An MRI study demonstrating consistent anatomic relation of central longitudinal artery and associated periosteal vessels with the medial femoral epicondyle and adductor tubercle-A visual landmark method for femoral tunnel placement in medial patellofemoral ligament reconstruction.

The two most common techniques to determine femoral tunnel placement during medial patellofemoral ligament (MPFL) reconstruction are radiographic and by palpation. Their intra/interobserver reliability is widely debated. Both techniques rely on identifying bony landmarks such as the medial epicondyle (ME) and adductor tubercle (AT) during surgery. During MPFL reconstructive surgery, the central longitudinal vessels (CLVs) are seen consistently. The aim of this study was to investigate the anatomic relationship of CLV to ME and AT and to determine if CLV might be used as a landmark during MPFL reconstruction. A retrospective review of MRI scans in skeletally mature patients was undertake. There were two groups, a PFI group that consisted of patients with a diagnosis of patellofemoral instabiliy (PFI) and a non-PFI group that underwent MRI scan for an alternative diagnosis. MRIs were measured for the CLV-ME-AT anatomy and relationship. Following exclusions, 50 patients were identified in each group. The CLV passed anterior to the AT and ME in all patients. ME morphology did not differ greatly between the groups except in the tubercle height, where there was statistically significant but not a clinically important difference (larger in the non-PFI group, 2.95 vs. 2.52 mm, p = 0.002). The CLV to ME tip distance was consistent between the groups (PFI group 3.8 mm and non-PFI group 3.9 mm). The CLV-ME-AT relationship remained consistent irrespective of patients' presenting pathology. The CLV consistently courses anterior to ME and AT. The CLV could be used as a vascular landmark assisting femoral tunnel placement during MPFL reconstruction.

"Right now, it's kind of haphazard"-Pediatric emergency care coordinators and quality of emergency care for children: A qualitative study.

Objectives: Pediatric readiness varies widely among emergency departments (EDs). The presence of a pediatric emergency care coordinator (PECC) has been associated with improved pediatric readiness and decreased mortality, but adoption of PECCs has been limited. Our objective was to understand factors associated with PECC implementation in general EDs. Methods: We conducted semistructured qualitative interviews with a purposively sampled set of EDs with and without PECCs. Interviews were completed, transcribed, and coded until thematic saturation was reached. Themes were identified through a consensus process and mapped to the Consolidated Framework for Implementation Research (CFIR). Results: Twenty-four interviews were conducted and mapped to themes related to innovation, individuals and implementation process, outer setting (health system), and inner setting (hospital/ED). Addressing innovation, individuals, and implementation process, the primary theme was variability in how the PECC role was defined and who was responsible for implementing it. Regarding the outer setting, participants reported that limited system resources affected their ability to implement the PECC role. Key inner setting themes included concerns about limited visit volume, a lack of systems for measuring pediatric quality of care, and significant tension around change. Conclusions: Implementation of the PECC role appears to be limited by heterogeneous interpretations of the PECC, de-prioritization of pediatrics, and limited system resources. However, many participants described motivation to improve pediatric care and implement the PECC role in context of increasing pediatric visits; they offered strategies for future implementation efforts.

High-Grade Endometrial Cancer: Molecular Subtypes, Current Challenges, and Treatment Options.

Although many recent advancements have been made in women's health, perhaps one of the most neglected areas of research is the diagnosis and treatment of high-grade endometrial cancer (EnCa). The molecular classification of EnCa in concert with histology was a major step forward. The integration of profiling for mismatch repair deficiency and Human Epidermal Growth Factor 2 (HER2) overexpression, can further inform treatment options, especially for drug resistant recurrent disease. Recent early phase trials suggest that regardless of subtype, combination therapy with agents that have distinct mechanisms of action is a fruitful approach to the treatment of high-grade EnCa. Unfortunately, although the importance of diagnosis and treatment of high-grade EnCa is well recognized, it is understudied compared to other gynecologic and breast cancers. There remains a tremendous need to couple molecular profiling and biomarker development with promising treatment options to inform new treatment strategies with higher efficacy and safety for all who suffer from high-grade recurrent EnCa.

Analysis of a Medication Safety Intervention in the Pediatric Emergency Department.

