Evidence against solar influence on nuclear decay constants.

The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements of mono-radionuclide sources were performed over periods from 200 days up to four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ from one data set to another and are attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of alpha, beta-minus, electron capture, and beta-plus decaying sources set an upper limit of 0.0006% to 0.008% to the amplitude of annual oscillations in the decay rate. Oscillations in phase with Earth's orbital distance to the Sun could not be observed within a 10-6 to 10-5 range of precision. There are also no apparent modulations over periods of weeks or months. Consequently, there is no indication of a natural impediment against sub-permille accuracy in half-life determinations, renormalisation of activity to a distant reference date, application of nuclear dating for archaeology, geo- and cosmochronology, nor in establishing the SI unit becquerel and seeking international equivalence of activity standards.

Descriptive epidemiology of smothering in Australian commercial free-range layer hen farms.

Since the early 2000 s the practice of free-range egg production has increased in developed countries, partly driven by consumer perception that free-range housing is better for hen welfare. While poultry in free-range systems have more behavioural opportunities compared with poultry in caged systems, free-range systems are associated with greater frequencies of infectious disease, predation and 'smothering', a condition where birds pile on top of one another with death occurring due to suffocation. Although the frequency of smothering deaths in Australian free-range layer poultry is anecdotally high, there is a lack of empirical evidence quantifying smothering cause-specific mortality rates and identifying factors that place birds at higher risk of death from smothering. This was a prospective cohort study of poultry flocks managed by three commercial free-range layer organisations in Eastern Australia. Flocks were enrolled into the study from 1 January 2019 to 29 March 2021 and were followed until the end of lay or until the end of the study on 31 March 2022, whichever occurred first. Throughout the follow-up period flock managers provided production details for each flock and details of smothering events using custom-designed logbooks.A total of 84 flocks were enrolled in the study: 32 from Organisation 1, 35 from Organisation 2 and 17 from Organisation 3. The number of birds per flock ranged from 16,000 to 45,000. The total mortality rate was 1131 deaths per 10,000 bird-years. Smothering mortality rate across the three organisations was 183 (minimum 133, maximum 223) deaths per 10,000 bird-years at risk. Smothering accounted for around 16% (minimum 9%, maximum 22%) of all deaths.We identified no distinctive temporal pattern in daily smothering risk as a function of either the number of days since placement or calendar date. The locations of smothering events in sheds and in the outdoor range were not consistent, with relatively large numbers of smothering events occurring in specific locations for some sheds but not others. To the best of our knowledge, this study is the largest prospective study of smothering mortality in commercial free-range layer flocks conducted to date. Estimates of smothering incidence rate and how that varies within and between flocks and organisations over time provides a critically important benchmark for further investigations into this substantial area of productivity loss.

Early human contact and housing for pigs - part 1: responses to humans, novelty and isolation.

The development of fear and stress responses in animals can be influenced by early life experiences, including interactions with humans, maternal care, and the physical surroundings. This paper is the first of three reporting on a large experiment examining the effects of the early housing environment and early positive human contact on stress resilience in pigs. This first paper reports on the responses of pigs to humans, novelty, and social isolation. Using a 2 × 2 factorial design, 48 litters of pigs were reared in either a conventional farrowing crate (FC) where the sow was confined or a loose farrowing pen (LP; PigSAFE pen) which was larger, more physically complex and allowed the sow to move freely throughout the farrowing and lactation period. Piglets were provided with either routine contact from stockpeople (C), or routine contact plus regular opportunities for positive human contact (+HC) involving 5 min of scratching, patting and stroking imposed to the litter 5 days/week from 0-4 weeks of age. The positive handling treatment was highly effective in reducing piglets' fear of humans, based on +HC piglets showing greater approach and less avoidance of an unfamiliar person at 3 weeks of age. There was evidence that this reduction in fear of humans lasted well beyond when the treatment was applied (lactation), with +HC pigs showing greater approach and less avoidance of humans in tests at 6, 9 and 14 weeks of age. The +HC treatment also reduced piglets' fear of a novel object at 3 weeks of age, and for pigs in FC, the cortisol response after social isolation at 7 weeks of age. Rearing in FC compared to LP reduced piglets' fear of novelty at 3 weeks of age, as well as their vocalisations and cortisol response to isolation at 7 weeks of age. The FC pigs showed greater approach and less avoidance of humans compared to LP pigs at 3, 4 and 6 weeks of age, but not at 9 and 14 weeks of age. These results show that positive handling early in life can reduce pigs' fear of humans, fear of novelty and physiological stress response to social isolation. The LP pigs were reared in a more isolated environment with less overall contact with stockpeople and other pigs, which may have increased their fear responses to humans and novel situations, suggesting that different housing systems can modulate these pigs' responses.

