Intraosseous pressure during loading and with vascular occlusion in an animal model

Objectives

We studied subchondral intraosseous pressure (IOP) in an animal model during loading, and with vascular occlusion. We explored bone compartmentalization by saline injection.

Materials and Methods

Needles were placed in the femoral condyle and proximal tibia of five anaesthetized rabbits and connected to pressure recorders. The limb was loaded with and without proximal vascular occlusion. An additional subject had simultaneous triple recordings at the femoral head, femoral condyle and proximal tibia. In a further subject, saline injections at three sites were carried out in turn.

Results

Loading alone caused a rise in subchondral IOP from 11.7 mmHg (sd 7.1) to 17.9 mmHg (sd 8.1; p < 0.0002). During arterial occlusion, IOP fell to 5.3 mmHg (sd 4.1), then with loading there was a small rise to 7.6 mmHg (sd 4.5; p < 0.002). During venous occlusion, IOP rose to 20.2 mmHg (sd 5.8), and with loading there was a further rise to 26.3 mmHg (sd 6.3; p < 0.003). The effects were present at three different sites along the limb simultaneously. Saline injections showed pressure transmitted throughout the length of the femur but not across the knee joint.

Conclusion

This is the first study to report changes in IOP in vivo during loading and with combinations of vascular occlusion and loading. Intraosseous pressure is not a constant. It is reduced during proximal arterial occlusion and increased with proximal venous occlusion. Whatever the perfusion state, in vivo load is transferred partly by hydraulic pressure. We propose that joints act as hydraulic pressure barriers. An understanding of subchondral physiology may be important in understanding osteoarthritis and other bone diseases.

Cite this article: M. Beverly, S. Mellon, J. A. Kennedy, D. W. Murray. Intraosseous pressure during loading and with vascular occlusion in an animal model. Bone Joint Res 2018;7:511–516. DOI: 10.1302/2046-3758.78.BJR-2017-0343.R2.

The influence of cemented femoral stem choice on the incidence of revision for periprosthetic fracture after primary total hip arthroplasty

Aims

Periprosthetic fracture (PF) after primary total hip arthroplasty (THA) is an uncommon but potentially devastating complication. This study aims to investigate the influence of cemented stem designs on the risk of needing a revision for a PF.

Patients and Methods

We analysed data on 257 202 primary THAs with cemented stems and 390 linked first revisions for PF recorded in the National Joint Registry (NJR) of England, Wales and Northern Ireland to determine if a cemented femoral stem brand was associated with the risk of having revision for a PF after primary THA. All cemented femoral stem brands with more than 10 000 primary operations recorded in the NJR were identified. The four most commonly used cemented femoral stems were the Exeter V40 (n = 146 409), CPT (n = 24 300), C-Stem (n = 15 113) and Charnley (n = 20 182). We compared the revision risk ratios due to PF amongst the stems using a Poisson regression model adjusting for patient factors. Compared with the Exeter V40, the age, gender and ASA grade adjusted revision rate ratio was 3.89 for the cemented CPT stem (95% confidence interval (CI) 3.07 to 4.93), 0.89 for the C-Stem (95% CI 0.57 to 1.41) and 0.41 for the Charnley stem (95% CI 0.24 to 0.70).

Conclusions

The limitations of the study include incomplete data capture, analysis of only PF requiring revision and that observation does not imply causality. Nevertheless, this study demonstrates that the choice of a cemented stem may influence the risk of revision for PF. Cite this article: Bone Joint J 2016;98-B:1347–54.

