Metal-carbon fiber composite femoral stems in hip replacements: a randomized controlled parallel-group study with mean ten-year follow-up

BACKGROUND

Attempts to improve proximal load transfer and minimize stress shielding have included reducing the stiffness of femoral stems and using alternative stem materials, including carbon fiber composites. An uncemented implant (SR71) composed of a carbon-fiber-composite distal section and a porous-coated titanium-alloy proximal section, designed to improve proximal load transfer and provide good fixation, was clinically evaluated in a prospective randomized study.

METHODS

Sixty patients were enrolled and randomized to receive either the SR71 stem or an all-metal stem (Stability). All patients received a cemented all-polyethylene acetabular component and a 28-mm metal femoral head. All uncemented stems were implanted by the same surgeon. Patients were followed for up to ten years with repeated assessments of bone mineral density, radiographs, Harris hip scores (HHS), and visual analog scale (VAS) pain scores.

RESULTS

Ten years postoperatively, nineteen patients who had been treated with the SR71 stem and not lost to follow-up showed a significantly greater increase in proximal bone mineral density (Gruen zones 1 [p = 0.003] and 7 [p = 0.0007]) from baseline than did the twenty-two who had been treated with the Stability stem and not lost to follow-up. In contrast, the Stability group showed a significantly greater increase in distal bone mineral density (Gruen zones 2 [p = 0.0004], 3 [p = 0.0001], and 5 [p = 0.0035]) compared with the SR71 group. Radiographs demonstrated one case of progressive migration of an acetabular component used with an SR71 stem and one case of bone resorption in Gruen zones 7 and 14 in a patient treated with a Stability stem. There was no significant difference between the SR71 and Stability stems in terms of changes in the total HHS, HHS for pain, HHS for range of motion, or VAS pain scores ten years postoperatively relative to preoperative levels. There was one reported revision of an SR71 femoral stem at the ten-year review.

CONCLUSIONS

The investigational SR71 implant provided increased proximal bone density and reduced distal bone density. The implant showed promising results at the time of early follow-up, and the clinical outcomes were similar to those of an all-metal stem at the time of a ten-year follow-up.

Whole-genome analyses resolve early branches in the tree of life of modern birds

To better determine the history of modern birds, we performed a genome-scale phylogenetic analysis of 48 species representing all orders of Neoaves using phylogenomic methods created to handle genome-scale data. We recovered a highly resolved tree that confirms previously controversial sister or close relationships. We identified the first divergence in Neoaves, two groups we named Passerea and Columbea, representing independent lineages of diverse and convergently evolved land and water bird species. Among Passerea, we infer the common ancestor of core landbirds to have been an apex predator and confirm independent gains of vocal learning. Among Columbea, we identify pigeons and flamingoes as belonging to sister clades. Even with whole genomes, some of the earliest branches in Neoaves proved challenging to resolve, which was best explained by massive protein-coding sequence convergence and high levels of incomplete lineage sorting that occurred during a rapid radiation after the Cretaceous-Paleogene mass extinction event about 66 million years ago.

HIV in (and out of) the clinic: biomedicine, traditional medicine and spiritual healing in Harare

Contemporary lived experiences of the human immunodeficiency virus (HIV) are shaped by clinical and cultural encounters with illness. In sub-Saharan countries such as Zimbabwe, HIV is treated in very different ways in various therapeutic contexts including by biomedical experts, traditional medicine and faith healers. The co-existence of such expertise raises important questions around the potencies and limits of medicalisation and alternative healing practices in promoting HIV recovery. First, in this study, drawing on in-depth qualitative interviews with 60 people from poor urban areas in Harare, we explore the experiences of people living with and affected by HIV. Specifically, we sought to document, interrogate and reflect on their perceptions and experiences of biomedicine in relation to traditional medicine and spiritual healing. Their accounts indicate that traditional medicine and spiritual beliefs continue to significantly influence the way in which HIV is understood, and the forms of help and care people seek. Second, we observe the dramatic and overwhelmingly beneficial impact of Antiretroviral Therapy and conclude through Zimbabwean's own stories that limitations around delivery and wider structural inequalities impede its potential. Lastly, we explore some practical implications of the biomedical clinic (and alternative healing practices) being understood as sites of ideological and expert contestation. This paper aimed to add to our knowledge of the relationships between traditional medicine and spiritual healing in connection with biomedicine and how this may influence HIV treatment and prevention.

