Higher risk of 2-year cup revision of ceramic-on-ceramic versus ceramic-on-polyethylene bearing: analysis of 33,454 primary press-fit total hip arthroplasties registered in the Dutch Arthroplasty Register (LROI)

Background and purpose: The influence of bearing on short-term revision in press-fit total hip arthroplasty (THA) remains under-reported. The aim of this study was to describe 2-year cup revision rates of ceramic-on-ceramic (CoC) and ceramic-on-polyethylene (CoPE). Patients and methods: Primary press-fit THAs with one of the three most used cups available with both CoC or CoPE bearing recorded in the Dutch Arthroplasty Register (LROI) were included (2007–2019). Primary outcome was 2-year cup revision for all reasons. Secondary outcomes were: reasons for revision, incidence of different revision procedures and use of both bearings over time. Results: 2-year Kaplan-Meier cup revision rate in 33,454 THAs (12,535 CoC; 20,919 CoPE) showed a higher rate in CoC (0.67% [95% CI, 0.54–0.81]) compared to CoPE (0.44% [95% CI, 0.34–0.54]) ( p = 0.004). Correction for confounders (age, gender, cup type, head size) resulted in a hazard ratio (HR) of 0.64 [95%CI, 0.48–0.87] ( p = 0.019). Reasons for cup revision differed only by more cup revision due to loosening in CoC (26.2% vs.1 3.2%) ( p = 0.030). For aseptic loosening a revision rate of 0.153% [95% CI, 0.075–0.231] was seen in CoC and 0.058% [95%CI 0.019–0.097] in CoPE ( p = 0.007). Correction for head size resulted in a HR of 0.475 [95% CI, 0.197–1.141] ( p = 0.096). Incidence of different revision procedures did not differ between bearings. Over time the use of CoPE has increased and CoC decreased. Conclusions: A higher 2-year cup revision rate in press-fit THA was observed in CoC compared to CoPE. Cup loosening was the only significantly different reason for revision and seen more often in CoC and mostly aseptic. Future randomised controlled trials need to confirm causality, since the early cup revision data provided has the potential to be useful when choosing the bearing in press-fit THA, when combined with other factors like bone quality and patient and implant characteristics.

Analysis of biomechanical gait parameters in patients after total hip replacement operated via anterolateral approach depending on size of the femoral head implant: retrospective matched-cohort study

Introduction Total hip replacement (THR) is considered one of the most effective medical procedures in treatment of osteoarthritis. Since its introduction, there has been a worldwide debate over proper implant selection in terms of size, bearing type and shape. Following study was designed to assess the importance of femoral head size in long-term follow-up. Materials and methods A cohort of 30 patients with primary end stage osteoarthritis who underwent total hip replacement was analysed retrospectively. A homogenous group was chosen with no major differences in BMI. Patients’ gait parameters were measured in a biomechanics laboratory using the 3D BTS Smart system. WOMAC and VAS questionnaires were used to assess patient reported outcome. Results The subgroup with larger implant head size had several outcomes significantly superior to the subgroup with standard head size and non-inferior to healthy hips. Following variables were measured during this study: time of support phase, time of swing phase, double support time, walking hip extension angle. Conclusions Use of larger sized femoral heads during THR gives better results in terms of gait pattern. Since restoring the gait pattern is one of the aspects of rehabilitation and returning to daily activities it seems to be an important observation.

CLAY HEADS OF ANTHROPOMORPHIC STATUETTES DISCOVERED BY THE EXCAVATIONS OF THE CHALCOLITHIC UPPER HORIZON AT TELL YUNATSITE, BULGARIA

Тема настоящей публикации - головы от статуэток финального халколита на телле Юнаците. Особенности их моделировки и пропорции рассматриваются на фоне обобщенной морфологии и пропорций головы человека. Их отклонения от условных констант позволяют оценить характер стилизации. Большинство голов в коллекции имеет укороченное темя и плоские затылки, нос лепился от уровня темени. По соотношению высоты, ширины и толщины глиняные головы разделены на три совокупности: 1. Наиболее узкие головы (рис. 1: 1, 2); 2. Головы несколько шире шеи с плоскими затылками (рис. 1: 3); 3. Относительно широкие, чаще всего с прямым затылком, укороченным теменем и приподнятым лицом (рис. 1: 4-9; 2; 3). Рассматриваются особенности морфологии широких голов, их пропорции и размеры. На некоторых головках имеются прически. В отдельных случаях выявлены штифты либо штифтовые углубления. На памятниках культур Караново VI - Гумельница - Коджадермен (КГК) и Криводол - Сэлкуца III встречаются те же особенности моделировки уплощенных голов, что свидетельствует о широком распространении групп данного типа и, возможно, указывает на существование общего канона их стилизации. Выделены три размерных варианта широких голов: крупные, средние и мелкие. Поскольку данные о контексте находок часто ограничены, разницы в распределении для групп широких головок выявить не удалось. Судя по целым изображениям, широкие головы как без отверстий по сторонам лица, так и с отверстиями могут принадлежать статуэткам любого пола. This publication reports on the heads from the statuettes dating to the final stage of the Chalcolithic at Tell Yunatsite. Specific features of their modelling and proportions are reviewed in the context of generalized morphology and proportions of the human head. Their deviations from notional constants offer an opportunity to evaluate characteristics of their stylization. Most heads in the collection have a shortened top of the head and a flat back of the head, with the nose attached from the top. Regarding the height-width-thickness ratio, the clay heads are divided into three groups: 1. The most narrow heads (Fig. 1: 1, 2); 2. Heads with flat backs that are slightly wider than the neck (Fig. 1: 3); and 3. Relatively wide heads, in most cases, with the straight back of the head, the shortened top and the raised face (Fig. 1: 4-9; 2; 3). The paper examines specific features of morphology of the wide heads, their proportions and size. Some heads have a hair-do. Some statuettes reveal studs or grooves for studs. The sites of Karanovo VI - Gumelnitsa - Kodzhadermen and Krivodol - Salcuta III sometimes yield flattened heads with the same modelling, which suggests a common canon for their stylization. Three variants of wide head size are singled out such as large, medium and small. As the data on the context of the finds are often limited, it was not possible to identify differences in the distribution of the wide heads. Based on the preserved heads, the wide heads with and without apertures on the face sides can belong to the statuettes of any sex.

