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Background: In an earlier study with a 2-year follow-up of uncemented cups, we had reported low femoral-head penetration of vitamin E-infused highly cross-linked polyethylene liners (E1) compared with highly cross-linked liners without vitamin E (ArComXL). We studied the penetration rate of E1 compared with that of ArComXL, with a focus on changes occurring between 2 and 5 years after total hip arthroplasty.Methods: In this randomized controlled study, we performed radiostereometric analysis of the penetration rate up to 5 years in 63 hips.Results: During the total period of observation, the median proximal penetration for E1, 0.13 mm (mean, 0.11 mm [95% confidence interval (CI), 0.08 to 0.14 mm]), was lower than that for ArComXL, 0.20 mm (mean, 0.22 mm [95% CI, 0.17 to 0.26 mm]). The median proximal penetration rate between 2 and 5 years was 0.02 mm/yr (mean, 0.01 mm/yr [95% CI, 0.01 to 0.02 mm/yr]) for E1 and 0.04 mm/yr (mean, 0.04 mm/yr [95% CI, 0.03 to 0.05 mm/yr) for ArComXL. The corresponding median total (i.e., 3-dimensional resultant) penetration rates were 0.04 mm/yr (mean, 0.04 mm/yr [95% CI, 0.03 to 0.05 mm/yr]) for E1 and 0.07 mm/yr (mean, 0.08 mm/yr [95% CI, 0.06 to 0.10 mm/yr]) for ArComXL.Conclusions: From years 2 to 5, we observed increased penetration in both groups. The penetration rate was higher for ArComXL, resulting in more proximal and total penetration at 5 years than for E1.Level Of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Background: Radiostereometry (RSA) measurements of early micromotion can predict later failure in hip and knee prostheses. In hip implants, RSA has been particularly helpful in the evaluation of composite-beam stem designs. The Spectron EF Primary stem (Smith & Nephew, London, UK) has shown inferior performance compared with its predecessors in both clinical studies and registry reports. Early RSA studies have shown somewhat greater subsidence for the Spectron EF Primary stem compared with the earlier Spectron EF, but still within boundaries considered to be safe.Questions/purposes: Our primary research question was whether stem subsidence and rotation for this stem design measured with RSA at 2 years can predict later stem failure. A secondary question was whether high femoral stem offset and small stem sizes, both features specific to the Spectron EF Primary stem compared with its predecessors, are associated with stem failure rate.Methods: Two hundred forty-seven hips (209 patients with median age 63 years [range, 29-80 years], 65% female, and 77% primary osteoarthritis) with a valid RSA examination at 2 years were selected from four different RSA studies (totaling 279 hips in 236 patients) in our department. The studies were primarily aimed at evaluating cup fixation, bone cement, and polyethylene types. All study patients received a cemented Spectron EF Primary stem. The selected hips had complete followup until stem failure, death, or the end of the followup period. Stem failure was defined as revision of a loose femoral stem or radiological failure with significant osteolysis in Gruen zones 2 to 6. Cox regression analyses were performed to evaluate if stem subsidence and rotation after 2 years, adjusted for age, sex, stem size, standard/high stem offset, and conventional/highly crosslinked polyethylene, could predict later clinical aseptic failure of the stem. We identified 32 stem failures (27 revisions, five radiological failures) at 14 years median followup (range, 3-18 years). Ten-year stem survival was 94% (95% confidence interval [CI], 90%-96%).Results: Stem subsidence at 2 years (adjusted hazard ratio [HR], 6.0; 95% CI, 2.5-15; p < 0.001) and retrotorsion of the stem (adjusted HR, 1.7; 95% CI, 1.1-2.5; p = 0.018) were associated with later stem failure. Further risk factors were male sex (subsidence analysis HR, 6.9; p > 0.001), use of the two smallest stem sizes (HRsize 1, 8.0; p > 0.001, HRsize 2, 1 [reference], HRsize 3+, 0.06; p = 0.035), and the high offset option (HR, 3.1; p = 0.005).Conclusions: Stem subsidence and retrotorsion at 2 years can predict later failure in the Spectron EF Primary stem, consistent with earlier findings on composite-beam cemented stems. Small stem size and high-offset stems comprise the main group of underperforming stems. We recommend that premarket small-scale RSA studies be performed after any design change to a THA femoral component, because even seemingly minor design changes may unexpectedly result in inferior performance.Level Of Evidence: Level III, therapeutic study. [ABSTRACT FROM AUTHOR]