Carcinoembryonic antigen promotes colorectal cancer progression by targeting adherens junction complexes

Oncomarkers play important roles in the detection and management of human malignancies. Carcinoembryonic antigen (CEA, CEACAM5) and epithelial cadherin (E-cadherin) are considered as independent tumor markers in monitoring metastatic colorectal cancer. They are both expressed by cancer cells and can be detected in the blood serum. We investigated the effect of CEA production by MIP101 colorectal carcinoma cell lines on E-cadherin adherens junction (AJ) protein complexes. No direct interaction between E-cadherin and CEA was detected; however, the functional relationships between E-cadherin and its AJ partners: α-, β- and p120 catenins were impaired. We discovered a novel interaction between CEA and beta-catenin protein in the CEA producing cells. It is shown in the current study that CEA overexpression alters the splicing of p120 catenin and triggers the release of soluble E-cadherin. The influence of CEA production by colorectal cancer cells on the function of E-cadherin junction complexes may explain the link between the elevated levels of CEA and the increase in soluble E-cadherin during the progression of colorectal cancer.

The influence of immediate knee flexion on blood loss and other parameters following total knee replacement

In an initial randomised controlled trial (RCT) we segregated 180 patients to one of two knee positions following total knee replacement (TKR): six hours of knee flexion using either a jig or knee extension. Outcome measures included post-operative blood loss, fall in haemoglobin, blood transfusion requirements, knee range of movement, limb swelling and functional scores. A second RCT consisted of 420 TKR patients randomised to one of three post-operative knee positions: flexion for three or six hours post-operatively, or knee extension. Positioning of the knee in flexion for six hours immediately after surgery significantly reduced blood loss (p = 0.002). There were no significant differences in post-operative range of movement, swelling, pain or outcome scores between the various knee positions in either study. Post-operative knee flexion may offer a simple and cost-effective way to reduce blood loss and transfusion requirements following TKR. We also report a cautionary note regarding the potential risks of prolonged knee flexion for more than six hours observed during clinical practice in the intervening period between the two trials, with 14 of 289 patients (4.7%) reporting lower limb sensory neuropathy at their three-month review.

Allergy/hypersensitivity reactions as a predisposing factor to complex regional pain syndrome I in orthopedic patients

Several predisposing conditions have been associated with complex regional pain syndrome I (CRPS I). The purpose of this study was to determine the relationship between a history of allergy/hypersensitivity reactions and CRPS I in orthopedic patients. Orthopedic patients with CRPS I (n=115) who experienced pain relief after a successful sympathetic nerve blockade were identified for study inclusion; a control group (n=115) matched to the CRPS I group by age, sex, and location of injury was also included. All patients in the study had an average age of 42 years. In the CRPS I group, all participants were Caucasian and the majority (80.8%) were women. The skin of patients with CRPS I was described as fair (57.7%), mottled (57.7%), or sensitive (80.8%). Of the patients with CRPS I, 78 (67.8%) reported a statistically significant history of allergies compared with the 39 (33.9%) patients in the control group (P<.0001). Patients with CRPS I who experienced complete pain relief for at least 1 month following a single sympathetic nerve block were asked to answer a questionnaire (n=35), and some then underwent immediate hypersensitivity testing using a skin puncture technique (n=26). Skin hypersensitivity testing yielded an 83.3% positive predictive value with an accuracy of 76.9%. Based on these results, a positive history for allergy/hypersensitivity reactions is a predisposing condition for CRPS I in this subset of orthopedic patients. These hypersensitivity reactions may prove important in gaining a better understanding in the pathophysiology of CRPS I as a regional pain syndrome.

