Persistent soil carbon enhanced in Mollisols by well-managed grasslands but not annual grain or dairy forage cropping systems.

Intensive crop production on grassland-derived Mollisols has liberated massive amounts of carbon (C) to the atmosphere. Whether minimizing soil disturbance, diversifying crop rotations, or re-establishing perennial grasslands and integrating livestock can slow or reverse this trend remains highly uncertain. We investigated how these management practices affected soil organic carbon (SOC) accrual and distribution between particulate (POM) and mineral-associated (MAOM) organic matter in a 29-y-old field experiment in the North Central United States and assessed how soil microbial traits were related to these changes. Compared to conventional continuous maize monocropping with annual tillage, systems with reduced tillage, diversified crop rotations with cover crops and legumes, or manure addition did not increase total SOC storage or MAOM-C, whereas perennial pastures managed with rotational grazing accumulated more SOC and MAOM-C (18 to 29% higher) than all annual cropping systems after 29 y of management. These results align with a meta-analysis of data from published studies comparing the efficacy of soil health management practices in annual cropping systems on Mollisols worldwide. Incorporating legumes and manure into annual cropping systems enhanced POM-C, microbial biomass, and microbial C-use efficiency but did not significantly increase microbial necromass accumulation, MAOM-C, or total SOC storage. Diverse, rotationally grazed pasture management has the potential to increase persistent soil C on Mollisols, highlighting the key role of well-managed grasslands in climate-smart agriculture.

Femoral Head Penetration Rates and Oxidation of Highly Cross-Linked Polyethylene Hip Liners Implanted More Than 10 Years.

BACKGROUND: Highly cross-linked polyethylene (HXLPE) was introduced to improve wear in total hip arthroplasty, with manufacturers implementing different thermal treatments to reduce oxidation. It is important to understand how long-term time in vivo affects the wear of these materials. The purpose of this study was to investigate the wear and oxidative performance of first-generation HXLPE hip inserts implanted for greater than 10 years and compare annealed and remelted HXLPE formulations. METHODS: There were 49 total hip arthroplasty liners retrieved during routine revision surgery as part of an institutional review board-approved implant retrieval program. Penetration rates for the liners were calculated as the difference between the thickness of the unloaded and loaded regions divided by implantation time. Oxidation indices for the rim, locking mechanism, articulating surface, and backside regions were measured using Fourier-transform infrared spectroscopy according to American Society for Testing and Materials 2102. Mann-Whitney U tests were used to determine the statistical difference between annealed and remelted components. RESULTS: The cohort had an average implantation time of 13.1 ± 2.6 years for annealed and 12.1 ± 1.7 years for remelted components. The components were revised most often for polyethylene wear, instability, and loosening. The penetration rate averaged 0.0177 ± 0.014 mm/year for annealed components and 0.015 ± 0.022 mm/year for remelted components. Penetration rates did not differ between the remelted and annealed cohorts (P = .28). Oxidation indices were found to be significantly higher in the annealed cohort for all regions of interest (P < .001). CONCLUSIONS: Oxidation was found to be higher in the annealed HXLPE; however, this does not seem to be associated with greater wear as we found the average penetration rates for the cohorts were low, and the penetration rates were similar between the annealed and remelted cohorts.

Retrieval Analysis of Titanium Nitride Coatings for Orthopaedic Implants.