Importance: Strategies to reduce medication dosing errors are crucial for improving outcomes. The Medication Education for Dosing Safety (MEDS) intervention, consisting of a simplified handout, dosing syringe, dose demonstration and teach-back, was shown to be effective in the emergency department (ED), but optimal intervention strategies to move it into clinical practice remain to be described. Objective: To describe implementation of MEDS in routine clinical practice and associated outcomes. Design, Setting, and Participants: This mixed-methods interrupted time series study of MEDS was conducted April 2021 to December 2022 in an academic pediatric ED using a hybrid type 1 design. Parents and guardians of children aged 90 days to 11.9 years who were discharged with acetaminophen, ibuprofen, or both were eligible for inclusion in the quantitative portion. Clinicians from a diversity of role groups (attending physician, resident, and nurse) were eligible for the qualitative portion. Exposures: The study was conducted in 5 stages (baseline, intervention 1, washout, intervention 2, and sustainability phases). The 2 intervention phases taught clinical staff the MEDS intervention using different implementation strategies. During the intervention 1 phase, in-depth interviews were conducted until thematic saturation was reached; results were analyzed using thematic analysis. Interviews informed intervention 2 phase interventions. Main Outcomes and Measures: The primary outcome was any error (defined as dosing or frequency error) at a 48- to 72-hour follow-up phone call. Results: There were 256 participants (median [IQR] child age, 1.7 [3.0-7.0] years; median [IQR] parent and guardian age, 36.0 [31.0-41.0] years; 200 females among parents and guardians [78.1%]) who consented and completed follow-up. At baseline, 44 of 68 participants (64.7%) made an error compared with 34 of 65 participants (52.3%) during intervention 1, 31 of 63 participants (49.X%) during intervention 2, and 34 of 60 participants (57.X%) during sustainability. After adjustment for language and health literacy, the adjusted odds ratio for error during the combined intervention phases was 0.52 (95% CI, 0.28-0.97) compared with baseline. Conclusions and Relevance: This study found that both MEDS intervention phases were associated with decreased risk of error and that some improvement was sustained without active intervention. These findings suggest that attempts to develop simplified, brief interventions may be associated with improved medication safety for children after discharge from the ED.

Mapping Oral health and Local Area Resources (MOLAR): protocol for a randomised controlled trial connecting emergency department patients with social and dental resources.

INTRODUCTION: There are substantial inequities in oral health access and outcomes in the USA, including by income and racial and ethnic identity. People with adverse social determinants of health (aSDoH), such as housing or food insecurity, are also more likely to have unmet dental needs. Many patients with dental problems present to the emergency department (ED), where minimal dental care or referral is usually available. Nonetheless, the ED represents an important point of contact to facilitate screening and referral for unmet oral health needs and aSDoH, particularly for patients who may not otherwise have access to care. METHODS AND ANALYSIS: Mapping Oral health and Local Area Resources is a randomised controlled trial enrolling 2049 adult and paediatric ED patients with unmet oral health needs into one of three trial arms: (a) a standard handout of nearby dental and aSDoH resources; (b) a geographically matched listing of aSDoH resources and a search link for identification of geographically matched dental resources; or (c) geographically matched resources along with personalised care navigation. Follow-up at 3, 6, 9 and 12 months will evaluate oral health-related quality of life, linkage to resources and dental treatment, ED visits for dental problems and the association between linkage and neighbourhood resource density. ETHICS AND DISSEMINATION: All sites share a single human subjects review board protocol which has been fully approved by the Mass General Brigham Human Subjects Review Board. Informed consent will be obtained from all adults and adult caregivers, and assent will be obtained from age-appropriate child participants. Results will demonstrate the impact of addressing aSDoH on oral health access and the efficacy of various forms of resource navigation compared with enhanced standard care. Our findings will facilitate sustainable, scalable interventions to identify and address aSDoH in the ED to improve oral health and reduce oral health inequities. TRIAL REGISTRATION NUMBER: NCT05688982.

Risk behaviors among persons civilly committed for opioid use.

Despite the growth in civil commitment for persons who use opioids, we know little about the kinds of risk behaviors among those committed. This study examined the behaviors that a judge might use to determine if there is sufficient evidence that an individual's opioid use poses a risk for serious harm. The study recruited participants (n = 121) from three Massachusetts Department of Public Health civil commitment facilities in 2018. We used a list of risk behaviors that courts consider supportive of opioid-related civil commitment. Participants averaged 28 years of age, 56% were male, and 91% met criteria for severe opioid use disorder. Participants endorsed an average of 9 of the 27 risk behaviors. On average, participants endorsed three of the six drug use behaviors representing a danger to themselves, four of eleven behaviors representing an inability to care for or protect themselves (home safety, weight loss), and two of ten behaviors representing a danger to others (driving high or drunk). Participants who reported they were "not at all pleased" to have been civilly committed endorsed significantly (p = .009) fewer behaviors representing a danger to themselves than those who said they were at least "a little pleased." We conclude that the majority of individuals civilly committed for opioid use are engaging in multiple high-risk behaviors that pose a serious risk of harm to themselves.