Early human contact and housing for pigs - part 3: ability to cope with the environment.

Early experiences can have long-term impacts on stress adaptability. This paper is the last of three in a series on early experiences and stress in pigs, and reports on the effects of early human contact and housing on the ability of pigs to cope with their general environment. Using a 2 × 2 factorial design, 48 litters of pigs were reared in either a farrowing crate (FC) or a loose farrowing pen (LP; PigSAFE pen) which was larger, more physically complex and allowed the sow to move freely. Piglets were provided with either routine contact from stockpeople (C), or routine contact plus regular opportunities for positive human contact (+HC) involving 5 min of scratching, patting and stroking imposed to the litter 5 days/week from 0 to 4 weeks of age. At 4 weeks of age (preweaning), C piglets that were reared in FC had considerably lower concentrations of serum brain-derived neurotrophic factor (BDNF) than piglets from the other treatment combinations. Compared to C pigs, +HC pigs had fewer injuries at 4 weeks of age. There were no clear effects of human contact on BDNF concentrations or injuries after weaning, or on basal cortisol or immunoglobulin-A concentrations, behavioural time budgets, tear staining, growth, or piglet survival. Compared to FC piglets, LP piglets showed more play behaviour and interactions with the dam and less repetitive nosing towards pen mates during lactation. There was no evidence that early housing affected pigs' behavioural time budgets or physiology after weaning. Tear staining severity was greater in LP piglets at 4 weeks of age, but this may have been associated with the higher growth rates of LP piglets preweaning. There was no effect of lactation housing on growth after weaning. Preweaning piglet mortality was higher in the loose system. The findings on BDNF concentrations, injuries and play behaviour suggest improved welfare during the treatment period in +HC and LP piglets compared to C and FC piglets, respectively. These results together with those from the other papers in this series indicate that positive human interaction early in life promotes stress adaptability in pigs. Furthermore, while the farrowing crate environment deprives piglets of opportunities for play behaviour and sow interaction, there was no evidence that rearing in crates negatively affected pig welfare or stress resilience after weaning. Whether these findings are specific to the two housing systems studied here, or can be generalised to other housing designs, warrants further research.

Early human contact and housing for pigs - part 2: resilience to routine husbandry practices.

The ability of pigs to cope with routine farming practices can affect their welfare. This paper is part of a series on early experiences and stress, and reports on the effects of early human contact and housing on the responses of pigs to routine husbandry practices. Using a 2 × 2 factorial design, 48 litters of pigs were raised in either a conventional farrowing crate (FC) or a loose farrowing pen (LP; PigSAFE pen) which was larger, more physically complex and allowed the sow to move freely. Piglets were provided with either routine contact from stockpeople (C), or routine contact plus regular opportunities for positive human contact (+HC) involving 5 min of scratching, patting and stroking imposed to the litter 5 days/week from 0 to 4 weeks of age. At 4 weeks of age, piglets were weaned and re-housed with controlled mixing of litters within treatment. At 4 days of age, after only 3 bouts of the handling treatment, +HC pigs showed less escape behaviour than C pigs after capture by a stockperson for vaccinations and tail docking, and shorter durations of vocalisations throughout the procedures. The  +HC pigs also showed less escape behaviour when captured by a stockperson at 3 weeks of age. The FC pigs showed less escape behaviour than LP pigs after capture by a stockperson at 4 days of age but not at 3 weeks of age. Serum cortisol concentrations were lower in FC pigs than LP pigs 2 h after weaning but not at 49 h after weaning, whereas serum cortisol concentrations were lower in  +HC pigs than C pigs at 49 h after weaning but not at 2 h after weaning. In the period from 0 to 1 h after weaning, C pigs from LP performed the most escape attempts, although escape attempts were rare overall. When being moved out of the home pen by a stockperson at 21 weeks of age, FC pigs showed less baulking than LP pigs, but there were no detected effects of human contact treatment. In conclusion, both housing system and human contact during lactation affected the stress responses of pigs to routine husbandry practices. The +HC and FC pigs appeared to cope better than C and LP pigs, based on lower responses indicative of stress including escape behaviour, vocalisations and cortisol concentrations. These findings are consistent with corresponding reductions in fear that were reported in Part 1 of this series of papers.