BACKGROUND: The first generation of titanium nitride (TiN) coatings for orthopaedic implants was clinically introduced in the 1990s because of their promising biocompatibility, wear resistance, and corrosion resistance. This study evaluated the in vivo performance of early TiN-coated knee and hip implants, focusing on the bearing surfaces and mechanisms of in vivo damage. METHODS: There were 13 TiN-coated implants (5 knee and 8 hip) retrieved from 8 patients as part of a multi-institutional implant retrieval program. The average implantation time was 4.25 years for knees and 17.5 years for hips. Implant revisions occurred for various reasons, including polyethylene wear, loosening, pain, infection, and instability. Components were examined using a semiquantitative scoring method, and surface roughness measurements were performed using white-light interferometry. Surface morphology, chemistry, and particle characterization were also assessed by scanning electron microscopy. RESULTS: For hips, mild corrosion was found on femoral head tapers, along with severe scratching on certain femoral heads. Knee implants exhibited low burnishing and scratching for both mechanisms. Roughness measurements (Sa) were 37.3 nm (interquartile range = 22.0 to 62.4) for hips and 85.3 nm (interquartile range = 66.3 to 110) for knees. The observed scratch depth in both hip and knee implants due to third-body particles ranged from 0.3 to 1.3 µm. The coating coverage remained intact in the majority of the implants, with 2 cases of small, localized cohesive chipping and substrate exposure. CONCLUSIONS: The results of this study confirm the potential in vivo durability of early TiN coatings and will be useful in benchmarking wear tests for modern TiN-coated orthopaedic implants.

Publication Rates of Poster and Podium Presentations at the American Association of Hip and Knee Surgeons Annual Meetings 2016 to 2019.

BACKGROUND: The objective of this study was to provide the poster and podium publication rates from the 2016 to 2019 American Association of Hip and Knee Surgeons (AAHKS) annual meetings and assess the quality of presentations ultimately published during this time. METHODS: Posters and podiums from 2016 to 2019 were located through the AAHKS e-poster and meeting archives. Titles were queried on Google, Google Scholar, and PubMed. Presentation title, topic type, number of authors, degrees held by first author, and award status were collected. For each identified full-text publication, journal name, study type, dates of online and print publication, and journal impact factor (JIF) were also obtained. RESULTS: A total of 1,274 abstracts were presented at the 2016 to 2019 AAHKS annual meetings with an overall publication rate of 67.8% (864 of 1,274). Podiums (4.0 months, 95% confidence interval [CI]: 3.0 to 4.0) were more likely to be published earlier than posters (7.0 months, 95% CI: 6.0 to 7.0) (P < .001). The median JIF of published abstracts was 3.3 (95% CI: 3.3 to 3.7) with no significant difference in mean JIF of published posters or podiums (3.3 ± 1.0 versus 3.3 ± 1.0, P = .554). The likelihood of publication was significantly higher for podiums (odds ratio [OR]: 3.41, 95% CI: 2.29 to 5.07, P < .001), award-winning presentations (OR: 4.78, 95% CI: 1.69 to 13.55, P = .003), and with more authors (OR: 1.09, 95% CI: 1.02 to 1.16, P = .014). DISCUSSION: This analysis demonstrates abstracts presented at the AAHKS annual meetings from 2016 to 2019 had an overall publication rate of 67.8%, with podiums (86.4%) 3 times as likely to be published as posters (63.6%). If selected to present at the AAHKS annual meeting, individuals can be confident that their work has a high chance of eventual publication.

Titanium-Titanium Junctions in the Knee Corrode, Generating Damage Similar to the Hip.

BACKGROUND: Previous studies identified corrosion between the modular tibial components of total knee arthroplasty (TKA) devices. In this study, we investigated the damage modes present in titanium-titanium (Ti-Ti) junctions in the knee. We asked: under typical in vivo cyclic loading conditions, will the same alloy damage modes from TKA devices resemble those documented in the hip? METHODS: A total of 50 paired titanium alloy tibial baseplates and stems were collected and semi-quantitatively analyzed using Goldberg corrosion scoring. To characterize damage, a subsection of moderately and severely corroded components was sectioned and imaged using scanning electron and digital optical microscopy. RESULTS: Of the 100 device components, 95% showed visual evidence of corrosion. The initial contact area between the stem and bore generally occurred 3 mm from the stem taper base. Scanning electron microscopy revealed four damage modes, including oxide film formation, crevice corrosion, selective dissolution, and pitting. CONCLUSIONS: Each of the damage modes identified in modular Ti-Ti tibial junctions was previously reported by total hip arthroplasty retrieval studies. Cumulatively, our results suggest that mechanically assisted crevice corrosion promoted this damage in vivo.