Evidence for disrupted gray matter structural connectivity in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is characterized by atrophy within the prefrontal-limbic network. Graph analysis was used to investigate to what degree atrophy in PTSD is associated with impaired structural connectivity within prefrontal limbic network (restricted) and how this affects the integration of the prefrontal limbic network with the rest of the brain (whole-brain). 85 male veterans (45 PTSD neg, 40 PTSD pos) underwent volumetric MRI on a 3T MR. Subfield volumes were obtained using a manual labeling scheme and cortical thickness measurements and subcortical volumes from FreeSurfer. Regression analysis was used to identify regions with volume loss. Graph analytical Toolbox (GAT) was used for graph-analysis. PTSD pos had a thinner rostral anterior cingulate and insular cortex but no hippocampal volume loss. PTSD was characterized by decreased nodal degree (orbitofrontal, anterior cingulate) and clustering coefficients (thalamus) but increased nodal betweenness (insula, orbitofrontal) and a reduced small world index in the whole brain analysis and by orbitofrontal and insular nodes with increased nodal degree, clustering coefficient and nodal betweenness in the restricted analysis. PTSD associated atrophy in the prefrontal-limbic network results in an increased structural connectivity within that network that negatively affected its integration with the rest of the brain.

Proinflammatory milieu in combat-related PTSD is independent of depression and early life stress

BACKGROUND

Chronic inflammation may be involved in combat-related post-traumatic stress disorder (PTSD) and may help explain comorbid physical diseases. However, the extent to which combat exposure per se, depression, or early life trauma, all of which are associated with combat PTSD, may confound the relationship between PTSD and inflammation is unclear.

METHODS

We quantified interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and C-reactive protein (CRP) in 51 combat-exposed males with PTSD and 51 combat-exposed males without PTSD, and assessed PTSD and depression severity as well as history of early life trauma. To decrease the possibility of Type I errors, we summed standardized scores of IL-1β, IL-6, TNFα, IFNγ and CRP into a total "pro-inflammatory score". PTSD symptom severity was assessed with the Clinician Administered PTSD Scale (CAPS) rating scale.

RESULTS

Subjects with PTSD had significantly higher pro-inflammatory scores compared to combat-exposed subjects without PTSD (p=0.006), and even after controlling for early life trauma, depression diagnosis and severity, body mass index, ethnicity, education, asthma/allergies, time since combat and the use of possibly confounding medications (p=0.002). Within the PTSD group, the pro-inflammatory score was not significantly correlated with depressive symptom severity, CAPS total score, or with the number of early life traumas.

CONCLUSIONS

Combat-related PTSD in males is associated with higher levels of pro-inflammatory cytokines, even after accounting for depression and early life trauma. These results, from one of the largest studies of inflammatory cytokines in PTSD to date, suggest that immune activation may be a core element of PTSD pathophysiology more so than a signature of combat exposure alone.

2-Dimensional MEMS dielectrophoresis device for osteoblast cell stimulation

A fixed microelectrode device for cell stimulation has been designed and fabricated using micro-electro-mechanical systems (MEMS) technology. Dielectrophoretic forces obtained from non-uniform electric fields were used for manipulating and positioning osteoblasts. The experiments show that the osteoblasts experience positive dielectrophoresis (p-DEP) when suspended in iso-osmotic culture medium and exposed to AC fields at 5 MHz frequency. Negative dielectrophoresis (n-DEP) is obtained at 0.1 MHz. The viability of osteoblasts under dielectrophoresis has been investigated. The viability values for cells exposed to DEP are nearly three times higher than the control values, indicating that dielectrophoresis may have an anabolic effect on osteoblasts.

