Material loss at the femoral head taper: a comparison study of the Exeter metal-on-polyethylene and contemporary metal-on-metal total hip arthroplasty

AIMS

There are limited published data detailing the volumetric material loss from tapers of conventional metal-on-polyethylene (MoP) total hip arthroplasties (THAs). Our aim was to address this by comparing the taper wear rates measured in an explanted cohort of the widely used Exeter THA with those measured in a group of metal-on-metal (MoM) THAs.

PATIENTS AND METHODS

We examined an existing retrieval database to identify all Exeter V40 and Universal MoP THAs. Volumetric wear analysis of the taper surfaces was conducted using previously validated methodology. These values were compared with those obtained from a series of MoM THAs using non-parametric statistical methodology. A number of patient and device variables were accounted for using multiple regression modelling.

RESULTS

A total of 95 Exeter MoP and 249 MoM THAs were examined. The median volumetric loss from the MoM cohort was over four times larger than that from the MoP cohort (1.01 mm³ vs 0.23 mm³, p < 0.001), despite a significantly shorter median period in vivo for the MoM group (48 months vs 90 months, p < 0.001). Multiple regression modelling indicated that the dominant variables leading to greater female taper material loss were bearing diameter (p < 0.001), larger female taper angles (p < 0.001), and male titanium stem tapers (p < 0.001).

CONCLUSION

Consistent with the long-term clinical success of the device, the volumetric material loss from Exeter femoral head tapers was, in general, small compared with that from larger-diameter MoM head tapers. Cite this article: Bone Joint J 2018;100-B:1310-9.

Chemsex and new HIV diagnosis in gay, bisexual and other men who have sex with men attending sexual health clinics

OBJECTIVES

The aim of the study was to analyse associations between chemsex and new HIV and sexually transmitted infection (STI) diagnoses among gay, bisexual and other men who have sex with men (GBMSM) accessing sexual health clinics.

METHODS

A retrospective case note review was carried out for all GBMSM attending two London sexual health clinics between 1 June 2014 and 31 July 2015.

RESULTS

Chemsex status was documented for 1734 of 1840 patients. Overall, 27.1% (n = 463) disclosed current recreational drug use, of whom 286 (16.5%) disclosed chemsex participation and 74 of 409 (18.1%) injected drugs. GBMSM who were already HIV positive were more likely to disclose chemsex participation [adjusted odds ratio (AOR) 2.55; 95% confidence interval (CI) 1.89-3.44; P < 0.001]. Those disclosing chemsex participation had higher odds of being newly diagnosed with HIV infection (AOR 5.06; 95% CI 2.56-10.02; P < 0.001), acute bacterial STIs (AOR 3.94; 95% CI 3.00-5.17; P < 0.001), rectal STIs (AOR 4.45; 95% CI 3.37-6.06; P < 0.001) and hepatitis C (AOR 9.16; 95% CI 2.31-36.27; P = 0.002). HIV-negative chemsex participants were also more likely to have accessed post-exposure prophylaxis for HIV in the study period and to report sex with a discordant HIV- or hepatitis C virus-infected partner (P < 0.001).

CONCLUSIONS

Chemsex disclosure in sexual health settings is associated with higher rates of STI diagnoses, including HIV infection and hepatitis C. GBMSM attending sexual health services should therefore be assessed for chemsex participation and disclosure should prompt health promotion, harm minimization and wellbeing interventions.

Service provision for elderly people with long-term functional illness

A postal survey of old age psychiatrists was carried out to examine the pattern of services currently available for elderly people with chronic functional mental disorder, and to identify innovative models of care for this group. The opinion of respondents was sought regarding problems with service provision and additional resources that would be desirable. The majority of respondents felt that the needs of individual patients should determine whether they should be cared for by old age, general or rehabilitation services. Seventy-three per cent of respondents felt that more specialist residential care outside hospital was needed to improve the care of this group.

The effect of stage of HIV disease as determined by CD4 count on clinical outcomes of surgical sepsis in South Africa