Comparison of Early Postoperative Step and Stair Counts With the Direct Anterior Approach Versus the Posterior Approach for Total Hip Arthroplasty.

BACKGROUND: The purpose of this study was to evaluate the impact of direct anterior approach (DAA) or posterior approach (PA) on step and stair counts after total hip arthroplasty using a remotely monitored mobile application with a smartwatch while controlling for baseline characteristics. METHODS: This is a secondary data analysis from a prospective cohort study of patients utilizing a smartphone-based care management platform. The primary outcomes were step and stair counts and changes from baseline through one year. Step and stair counts were available for 1,501 and 847 patients, respectively. Longitudinal regression models were created to control for baseline characteristics. RESULTS: Patients in the DAA group had significantly lower body mass index (P = .049) and comorbidities (P = .028), but there were no significant differences in age (P = .225) or sex (P = .315). The DAA patients had a higher average and improvement from baseline in step count at 2 and 3 weeks postoperatively after controlling for patient characteristics (P = .028 and P = .044, respectively). The average stair counts were higher for DAA patients at one month postoperatively (P = .035), but this difference was not significant after controlling for patient demographics. Average stair ascending speeds and changes from baseline were not different between DAA and PA patients. Descending stair speed was higher at 2 weeks postoperatively for DAA patients, but was no longer higher after controlling for baseline demographics. CONCLUSIONS: After controlling for baseline characteristics, DAA patients demonstrate earlier improvement in step count than PA patients after total hip arthroplasty. However, patient selection and surgeon training may continue to influence outcomes through a surgical approach.

Improved patient reported outcomes with the direct anterior approach versus the posterior approach for total hip arthroplasty in the early post-operative period.

BACKGROUND: Patients undergoing total hip arthroplasty (THA) with the direct anterior approach (DAA) may experience faster recovery but may also have better baseline health than those who undergo THA with the posterior approach (PA). This study aimed to compare patient-reported outcome measures (PROMs) between the DAA and PA while controlling for baseline factors. METHODS: This is a secondary data analysis from a prospective cohort study of patients utilizing a smartphone-based care management platform following THA. The primary outcomes were HOOS JR and EQ-5D-5L through 1 year and change from baseline. Longitudinal regression models were created to control for baseline characteristics and investigate the impact of surgical approach on PROMs. RESULTS: Of 1364 THAs evaluated, 731 (53.6%) were female, and 840 (61.6%) used the PA. Patients in the PA group were of similar age but had higher body mass index and comorbidity scores. Pre-operative HOOS JR and EQ-5D-5L were comparable, but higher post-operatively in the DAA group through 6 months (p = 0.03 and p = 0.005). At 1 year post-operatively, HOOS JR and EQ-5D-5L did not vary between groups (p = 0.48 and p = 0.56), nor did changes from baseline (p = 0.47 and p = 0.11). After controlling baseline characteristics, DAA was significantly associated with higher average HOOS JR through 6 months (p = 0.03) and EQ-5D-5L through 3 months (p = 0.005), but not at 12 months (p = 0.89 and p = 0.56). CONCLUSION: THA patients undergoing DAA demonstrate earlier improvements in HOOS JR and EQ-5D-5L. However, these differences may not be clinically significant and are not evident at 1-year post-operative. Patient selection and surgeon training may continue to affect outcomes by surgical approach.

Short-Term Surface Damage Mechanisms of Retrieved Highly Cross-Linked Polyethylene Patellar Components.