A benchmark for Monte Carlo simulations in gamma-ray spectrometry Part II: True coincidence summing correction factors.

The goal of this study is to provide a benchmark for the use of Monte Carlo simulation when applied to coincidence summing corrections. The examples are based on simple geometries: two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The coincidence corrective factors are computed for four radionuclides. The exercise input files and calculation results with practical recommendations are made available for new users on a dedicated webpage.

Production of a carrier-free standard 56Mn source for the NRC manganese salt bath.

The National Research Council (NRC) of Canada's primary method for emission rate for radionuclide neutron sources utilizes a manganese salt bath which was last calibrated in the 1960s. At that time, an NRC RaBe neutron source was used to irradiate a solution of calcium permanganate to take advantage of the Szilard-Chalmers effect in producing the bulk 56Mn material for standardization and calibration of the bath. When attempting to repeat this exercise, a small amount (~100 kBq) was produced. This amount was sufficient for the standardization process but did not yield enough material to calibrate the bath to a sufficient level of precision. Improvements upon the previous separation scheme adopted at NRC for the separation of the 56Mn from the bulk irradiated material included the rinsing of the 56Mn dioxide precipitate using a mixture of sulfuric acid and hydrogen peroxide. While these improvements made in the separation chemistry improved the yield of 56Mn extraction from 60% to above 95% the maximum amount of activity was still quite low. Hence in March of 2018, the SLOWPOKE-2 Facility at the Royal Military College in Kingston, ON, was used to irradiate three vials of KMnO4 in solution. An estimated 2 GBq was produced and sent to NRC, from which the extraction procedure recovered essentially all of the available 56Mn. The 56Mn was standardized using the 4πß-γ anti-coincidence counting system and confirmed using the CIEMAT/NIST primary method. The resulting bulk material was certified with an uncertainty of 0.8% (k = 2). Minor quantities of 65Zn, 69mZn and 42K were unexpectedly observed but were in minute quantities so as not to affect the results of the standardization or calibration. The standardized 56Mn artifact was used to calibrate the Secondary Standard Ionizing Radiation Chamber System (SSIRCS) for a more rapid deployment of the calibrant in the future.

The first official measurement of 11C in the SIRTI.

In the summer of 2017, the Système International de Référence Transfer Instrument (SIRTI) of the Bureau International des Poids et Mesures (BIPM) was hosted by the National Research Council of Canada (NRC) in Ottawa, Canada. This SIRTI visit was unique in many aspects. It was the first visit of the SIRTI to Canada. NRC was the first National Metrological Institute (NMI) to perform comparisons of four isotopes (99mTc, 18F, 64Cu and 11C) during a single two-week period. Finally, this was the first official measurement of 11C in the SIRTI. The NRC had performed a primary standardization of 11C in February of 2017 and calibrated its Secondary Standard Ionizing Radiation Chamber System (SSIRCS) in preparation for the SIRTI comparison. Two primary Liquid Scintillation methods (CIEMAT/NIST and TDCR) were employed and the results agreed. The stock material was received from a local cyclotron in the form of a 11C-labelled sodium acetate (NaC2H3O2). Three ampoules were prepared for the purposes of comparison; one concentrated from the bulk material and two derived from a single dilution. Some inconsistency was evident due to a weighing problem for one of the ampoules containing the diluted solution, whose measurements were excluded from the analysis. The other two ampoules' results were consistent within their respective uncertainties. The SIRTI was very stable and the final BIPM report will detail the stability checks, performance and behaviour of the SIRTI during its measurement campaign in Canada. There is still no Key Comparison Reference Value (KCRV) for 11C as NRC is the first participant. However, during a test of the SIRTI at NPL in 2014, an equivalent SIRTI activity was measured as 9.87(5) kBq which was consistent with MonteCarlo predictions for 11C in the SIRTI of 9.867(15) kBq. The NRC SIRTI equivalent activity for 11C agrees within uncertainty with these results. This offers encouragement to other NMIs to request a 11C comparison given the consistency of experimental results from NRC and test results from the National Physical Laboratory, UK (NPL) and the BIPM. Finally a half-life measurement was determined from the NRC measurement of multiple half-lives of a 11C ampoule and was found to be 20.332(40)min. From the SIRTI measurements at NRC, the half-life was derived as 20.328(13) min. This is smaller but consistent with the DDEP recommended value of 20.361(23)min.