Multistabilities and symmetry-broken one-color and two-color states in closely coupled single-mode lasers

We theoretically investigate the dynamics of two mutually coupled, identical single-mode semi-conductor lasers. For small separation and large coupling between the lasers, symmetry-broken one-color states are shown to be stable. In this case the light outputs of the lasers have significantly different intensities while at the same time the lasers are locked to a single common frequency. For intermediate coupling we observe stable symmetry-broken two-color states, where both lasers lase simultaneously at two optical frequencies which are separated by up to 150 GHz. Using a five-dimensional model, we identify the bifurcation structure which is responsible for the appearance of symmetric and symmetry-broken one-color and two-color states. Several of these states give rise to multistabilities and therefore allow for the design of all-optical memory elements on the basis of two coupled single-mode lasers. The switching performance of selected designs of optical memory elements is studied numerically.

Comb transmission filters defined by phase-shifted superstructure Bragg gratings

We present a design method and numerical results describing the construction of distributed feedback grating filters that support discrete combs of transmission resonances. These filter designs define open superstructure grating resonators with transmission channels that can be placed at predetermined frequencies, such as those defined by the wavelength division multiplexing grid or by a secondary frequency comb source. Focusing on a specific example with 40 GHz channel spacing, we optimize an active structure that defines three low-threshold lasing modes. How our design approach relates to filter synthesis techniques based on cascaded grating resonators is also discussed.

Early postoperative predictors of satisfaction following total knee arthroplasty

BACKGROUND

Despite the excellent total knee arthroplasty (TKA) results reported using traditional outcome measures, dissatisfaction rates of up to 30% are reported following surgery. Although several preoperative factors have been identified as possible predictors of satisfaction, there is conflicting evidence. Identification of dissatisfaction in the early postoperative assessment may therefore be an alternative consideration.

METHODS

We examined the relationship between 12-month satisfaction, and early post-operative outcomes in a cohort of 486 TKA patients. Preoperative, and postoperative outcome measures at 3- and 12-months (Oxford knee score, pain score, SF12, and knee motion), were analysed and compared between patients who were satisfied and dissatisfied at 12-months following TKA. Mean scores, and postoperative change in scores were calculated. Postoperative outcomes were examined for correlation with satisfaction, and multivariate logistic regression models used to identify potential predictors of dissatisfaction.

RESULTS

Overall satisfaction was 77.0%. No preoperative differences were observed between groups. Dissatisfaction was associated with worse postoperative status across all outcome measures (p<0.001), except the 3-month SF12-physical component (p=0.052). Dissatisfied patients demonstrated minimal further improvement or even worsening of outcome scores between 3- and 12-months postoperatively (p<0.02). Both the 3-month OKS (OR=1.15, p<0.001), and knee flexion (OR=1.03, p=0.009) were significant predictors of subsequent 12-month satisfaction.

CONCLUSIONS

Dissatisfaction following TKA is associated with worse outcomes as early as 3months following surgery, with minimal further improvement subsequently achieved at 12-months. Early postoperative assessment following TKA should therefore be considered, including clinical assessment, to identify those patients at risk of dissatisfaction.