BACKGROUND: Previous retrieval studies of patellar components for total knee arthroplasty focused on historical designs and polyethylene materials that are no longer clinically relevant. Therefore, this study aimed to compare revision reasons and surface damage mechanisms of conventional, gamma inert sterilized polyethylene and highly cross-linked polyethylene (HXLPE) patellar components in contemporary designs from a single manufacturer. METHODS: A total of 114 gamma inert and 76 HXLPE patellar components were gathered in a multicenter orthopaedic implant retrieval program. Patient age and body mass index were similar between cohorts (P = .27 and P = .42, respectively); however, the gamma inert cohort was implanted longer (µdifference = 3.1 years; P = .005). A matched subset was created based on the total knee arthroplasty design, patellar shape, and implantation time. Revision reasons were gathered from revision operating notes, and surface damage was examined via the Hood scoring method. Differences between HXLPE and gamma inert cohorts were evaluated using Mann-Whitney U-tests. RESULTS: The most common revision reasons were infection, loosening, and instability, with the most common patellar complication resulting in revision being patellar loosening for both cohorts with similar incidences for both (chi-square; P = .60, P = .59). The most common surface damage modes were burnishing, scratching, and pitting in both cohorts. Total surface damage was significantly higher in the gamma inert components (P = .02), but not in the matched subset (P = .46). CONCLUSION: Overall, the clinical performance of HXLPE was similar to that of conventional polyethylene for patellar components with short implantation times. While this study provides much needed information on the performance of HXLPE patellae in short-term retrievals, long-term studies are still needed.

Are Corrosion and Material Loss a Threat for Titanium-Titanium Tapers in Total Hip Arthroplasty Modular Acetabular Components?

BACKGROUND: Extensive research has reported on fretting corrosion and material loss for a variety of metal taper interfaces in orthopedic devices. For modular acetabular shell-liner constructs, the interfaces studied thus far have consisted of mixed-metal pairings, and the risk of fretting corrosion and material loss for the all-titanium (Ti) shell-liner taper junction in one ceramic-on-ceramic (COC) design remains poorly understood. We asked: do Ti shell-liner taper interfaces in COC total hip arthroplasty devices show in vivo evidence of (1) fretting and/or corrosion, and (2) quantifiable potential material loss? METHODS: We examined 22 shell-liner pairs and 22 single liners from retrieved COC components. The taper interface surfaces were assessed for fretting corrosion using a semiquantitative scoring method and imaged with scanning electron microscopy. A subcohort of components was measured with a coordinate measuring machine, and volumetric material loss and maximum wear depth were calculated. RESULTS: Fretting corrosion at the taper interfaces was minimal to mild for 95% of liners and 100% of shells. Imaging revealed fretting marks within a band of corrosion on some implants and evidence of corrosion not in the proximity of mechanical damage. Estimated material loss ranged from 0.2 to 1.3 mm3 for liners, and 0.5 to 1.1 mm3 for shells. Maximum wear depth for all components was 0.03 mm or less. CONCLUSIONS: Our results indicate that, compared to other taper junctions in total joint arthroplasty, the risk of corrosion and material loss may be minimal for Ti shell-liner interfaces.

Hospital Charges Are Not Associated With Episode-of-Care Costs or Complications After Total Joint Arthroplasty.

BACKGROUND: The Centers for Medicare and Medicaid Services (CMS) now requires hospitals to publish charges for commonly performed procedures. This study aimed to evaluate compliance with the price transparency mandate and to determine if there is a correlation between hospital charges and episode-of-care claims costs and outcomes after total hip arthroplasty (THA) and total knee arthroplasty (TKA). METHODS: We identified a consecutive series of 2476 Medicare patients who underwent primary THA or TKA from 2018 to 2019 at one of 18 hospitals. Each hospital website was explored to assess compliance with the new price transparency requirements. Demographics, comorbidities, complications, and readmissions were recorded. Ninety-day episode-of-care claims costs were calculated using CMS claims data. Multivariate regression was performed to determine whether hospital charges had any association with complications, readmissions, or episode-of-care costs. RESULTS: There was no correlation between published hospital charges and inpatient costs (r = 0.087), postacute care costs (r = 0.126), or episode-of-care costs (r = 0.131). When controlling for demographics and comorbidities, there was no association between published charges and complications (P = .433) or readmissions (P = .141). All hospitals posted some shoppable services information online, but only 7 (39%) were fully compliant by publishing all price data. Of the 11 hospitals (61%) publishing hospital THA and TKA charges, the mean charge was $48,325 (range, $12,625-$79,531). CONCLUSION: Published charges for TKA and THA had no correlation with episode-of-care claims costs and were not associated with clinical outcomes. Despite efforts by CMS to increase price transparency, few hospitals were fully compliant, and a wide range in published charges was found.

