Clinical effects of combined anteversion and offset on postoperative dislocation in total hip arthroplasty.

BACKGROUND: Implant impingement and soft tissue tension are factors involved in dislocation after total hip arthroplasty (THA). Combined anteversion (CA) has been used as an indicator for implant placement. However, optimal implant placement remains a challenge. Moreover, the effect of changes in offset on dislocation is still unclear. In this study, we aimed to clarify the effects of postoperative CA and pre- and postoperative changes in offset on dislocation. METHODS: Included were patients who underwent primary cementless THA between 2013 and 2020. The mean values of CA and offset in the dislocation and non-dislocation groups were compared. The CA values within ± 10% of the recommended values were defined as good CA, and those outside the range were rated as poor CA. The dislocation rates were compared between the good and poor CA groups and between the groups with and without increased offset. RESULTS: A total of 283 hips were included. The mean values of CA in the dislocation and non-dislocation groups were significantly different (P < 0.05). The dislocation rate was significantly lower in the good CA group (P < 0.05). The dislocation rates in the groups with and without increased total offset were 0.5% and 4.3%, respectively (P = 0.004). There were no dislocations in patients with good CA and increased offset. CONCLUSIONS: The dislocation rate was significantly lower when implants were placed within ± 10% of the recommended CA value. Our results suggest that dislocation can be avoided by placing the implant in the good CA range and considering the increase in total offset on the operative side.

Initial stability of cementless acetabular cups using robotic-assisted total hip arthroplasty compared with the conventional manual technique: An in vitro biomechanical study.

BACKGROUND: The aim of this study is to determine whether the initial stability of a cementless cup with the Mako system is superior to that of a conventional manual technique using bone models. METHODS: The bone models were prepared using a polyurethane foam block. Two hemispherical cementless cups (highly porous titanium cup [Trident II Tritanium, Stryker] and hydroxyapatite-coated titanium cup [Trident HA, Stryker]) were implanted using the Mako system. The torque of the cups was measured by rotational and lever-out torque testing and compared with that of a conventional manual technique. RESULTS: The two types of cups that were implanted using the Mako system demonstrated significantly higher mean rotational torque than that of the manual technique (p < 0.01, p = 0.01, respectively). CONCLUSIONS: This study provides the advantage of the initial stability of a cementless hemispherical cup implanted by the Mako system compared with that of the conventional manual technique.

Association of high kinesiophobia and pain catastrophizing with quality of life in severe hip osteoarthritis: a cross-sectional study.

BACKGROUND: While fear of movement is an important predictor of pain and disability in osteoarthritis (OA), its impact on patients with hip OA remains uncertain. This study aimed to determine whether fear of movement, evaluated by the Tampa Scale for Kinesiophobia (TSK)-11, and pain catastrophizing, evaluated by the Pain Catastrophizing Scale (PCS), were associated with quality of life (QOL) in patients with hip OA. METHODS: This cross-sectional study was conducted between November 2017 and December 2018. Ninety-one consecutively enrolled patients with severe hip OA were scheduled for primary unilateral total hip arthroplasty. The EuroQOL-5 Dimensions questionnaire was used to measure general QOL. The Japanese Orthopedic Association Hip Disease Evaluation Questionnaire was used to assess disease-specific QOL. The covariates included age, sex, body mass index (BMI), pain intensity, high pain catastrophizing (PCS ≥ 30), and high kinesiophobia (TSK-11 ≥ 25). Variables were subjected to multivariate analysis using each QOL scale. RESULTS: In multiple regression analysis, pain intensity, high pain catastrophizing, and BMI were independently correlated with the disease-specific QOL scale. High pain catastrophizing, pain intensity, and high kinesiophobia were independently correlated with the general QOL scale. CONCLUSIONS: High pain catastrophizing (PCS ≥ 30) was independently associated with disease and general QOL scales. High kinesiophobia (TSK-11 ≥ 25) was independently associated with the general QOL scale in preoperative patients with severe hip OA.

A study combining magic-angle spinning NMR and small-angle X-ray scattering on the interaction in the mixture of poly(benzyl methacrylate) and ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide.