A constrained-condylar fixed-bearing total knee arthroplasty is stabilised by the medial soft tissues.

PURPOSE: Revision constrained-condylar total knee arthroplasty (CCK-TKA) is often used to provide additional mechanical constraint after failure of a primary TKA. However, it is unknown how much this translates to a reliance on soft-tissue support. The aim of this study was therefore to compare the laxity of a native knee to the CCK-TKA implanted state and quantify how medial soft-tissues stabilise the knee following CCK-TKA. METHODS: Ten intact cadaveric knees were tested in a robotic system at 0°, 30°, 60° and 90° flexion with ± 90  N anterior-posterior force, ± 8 Nm varus-valgus and ± 5 Nm internal-external torques. A fixed-bearing CCK-TKA was implanted and the laxity tests were repeated with the soft tissues intact and after sequential cutting. The deep and superficial medial collateral ligaments (dMCL, sMCL) and posteromedial capsule (PMC) were sequentially transected and the percentage contributions of each structure to restraining the applied loads were calculated. RESULTS: Implanting a CCK-TKA did not alter anterior-posterior laxity from that of the original native knee, but it significantly decreased internal-external and varus-valgus rotational laxity (p < 0.05). Post CCK-TKA, the sMCL restrained 34% of the tibial displacing load in anterior drawer, 16% in internal rotation, 17% in external rotation and 53% in valgus, across the flexion angles tested. The dMCL restrained 11% of the valgus rotation moment. CONCLUSIONS: With a fully-competent sMCL in-vitro, a fixed-bearing CCK-TKA knee provided more rotational constraint than the native knee. The robotic test data showed that both the soft-tissues and the semi-constrained implant restrained rotational knee laxity. Therefore, in clinical practice, a fixed-bearing CCK-TKA knee could be indicated for use in a knee with lax, less-competent medial soft tissues. LEVEL OF EVIDENCE: Controlled laboratory study.

Ethylenediurea (EDU) effects on Japanese larch: an one growing season experiment with simulated regenerating communities and a four growing season application to individual saplings.

Japanese larch (Larix kaempferi (Lamb.) Carr.) and its hybrid are economically important coniferous trees widely grown in the Northern Hemisphere. Ground-level ozone (O3) concentrations have increased since the pre-industrial era, and research projects showed that Japanese larch is susceptible to elevated O3 exposures. Therefore, methodologies are needed to (1) protect Japanese larch against O3 damage and (2) conduct biomonitoring of O3 in Japanese larch forests and, thus, monitor O3 risks to Japanese larch. For the first time, this study evaluates whether the synthetic chemical ethylenediurea (EDU) can protect Japanese larch against O3 damage, in two independent experiments. In the first experiment, seedling communities, simulating natural regeneration, were treated with EDU (0, 100, 200, and 400 mg L-1) and exposed to either ambient or elevated O3 in a growing season. In the second experiment, individually-grown saplings were treated with EDU (0, 200 and 400 mg L-1) and exposed to ambient O3 in two growing seasons and to elevated O3 in the succeeding two growing seasons. The two experiments revealed that EDU concentrations of 200-400 mg L-1 could protect Japanese larch seedling communities and individual saplings against O3-induced inhibition of growth and productivity. However, EDU concentrations ≤ 200 mg L-1 did offer only partial protection when seedling communities were coping with higher level of O3-induced stress, and only 400 mg EDU L-1 fully protected communities under higher stress. Therefore, we conclude that among the concentrations tested the concentration offering maximum protection to Japanese larch plants under high competition and O3-induced stress is that of 400 mg EDU L-1. The results of this study can provide a valuable resource of information for applied forestry in an O3-polluted world.

Rapid, deep and precise profiling of the plasma proteome with multi-nanoparticle protein corona.

