results.