A mixture of poly(benzyl methacrylate) (PBnMA) and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C2mim][NTf2]) exhibits lower-critical-solution-temperature (LCST)-type phase separation. An investigation combining magic-angle spinning NMR spectroscopy and small-angle scattering was performed to gain new insights into the interaction between PBnMA and the ionic liquid. The molecular mobility and the solute-solvent interaction in the system were investigated using 1H high-resolution magic-angle spinning NMR. Applying a magic-angle spinning frequency of 2 kHz allowed identifying the PBnMA peaks, which were not observed by conventional solution-state NMR. The peaks of [C2mim]+ almost coincided in the presence and absence of PBnMA, indicating the decoupling of the bulk solvent and polymer. The conformational state of PBnMA in [C2mim][NTf2] was investigated using small-angle X-ray scattering (SAXS). The pair distribution functions of PBnMA chains calculated from SAXS profiles suggest that PBnMA adopts a random coil conformation upon dissolution in [C2mim][NTf2]. The combined study clarifies the decoupled low mobility of polymers with a random coil conformation. It is considered that the specific decoupled low mobility is one of the origins of the decoupling conductivity of [C2mim][NTf2] in a matrix polymer. In addition, an increase in temperature induced a downfield shift and broadening of the [C2mim]+ peaks, suggesting that a larger amount of [C2mim]+ was bound to the PBnMA chains even at temperatures approaching the LCST.

Optimal combined anteversion range for obtaining a wider range of motion without prosthetic impingement after total hip arthroplasty: a three-dimensional analysis study.

BACKGROUND: Obtaining a larger theoretical range of motion (ROM) is crucial to avoid prosthetic impingement after total hip arthroplasty (THA); however, no reports have examined the permissible range values of combined anteversion (CA) satisfying targeted ROM without prosthetic impingement. This retrospective study aimed to evaluate the possible postoperative CA extent that would allow meeting target ROM criteria according to Yoshimine's theory using computed tomography (CT)-based three-dimensional motion analysis after THA. METHODS: This study included 114 patients (133 hips) who underwent cementless primary THA using a CT-based navigation system and implants (oscillation angle ≥ 135°). Implant positions were determined using Yoshimine's CA formula. Postoperative evaluation was conducted using a three-dimensional templating software for CT data. The postoperative Yoshimine's and Widmer's CA was calculated, and the difference between the target and postoperative values was defined as the error of Yoshimine's CA and Widmer's CA. Prosthetic ROM was assessed by Yoshimine's stringent criteria for activities of daily living. Based on fulfilling these criteria, all patients were divided into the ROM (+) and ROM (-) groups. Evaluation items were compared between the two groups. RESULTS: There were 111 and 22 hips in the ROM (+) and ROM (-) groups, respectively. A significant difference was noted in the absolute error of Yoshimine's and Widmer's CA between the two groups. Using receiver operating characteristic analysis, threshold values of 6.0 (higher values indicate greater disability; sensitivity 90.9%, specificity 72.1%) for the absolute Yoshimine's CA difference (area under the curve [AUC] 0.87, P < 0.01) and 6.9 (higher values indicate greater disability; sensitivity 68.2%, specificity 88.3%) for the absolute Widmer's CA difference (AUC 0.83, P < 0.01) were predictors in the ROM (-) group. CONCLUSIONS: The target range of Yoshimine's CA (90.8° ± 6.0°) and Widmer's CA values (37.3° ± 6.9°) was crucial in implant orientation for obtaining theoretical ROM without prosthetic impingement after THA.

A new classification system for evaluating fatty infiltration of the gluteus minimus in hip osteoarthritis using plain computed tomography.

BACKGROUND: Fatty infiltration of the gluteus muscles increases due to the presence of hip osteoarthritis (OA); it is often evident in the gluteus minimus. The gluteus minimus acts not only as an abductor and rotator but also helps stabilize the femur's head. Moreover, the atrophy or fatty infiltration of the gluteus minimus leads to an increased risk of fall and fracture. Until now, fatty infiltration of this muscle has often been evaluated using magnetic resonance imaging using the Goutallier classification system, originally developed for the rotator cuff. However, the accessibility of magnetic resonance imaging remains problematic, and the reliability of the classification has room for improvement. Thus, this study aimed to devise a new classification system for the fatty infiltration of the gluteus minimus using plain computed tomography (CT). METHODS: We retrospectively reviewed 71 patients (141 hips) who underwent unilateral total hip arthroplasty for hip OA. To assess the system's reliability, three doctors classified the fatty infiltration of the gluteus minimus based on the CT images of 20 hips randomly selected from the study participants using both the Goutallier and the new classification systems. Then, we selected 113 hips with Crowe type 1 and evaluated them using the new classification system to assess the association between the extent of fatty infiltration and the severity of hip OA. RESULTS: Both classifications had good intra- and inter-observer reliability. The kappa values of the new classification system (0.83-0.95) were higher than that of the Goutallier classification system (0.72-0.87). The Jonckheere-Terpstra test showed that the degree of fatty infiltration of the gluteus minimus according to the new system progressed incrementally with the progression of hip OA (p = 0.016). CONCLUSIONS: The new classification system can be recommended for clinical use.