Patient Satisfaction with Orthopedic Telemedicine Health Visits During the COVID-19 Pandemic.

Background:Telemedicine usage in orthopedic surgery has seen a dramatic increase as a result of the severe acute respiratory syndrome coronavirus 2 pandemic. The purpose of this study was to examine patient perceptions with telemedicine at a large orthopedic practice.Materials and Methods:An anonymous online survey was distributed to all patients who received a telemedicine health visit at our institution for musculoskeletal complaints from March 17 to June 1, 2020. Responses were scored on a 5-point Likert scale (strongly disagree, disagree, neutral, agree, and strongly agree, 1-5) and analyzed by average score and percent reaching top box.Results:A majority of patients (76.5%) were satisfied with their visit, and only 19.2% did not want telemedicine as a future option. Patients who presented for follow-up visits (4.11 vs. 3.94, p = 0.0053; 48% vs. 41%, p = 0.02) and utilized video (4.21 vs. 3.88, p < 0.001; 51% vs. 39%, p < 0.001) were more satisfied. Average satisfaction between older (>65 years) and younger patients was similar (4.06 vs. 4.06, p = 0.97), however, younger patients were more likely to reach top box (42% vs. 51%, p < 0.001). Confidence that the physician came to the correct diagnosis (r = 0.78, p < 0.001) and receiving the same information and care as an in-office visit (r = 0.60, p < 0.001) demonstrated the strongest correlation with satisfaction and desire for future telemedicine visits, respectively. Interestingly, 31.1% of patients would have sought treatment elsewhere had telemedicine not been an option.Conclusions:Overall, satisfaction rates are high for orthopedic patients undergoing telemedicine visits. Patients are more confident in telemedicine when presenting for a follow-up visit and with the use of video.

Identifying factors related to school closures due to COVID-19 in the Middle East and North Africa region.

The COVID-19 pandemic has had devastating effects on the Middle East and North Africa (MENA) region, and MENA states have taken dramatic steps in response. This study focuses on school closures, an intervention that all MENA states adopted, some much earlier than others. It seeks to identify policy factors related to MENA governments' decisions to close schools during the first wave of the pandemic. Results suggest external issues regarding temporal and geographic diffusion played the largest role. They also indicate that factors related to disease risk, the economy, political institutions, and women's position in society mattered as well, all of which suggest the decisions were complex.

Distal Femoral Replacement and Periprosthetic Joint Infection After Non-Oncological Reconstruction: A Retrospective Analysis.

BACKGROUND: Distal femoral replacement (DFR) is commonly used to manage massive bone loss around the knee arising from aseptic loosening, periprosthetic joint infection (PJI), and distal femoral fractures. A number of studies report the outcome of DFR with considerable variation in long-term survivorship. This study investigated the outcome of DFR for patients with aseptic failures, fractures, and PJI. METHODS: A retrospective review of 182 patients who underwent DFR for non-oncological indications between 2002 and 2018 was conducted. Data collected included the following: indication, postoperative complications, reoperation, revision, and follow-up. Implant survivorship with Kaplan-Meier curves along with a log-rank test for different preoperative indications was performed. A Cox regression model was used to evaluate the risk of revision. RESULTS: The overall postoperative complication rate was very high at 36%. The most common complication was PJI (17%). The rate of reoperation for any cause was 29.7%, and the revision rate was 13.7%. The most common cause of re-revision was PJI (7.1%). Revision-free survivorship of the DFR implant was 91.6% at 1 year, 87.9% at 2 years, 82.5% at 5 years, and 73.4% at 10 years. Patients who had a prior-PJI had the lowest survivorship compared to patients undergoing DFR for management of periprosthetic fracture and mechanical loosening. Additionally, the prior-PJI group was at a fourfold increased risk of postoperative PJI compared to the aseptic group. CONCLUSION: DFR is a valuable reconstructive option for patients with massive bone loss around the knee. However, patients undergoing DFR are at high risk of complications, reoperations, and failure.