A benchmark for Monte Carlo simulation in gamma-ray spectrometry.

Monte Carlo (MC) simulation is widely used in gamma-ray spectrometry, however, its implementation is not always easy and can provide erroneous results. The present action provides a benchmark for several MC software for selected cases. The examples are based on simple geometries, two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The action outputs (input files and efficiency calculation results, including practical recommendations for new users) are made available on a dedicated webpage.

EGSnrc calculation of activity calibration factors for the Vinten ionization chamber.

The National Physical Laboratory Vinten 671 chamber was selected as a proving ground for a new radionuclide source model in the EGSnrc software. The computational Vinten model is validated against measurements of radionuclide artifacts whose activities were determined by absolute methods. The response of the Vinten chamber is first calculated as a function of gamma energy, but more strikingly, an explicit simulation of radionuclide decay was implemented and now permits the direct determination of a calibration factor, including additional effects due to all decay paths of the radionuclide. The Monte Carlo and experimental calibration factors are found to agree at the percent level, in absolute terms.

Renewing the radiopharmaceutical accuracy check service for Canadian radionuclide calibrators.

From 1986 to 2000, a fraction of the Canadian nuclear medicine community participated in a service offered by the National Research Council (NRC) of Canada to check the accuracy of administered doses of radiopharmaceuticals. The NRC renewed this service in recent years with a revalidation and reviving of the Secondary Standard Ionizing Radiation Chamber System (SSIRCS). The NRC conducted mock services for (99m)Tc, in varying geometries (syringes and serum vials), on two NRC commercial radionuclide calibrators, and at a nuclear medicine department in Canada. These tests showed the measured doses to be within 10% of the prepared standard but in some cases were sufficiently different from unity to warrant specific geometry factors to be derived.

Premature response to luteinizing hormone of granulosa cells from anovulatory women with polycystic ovary syndrome: relevance to mechanism of anovulation.

Polycystic ovary syndrome is the most common cause of anovulatory infertility. Anovulation in polycystic ovary syndrome is characterized by the failure of selection of a dominant follicle with arrest of follicle development at the 5-10 mm stage. In an attempt to elucidate the mechanism of anovulation associated with this disorder we have investigated at what follicle size human granulosa cells from normal and polycystic ovaries respond to LH. Granulosa cells were isolated from individual follicles from unstimulated human ovaries and cultured in vitro in serum-free medium 199 in the presence of LH or FSH. At the end of a 48-h incubation period, estradiol (E2) and progesterone (P) were determined in the granulosa cell-conditioned medium by RIA. In ovulatory subjects (with either normal ovaries or polycystic ovaries), granulosa cells responded to LH once follicles reached 9.5/10 mm. In contrast, granulosa cells from anovulatory women with polycystic ovaries responded to LH in smaller follicles of 4 mm. Granulosa cells from anovulatory women with polycystic ovaries were significantly more responsive to LH than granulosa cells from ovulatory women with normal ovaries or polycystic ovaries (E2, P < 0.0003; P, P < 0.03). The median (and range) fold increase in estradiol and progesterone production in response to LH in granulosa cell cultures from size-matched follicles 8 mm or smaller were E2, 1.0 (0.5-3.9) and P, 1.0 (0.3-2.5) in ovulatory women and E2, 1.4 (0.7-25.4) and P, 1.3 (0.3-7.0) in anovulatory women. Granulosa cells from anovulatory (but not ovulatory) women with polycystic ovaries prematurely respond to LH; this may be important in the mechanism of anovulation in this common endocrinopathy.

How low can you get?