Rapid Destruction of the Hip Joint After Acetabular Fracture in an Elderly Patient.

Cases of rapidly progressive destruction of the hip joint after acetabular fractures are rarely reported. A 78-year-old woman fell from a chair. There was no fracture diagnosis; however, retrospective evaluation of the plain radiograph showed a slightly displaced fracture of the acetabulum. Her pain worsened after experiencing additional minor falls. The left hip joint had severe bone defects at 3 months after the initial injury. She underwent total hip arthroplasty using a KT-plate with an autogenous bone graft for acetabular bone defects. This case indicates that rapid destruction of the hip joint may occur after acetabular fracture from minor falls and bone fragility in elderly patients. In such cases, closer follow-up with advanced imaging can lead to early surgical intervention before severe destruction develops.

High-performance combinatorial optimization based on classical mechanics.

Quickly obtaining optimal solutions of combinatorial optimization problems has tremendous value but is extremely difficult. Thus, various kinds of machines specially designed for combinatorial optimization have recently been proposed and developed. Toward the realization of higher-performance machines, here, we propose an algorithm based on classical mechanics, which is obtained by modifying a previously proposed algorithm called simulated bifurcation. Our proposed algorithm allows us to achieve not only high speed by parallel computing but also high solution accuracy for problems with up to one million binary variables. Benchmarking shows that our machine based on the algorithm achieves high performance compared to recently developed machines, including a quantum annealer using a superconducting circuit, a coherent Ising machine using a laser, and digital processors based on various algorithms. Thus, high-performance combinatorial optimization is realized by massively parallel implementations of the proposed algorithm based on classical mechanics.

Midterm results of revision total hip arthroplasty for migrated bipolar hemiarthroplasty in patients with hip osteoarthritis using cementless cup with the rim-fit technique.

PURPOSE: The results of reamed bipolar hemiarthroplasty (BHA) in patients with hip osteoarthritis (OA) are reported to be unfavorable. Acetabular reaming for sufficient bony coverage caused bipolar head migration into the superomedial direction, and most patients required revision surgeries. Several methods are applicable to treat decreased bone stock. This study aimed to investigate the midterm results of revision surgeries using the cementless cup with the rim-fit technique. METHODS: Between 1996 and 2014, acetabular revision surgeries using the cementless cup with the rim-fit technique were performed in 86 hips (74 patients). We evaluated radiographic outcomes, including positional change of the rotation center of the artificial femoral head, presence of implant loosening, and filling of the initial gap. We also evaluated clinical outcomes, including the Harris hip score (HHS), and postoperative complications. RESULTS: The average positional changes from BHA to prerevision surgeries were 8.0 mm superiorly and 4.1 mm medially. The average changes from prerevision to postrevision surgeries were 3.7 mm inferiorly and 2.4 mm laterally. No implant loosening was found in all cases; the initial gap between the acetabular host bone and the acetabular cup was filled in 53 (93%) among 57 hips. The average HHS improved from 65.9 before revision surgeries to 83.8 in the latest follow-up. Dislocation and postoperative periprosthetic fracture occurred in two and five hips, respectively; no cases required rerevision surgeries. CONCLUSION: There were favorable midterm results of the revision total hip arthroplasty for migrated BHA in patients with hip OA using cementless cup with the rim-fit technique.

Effects of a roughened femoral head and the locus of grafting on the wear resistance of the phospholipid polymer-grafted acetabular liner.