Background: Highly cross-linked polyethylene infused with vitamin E (E-poly) was developed to increase oxidative resistance without affecting mechanical properties. We evaluated this type of polyethylene in a randomized clinical study that used radiostereometric analysis. Our objective was to compare the early-term femoral head penetration of an E-poly liner with that of a heat-treated polyethylene liner, ArComXL. We hypothesized that the clinical outcome at two years following total hip arthroplasty would be unaffected by the choice of polyethylene.Methods: In this prospective study, sixty-one patients (seventy hips) with noninflammatory hip osteoarthritis and a median age of fifty-eight years were randomized to receive either an implant with an E-Poly or a heat-treated highly cross-linked polyethylene liner. The patients were followed for two years and evaluated at three time points (three months, one year, and two years).Results: The median proximal penetration in the E-poly group increased from 0.04 mm at three months to 0.06 mm at two years of follow-up. Corresponding values for the ArComXL group were 0.03 mm and 0.10 mm. In both groups, significantly increased penetration was observed between three months and two years (E-poly, p = 0.02; ArComXL, p < 0.001), but between one and two years, the increase was significant only in the control group (E-poly, p = 0.23; ArComXL, p = 0.002).Conclusions: The femoral head penetration of E-poly was very low at two years. Whether the increase observed between three months and two years was caused by creep, deformation, wear, or a combination of these cannot be determined by our study. There were no significant differences observed in femoral head penetration rates between E-poly and ArComXL. Currently, the theoretical advantages of E-poly remain to be confirmed. [ABSTRACT FROM AUTHOR]

Background: Polyethylene (PE) wear particles are believed to cause aseptic loosening and thereby impair function in hip arthroplasty. Highly crosslinked polyethylene (XLPE) has low short- and medium-term wear rates. However, the long-term wear characteristics are unknown and it is unclear whether reduced wear particle burden improves function and survival of cemented hip arthroplasty. Questions/purposes: We asked whether XLPE wear rates remain low up to 10 years and whether this leads to improved implant fixation, periprosthetic bone quality, and clinical function compared to conventional PE. Methods: We randomized 60 patients (61 hips) to receive either PE or XLPE cemented cups combined with a cemented stem. At 10 years postoperatively, 51 patients (52 hips) were evaluated for polyethylene wear and component migration estimation by radiostereometry, for radiolucent lines, bone densitometry, and Harris hip and pain scores. Revisions were recorded. Results: XLPE cups had a lower mean three-dimensional wear rate between 2 and 10 years compared to conventional PE hips: 0.005 mm/year versus 0.056 mm/year. We found no differences in cup migration, bone mineral density, radiolucencies, functional scores, and revision rate. There was a trend toward improved stem fixation in the XLPE group. The overall stem failure rate was comparably high, without influencing wear rate in XLPE hips. Conclusions: XLPE displayed a low wear rate up to 10 years when used in cemented THA, but we found no clear benefits in any other parameters. Further research is needed to determine whether cemented THA designs with XLPE are less prone to stem loosening. Level of Evidence: Level I, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Introduction: Cardiovascular outcome trials (CVOTs) are essential to explore the long term cardiovascular effects of medicines, and since 2008 it is also mandatory for all new antidiabetic drugs, targeting T2DM, to demonstrate CV no harm. Since CVOTs normally recruit thousands of patients and are running for many years, trial design is extra important since an incorrect estimate of the expected event rate can generate unwelcome costs and delays. Hypothesis: In this work, we investigate the prevalence and rate of over optimistic event rate estimation when designing outcomes trials and its potential impact on chance of successful trials. Methods: In this systematic review, we compare predicted event rate, extracted from earliest available study protocol, to reported event rate, from main publication in NEJM or Lancet, in all CVOTs with at least 1000 subjects published between start of 2010 and end of 2016. A linear regression model was used estimate relation between predicted and observed event rate. A model weighted on planned follow-up (patient years) as well as sensitivity analyses on several covariates were also performed. Logistic regression was used to test covariate influence on likelihood of trial success. Results: Out of 2205 articles, 173 trials were identified and 78 were eligible for the analysis. On average, the observed event rate was 14 percent lower (slope=0.86, p<0.0001) than what was originally predicted in the study protocol. In the model weighted on planned patient years, the overestimation was 24 percent. Publication year, journal, Industry or non-industry sponsor, active comparator or primary endpoint (MACE, MACE+ or other) did not affect the predictability. Thirty of the 78 trials (38 percent) met their primary objective. Most variables did not influence likelihood of success, but non-inferiority trials were more likely to succeed than superiority studies, 76.9% vs 30.8%, respectively. Conclusions: In CVOTs reported during 2010-2016, the estimation of event rate in general was significantly over-optimistic. The consequences of such mispredictions normally result in prolonged study duration, increased sample size or a decreased power. To decrease the risk when investments are made in CVOTs, the identification of highly relevant source data is critical. [ABSTRACT FROM AUTHOR]