Failure Mode Analysis of an Exeter Stem Fracture Initiated at the Introducer Hole: Time for a Design Change?
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ABSTRACT:
SUBMITTER: Jeuken R
PROVIDER: S-EPMC8551419 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundThe purpose of this study was to compare the cumulative incidence of postoperative periprosthetic fracture (PPF) in a cohort of femoral neck fracture (FNF) patients treated with two commonly used cemented stems: either a collarless, polished, tapered Exeter stem or the anatomic Lubinus SP2 stem.MethodsIn this retrospective multicenter cohort study of a consecutive series of patients, we included 2528 patients of age 60 years and above with an FNF who were treated with either hemiarthroplasty or total hip arthroplasty using either a polished tapered Exeter stem or an anatomic Lubinus SP2 stem. The incidence of PPF was assessed at a minimum of 2 years postoperatively.ResultsThe incidence of PPF was assessed at a median follow-up of 47 months postoperatively. Thirty nine patients (1.5%) sustained a PPF at a median of 27 months (range 0-96 months) postoperatively. Two of the operatively treated fractures were Vancouver A (5%), 7 were Vancouver B1 (18%), 10 were Vancouver B2 (26%), 7 were Vancouver B3 (18%), and 13 were Vancouver C (32%). The cumulative incidence of PPF was 2.3% in the Exeter group compared with 0.7% in the SP2 group (p < 0.001). The HR was 5.4 (95% CI 2.4-12.5, p < 0.001), using the SP2 group as the denominator.ConclusionsThe Exeter stem was associated with a higher risk for PPF than the Lubinus SP2 stem. We suggest that the tapered Exeter stem should be used with caution in the treatment of FNF.Trial registrationThe study was registered at clinicaltrials.gov (identifier: NCT03326271).
| S-EPMC8187181 | biostudies-literature
Project description:Nucleosomes were reconstituted from recombinant histones and a 147-mer DNA sequence containing the damage reporter sequence 5'-…d([2AP]T[GGG](1)TT[GGG](2)TTT[GGG](3)TAT)… with 2-aminopurine (2AP) at position 27 from the dyad axis. Footprinting studies with ˙OH radicals reflect the usual effects of "in" and "out" rotational settings, while, interestingly, the guanine oxidizing one-electron oxidant CO(3)(˙-) radical does not. Site-specific hole injection was achieved by 308 nm excimer laser pulses to produce 2AP(˙+) cations, and superoxide via the trapping of hydrated electrons. Rapid deprotonation (~100 ns) and proton coupled electron transfer generates neutral guanine radicals, G(-H)˙ and hole hopping between the three groups of [GGG] on micro- to millisecond time scales. Hole transfer competes with hole trapping that involves the combination of O(2)(˙-) with G(-H)˙ radicals to yield predominantly 2,5-diamino-4H-imidazolone (Iz) and minor 8-oxo-7,8-dihydroguanine (8-oxoG) end-products in free DNA (Misiaszek et al., J. Biol. Chem. 2004, 279, 32106). Hole migration is less efficient in nucleosomal than in the identical protein-free DNA by a factor of 1.2-1.5. The Fpg/piperidine strand cleavage ratio is ~1.0 in free DNA at all three GGG sequences and at the "in" rotational settings [GGG](1,3) facing the histone core, and ~2.3 at the "out" setting at [GGG](2) facing away from the histone core. These results are interpreted in terms of competitive reaction pathways of O(2)(˙-) with G(-H)˙ radicals at the C5 (yielding Iz) and C8 (yielding 8-oxoG) positions. These differences in product distributions are attributed to variations in the local nucleosomal B-DNA base pair structural parameters that are a function of surrounding sequence context and rotational setting.
| S-EPMC3674890 | biostudies-literature
Project description:This report contains 2 acute fractures of the Exeter V40 stem with 2 different types of neck fracture, one at the subcapital level and another at the base of the neck. A review of relevant literature provides an insight into a similar pattern of failures reported in a certain subset of cases. We hypothesize that for high-BMI cases, attention to proper preoperative templating is mandatory. The operating surgeon should try to restore offset without having to use a long head in this subgroup of patients. We feel that trying to compensate for the offset with a long head may lead to high-stress concentration in the neck. This, in turn, may be responsible for the failure of the stem, as seen in the reported cases. We advocate, based on the literature, the need to recreate the offset carefully with as big a stem as possible to avoid these unique and rare complications. Reducing such failures may further improve the overall survivorship of the V40 Exeter stem.