Although laboratory tests and mid-term clinical outcomes show the clinical safety and remarkable wear resistance of the highly cross-linked polyethylene (HXLPE) acetabular liner with a nanometer-scaled graft layer of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), the wear resistance of the layer under severe abrasive conditions is concerning. We evaluated the effects of a roughened femoral head and the grafting locus on the wear resistance of the PMPC-grafted HXLPE liner and the effect of PMPC grafting on wear resistance of the HXLPE substrate by removing the PMPC-grafted layer using a severely roughened femoral head. Against a moderately roughened femoral head, the PMPC-grafted HXLPE liner showed negative wear, although an untreated HXLPE liner increased the wear by 154.1% compared with wear against a polished femoral head, confirming that PMPC grafts were unaffected. Against a severely roughened femoral head, the PMPC-grafted layer of the head contact area might be removed under severe conditions. However, the wear rate was reduced by 52.5% compared to that of untreated HXLPE liners. Moreover, the head non-contact area-modified PMPC-grafted HXLPE liner against a polished femoral head reduced the wear by 76.8% compared with untreated HXLPE liner; thus, this area may be also important in the development of fluid-film lubrication. STATEMENT OF SIGNIFICANCE: Here we describe effects of a roughened femoral head and the locus of grafting on the wear-resistance of the phospholipid polymer grafted highly cross-linked polyethylene (PMPC-HXLPE) liner. Against a moderately roughened femoral head, the PMPC-HXLPE liner showed negative wear, confirming that PMPC grafts were unaffected. After removing the PMPC layer of the head contact area using a severely roughened femoral head, the wear rate not only exceeded that of untreated HXLPE liners, but was reduced by 52.5%, confirming that PMPC grafting does not affect the wear-resistance of the HXLPE substrate. In addition, the head non-contact area-modified PMPC-HXLPE liner reduced the wear by 76.8%. Thus, this area may also may be important in the development of fluid-film lubrication.

Diabetes Impairs Wnt3 Protein-induced Neurogenesis in Olfactory Bulbs via Glutamate Transporter 1 Inhibition.

Diabetes is associated with impaired cognitive function. Streptozotocin (STZ)-induced diabetic rats exhibit a loss of neurogenesis and deficits in behavioral tasks involving spatial learning and memory; thus, impaired adult hippocampal neurogenesis may contribute to diabetes-associated cognitive deficits. Recent studies have demonstrated that adult neurogenesis generally occurs in the dentate gyrus of the hippocampus, the subventricular zone, and the olfactory bulbs (OB) and is defective in patients with diabetes. We hypothesized that OB neurogenesis and associated behaviors would be affected in diabetes. In this study, we show that inhibition of Wnt3-induced neurogenesis in the OB causes several behavioral deficits in STZ-induced diabetic rats, including impaired odor discrimination, cognitive dysfunction, and increased anxiety. Notably, the sodium- and chloride-dependent GABA transporters and excitatory amino acid transporters that localize to GABAergic and glutamatergic terminals decreased in the OB of diabetic rats. Moreover, GAT1 inhibitor administration also hindered Wnt3-induced neurogenesis in vitro Collectively, these data suggest that STZ-induced diabetes adversely affects OB neurogenesis via GABA and glutamate transporter systems, leading to functional impairments in olfactory performance.

MicroRNAs and epigenetics in adult neurogenesis.

Neurogenesis occurs throughout adulthood in the mammalian brain. Neural stem cells (NSCs) exist in three distinct areas of the brain: the subventricular zone, the olfactory bulb, and the dentate gyrus of the hippocampus. MicroRNAs (miRNAs) are small noncoding RNA molecules that posttranscriptionally regulate gene expression. Epigenetic regulation of gene expression, which includes DNA methylation and histone modification, plays a significant role in modulating NSC proliferation and differentiation. However, the functions of miRNAs in neurogenesis are just beginning to be understood. Based on the recent literature, miRNAs are suggested to play an important role in the epigenetic regulation of NSCs and differentiation of lineage populations, which include neurons, astrocytes, and oligodendrocytes. Recent studies have elucidated the roles of miRNAs in embryonic and adult neurogenesis, specifically, their involvement in stem cell maintenance and differentiation, neuronal maturation and neurite outgrowth, dendritogenesis, and spine formation. The cross-talk between miRNAs and epigenetic regulators appears to modulate neurogenesis in the adult mammalian brain. Since the dysfunction in miRNA machinery contributes to many types of neurodegenerative disorders, a better understanding of how miRNAs influence the neurogenesis and differentiation may offer novel targets for therapeutic application.

Wnt protein-mediated satellite cell conversion in adult and aged mice following voluntary wheel running.

Muscle represents an abundant, accessible, and replenishable source of adult stem cells. Skeletal muscle-derived stem cells, called satellite cells, play essential roles in regeneration after muscle injury in adult skeletal muscle. Although the molecular mechanism of muscle regeneration process after an injury has been extensively investigated, the regulation of satellite cells under steady state during the adult stage, including the reaction to exercise stimuli, is relatively unknown. Here, we show that voluntary wheel running exercise, which is a low stress exercise, converts satellite cells to the activated state due to accelerated Wnt signaling. Our analysis showed that up-regulated canonical Wnt/ß-catenin signaling directly modulated chromatin structures of both MyoD and Myf5 genes, resulting in increases in the mRNA expression of Myf5 and MyoD and the number of proliferative Pax7(+)Myf5(+) and Pax7(+) MyoD(+) cells in skeletal muscle. The effect of Wnt signaling on the activation of satellite cells, rather than Wnt-mediated fibrosis, was observed in both adult and aged mice. The association of ß-catenin, T-cell factor, and lymphoid enhancer transcription factors of multiple T-cell factor/lymphoid enhancer factor regulatory elements, conserved in mouse, rat, and human species, with the promoters of both the Myf5 and MyoD genes drives the de novo myogenesis in satellite cells even in aged muscle. These results indicate that exercise-stimulated extracellular Wnts play a critical role in the regulation of satellite cells in adult and aged skeletal muscle.