Large-scale, unbiased proteomics studies are constrained by the complexity of the plasma proteome. Here we report a highly parallel protein quantitation platform integrating nanoparticle (NP) protein coronas with liquid chromatography-mass spectrometry for efficient proteomic profiling. A protein corona is a protein layer adsorbed onto NPs upon contact with biofluids. Varying the physicochemical properties of engineered NPs translates to distinct protein corona patterns enabling differential and reproducible interrogation of biological samples, including deep sampling of the plasma proteome. Spike experiments confirm a linear signal response. The median coefficient of variation was 22%. We screened 43 NPs and selected a panel of 5, which detect more than 2,000 proteins from 141 plasma samples using a 96-well automated workflow in a pilot non-small cell lung cancer classification study. Our streamlined workflow combines depth of coverage and throughput with precise quantification based on unique interactions between proteins and NPs engineered for deep and scalable quantitative proteomic studies.

Acute Airway Inflammation Caused By Incomplete Ingestion of Extended-Release Diltiazem: A Case Report.

BACKGROUND: Diltiazem in its extended-release formulation is widely prescribed and is generally well-tolerated. Currently, there are no published case reports of localized inflammation related to extended-release diltiazem causing either significant pill esophagitis or airway inflammation when swallowed incompletely. CASE REPORT: We present a case of an 85-year-old female who reported difficulty swallowing roughly 18 h after incomplete ingestion of an extended-release diltiazem tablet. She had mild stridor and visible right-sided neck swelling on examination. Imaging revealed a large inflammatory mass, which was believed to be a subacute to chronic neoplastic process when reviewed both by radiology and otolaryngology. Two days after presentation, however, the patient's symptoms and the inflammatory mass had resolved entirely. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Extended-release diltiazem can cause an inflammatory mass when ingested incompletely, leading to possible acute airway compromise. Any invasive airway intervention should be approached with caution, given the degree of acute inflammation. Even in patients who do not require intervention, close observation until clinical improvement is warranted in symptomatic patients with a history of recent incomplete ingestion of extended-release diltiazem.

Improved mediolateral load distribution without adverse laxity pattern in robot-assisted knee arthroplasty compared to a standard manual measured resection technique.

PURPOSE: Robot-assisted total knee arthroplasty (rTKA) remains in its infancy, is expensive but offers the promise of improved kinematic performance through precise bone cuts, with minimal soft tissue disruption, based on pre-resection soft tissue behaviour. This cadaveric study examined load transfer, soft tissue performance and radiographic indices for conventional (sTKA) versus rTKA. The null hypothesis was there would be no difference between the two modes of implantation. METHODS: Whole (ten) cadaveric limbs were randomised to receive either robotic (rTKA, N = 5) or conventional measured resection (sTKA, N = 5) knee arthroplasty. Laxity patterns were established using validated fixed sensors (Verasense) with manual maximum displacement for six degrees of freedom. Tibiofemoral load and contact points were determined dynamically using remote sensor technology for medial and lateral compartments through a functional arc of motion (0-110 degrees of motion). Final component position was assessed using pre- and post-implantation CT. RESULTS: No significant intergroup differences for laxity were found (n.s.). The rTKA group exhibited consistently balanced mediolateral load throughout the full arc with significantly reduced overall total load across the joint (for distinct points of measurement, p < 0.05). Despite using flexion-extension and mediolateral gap balancing with measured resection, the sTKA group failed to achieve balance in at least three points of the flexion arc. Post-operative CT confirmed satisfactory component alignment with no significant differences for positioning between the two groups. CONCLUSION: This work found improved load sharing for rTKA when compared to conventional surgery for same donor knees. Laxity and CT determined final component positioning was not significantly different. The work supports the contention that robot-assisted TKA delivers improved tibiofemoral load sharing in time zero studies under defined conditions but such offers the promise of improved clinical performance and reduced implant wear.

Effects of Elevated CO2 on Leaf Senescence, Leaf Nitrogen Resorption, and Late-Season Photosynthesis in Tilia americana L.