Structure and performance of dielectric films based on self-assembled nanocrystals with a high dielectric constant

Self-assembled films built from nanoparticles with a high dielectric constant are attractive as a foundation for new dielectric media with increased efficiency and range of operation, due to the ability to exploit nanofabrication techniques and emergent electrical properties originating from the nanoscale. However, because the building block is a discrete one-dimensional unit, it becomes a challenge to capture potential enhancements in dielectric performance in two or three dimensions, frequently due to surface effects or the presence of discontinuities. This is a recurring theme in nanoparticle film technology when applied to the realm of thin film semiconductor and device electronics. We present the use of chemically synthesized (Ba,Sr)TiO3 nanocrystals, and a novel deposition-polymerization technique, as a means to fabricate the dielectric layer. The effective dielectric constant of the film is tunable according to nanoparticle size, and effective film dielectric constants of up to 34 are enabled. Wide area and multilayer dielectrics of up to 8 cm(2) and 190 nF are reported, for which the building block is an 8 nm nanocrystal. We describe models for assessing dielectric performance, and distinct methods for improving the dielectric constant of a nanocrystal thin film. The approach relies on evaporatively driven assembly of perovskite nanocrystals with uniform size distributions in a tunable 7-30 nm size range, coupled with the use of low molecular weight monomer/polymer precursor chemistry that can infiltrate the porous nanocrystal thin film network post assembly. The intercrystal void space (low k dielectric volume fraction) is minimized, while simultaneously promoting intercrystal connectivity and maximizing volume fraction of the high k dielectric component. Furfuryl alcohol, which has good affinity to the surface of (Ba,Sr)TiO3 nanocrystals and miscibility with a range of solvents, is demonstrated to be ideal for the production of nanocomposites. The nanocrystal/furfuryl alcohol dispersions are suitable for the fabrication of thin films by chemical deposition techniques, including spin-coating, printing or a spraying process. To demonstrate the application of this technique to device fabrication, a multilayer capacitor with capacitance of 0.83 nF mm(-2) at 1 MHz is presented.

The effects of age and gender on the diameter of the femoral canal in patients who undergo total hip replacement

With greater numbers of younger patients undergoing total hip replacement (THR), the effect of patient age on the diameter of the femoral canal may become more relevant. This study aimed to investigate the relationship between the diameter of the diaphysis of the femoral canal with increasing age in a large number of patients who underwent THR. A total of 1685 patients scheduled for THR had their femoral dimensions recorded from calibrated radiographs. There were 736 males and 949 females with mean ages of 67.1 years (34 to 92) and 70.2 years (29 to 92), respectively. The mean diameter of the femoral canal was 13.3 mm (8.0 to 23.0) for males and 12.7 mm (6.0 to 26.0) for females. There was a poor correlation between age and the diameter of the canal in males (r = 0.071, p = 0.05) but a stronger correlation in females (r = 0.31, p < 0.001). The diameter of the femoral canal diameter of a female patient undergoing THR could be predicted to increase by 3.2 mm between the ages of 40 and 80 years, in contrast a male would be expected to experience only a 0.6 mm increase during the same period. This increase in the diameter of the canal with age might affect the long-term survival of the femoral component in female patients.

Cementless fixation in Oxford unicompartmental knee replacement: a multicentre study of 1000 knees

The Cementless Oxford Unicompartmental Knee Replacement (OUKR) was developed to address problems related to cementation, and has been demonstrated in a randomised study to have similar clinical outcomes with fewer radiolucencies than observed with the cemented device. However, before its widespread use it is necessary to clarify contraindications and assess the complications. This requires a larger study than any previously published. We present a prospective multicentre series of 1000 cementless OUKRs in 881 patients at a minimum follow-up of one year. All patients had radiological assessment aligned to the bone-implant interfaces and clinical scores. Analysis was performed at a mean of 38.2 months (19 to 88) following surgery. A total of 17 patients died (comprising 19 knees (1.9%)), none as a result of surgery; there were no tibial or femoral loosenings. A total of 19 knees (1.9%) had significant implant-related complications or required revision. Implant survival at six years was 97.2%, and there was a partial radiolucency at the bone-implant interface in 72 knees (8.9%), with no complete radiolucencies. There was no significant increase in complication rate compared with cemented fixation (p = 0.87), and no specific contraindications to cementless fixation were identified. Cementless OUKR appears to be safe and reproducible in patients with end-stage anteromedial osteoarthritis of the knee, with radiological evidence of improved fixation compared with previous reports using cemented fixation.

