‹‹Skal jeg i grupperom igjen?›› En intervjuundersøkelse av elever som viser utagerende atferd

Objectives Few studies have assessed outcomes following non-metal-on-metal hip arthroplasty (nonMoMHA) revision surgery performed for adverse reactions to metal debris (ARMD). We assessed outcomes following non-MoMHA revision surgery performed for ARMD, and identified predictors of re-revision. Methods We performed a retrospective observational study using data from the National Joint Registry for England and Wales. All non-MoMHAs undergoing revision surgery for ARMD between 2008 and 2014 were included (185 hips in 185 patients). Outcome measures following ARMD revision were intra-operative complications, mortality and re-revision surgery. Predictors of re-revision were identified using Cox regression. Results Intra-operative complications occurred in 6.0% (n = 11) of the 185 cases. The cumulative four-year patient survival rate was 98.2% (95% CI 92.9 to 99.5). Re-revision surgery was performed in 13.5% (n = 25) of hips at a mean time of 1.2 years (0.1 to 3.1 years) following ARMD revision. Infection (32%; n = 8), dislocation/subluxation (24%; n = 6), and aseptic loosening (24%; n = 6) were the most common re-revision indications. The cumulative fouryear implant survival rate was 83.8% (95% CI 76.7 to 88.9). Multivariable analysis identified three predictors of re-revision: multiple revision indications (hazard ratio (HR) = 2.78; 95% CI 1.03 to 7.49; p = 0.043); selective component revisions (HR = 5.76; 95% CI 1.28 to 25.9; p = 0.022); and ceramic-on-polyethylene revision bearings (HR = 3.08; 95% CI 1.01 to 9.36; p = 0.047). Conclusions Non-MoMHAs revised for ARMD have a high short-term risk of re-revision, with important predictors of future re-revision including selective component revision, multiple revision indications, and ceramic-on-polyethylene revision bearings. Our findings may help counsel patients about the risks of ARMD revision, and guide reconstructive decisions. Future studies attempting to validate the predictors identified should also assess the effects of implant design (metallurgy and modularity), given that this was an important study limitation potentially influencing the reported prognostic factors

Prevalence of and Risk Factors for Hip Resurfacing Revision:A Cohort Study Into the Second Decade After the Operation

Background Most metal-on-metal hip resurfacing (MoMHR) designs have experienced high short-term failure rates because of pseudotumors. The impact of this complication into the second decade after the procedure is unknown. We investigated (1) the prevalence of, and risk factors for, all-cause and pseudotumor-related revision at up to 15 years following MoMHR and (2) whether risk factors were sex-specific. Methods This single-center prospective cohort study included 1,429 MoMHRs (1216 patients; 40% female) implanted between 1999 and 2009. Patients were contacted in 2010 and 2012 as per national recommendations. Patients with symptoms related to the hip and/or suboptimal Oxford Hip Scores (£41 of 48 points) underwent cross-sectional imaging and blood metal-ion sampling. Revision diagnoses were established using operative and histopathologicalfindings. Multivariate Cox proportional hazard models were used to assess the association of predictor variables with the time to all-cause and pseudotumor-related revisions. Results One hundred and eighty MoMHRs (12.6%) were revised for all causes, and 111 (7.8% of the series and 61.7 % of all revisions) were revised because of pseudotumor. Survival analysis showed the 15-year cumulative revision rate for all causes to be 19.5% (95% confidence interval [CI]=16.2% to 23.2%) and the 15-year rate of revision due to pseudotumor to be 14.0% (95% CI=11.0% to 17.7%). Small femoral head size (hazard ratio [HR] per 2 mm=0.92, 95% CI=0.88 to 0.97; p=0.003) and certain implant designs (HR=1.55 to 3.01; p£0.029) significantly increased the all-cause revision risk. Female sex (HR=2.03, 95% CI=1.19 to 3.44; p=0.009) and young age (HR per year=0.98, 95% CI=0.96 to 1.00; p= 0.020) significantly increased the pseudotumor-related revision risk but not the all-cause revision risk. Risk factors for allcause and pseudotumor-related revision were sex-specific. In females, small femoral head size (p=0.014) increased the allcause revision risk, and young age was the only predictor of pseudotumor-related revision (p=0.019). In males, implant design was the only predictor of all-cause revision (p£0.015) and pseudotumor-related revision (p=0.001). Conclusions The prevalence and rates of revision for all causes and pseudotumor were high at up to 15 years following MoMHR. Predictors of revision differed between all-cause and pseudotumor-related revisions and were sex-specific. These factors must be appropriately weighted when risk-stratifying patients with MoMHRs for surveillance

Return attribution analysis of the UK insurance portfolios

Insurance premiums, Monte Carlo integration, Non-negativity constraints, Return attribution, Sharpe style analysis, C1, C3, C5, E3, G2, G22,