Intrinsic ability of adult stem cell in skeletal muscle: an effective and replenishable resource to the establishment of pluripotent stem cells.

Adult stem cells play an essential role in mammalian organ maintenance and repair throughout adulthood since they ensure that organs retain their ability to regenerate. The choice of cell fate by adult stem cells for cellular proliferation, self-renewal, and differentiation into multiple lineages is critically important for the homeostasis and biological function of individual organs. Responses of stem cells to stress, injury, or environmental change are precisely regulated by intercellular and intracellular signaling networks, and these molecular events cooperatively define the ability of stem cell throughout life. Skeletal muscle tissue represents an abundant, accessible, and replenishable source of adult stem cells. Skeletal muscle contains myogenic satellite cells and muscle-derived stem cells that retain multipotent differentiation abilities. These stem cell populations have the capacity for long-term proliferation and high self-renewal. The molecular mechanisms associated with deficits in skeletal muscle and stem cell function have been extensively studied. Muscle-derived stem cells are an obvious, readily available cell resource that offers promise for cell-based therapy and various applications in the field of tissue engineering. This review describes the strategies commonly used to identify and functionally characterize adult stem cells, focusing especially on satellite cells, and discusses their potential applications.

Monitoring neurodegeneration in diabetes using adult neural stem cells derived from the olfactory bulb.

INTRODUCTION: Neurons have the intrinsic capacity to produce insulin, similar to pancreatic cells. Adult neural stem cells (NSCs), which give rise to functional neurons, can be established and cultured not only by intracerebral collection, which requires difficult surgery, but also by collection from the olfactory bulb (OB), which is relatively easy. Adult neurogenesis in the hippocampus (HPC) is significantly decreased in diabetes patients. As a result, learning and memory functions, for which the HPC is responsible, decrease. METHODS: In the present study, we compared the effect of diabetes on neurogenesis and insulin expression in adult NSCs. Adult NSCs were derived from the HPC or OB of streptozotocin-induced diabetic rats. Comparative gene-expression analyses were carried out by using extracted tissues and established adult NSC cultures from the HPC or OB in diabetic rats. RESULTS: Diabetes progression influenced important genes that were required for insulin expression in both OB- and HPC-derived cells. Additionally, we found that the expression levels of several genes, such as voltage-gated sodium channels, glutamate transporters, and glutamate receptors, were significantly different in OB and HPC cells collected from diabetic rats. CONCLUSIONS: By using identified diabetes-response genes, OB NSCs from diabetes patients can be used during diabetes progression to monitor processes that cause neurodegeneration in the central nervous system (CNS). Because hippocampal NSCs and OB NSCs exhibited similar gene-expression profiles during diabetes progression, OB NSCs, which are more easily collected and established than HPC NSCs, may potentially be used for screening of effective drugs for neurodegenerative disorders that cause malignant damage to CNS functions.

The insulin regulatory network in adult hippocampus and pancreatic endocrine system.

There is a very strong correlation between the insulin-mediated regulatory system of the central nervous system and the pancreatic endocrine system. There are many examples of the same transcriptional factors being expressed in both regions in their embryonic development stages. Hormonal signals from the pancreatic islets influence the regulation of energy homeostasis by the brain, and the brain in turn influences the secretions of the islets. Diabetes induces neuronal death in different regions of the brain especially hippocampus, causes alterations on the neuronal circuits and therefore impairs learning and memory, for which the hippocampus is responsible. The hippocampus is a region of the brain where steady neurogenesis continues throughout life. Adult neurogenesis from undifferentiated neural stem cells is greatly decreased in diabetic patients, and as a result their learning and memory functions decline. Might it be possible to reactivate stem cells whose functions have deteriorated and that are present in the tissues in which the lesions occur in diabetes, a lifestyle disease, which plagues modern humans and develops as a result of the behavior of insulin-related factor? In this paper we summarize research in regard to these matters based on examples in recent years.