Effect of head size and rotation on taper corrosion in a hip simulator

Aims This study investigates head-neck taper corrosion with varying head size in a novel hip simulator instrumented to measure corrosion related electrical activity under torsional loads. Methods In all, six 28 mm and six 36 mm titanium stem-cobalt chrome head pairs with polyethylene sockets were tested in a novel instrumented hip simulator. Samples were tested using simulated gait data with incremental increasing loads to determine corrosion onset load and electrochemical activity. Half of each head size group were then cycled with simulated gait and the other half with gait compression only. Damage was measured by area and maximum linear wear depth. Results Overall, 36 mm heads had lower corrosion onset load (p = 0.009) and change in open circuit potential (OCP) during simulated gait with (p = 0.006) and without joint movement (p = 0.004). Discontinuing gait’s joint movement decreased corrosion currents (p = 0.042); however, wear testing showed no significant effect of joint movement on taper damage. In addition, 36 mm heads had greater corrosion area (p = 0.050), but no significant difference was found for maximum linear wear depth (p = 0.155). Conclusion Larger heads are more susceptible to taper corrosion; however, not due to frictional torque as hypothesized. An alternative hypothesis of taper flexural rigidity differential is proposed. Further studies are necessary to investigate the clinical significance and underlying mechanism of this finding. Cite this article: Bone Jt Open 2021;2(11):1004–1016.

Maternal One-carbon Metabolism during the Periconceptional Period and Human Foetal Brain Growth: A Systematic Review

The maternal environment during the periconceptional period influences foetal growth and development, in part, via epigenetic mechanisms moderated by one-carbon metabolic pathways. During embryonic development, one-carbon metabolism is involved in brain development and neural programming. Derangements in one-carbon metabolism increase (i) the short-term risk of embryonic neural tube-related defects and (ii) long-term childhood behaviour, cognition, and autism spectrum disorders. Here we investigate the association between maternal one-carbon metabolism and foetal and neonatal brain growth and development. Database searching resulted in 26 articles eligible for inclusion. Maternal vitamin B6, vitamin B12, homocysteine, and choline were not associated with foetal and/or neonatal head growth. First-trimester maternal plasma folate within the normal range (> 17 nmol/L) associated with increased foetal head size and head growth, and high erythrocyte folate (1538–1813 nmol/L) with increased cerebellar growth, whereas folate deficiency (< 7 nmol/L) associated with a reduced foetal brain volume. Preconceptional folic acid supplement use and specific dietary patterns (associated with increased B vitamins and low homocysteine) increased foetal head size. Although early pregnancy maternal folate appears to be the most independent predictor of foetal brain growth, there is insufficient data to confirm the link between maternal folate and offspring risks for neurodevelopmental diseases.

Sexual dimorphism in size and shape of the head in the sea snake Emydocephalus annulatus (Hydrophiinae, Elapidae)

In snakes, divergence in head size between the sexes has been interpreted as an adaptation to intersexual niche divergence. By overcoming gape-limitation, a larger head enables snakes of one sex to ingest larger prey items. Under this hypothesis, we do not expect a species that consumes only tiny prey items to exhibit sex differences in relative head size, or to show empirical links between relative head size and fitness-relevant traits such as growth and fecundity. Our field studies on the sea snake Emydocephalus annulatus falsify these predictions. Although these snakes feed exclusively on fish eggs, the heads of female snakes are longer and wider than those of males at the same body length. Individuals with wider heads grew more rapidly, reproduced more often, and produced larger litters. Thus, head shape can affect fitness and can diverge between the sexes even without gape-limitation. Head size and shape may facilitate other aspects of feeding (such as the ability to scrape eggs off coral) and locomotion (hydrodynamics); and a smaller head may advantage the sex that is more mobile, and that obtains its prey in narrow crevices rather than in more exposed situations (i.e., males).