Fretting Corrosion, Third-Body Polyethylene Damage, and Cup Positioning in Primary vs Revision Dual Mobility Total Hip Arthroplasty.

BACKGROUND: Dual mobility (DM) articulations were introduced for total hip arthroplasty to reduce the risk of instability for patients who have a high risk of dislocation. The use of DM constructs in both primary and revision total hip arthroplasty has been steadily increasing, leading to concerns regarding potential risks of fretting corrosion, polyethylene wear, metal release, and failure due to component positioning. METHODS: A total of 56 retrieved DM constructs were collected. The inner and outer polyethylene liner surfaces were assessed for 7 damage mechanisms, and fretting corrosion was evaluated for the femoral stem, head, and modular liner. Three polyethylene liners with the greatest amounts of embedded debris were examined using scanning electron microscopy. Energy-dispersive X-ray spectroscopy was used to determine the elemental content of the debris. Acetabular cup orientation was analyzed radiographically using the EBRA (Einzel-Bild-Roentgen-Analyse) method. RESULTS: The devices were revised most frequently for infection (36%), loosening (21%), and instability/dislocation (18%). The most common polyethylene damage mechanisms were scratching, pitting, burnishing, and embedded debris, and no difference in total damage was found between primary and revision cases. Scanning electron microscopy/energy-dispersive X-ray spectroscopy revealed that debris morphology and composition were consistent with porous titanium coating, resulting from cup loosening or broken screws and augments. A total of 71% and 50% of the constructs were determined to be within the Lewinnek safe zone for inclination and anteversion, respectively. CONCLUSION: The most notable mechanisms of surface damage were due to third-body debris, especially for the polyethylene surfaces which articulate against cobalt-chromium femoral heads and acetabular liners. Scratching of the femoral head and the metal liner from this debris may support the clinical use of ceramic for DM bearing surfaces in the future.

Genetic evidence supports a range extension for the Brazilian cownose ray Rhinoptera brasiliensis in the western North Atlantic.

We report 24 new records of the Brazilian cownose ray Rhinoptera brasiliensis outside its accepted geographic range. Sequencing of a 442-base pair portion of the mitochondrial NADH dehydrogenase subunit 2 gene for 282 Rhinoptera samples revealed eight records off the east coast of the USA and 16 from the eastern Gulf of Mexico. Both sexes of all life stages were documented in all seasons over multiple years in the Indian River and Lake Worth lagoons, Florida, indicating that their range extends further in the western North Atlantic than previously described.

Thermal performance responses in free-ranging elasmobranchs depend on habitat use and body size.

Temperature is one of the most influential drivers of physiological performance and behaviour in ectotherms, determining how these animals relate to their ecosystems and their ability to succeed in particular habitats. Here, we analysed the largest set of acceleration data compiled to date for elasmobranchs to examine the relationship between volitional activity and temperature in 252 individuals from 8 species. We calculated activation energies for the thermal performance response in each species and estimated optimum temperatures using an Arrhenius breakpoint analysis, subsequently fitting thermal performance curves to the activity data. Juveniles living in confined nursery habitats not only spent substantially more time above their optimum temperature and at the upper limits of their performance breadths compared to larger, less site-restricted animals, but also showed lower activation energies and broader performance curves. Species or life stages occupying confined habitats featured more generalist behavioural responses to temperature change, whereas wider ranging elasmobranchs were characterised by more specialist behavioural responses. The relationships between the estimated performance regimes and environmental temperature limits suggest that animals in confined habitats, including many juvenile elasmobranchs within nursery habitats, are likely to experience a reduction of performance under a warming climate, although their flatter thermal response will likely dampen this impact. The effect of warming on less site-restricted species is difficult to forecast since three of four species studied here did not reach their optimum temperature in the wild, although their specialist performance characteristics may indicate a more rapid decline should optimum temperatures be exceeded.