Since the early 1960s the side effects of oral contraceptives have been known to be related to the high doses (50 micro g) of ethinyl estradiol used. Research has focused on reducing the dose of both the estrogen and progestin components to reduce these side effects. While reducing the dose of both components, the contraceptive efficacy has to be maintained so as to retain a satisfactory Pearl index. These requirements appear to have been attained with 24-day regimen of a low-dose pill (15 microg of ethinyl estradiol and 60 microg of gestedone) as one part of an open-label noncomparative multicenter study. This paper reports our unit's results, which indicate that the low-dose pill promises to reduce contraceptive-related side effects, to encourage better compliance, and as corollary, to retain a satisfactory Pearl index.

Carotid artery wall changes in estrogen-treated and -untreated postmenopausal women.

OBJECTIVE: To investigate whether the thickness of the layers of the carotid artery (externa, media, and intima) are affected by menopause and its treatment with hormone replacement therapy (HRT). METHODS: One hundred twenty-nine postmenopausal women were recruited sequentially and classified into three groups. Forty-six were taking oral HRT, 32 had estradiol implants, and 51 had never taken HRT. The three layers of the externa wall of the carotid artery were identified and measured by high-resolution ultrasound. RESULTS: Women with implants had thicker carotid artery wall measurements (0.84 +/- 0.26 mm) than the other groups. The media (0.32 +/- 0.11 mm) was significantly thicker in the implant group. This layer has a high connective tissue component, including collagen type I, collagen type III, and elastin fibers. The intima layer was thinner (0.25 +/- 0.09 mm) in the oral HRT group compared with controls (0.29 +/- 0.1 mm). A statistically significant higher intima-media ratio (1.17 +/- 0.05) was calculated for the control group, compared with both the oral HRT (0.92 +/- 0.04) and implant groups (0.94 +/- 0.03). CONCLUSION: Our findings suggest that HRT given to postmenopausal women influences differentially the layers of the carotid artery. Hormones seem to encourage thickening of the layers with the highest connective tissue component (externa and media) and to delay thickening of the atheromatous intima layer. These effects on the vascular system may be partly responsible for the cardioprotection attributed to HRT.

Carotid artery wall thickness in women treated with hormone replacement therapy.

OBJECTIVE: To measure the thickness of the individual layers (externa, media, intima) of the carotid artery in two groups of postmenopausal women. METHODS: A high resolution ultrasound (25-MHz Osteoson DIII Minhorst) was used to assess the distal end of the common carotid artery. Forty-six women were on hormone replacement therapy (Premarin 0.625 mg and Norgestrel 1 mg) for more than 1 year. The measurements of the treated group were compared to those of 51 postmenopausal women who acted as controls. RESULTS: No significant difference between the externa and media layers of both groups of women were noted. The media showed a tendency to be thicker in the treated group. The intima of the untreated group was found to be significantly thicker than that of the treated group (P < 0.05). Significant correlations were found between the layers of the carotid artery especially between the externa and media both mainly composed of connective tissue (Collagen Type I and III and elastin). The media/intima ratio of the treated women was significantly higher than that of the untreated group (P< 0.003). CONCLUSION: It is postulated that the changes observed may be due to the effect of oestrogen on connective tissue. These arterial changes induced by hormone replacement therapy may partially explain the cardioprotective effect this treatment has on postmenopausal women. The increased intimal thickness in untreated women compared to treated ones on the other hand would represent the reduction in atheromatous plaque formation in women on oestrogen replacement therapy.

Changes in bone collagen markers and in bone density in hormone treated and untreated postmenopausal women.

OBJECTIVE: This study aims to compare bone mineral density measurements (BMD), pyridinium crosslink levels and pyridinium crosslink levels in untreated and hormone treated postmenopausal women. METHODS: A cross-sectional study comparing biophysical (BMD) and biochemical (pyridinium crosslink and PCICP) parameters in a group of untreated postmenopausal women (n = 145) to a group of postmenopausal women on hormone replacement therapy (HRT) (n = 92). RESULTS: Untreated postmenopausal women compared to postmenopausal women on HRT had higher Osteoblastic and Osteoclastic activity. Procollagen I C-end terminal peptide (PCICP) was 11.3% lower in the women on HRT compared to controls whilst crosslinks were 27.2% lower than in controls. This seems to indicate that women on HRT had a bone balance that was higher compared to the control group (15.9%). The difference in bone density of L2-L4 between the two groups was (16.1%). CONCLUSIONS: This study seems to indicate that postmenopausal women receiving HRT readjust their bone remodelling so that although osteoblastic function is reduced, there is a much greater deduction in osteoclastic function and this results in an overall higher bone mass observed in the BMD of women on HRT.