We investigated the effects of elevated CO2 concentrations ([CO2]) on autumnal leaf falling, late-season photosynthesis, and leaf N resorption efficiency by exposing Tilia americana L. to three CO2 levels (800 ppm A8, 600 ppm A6, and ambient air A4) in nine continuous stirred tank reactors (CSTRs). All leaves were subdivided into the first (Z1), second (Z2), and third bud break (Z3) leaves. Whole plant photosynthesis (PNsat) was determined by summing the products of PNsat and total leaf area in Z1, Z2, and Z3, respectively. The results indicated that 1) the timing of leaf senescence in A8 treatments was 21 days in advance, while the senescence duration sustained 20 days longer than ambient treatment; 2) elevated [CO2] significantly induced the early formation of overwintering buds, with the number increased by 42 and 29% in A8 and A6 treatments, respectively; 3) Z3 leaf photosynthesis increases consistently until the end of the growing season, but Z2 leaves and whole plant showed acclimation when senescence happened; and 4) autumnal N resorption efficiency in A8 and A6 leaves were 25.5% and 22.7% higher than A4, respectively. In conclusion, autumnal senescence of T. americana was accelerated, while the leaf falling duration was extended by elevated [CO2]. The change in leaf phenology makes higher N resorption efficiency and earlier and more winter bud formation possible. Meanwhile, a different response of PNsat within different bud break leaves leads to the disparity between instantaneous measurements of leaf photosynthesis and whole plant photosynthesis in end season.

A load-measuring device can achieve fine-tuning of mediolateral load at knee arthroplasty but may lead to a more lax knee state.

PURPOSE: A balanced knee arthroplasty should optimise survivorship and performance. Equilibration of medial and lateral femorotibial load requires guided judicious pericapsular ligament release. The null hypothesis was that there would be no difference between use of a tensiometer device and a remote load sensor final load transfer across the joint through functional arc of motion. METHODS: A cadaveric study, using eight knees, was performed to define the impact of an established gap distraction device against load sensor-aimed soft tissue release in a TKA setting. Using validated measures of laxity in six degrees of freedom and true real-time load sensing four states were examined: native knee, TKA using spacer blocks (TKA), TKA with soft tissue release aided by a monogram tensiometer (TKA-T) and finally where load across the tibiofemoral articulation remains unbalanced final soft tissue release using a sensor device (TKA-OS). RESULTS: The laxity pattern was equivalent for TKA-T and TKA-OS. However, in only four of these seven knees despite the tensiometer confirming equivalence of rectangular flexion-extension gap dimensions and centralisation of collateral ligament distraction, there remained a > 15lb medial to lateral load difference for at least one point of the flexion arc. This was corrected by further final soft tissue release guided by the OS sensor device in the final three knees. CONCLUSION: Tensiometer-guided soft tissue release at two points of flexion failed to achieve balance for three out of seven knee arthroplasty procedures. Sensor technology guided final soft tissue balancing to equilibrate load across the joint through full arc of motion. This work argues for the role of continuous sensor readings to guide the soft tissue balancing during total knee arthroplasty.

Commentary: EPA's proposed expansion of dose-response analysis is a positive step towards improving its ecological risk assessment.

The United States Environmental Protection Agency (US EPA) has recently proposed changes to strengthen the transparency of its pivotal regulatory science policy and procedures. In this context, the US EPA aims to enhance the transparency of dose-response data and models, proposing to consider for the first time non-linear biphasic dose-response models. While the proposed changes have the potential to lead to markedly improved ecological risk assessment compared to past and current approaches, we believe there remain open issues for improving the quality of ecological risk assessment, such as the consideration of adaptive, dynamic and interactive effects. Improved risk assessment including adaptive and dynamic non-linear models (beyond classic threshold models) can enhance the quality of regulatory decisions and the protection of ecological health. We suggest that other countries consider adopting a similar scientific-regulatory posture with respect to dose-response modeling via the inclusion of non-linear biphasic models, that incorporate the dynamic potential of biological systems to adapt (i.e., enhancing positive biological endpoints) or maladapt to low levels of stressor agents.

Early shape change behaviour of an uncemented contemporary hip cup: A cadaveric experiment replicating host bone behaviour through temperature control.

Modular uncemented acetabular components are in common use. Fixation is dependent upon press-fit but the forces necessary to achieve initial stability of the construct at implantation may deform the shell and prevent optimal seating of the polyethylene liner insert. Previous work using single-time point measurements in uncontrolled ambient temperature poorly replicates the native state. A controlled study was performed to observe the time-dependent behaviour of an uncemented acetabular shell in the early phase after implantation into the human acetabulum at near physiological temperature. Using a previously validated cadaveric hip model at controlled near physiological temperature with standardised surgical technique, immediate and delayed shell geometry was determined. Eight custom made 3-mm-thick titanium alloy (TiAl6V4) shells were implanted into four cadavers (eight hips). Time-dependent shell deformation was determined using the previously validated ATOS Triple Scan III (ATOS) optical measurement system. The pattern of change in the shape of the surgically implanted shell was measured at three time points after insertion. We found a consistent pattern for quantitative and directional deformation of the shells. In addition, there was consistency for relaxation of the deformation with time. Immediate mean change in shell radius was 104 µm (standard deviation 32, range 67-153) relaxing to mean 96 µm (standard deviation 32, range 63-150) after 10 min and mean 92 µm (standard deviation 28, range 66-138) after 20 min. The clinical significance of this work is the finding of a time-dependent early deformation of acetabular titanium shells on insertion adjusted for near physiological temperature-controlled host bone.