Invasive mammal eradication on islands results in substantial conservation gains.

More than US$21 billion is spent annually on biodiversity conservation. Despite their importance for preventing or slowing extinctions and preserving biodiversity, conservation interventions are rarely assessed systematically for their global impact. Islands house a disproportionately higher amount of biodiversity compared with mainlands, much of which is highly threatened with extinction. Indeed, island species make up nearly two-thirds of recent extinctions. Islands therefore are critical targets of conservation. We used an extensive literature and database review paired with expert interviews to estimate the global benefits of an increasingly used conservation action to stem biodiversity loss: eradication of invasive mammals on islands. We found 236 native terrestrial insular faunal species (596 populations) that benefitted through positive demographic and/or distributional responses from 251 eradications of invasive mammals on 181 islands. Seven native species (eight populations) were negatively impacted by invasive mammal eradication. Four threatened species had their International Union for the Conservation of Nature (IUCN) Red List extinction-risk categories reduced as a direct result of invasive mammal eradication, and no species moved to a higher extinction-risk category. We predict that 107 highly threatened birds, mammals, and reptiles on the IUCN Red List-6% of all these highly threatened species-likely have benefitted from invasive mammal eradications on islands. Because monitoring of eradication outcomes is sporadic and limited, the impacts of global eradications are likely greater than we report here. Our results highlight the importance of invasive mammal eradication on islands for protecting the world's most imperiled fauna.

Reasons for Revision, Oxidation, and Damage Mechanisms of Retrieved Vitamin E-Stabilized Highly Crosslinked Polyethylene in Total Knee Arthroplasty.

BACKGROUND: In order to improve oxidation resistance, antioxidants such as vitamin-E are added to polyethylene used in the bearing surfaces of orthopedic components. Currently, little is known about the efficacy of this treatment in vivo. This study therefore reports on the reasons for revision, surface damage mechanisms, and oxidation of retrieved vitamin E-stabilized highly crosslinked polyethylene (HXLPE) for total knee arthroplasty. METHODS: We examined 103 retrieved knee inserts fabricated from vitamin E (VE)-stabilized HXLPE and 67 fabricated from remelted HXLPE as a control. The implantation times were 1.2 ± 1.3 and 1.5 ± 1.3 years for the VE and control cohorts, respectively. The inserts were evaluated for 7 surface damage mechanisms using a semiquantitative scoring method and analyzed for oxidation using Fourier-transform infrared spectroscopy. Reasons for revision were also assessed using operative notes created at time of retrieval. RESULTS: Both groups were revised primarily for instability, infection, and loosening. Burnishing, pitting, and scratching were the most common damage mechanisms observed, with the VE cohort demonstrating less surface damage than the control. Measured oxidation for the cohort was low, with a median oxidation index of 0.09 ± .05 for the articulating surface, 0.05 ± 0.06 for the backside, 0.08 ± 0.06 for the anterior/posterior surfaces, and 0.08 ± 0.05 for the stabilizing post. As compared to the control cohort, oxidation tended to be less for the VE group at the articulating (P < .001) and backside (P = .003) surfaces, although the median differences were minimal and may not be clinically significant. CONCLUSION: The results indicate positive fatigue damage resistance and oxidation resistance for the retrieved VE-stabilized total knee arthroplasty inserts.