| S-EPMC7818608 | biostudies-literature
Project description:It is generally observed that the existence of geometrical discontinuity like notches in materials will lead to strength weakening, as a resultant of local stress concentration. By comparing the influence of notches to the strength of three typical materials, aluminum alloys with intermediate tensile ductility, metallic glasses with no tensile ductility, and brittle ceramics, we observed strengthening in aluminum alloys and metallic glasses: Tensile strength of the net section in circumferentially notched cylinders increases with the constraint quantified by the ratio of notch depth over notch root radius; in contrast, the ceramic exhibit notch weakening. The strengthening in the former two is due to resultant deformation transition: Shear failure occurs in intact samples while samples with deep notches break in normal mode fracture. No such deformation transition was observed in the ceramic, and stress concentration leads to its notch weakening. The experimental results are confirmed by theoretical analyses and numerical simulation. The results reported here suggest that the conventional criterion to use brittleness and/or ductility to differentiate notch strengthening or weakening is not physically sound. Notch strengthening or weakening relies on the existence of failure mode transition and materials exhibiting shear failure while subjected to tension will notch strengthen.
| S-EPMC4448505 | biostudies-other
Project description:Recurrent event data arise frequently in various fields such as biomedical sciences, public health, engineering, and social sciences. In many instances, the observation of the recurrent event process can be stopped by the occurrence of a correlated failure event, such as treatment failure and death. In this article, we propose a joint scale-change model for the recurrent event process and the failure time, where a shared frailty variable is used to model the association between the two types of outcomes. In contrast to the popular Cox-type joint modeling approaches, the regression parameters in the proposed joint scale-change model have marginal interpretations. The proposed approach is robust in the sense that no parametric assumption is imposed on the distribution of the unobserved frailty and that we do not need the strong Poisson-type assumption for the recurrent event process. We establish consistency and asymptotic normality of the proposed semiparametric estimators under suitable regularity conditions. To estimate the corresponding variances of the estimators, we develop a computationally efficient resampling-based procedure. Simulation studies and an analysis of hospitalization data from the Danish Psychiatric Central Register illustrate the performance of the proposed method.
| S-EPMC5607035 | biostudies-literature
Project description:E.coli K-12 W3110 was grown in LB medium and harvested at each time point. And time-series microarray experiments were performed based on Sequential Design. In Sequential Design, the control sample is set to closest previous time point so that adjacent time points are compared directly. Combining with data from reference design, more accurate and reliable expression series could be collected. Keywords: timecourse
2018-03-01 | GSE6100 | GEO
Project description:E.coli K-12 W3110 was grown in LB medium and harvested at each time point. And time series microarray experiments were performed based on reference desgin. In reference design, the control sample is collected at one representative time point. Combining with data from sequential design, more acculate and reliable expression series could be collected. Keywords: Reference design
2011-03-31 | GSE6033 | GEO
Project description:IntroductionAchieving target door-needle times for ST elevation myocardial infarction remains challenging. Data on emergency department (ED) doctor-led thrombolysis in developing countries and factors causing delay are limited.ObjectivesTo assess the effect on door-needle times by transferring responsibility for thrombolysis to the ED doctors and to identify predictors of prolonged door-needle times.MethodologyData on medical on-call team-led thrombolysis at a tertiary Asian hospital were prospectively collected from May 2007 to Aug 2008 (1st study period). In September 2008, ED doctors were empowered to perform thrombolysis. The practice change was accompanied by new guidelines, tick chart implementation, and training sessions. Data were then consecutively collected from September 2008 to May 2009 (2nd study period). Door-to-needle times for the 1st and 2nd study periods were compared. All cases were analysed for factors of delay by multiple logistic regression.Results297 patients were thrombolysed, 169 by the medical on-call team during the 1st study period and 128 by the ED doctors during the 2nd study period. Median door-needle times were 54 and 48 min, respectively (p=0.76). Significant delays were predicted by 'incorrect initial ECG interpretation' (adjusted OR (aOR) 14.3), 'inappropriate triage' (aOR 10.4) and 'multiple referrals' (aOR 5.9). No cases of inappropriate thrombolysis were recorded.ConclusionsTransfer of responsibility for thrombolysis to the ED doctors did not improve door-needle times despite measures introduced to facilitate this change. Key causative factors for this failure were identified.