INTRODUCTION This paper reviews the impact of the stage of human immunodeficiency virus (HIV) disease on the outcome of surgical sepsis. METHODS All adult emergency general surgical patients (aged >15 years) who fulfilled the criteria for sepsis or septic shock, with a documented surgical source of infection, and who were HIV positive were reviewed. RESULTS During the 5-year study period, a total of 675 patients with a documented surgical source of sepsis were managed by our service; 142 (21%) of these were HIV positive. Among the individuals who were HIV positive, the CD4 count was <200 cells/µl in 21 patients and ≥200 cells/µl in 121 patients. There was no difference between these two cohorts in terms of demography or spectrum of surgical conditions. The range of surgical procedures and complications was also similar in both groups. Nevertheless, patients with a CD count of <200 cells/µl had a significantly longer length of hospital stay than those in the cohort with ≥200 cells/µl. For HIV positive patients with a CD4 count of <200 cells/µl, the mortality rate was 66.7% (14/21) while the mortality rate for individuals with HIV and a CD4 count of ≥200 cells/µl was 2.5% (2/121). This difference was statistically significant (p<0.001). CONCLUSIONS The clinical presentation and spectrum of surgical sepsis disease in cases with stage 1 and stage 2 HIV is not markedly different. However, in patients with a CD4 count of <200 cells/µl, the length of hospital stay and mortality is significantly higher. Stage of HIV disease must be considered when stratifying patients' risk for surgery.

Higgs physics at the CLIC electron-positron linear collider

The Compact Linear Collider (CLIC) is an option for a future [Formula: see text] collider operating at centre-of-mass energies up to [Formula: see text], providing sensitivity to a wide range of new physics phenomena and precision physics measurements at the energy frontier. This paper is the first comprehensive presentation of the Higgs physics reach of CLIC operating at three energy stages: [Formula: see text], 1.4 and [Formula: see text]. The initial stage of operation allows the study of Higgs boson production in Higgsstrahlung ([Formula: see text]) and [Formula: see text]-fusion ([Formula: see text]), resulting in precise measurements of the production cross sections, the Higgs total decay width [Formula: see text], and model-independent determinations of the Higgs couplings. Operation at [Formula: see text] provides high-statistics samples of Higgs bosons produced through [Formula: see text]-fusion, enabling tight constraints on the Higgs boson couplings. Studies of the rarer processes [Formula: see text] and [Formula: see text] allow measurements of the top Yukawa coupling and the Higgs boson self-coupling. This paper presents detailed studies of the precision achievable with Higgs measurements at CLIC and describes the interpretation of these measurements in a global fit.

An experimental demonstration of a new type of proton computed tomography using a novel silicon tracking detector

PURPOSE

Radiography and tomography using proton beams promise benefit to image guidance and treatment planning for proton therapy. A novel proton tracking detector is described and experimental demonstrations at a therapy facility are reported. A new type of proton CT reconstructing relative "scattering power" rather than "stopping power" is also demonstrated. Notably, this new type of imaging does not require the measurement of the residual energies of the protons.

METHODS

A large area, silicon microstrip tracker with high spatial and temporal resolution has been developed by the Proton Radiotherapy Verification and Dosimetry Applications consortium and commissioned using beams of protons at iThemba LABS, Medical Radiation Department, South Africa. The tracker comprises twelve planes of silicon developed using technology from high energy physics with each plane having an active area of ∼10 × 10 cm segmented into 2048 microstrips. The tracker is organized into four separate units each containing three detectors at 60° to one another creating an x-u-v coordinate system. Pairs of tracking units are used to reconstruct vertices for protons entering and exiting a phantom containing tissue equivalent inserts. By measuring the position and direction of each proton before and after the phantom, the nonlinear path for each proton through an object can be reconstructed.

RESULTS

Experimental results are reported for tracking the path of protons with initial energies of 125 and 191 MeV. A spherical phantom of 75 mm diameter was imaged by positioning it between the entrance and exit detectors of the tracker. Positions and directions of individual protons were used to create angular distributions and 2D fluence maps of the beam. These results were acquired for 36 equally spaced projections spanning 180°, allowing, for the first time, an experimental CT image based upon the relative scattering power of protons to be reconstructed.

CONCLUSIONS

Successful tracking of protons through a thick target (phantom) has demonstrated that the tracker discussed in this paper can provide the precise directional information needed to perform proton radiography and tomography. When synchronized with a range telescope, this could enable the reconstruction of proton CT images of stopping power. Furthermore, by measuring the deflection of many protons through a phantom, it was demonstrated that it is possible to reconstruct a new kind of CT image (scattering power) based upon this tracking information alone.

[Vismodegib Therapy for Periocular Basal Cell Carcinoma]

Background Basal cell carcinoma (BCC) is the commonest periorbital tumour. Mohs' micrographic surgery and secondary reconstruction is the therapeutic gold standard for periorbital BCC. In cases of inoperability for any reason, therapeutic alternatives are needed. Since the approval of vismodegib, an orally administered, targeted BCC therapy is available. Nevertheless there is little information on the use of vismodegib for periorbital BCC. Patients and Methods In a retrospective study, we analysed the data of 4 patients treated with vismodegib since 2014. The patients' mean age before starting therapy was 87 years. The mean maximum tumour diameter was 22.0 mm. Results The median follow-up was 17 months. The median treatment duration was 7.5 months. In 75 % of patients, complete clinical remission of BCC was achieved. In 25 % of patients, interim stabilisation of tumour growth was possible. The most common side effect of therapy was muscle spasm. Conclusion Vismodegib is an effective treatment option for patients with periorbital BCC, in whom surgical treatment is not possible for any reason.

