Risk factors for early dislocation of the hip after periacetabular tumour resection and endoprosthetic reconstruction of the hemipelvis

Aims There is an increased risk of dislocation of the hip after the resection of a periacetabular tumour and endoprosthetic reconstruction of the defect in the hemipelvis. The aim of this study was to determine the rate and timing of dislocation and to identify its risk factors. Methods To determine the dislocation rate, we conducted a retrospective single-institution study of 441 patients with a periacetabular tumour who had undergone a standard modular hemipelvic endoprosthetic reconstruction between 2003 and 2019. After excluding ineligible patients, 420 patients were enrolled. Patient-specific, resection-specific, and reconstruction-specific variables were studied using univariate and multivariate analyses. Results The dislocation rate was 9.3% (n = 41). Dislocation was most likely to occur in the first three months after surgery. Four independent risk factors were found, one of which was older age at operation (p = 0.039). The odds ratios (ORs) of those aged ≥ 60 years and 30 to 60 years were 8.50 and 4.64, respectively, compared with those aged < 30 years. The other three risk factors were resection of gluteus maximus (p = 0.010, OR = 5.8), vertical shift of the centre of rotation (COR) of the hip by ≥ 20 mm (p = 0.008, OR = 3.60), and a type I+II+III pelvic resection (p = 0.014, OR = 3.04). Conclusion Hemipelvic endoprosthetic reconstruction after resection of a periacetabular tumour has a dislocation rate of 9.3% (n = 41). Patients are most likely to dislocate in the first three months after surgery. The risk is increased for older patients (especially those aged > 60 years) and for those with gluteus maximus resection, vertical shift of the COR ≥ 20 mm, and a type I+II+III pelvic resection. Cite this article: Bone Joint J 2021;103-B(2):382–390.

Vertical shift of submerged body moving near the free surface

Object and purpose of research. The object of the research is model tests of the submerged body motions near the free surface in test basin. The purpose of the study is to determine how the magnitude of the relative vertical shift of the submerged body depends on its speed. Materials and methods. The material for research is the modeling technique, technology and the results of model experiments in the test basin. Numerical modeling was performed using the ANSYS software package. Main results. Model tests and numerical experiments were carried out to determine the magnitude of the vertical displacement of the submerged body moving near the free surface and the forces acting on it. Conclusion. The results obtained are useful for horizontal stabilization of submerged body moving near free surface at different speeds.

Radiographic characterisation of spinal curvature development in farmed New Zealand Chinook salmon Oncorhynchus tshawytscha throughout seawater production

Spinal anomalies are a recognised source of downgrading in finfish aquaculture, but identifying their cause(s) is difficult and often requires extensive knowledge of the underlying pathology. Late-onset spinal curvatures (lordosis, kyphosis, scoliosis) can affect up to 40% of farmed New Zealand Chinook (king) salmon (Oncorhynchus tshawytscha) at harvest, but little is known about their pathogenesis. Curvature development was radiographically documented in two related cohorts of commercially-farmed Chinook salmon throughout seawater production to determine (1) the timing of radiographic onset and relationships between (2) the curvature types, (3) the spinal regions in which they develop and (4) their associations with co-existing vertebral body anomalies (vertebral compression, fusion and vertical shift). Onset of curvature varied between individuals, but initially occurred eight months post-seawater transfer. There were strong associations between the three curvature types and the four recognised spinal regions: lordosis was predominantly observed in regions (R)1 and R3, kyphosis in R2 and R4, manifesting as a distinct pattern of alternating lordosis and kyphosis from head to tail. This was subsequently accompanied by scoliosis, which primarily manifested in spinal regions R2 and R3, where most of the anaerobic musculature is concentrated. Co-existing vertebral body anomalies, of which vertebral compression and vertical shift were most common, appeared to arise either independent of curvature development or as secondary effects. Our results suggest that spinal curvature in farmed New Zealand Chinook salmon constitutes a late-onset, rapidly-developing lordosis–kyphosis–scoliosis (LKS) curvature complex with a possible neuromuscular origin.

Вертикальное смещение магнитооптической петли гистерезиса в магнитоплазмонном нанокомпозите

In article the synthesis and investigation results of magneto-optical (MO) properties of thin-film nanocomposite, which is a bismuth-substituted Bi: YIG ferrite garnet layer with Au plasmon nanoparticles are representative. The effect of vertical shift of MO hysteresis loops (relative to the origin of coordinates) was detected with study of MO properties during remagnetization of the magnetoplasmon composite structure. It’s shown that the observed effect is most pronounced near the condition of localized plasmon resonance in the metal nanoparticles system which make up the magnetoplasmonic composite.