| S-EPMC3664394 | biostudies-literature
Project description:AimsThe Exeter short stem was designed for patients with Dorr type A femora and short-term results are promising. The aim of this study was to evaluate the minimum five-year stem migration pattern of Exeter short stems in comparison with Exeter standard stems.MethodsIn this case-control study, 25 patients (22 female) at mean age of 78 years (70 to 89) received cemented Exeter short stem (case group). Cases were selected based on Dorr type A femora and matched first by Dorr type A and then age to a control cohort of 21 patients (11 female) at mean age of 74 years (70 to 89) who received with cemented Exeter standard stems (control group). Preoperatively, all patients had primary hip osteoarthritis and no osteoporosis as confirmed by dual X-ray absorptiometry scanning. Patients were followed with radiostereometry for evaluation of stem migration (primary endpoint), evaluation of cement quality, and Oxford Hip Score. Measurements were taken preoperatively, and at three, 12, and 24 months and a minimum five-year follow-up.ResultsAt three months, subsidence of the short stem -0.87 mm (95% confidence interval (CI) -1.07 to -0.67) was lower compared to the standard stem -1.59 mm (95% CI -1.82 to -1.36; p < 0.001). Both stems continued a similar pattern of subsidence until five-year follow-up. At five-year follow-up, the short stem had subsided mean -1.67 mm (95% CI -1.98 to -1.36) compared to mean -2.67 mm (95% CI -3.03 to -2.32) for the standard stem (p < 0.001). Subsidence was not influenced by preoperative bone quality (osteopenia vs normal) or cement mantle thickness.ConclusionThe standard Exeter stem had more early subsidence compared with the short Exeter stem in patients with Dorr type A femora, but thereafter a similar migration pattern of subsidence until minimum five years follow-up. Both the standard and the short Exeter stems subside. The standard stem subsides more compared to the short stem in Dorr type A femurs. Subsidence of the Exeter stems was not affected by cement mantle thickness.
| S-EPMC10322230 | biostudies-literature
Project description:Background:Pelvic ring-comminuted transforaminal sacral fracture injuries are rotationally and vertically unstable and have a high rate of failure. Objective:Our study purpose was to use three-dimensional (3D) optical tracking to detect onset location of bone-implant interface failure and measure the distances and angles between screws and line of applied force for correlation to strength of pelvic fracture fixation techniques. Methods:3D relative motion across sacral-rami fractures and screws relative to bone was measured with an optical tracking system. Synthetic pelves were used. Comminuted transforaminal sacral-rami fractures were modelled. Each pelvis was stabilised by either (1) two iliosacral screws in S1, (2) one transsacral screw in S1 and one iliosacral screw in S1 and (3) one trans-alar screw in S1 and one iliosacral screw in S1; groups 4-6 consisted of fixation groups with addition of anterior inferior iliac pelvic external fixator. Eighteen-instrumented pelvic models with right ilium fixed simulate single-leg stance. Load was applied to centre of S1 superior endplate. Five cycles of torque was initially applied, sequentially increased until permanent deformation occurred. Five cycles of axial load compression was next applied, sequentially increased until permanent deformation occurred, followed by axial loading to catastrophic failure. A Student t test was used to determine significance (p < 0.05). Results:The model, protocol and 3D optical system have the ability to locate how sub-catastrophic failures initiate. Our results indicate failure of all screw-based constructs is due to localised bone failure (screw pull-in push-out at the ipsilateral ilium-screw interface, not in sacrum); thus, no difference was observed when not supplemented with external fixation. Conclusion:Inclusion of external fixation improved resistance only to torsional loading. Translational Potential of this Article:Patients with comminuted transforaminal sacral-ipsilateral rami fractures benefit from this fixation.
| S-EPMC6350021 | biostudies-other