Methyl isobutyl ketone-induced hepatocellular carcinogenesis in B6C3F1 mice: A constitutive androstane receptor (CAR)-mediated mode of action

In a National Toxicology Program (NTP) chronic inhalation study with methyl isobutyl ketone (MIBK), increases in hepatocellular adenomas and hepatocellular adenomas and carcinomas (combined) were observed in male and female B6C3F₁ mice at 1800 ppm. A DNA reactive Mode-of-Action (MOA) for this liver tumor response is not supported by the evidence as MIBK and its major metabolites lack genotoxicity in both in vitro and in vivo studies. Constitutive androstane receptor (CAR) nuclear receptor-mediated activation has been hypothesized as the MOA for MIBK-induced mouse liver tumorigenesis. To further investigate the MOA for MIBK-induced murine liver tumors, male and female B6C3F1, C57BL/6, and CAR/PXR Knockout (KO) mice were exposed to either 0 or 1800 ppm MIBK for 6 h/day, 5 days/week for a total of 10 days. On day 1, mice were implanted with osmotic mini-pumps containing 5-Bromo-2-deoxyuridine (BrdU) 1 h following exposure and humanely euthanized 1-3 h following the final exposure. B6C3F₁ and C57BL/6 mice had statistically significant increases in liver weights compared to controls that corresponded with hepatocellular hypertrophy and increased mitotic figures. Hepatocellular proliferation data indicated induction of S-phase DNA synthesis in B6C3F₁ and C57BL/6 mice exposed to 1800 ppm MIBK compared to control, and no increase was observed in MIBK exposed CAR/PXR KO mice. Liver gene expression changes indicated a maximally-induced Cyp2b10 (CAR-associated) transcript and a slight increase in Cyp3a11(PXR-associated) transcript in B6C3F₁ and C57BL/6 mice exposed to 1800 ppm MIBK compared to controls, but not in Cyp1a1 (AhR-associated) or Cyp4a10 (PPAR-α-associated) transcripts. CAR/PXR KO mice exposed to 1800 ppm MIBK showed no evidence of activation of AhR, CAR, PXR or PPAR-α nuclear receptors via their associated transcripts. MIBK induced hepatic effects are consistent with a phenobarbital-like MOA where the initiating events are activation of the CAR and PXR nuclear receptors and resultant hepatocellular proliferation leading to rodent liver tumors.

Chemsex and the city: sexualised substance use in gay bisexual and other men who have sex with men attending sexual health clinics

The objective of this study was to analyse associations between sexualised substance use (chemsex), STI diagnoses and sexual behaviour among gay bisexual and other men who have sex with men accessing sexual health clinics to better inform clinical pathways. A retrospective case notes review was undertaken following the introduction of more detailed and holistic profomas for all gay bisexual and other men who have sex with men attending two London sexual health clinics between 1 June 2014 and 31 January 2015. Chemsex status was documented for 655/818. Overall, 30% disclosed recreational drug use of whom 113 (57%) disclosed chemsex and 27 (13.5%) injecting drugs. HIV-positive gay bisexual and other men who have sex with men were more likely to disclose chemsex (AOR 6.68; 95% CI 3.91–11.42; p < 0.001). Those disclosing chemsex had a higher incidence of acute bacterial STIs (AOR 2.83 CI 1.79–4.47; p < 0.001), rectal STIs (AOR 3.10 CI 1.81–5.32; p < 0.001) or hepatitis C (AOR 15.41 CI 1.50–158.17; p = 0.021). HIV incidence in the study period was 1.8% (chemsex) vs. 0.9% (no chemsex) (p = 0.61). Chemsex was associated with having more sexual partners, transactional sex, group sex, fisting, sharing sex toys, injecting drug use, higher alcohol consumption and the use of ‘bareback’ sexual networking applications (p < 0.004). Chemsex participants were also more likely to have accessed post-exposure prophylaxis for HIV in the study period and report sex with a discordant HIV or hepatitis C-infected partner (p < 0.001). Chemsex disclosure is associated with higher risk-taking behaviours, acute bacterial STIs, rectal STIs and hepatitis C incidence. HIV incidence was higher but not significantly so in the study period. Chemsex disclosure in sexual health clinics should prompt an opportunity for prevention, health promotion and wellbeing interventions.