Niemann pick type C disease as a model for defects in neurosteroidogenesis

Many functions have been attributed to neurosteroids including actions as anxiolytics, roles in myelination, inhibitors of neuronal toxicity and ischemia, and roles in neuronal growth and differentiation. To understand the functions of neurosteroids during nervous system development, we used two mouse models: one, in which the cyp17 gene was ablated, thus ablating synthesis of the neurosteroid DHEA, and a second, in a mouse model of a human childhood fatal neurodegenerative disease, Niemann-Pick Type C (NP-C). Cyp17-/- mice died unexpectedly approximately embryonic day 7. Cyp17 was expressed in the embryonic endoderm at E7, where 17alpha hydroxylase and c17,20 lyase activities were found. Hormonal replacement was ineffective in rescuing the embryos. The function of P450c17 and/or its steroid products in early mouse development is unknown. In the second model, we used a naturally-occurring NP-C mutant mouse. Mutations in the npc1 gene results in lysosomal accumulation of cholesterol and gangliosides in humans and in the mouse, which also recapitulates the onset of neurological deficits, neuronal loss and death typical of the most severe form of the human disease. We showed that there is a substantial reduction in the synthesis of the neurosteroid allopregnanolone (ALLO) at birth, which may lead to abnormal neural development. ALLO treatment was highly effective; ALLO-treated NP-C mice had substantially increased survival and delays in neurologic impairments, coinciding with marked improvements in neuronal survival, and reduction of gangliosides. These data suggest that neurosteroids play an important role in brain development and maturation and may be an effective therapy for NP-C and perhaps other lysosomal storage diseases.

Family survivorship and quality of life following a cancer diagnosis

The objectives of this study were: (a) to examine the quality of life of the family as a unit during the long-term survivor phase of illness and (b) to test a family model of factors that may influence family quality of life. The family survivorship model, which includes illness survival stressors (family stressors, fear of recurrence, and patient somatic concerns), resources (family hardiness and family social support), appraisal (family meaning of the illness), and the outcome, family quality of life, was used to guide this exploratory cross-sectional study. A random, stratified sample of 123 families (N = 246 individuals) was interviewed 1-5 years after treatment ended. The model explained 63% of the variance in family quality of life, with the strongest predictors being concurrent family stressors, family social support, family member fear of recurrence, family meaning of the illness, and patient employment status. The study findings suggest the importance of addressing cancer-related stressors, family resources, and family meaning as key factors related to family quality of life.

Couples' patterns of adjustment to colon cancer

The objectives for this longitudinal study were to: (a) compare colon cancer patients' and their spouses' appraisal of illness, resources, concurrent stress, and adjustment during the first year following surgery; (b) examine the influence of gender (male vs female) and role (patient vs spouse caregiver) on study variables; (c) assess the degree of correlation between patients' and spouses' adjustments; and (d) identify factors that affect adjustment to the illness. Fifty-six couples were interviewed at one week post diagnosis, and at 60 days and one year post surgery. Based on a cognitive-appraisal model of stress, the Smilkstein Stress Scale was used to measure concurrent stress; the Family APGAR, Social Support Questionnaire, and Dyadic Adjustment Scale were used to measure social resources; the Beck Hopelessness Scale and Mishel Uncertainty in Illness Scales were used to measure appraisal of illness; and the Brief Symptom Inventory and Psychosocial Adjustment to Illness Scale were used to measure psychosocial adjustment. Repeated Measures Analysis of Variance indicated that spouses reported significantly more emotional distress and less social support than patients. Gender differences were found, with women reporting more distress, more role problems, and less marital satisfaction, regardless of whether they were patient or spouse. Both patients and spouses reported decreases in their family functioning and social support, but also decreases in emotional distress over time. Moderately high autocorrelations and modest intercorrelations were found among and between patients' and spouses' adjustment scores over time. The strongest predictors of patients' role adjustment problems were hopelessness and spouses' role problems. The strongest predictors of spouses' role problems were spouses' own baseline role problems and level of marital satisfaction. Interventions need to start early in the course of illness, be family-focused, and identify the couples at risk of poorer adjustment to colon cancer.

Leadership experiences in the community for nursing students. Redesigning education for the 21st century

To respond to massive changes in health care delivery, nursing curriculum redesign requires that we return to our roots in the community and the visionary leadership of Lillian Wald, whose Henry Street Settlement (1,2) remains a model for community-based leadership. Wald's mission--to serve those in need, wherever they may be found--remains our legacy. But while the challenge of preparing students to function within a multitude of settings is not new, the changes now confronting faculty, students, and the entire health care system are taking place at a startling pace.