Gender, culture and changing attitudes: experiences of HIV in Zimbabwe

This paper draws on a series of qualitative interviews with 60 people living in economically poor communities of Harare, the capital of Zimbabwe, to provide new insight into the cultural landscape of HIV. While there has been extensive exploration of gender, sexuality, culture and HIV in Zimbabwe, there is a need to revisit these issues given the country's recent political and economic history. These questions have shaped the meanings that have been created around HIV (i.e., notions of HIV-as-death and as being produced by promiscuity) and the gendered mediation of cultural practices (i.e., forms of sexual expression and treatment uptake). Drawing on the accounts from a group directly affected by HIV, we illustrate the persistence of gendered and spiritualised ideas about 'blame', 'transmission' and 'treatment' and the disproportionate burden that still falls on Zimbabwean women. We conclude with an exploration of how everyday understandings of HIV may be shifting and the ways in which marginality, discrimination and stigma may be being challenged by openness, dialogue and attitude change.

Patterns of chemotherapy treatment for women with invasive epithelial ovarian cancer--a population-based study

OBJECTIVE

Ovarian cancer five-year survival is poor at <40%. In the absence of effective screening or new treatments, ensuring all women receive optimal treatment is one avenue to improve survival. There is little population-based information regarding the primary chemotherapy treatment that women with epithelial ovarian cancer receive. This information is essential to identify potential gaps in care.

METHODS

Cancer registries identified all women diagnosed with invasive epithelial ovarian cancer in Australia in 2005 (n=1192). Histopathology, chemotherapy and comorbidity information was abstracted from medical records. Multivariable logistic regression was used to identify factors associated with chemotherapy commencement, regimen, and completion.

RESULTS

Women >70 years (p<0.0001), those with high-grade, stage IA/IB cancers (vs. stages IC-IV, p=0.003) and those with mucinous cancers (p=0.0002) were less likely to start chemotherapy. Most treated women received platinum-based drugs (97%), but only 68% received combination carboplatin-paclitaxel and only half completed six cycles without treatment modification/delay. Approximately 19% received single-agent carboplatin: mostly those aged >70 (p<0.0001) and/or with co-morbidities (p<0.0001). Age was the strongest predictor of completing six cycles of combination therapy.

CONCLUSIONS

For specific patient groups, particularly older women, there is notable variation from standard treatment. Understanding how treatment variations affect survival and determining optimal regimens for these groups are research priorities.

Prognostic significance of 11q23 aberrations in adult acute myeloid leukemia and the role of allogeneic stem cell transplantation

The clinical features and outcomes of 148 patients with acute myeloid leukemia (AML) and 11q23 chromosomal abnormalities were compared with those of 2640 patients with non-11q23 AML. Patients with t(9;11) ), t(6;11) or other 11q23 balanced translocations (t(11;v)(q23;v)) presented at a younger age and with higher percentage of bone marrow blasts. Unbalanced 11q23 abnormalities were commonly associated with deletions of chromosomes 5q, 7q and/or complex karyotypes. In multivariate analysis, when compared with patients with non-11q23 AML and unfavorable-risk karyotype, there was a significant difference in overall survival (OS) for patients with t(9;11) (P=0.004), whereas there were no differences in OS for patients with t(6;11) (P=0.62), t(11;19) (P=0.20) and unbalanced 11q23 aberrations (P=0.85) or t(11;v)(q23;v) (P=0.59), indicating that t(9;11) has an independent intermediate prognostic significance, with all others being poor prognostic factors for OS; this was further confirmed by comparing them with patients with non-11q23 AML and intermediate-risk karyotype. Using intention-to treat analysis based on donor availability, we also noted that allogeneic stem cell transplant in first remission had a significant benefit toward improving OS (P<0.001) and relapse-free survival (P<0.001) in patients with AML and 11q23 abnormalities.