Ethylenediurea (EDU) mitigates the negative effects of ozone in rice: Insights into its mode of action.

Monitoring of ozone damage to crops plays an increasingly important role for the food security of many developing countries. Ethylenediurea (EDU) could be a tool to assess ozone damage to vegetation on field scale, but its physiological mode of action remains unclear. This study investigated mechanisms underlying the ozone-protection effect of EDU in controlled chamber experiments. Ozone sensitive and tolerant rice genotypes were exposed to ozone (108 ppb, 7 hr day-1 ) and control conditions. EDU alleviated ozone effects on plant morphology, foliar symptoms, lipid peroxidation, and photosynthetic parameters in sensitive genotypes. Transcriptome profiling by RNA sequencing revealed that thousands of genes responded to ozone in a sensitive variety, but almost none responded to EDU. Significant interactions between ozone and EDU application occurred mostly in ozone responsive genes, in which up-regulation was mitigated by EDU application. Further experiments documented ozone degrading properties of EDU, as well as EDU deposits on leaf surfaces possibly related to surface protection. EDU application did not mitigate the reaction of plants to other abiotic stresses, including iron toxicity, zinc deficiency, and salinity. This study provided evidence that EDU is a surface protectant that specifically mitigates ozone stress without interfering directly with the plants' stress response systems.

Effects of ozone (O3) and ethylenediurea (EDU) on the ecological stoichiometry of a willow grown in a free-air exposure system.

Ground-level ozone (O3) concentrations have been elevating in the last century. While there has been a notable progress in understanding O3 effects on vegetation, O3 effects on ecological stoichiometry remain unclear, especially early in the oxidative stress. Ethyelenediurea (EDU) is a chemical compound widely applied in research projects as protectant of plants against O3 injury, however its mode of action remains unclear. To investigate O3 and EDU effects early in the stress, we sprayed willow (Salix sachalinensis) plants with 0, 200 or 400 mg EDU L-1, and exposed them to either low ambient O3 (AOZ) or elevated O3 (EOZ) levels during the daytime, for about one month, in a free air O3 controlled exposure (FACE); EDU treatment was repeated every nine days. We collected samples for analyses from basal, top, and shed leaves, before leaves develop visible O3 symptoms. We found that O3 altered the ecological stoichiometry, including impacts in nutrient resorption efficiency, early in the stress. The relation between P content and Fe content seemed to have a critical role in maintaining homeostasis in an effort to prevent O3-induced damage. Photosynthetic pigments and P content appeared to play an important role in EDU mode of action. This study provides novel insights on the stress biology which are of ecological and toxicological importance.

Mechanical properties of cancellous bone from the acetabulum in relation to acetabular shell fixation and compared with the corresponding femoral head.

To gain initial stability for cementless fixation the acetabular components of a total hip replacement are press-fit into the acetabulum. Uneven stiffness of the acetabular bone will result in irregular deformation of the shell which may hinder insertion of the liner or lead to premature loosening. To investigate this, we removed bone cores from the ilium, ischium and pubis within each acetabulum and from selected sites in corresponding femoral heads from four cadavers for mechanical testing in unconfined compression. From a stress-relaxation test over 300 s, the residual stress, its percentage of the initial stress and the stress half-life were calculated. Maximum modulus, yield stress and energy to yield (resilience) were calculated from a load-displacement test. Acetabular bone had a modulus about 10-20%, yield stress about 25% and resilience about 40% of the values for the femoral head. The stress half-life was typically between 2-4 s and the residual stress was about 60% of peak stress in both acetabulum and femur. Pubic bone was mechanically the poorest. These results may explain uneven deformation of press-fit acetabular shells as they are inserted. The measured half-life of stress-relaxation indicates that waiting a few minutes between insertion of the shell and the liner may allow seating of a poorly congruent liner.