Abstract Background Overuse of clinical laboratory testing in the inpatient setting is a common problem. The objective of this project was to develop an inexpensive and easily implemented ...intervention to promote rational laboratory use without compromising resident education or patient care. Methods The study comprised of a cluster-randomized, controlled trial to assess the impact of a multifaceted intervention of education, guideline development, elimination of recurring laboratory orders, unbundling of laboratory panels, and redesign of the daily progress note on laboratory test ordering. The population included all patients hospitalized “general medicine” was duplicated during 2 consecutive months on a general medicine teaching service within a 999-bed tertiary care hospital in Boston, Massachusetts. The primary outcome was the total number of commonly used laboratory tests per patient day during 2 months in 2008. Secondary outcomes included a subgroup analysis of each individual test per patient day, adverse events, and resident and nursing satisfaction. Results A total of 5392 patient days were captured. The intervention produced a 9% decrease in aggregate laboratory use (rate ratio, 0.91; P = .021; 95% confidence interval, 0.84-0.98). Six instances of delayed diagnosis of acute kidney injury and 11 near misses were reported in the intervention arm. Conclusions A bundled educational and administrative intervention promoting rational ordering of laboratory tests on a single academic general medicine service led to a modest but significant decrease in laboratory use. To our knowledge, this was the first study to examine the daily progress note as a tool to limit excessive test ordering. Unadjudicated near misses and possible harm were reported with this intervention. This finding warrants further study.
Abstract Background Modularity at the head-neck junction in total hip arthroplasty (THA) allows for intraoperative adjustments, but may be a source of metallic debris. We determined how flexural ...rigidity, taper angle, contact length, and lever arm affect fretting and corrosion at this junction. Methods 77 metal-on-polyethylene THAs retrieved over a 10-year period at a single institution were obtained. Head tapers and stem trunnions were graded for fretting and corrosion. Results Stem fretting was inversely related to rigidity and taper angle, while positively correlated to contact length. Head fretting and head and stem corrosion were not associated with any of these parameters. Conclusion Design and assembly factors at the modular head-neck connection affected stem fretting among the retrieved components, suggesting that these parameters are important to consider when choosing a modular system.
Abstract Background The severity and location of adverse local tissue reaction seen in metal-on-polyethylene (MoP) total hip arthroplasty (THA) is not well described. Methods We retrospectively ...reviewed the records of patients who underwent a revision THA using our biomechanics database. We included all patients who underwent revision surgery for the diagnosis of ALTR with THA implants that had modularity solely at the head-neck junction and excluded patients with implant modularity at sites other than the head-neck junction. Magnetic resonance imaging (MRI) was evaluated by a fellowship trained radiologist who specializes in evaluating metal artifact reducing MRI sequences in order to quantify the ALTR lesions. Histology was evaluated for findings of ALTR using the Campbell score. Results We identified eleven patients in the database. Eight patients had a MRI ALTR grade of severe and seven did based on the histology score. The mean synovial volume was 218,658 mm3 (range 23,461-451,435 mm3) with a mean maximal synovial thickness of 15.3 mm (range 3-34.3 mm). A disruptive infiltration of the abductors due to pseudocapsule invasion was seen in 67% of the patients with three not having abductor involvement. Mean preoperative cobalt and chromium levels were 5.4 ppb (range 1-12.3) and 1.1 ppb (range 0.6-2.4) respectively. Conclusion Patients with ALTR from head-neck junction corrosion in MoP THA may present with large pseudotumors that have previously been under appreciated. Mean preoperative serum cobalt and chromium ion levels remained relatively low, and MRI was an effective way to characterize the size and location of these lesions.
Abstract The aims of this study were to assess damage on the surface of retrieved oxidized zirconium (OxZr) metal femoral heads, to measure surface roughness of scratches, and to evaluate the extent ...of surface effacement using scanning electron microscopy (SEM). Ceramic zirconia-toughened alumina heads were analyzed for comparison. OxZr femoral heads explanted for recurrent dislocation had the most severe damage ( P < 0.001). The median surface roughness of damaged OxZr femoral heads was 1.49 μm, compared to 0.084 μm for damaged ceramic heads and 0.052 μm for undamaged OxZr ( P < 0.001). This may be of clinical concern because increased surface roughness has the potential to increase the wear of polyethylene liners articulating against these OxZr heads in THA.
Abstract Ceramic femoral heads have had promising results as a bearing surface in total hip arthroplasty. Our objective was to evaluate a series of retrieved alumina-zirconia composite ceramic ...femoral heads for evidence of the tetragonal to monoclinic zirconia phase transformation, metal transfer and articular surface roughness. Raman spectra showed evidence of the zirconia phase transformation in all retrieved specimens, with distinct monoclinic peaks at 183, 335, 383, and 479 cm − 1 . All components displayed metal transfer. An increase in the zirconia phase transformation was seen with increasing time in vivo. No correlation between extent of zirconia phase transformation and the surface roughness was found. These short-term results suggest that the use of an alumina-zirconia composite ceramic is a viable option for femoral heads in THA.
Abstract Objective methods for analyzing arthroplasty retrieval implants are needed. To address this, we used a readily available laser scanner to analyze damage deviations between cohorts of ...rotating platform and fixed bearing inserts previously analyzed using traditional, subjective retrieval analysis methods. We asked the following research questions: 1) Do articular surface deviations measured by the scanner correlate with the subjective damage scores? 2) Do articular surface deviations differ between inserts due to design differences? Correlations between deviations and damage scores were present in RP but not FB inserts. Seven different deviation patterns were present between the RP and FB inserts and were a function of design. In conclusion laser scanning was found to be a useful objective tool for analyzing arthroplasty retrievals.
Large angular deformities can be a challenge when performing primary total knee replacement. Some investigators have advocated the use of increased component constraint in these settings. The goal of ...this study was to determine the location and extent of damage to a consecutive series of retrieved constrained tibial inserts used in primary arthroplasty. There was significant post and articular damage in retrieved implants. Reliance on the polyethylene post for implant stability was associated with post and articular surface damage and may be a potential source of failure. Attempts to achieve implant stability using soft tissue techniques seem justified.
Abstract Eighty-six polyethylene liners and 56 metallic shells of acetabular components were evaluated by visual and stereomicroscopic examination for impingement, backside polyethylene wear, creep, ...and fretting at the screw-metallic shell interface using a subjective scoring system. Medical records and radiological data were available in 65 and 46 patients, respectively. Impingement was found in 62 components (75%). Backside polyethylene wear and screw-metallic shell corrosion and fretting were significantly correlated ( P < .001) with impingement. Polyethylene creep was significantly correlated to backside wear and tended to be higher for the cups that had impingement ( P = .06). No correlation was found between backside polyethylene wear and implant design or cup position. Our results suggest that impingement in a modular acetabular component correlated with increased backside wear and screw-metallic shell corrosion and fretting.
Abstract Despite the large loads placed upon constrained acetabular liners, little is known of their mechanical performance. We analyzed retrieved liners to determine wear and other damage modes and ...assess associations between types and severity of damage and clinical, radiographic, and implant variables. Outer rim impingement frequency and severity were higher than that for the inner rim. The 20° elevation was most frequently affected by impingement. Inner rim impingement was more frequent with small heads. Outer bearing surface wear scores were higher than inner bearing scores. Liners removed for infection or stem failure had similar damage compared with other groups, demonstrating the complex relationship of impingement and wear with clinical performance. No association was found between liner damage and clinical and radiographic variables.
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