Therapeutic community retention among Alaska Natives. Akeela house.

The purpose of the study was to determine whether a change in the treatment program at Akeela House Incorporated a therapeutic community in Anchorage. Alaska, significantly increased the time in treatment for Alaska Native residents. The change in treatment involved implementation of culturally sensitive approaches that incorporated and reinforced Native lifestyles. Data were obtained from the Alaska Management Information System on all treatment admissions from January 1988 to January 1995. Prior to implementation, Alaska native residents had significantly shorter times in treatment that Black or White residents. After implementation of the change in the treatment program, Alaska Native residents' times in treatment were no longer significantly different from those of Black or White residents and all three ethnic groups had significantly longer times in treatment than before the intervention.

Increased reduction in bone density and skin thickness in postmenopausal women on long-term corticosteroid therapy. A suggested role for estrogen add back therapy.

BACKGROUND: Long term steroid therapy is complicated by osteoporosis and generalised thinning of the skin. These two complications of long term corticosteroid therapy were routinely assessed at the Menopause Clinic of St. Luke's Hospital, Medical School, University of Malta. METHODS: A cross sectional study was performed on 64 postmenopausal women who had been on long term corticosteroids. Each woman had her skin thickness measured using high resolution ultrasound (22 mhz) and their bone density measured using a DEXA Norland. These measurements were compared to a control group (n = 557), a group of women who had sustained osteoporotic fractures (n = 180), and a group of women on hormone replacement therapy (HRT) (n = 399). A longitudinal study on 29 postmenopausal women on corticosteroids was also performed. In this study results were compared between women who in addition to their corticosteroids were on HRT and those who were on corticosteroids alone. RESULTS: The cross sectional study showed the corticosteroid therapy was associated with the thinnest skin thickness measurements mean 0.83 mm. Similarly, low bone density measurements lumbar spine mean 0.81 g/cm2 and left hip mean 0.71 g/cm2 were obtained for this group. The skin thickness in controls and in the HRT groups had a mean thickness of 0.93 mm while that of the osteoporotic fracture group was 0.88 mm. The bone density of the osteoporotic fractures in the fracture group was similar to that of group of women on long term corticosteroids. The lumbar spine had a mean density of 0.81 g/cm2 and left hip that of 0.71 g/cm2. The bone density of the control group and HRT group was significantly higher. The lumbar spine had a mean density of 0.93 g/cm2 and that of left hip was 0.82 g/cm2. The small longitudinal study compared postmenopausal women on long term corticosteroid therapy on HRT to another group who was not on HRT. The longitudinal study over four years revealed a constant increase in skin thickness (mean 6% per year) and bone density (left hip mean 5% per year, lumbar spine mean 5% per year). CONCLUSION: In postmenopausal women on long term corticosteroids, skin thickness and bone density were both decreased, but the addition of HRT as add back improved the situation dramatically. Skin thickness and bone density level in women on long term corticosteroids were comparable to that of women who had sustained osteoporotic fractures. It is therefore suggested that HRT be used as add back therapy in postmenopausal women on long term corticosteroid therapy.

[Dissociation of a modular acetabular component in an uncemented total hip prosthesis. Effect of the modular design and anti-luxation rim. A case report]. / Dissociation du composant acétabulaire modulaire d'une prothèse totale de hanche non scellée. Effet de la modularité et du rebord anti-luxation. A propos d'un cas.

We report a case of dissociation between polyethylene and metal-backing of the acetabular component of a total hip prosthesis after reduction of a late dislocation. We refer to advantages and disadvantages of an elevated-rim acetabular liner in total hip arthroplasty. The position of the metallic markers of the polyethylene and/or excentric situation of the neck-head complex from the metal-back allowed us to diagnose it. An appropriate surgical technique avoiding the joint laxity, firm assembly of the modular components when they are implanted, gentle reduction of an eventual dislocation and fluoroscopic control, are factors which can avoid this rare complication.