Repression of osteocyte Wnt/β-catenin signaling is an early event in the progression of renal osteodystrophy

Chronic kidney disease-mineral bone disorder (CKD-MBD) is defined by abnormalities in mineral and hormone metabolism, bone histomorphometric changes, and/or the presence of soft-tissue calcification. Emerging evidence suggests that features of CKD-MBD may occur early in disease progression and are associated with changes in osteocyte function. To identify early changes in bone, we utilized the jck mouse, a genetic model of polycystic kidney disease that exhibits progressive renal disease. At 6 weeks of age, jck mice have normal renal function and no evidence of bone disease but exhibit continual decline in renal function and death by 20 weeks of age, when approximately 40% to 60% of them have vascular calcification. Temporal changes in serum parameters were identified in jck relative to wild-type mice from 6 through 18 weeks of age and were subsequently shown to largely mirror serum changes commonly associated with clinical CKD-MBD. Bone histomorphometry revealed progressive changes associated with increased osteoclast activity and elevated bone formation relative to wild-type mice. To capture the early molecular and cellular events in the progression of CKD-MBD we examined cell-specific pathways associated with bone remodeling at the protein and/or gene expression level. Importantly, a steady increase in the number of cells expressing phosphor-Ser33/37-β-catenin was observed both in mouse and human bones. Overall repression of Wnt/β-catenin signaling within osteocytes occurred in conjunction with increased expression of Wnt antagonists (SOST and sFRP4) and genes associated with osteoclast activity, including receptor activator of NF-κB ligand (RANKL). The resulting increase in the RANKL/osteoprotegerin (OPG) ratio correlated with increased osteoclast activity. In late-stage disease, an apparent repression of genes associated with osteoblast function was observed. These data confirm that jck mice develop progressive biochemical changes in CKD-MBD and suggest that repression of the Wnt/β-catenin pathway is involved in the pathogenesis of renal osteodystrophy.

Modifiable factors delaying early discharge following primary joint arthroplasty

AIMS

Recent NHS reforms have incentivised reduction in length of stay, with the UK department of health expecting health trusts to reduce bed days and ultimately reduce overall costs. The aim of this study was to identify avoidable causes for protracted hospital admission following total hip arthroplasty (THA) or total knee arthroplasty (TKA) within a fast-track unit.

METHODS

During a 6-month period, 535 consecutive patients underwent primary THA or TKA under the care of a single surgeon. All patients with a post-operative stay of greater than 72 h were identified, and reasons for delayed discharge were determined.

RESULTS

The majority of arthroplasty patients were discharged within 3 days post-operatively. Twenty-one per cent of THA patients and 25 % of TKA patients remained as inpatients for greater than 72 h. For the THA population, this equates to 43 % of bed days used by 21 % of patients, and for the TKA population, 44 % of bed days were used by 25 % of patients. The major factor within both groups for delayed discharge was attributed to inadequate social support.

CONCLUSIONS

Delayed discharge can never be totally prevented. This unit aims to develop improvement in social work provision, with a greater focus on pre-admission discharge planning to reduce the number of delayed discharges and ultimately reduce the cost burden of joint replacement surgery. It is not conducive with the ethos of fast-track arthroplasty to only identify social circumstances upon admission.

On-off intermittency in an optically injected semiconductor laser

We report on the observation of on-off intermittency in an optically injected dual-mode semiconductor laser. It is shown that quasi-single-mode chaotic dynamics of the injected mode are accompanied by intermittent and irregular bursts of the intensity of the uninjected mode. We define a threshold intensity of the uninjected mode to distinguish laminar and bursting states of the system. For small values of the threshold parameter we observe excellent agreement with the predictions of theory for the distribution of the laminar phase durations. For larger values of the threshold parameter, a gap appears in the distribution of laminar phase durations. Numerical simulations demonstrate that this gap is a consequence of the fact that in this case the on states of the system define large intensity spikes, which can belong either to the same or to distinct bursts away from the single-mode manifold.