Unidirectional porous beta-tricalcium phosphate as a potential bone regeneration material for infectious bony cavity without debridement in pyogenic spondylitis.

An 81-year-old man was initially diagnosed with T11 osteoporotic vertebral fracture. The fractured vertebral body was filled with unidirectional porous beta-tricalcium phosphate (ß-TCP) granules, and posterior spinal fixation was conducted using percutaneous pedicle screws. However, the pain did not improve, the inflammatory response increased, and bone destructive changes extended to T10. The correct diagnosis was pyogenic spondylitis with concomitant T11 fragility vertebral fracture. Revision surgery was conducted 2 weeks after the initial surgery, the T10 and T11 pedicle screws were removed, and refixation was conducted. After the revision surgery, the pain improved and mobilization proceeded. The infection was suppressed by the administration of sensitive antibiotics. One month after surgery, a lateral bone bridge appeared at the T10/11 intervertebral level. This increased in size over time, and synostosis was achieved at 6 months. Resorption of the unidirectional porous ß-TCP granules was observed over time and partial replacement with autologous bone was evident from 6 months after the revision surgery. Two years and 6 months after the revision surgery, although there were some residual ß-TCP and bony defect in the center of the vertebral body, the bilateral walls have well regenerated. This suggested that given an environment of sensitive antibiotic administration and restricted local instability, unidirectional porous ß-TCP implanted into an infected vertebral body may function as a resorbable bone regeneration scaffold without impeding infection control even without debridement of the infected bony cavity.

Unidirectional porous beta-tricalcium phosphate and hydroxyapatite artificial bone: a review of experimental evaluations and clinical applications.

In Japan, where allograft bone transplantation is not widespread, prospects for artificial bones are very high. Therefore, artificial bones with various compositions, porous structures, and porosities have been developed and employed for clinical use. Both Affinos® and Regenos® (made of beta-tricalcium phosphate and hydroxyapatite, respectively) are artificial bones with a unique unidirectional porous structure, in which pores with a diameter suitable for tissue penetration (25-300 µm) are aligned in one direction. The unidirectional porous structure allows rapid penetration of blood deep into the materials by a capillary effect. In animal experiments, Affinos® showed well-balanced resorption and was replaced with the host's own bone from an early stage after implantation and new bone formation and remodeling were observed in the cortical bone and medullary cavity. When implanted for clinical situation, resorption from an early stage and good replacement with the patient's own bone were also observed. Regenos® has an internal osteon-like material and a vascular-like structure that is maintained within the pores even after long-term implantation, as noted in an animal experiment. When implanted for clinical situation, good osteoconductivity was observed from an early stage of implantation. In addition, the material was observed to be slowly absorbed over time in some cases. We have discussed the beneficial effects of combining teriparatide and platelet-rich plasma impregnation and the potential prospects of these artificial bones.

eQTL variants in COL22A1 are associated with muscle injury in athletes.

The myotendinous junction (MTJ) is at high risk of muscle injury, and collagen XXII is strictly expressed at tissue junctions, specifically at the MTJ. We investigated the hypothesis that single-nucleotide polymorphisms (SNPs) related to collagen type XXII α-1 chain gene (COL22A1) mRNA expression are associated with susceptibility to muscle injury in athletes. History of muscle injury was assessed in 3,320 Japanese athletes using a questionnaire, and two expression quantitative trait loci (eQTL) SNPs for COL22A1 (rs11784270 A/C and rs6577958 T/C) were analyzed using the TaqMan SNP Genotyping Assay. rs11784270 [odds ratio (OR) = 1.80, 95% confidence interval (CI) = 1.27-2.62, P = 0.0006] and rs6577958 (OR = 1.45, 95% CI = 1.10-1.94, P = 0.0083) were significantly associated with muscle injury under A and T allele additive genetic models, respectively. These results suggest that the expression level of COL22A1 at the MTJ influences muscle injury risk in athletes.

Effect of sleep efficiency on salivary metabolite profile and cognitive function during exercise in volleyball athletes.

PURPOSE: Sleep duration is known to affect physiological and circadian metabolites and human homeostasis. However, little is known about the relationship between sleep quality and metabolite and cognitive function during exercise. Therefore, the aim of the present study was to investigate the impact of sleep quality on metabolite level and cognitive function in female volleyball athletes. METHODS: Twelve female volleyball athletes participated in this study. Sleep efficiency was measured for 1 week using NemuriSCAN (Paramount Bed Co. Ltd., Japan) as an index of sleep quality. The subjects were divided into better (n = 6) and lesser (n = 6) sleep quality groups by the median value of sleep efficiency. Saliva samples were collected using a Salimetric oral swab cotton and salivary metabolites were analysed using capillary electrophoresis and time-of-flight mass spectrometry. The subjects performed Stroop tasks (simple and difficult tasks) at rest and during aerobic exercise in recumbent cycle ergometer at light and heavy intensity. RESULTS: Increased sleep efficiency was found in the better sleep quality group, whereas total sleep time was similar. There were differences in urea cycle and Krebs cycle metabolites between the two groups; their levels were correlated with sleep efficiency. The difficult-task response time during heavy exercise was faster in the better sleep quality group. CONCLUSION: We demonstrated that sleep efficiency was associated with urea cycle and Krebs cycle metabolite levels and response time during heavy exercise in volleyball athletes. These results suggested that sleep quality may affect amino acid and energy metabolism and cognitive function during heavy exercise.

Angiogenesis and new bone formation in novel unidirectional porous beta-tricalcium phosphate: a histological study.

Affinos® (Kuraray Co., Ltd., Tokyo, Japan) is a beta-tricalcium phosphate (TCP) artificial bone comprising a novel unidirectional porous structure with 57% porosity. This study examined angiogenesis and bone formation over time with unidirectional porous beta-TCP (UDPTCP). Ten Japanese White rabbits were used in this study. A 5 × 8-mm rectangular area of periosteum was resected, followed by preparation of a cortical bone defect using a high-speed bur. UDPTCP was embedded in the defect in the direction of the pores, parallel to the axis of the tibia. Tissue samples were harvested at 2 weeks (n = 3) and 6 weeks (n = 7) after implantation. Just before euthanasia, the vasculature of the lower limb was perfused with saline from the femoral artery and filled with MICROFIL® (Flow Tech, Inc., Carver, MA) to create a vascular cast. The tibia was cut longitudinally at the center of the material. Decalcified sagittal sections treated with hematoxylin and eosin staining, undecalcified sagittal sections treated with Villanueva-Goldner staining, and axial unstained sections were used for histological evaluation. The lengths of the largest vessels and newly formed bone at the material border were measured in a sagittal section. Both lengths were significantly larger at 6 weeks than at 2 weeks. In the axial sections at 2 weeks, newly formed vessels filled with blue dye grew along the pores of the UDPTCP. Mature bone tissue with a lamellar structure was observed at 6 weeks. Our histological findings demonstrated that angiogenesis and bone formation occur over time in UDPTCP.

Bone bonding, displacement, and absorption in cases of double-door laminoplasty with unidirectional porous hydroxyapatite spacers.

We used a newly developed, high-porosity unidirectional porous hydroxyapatite spacer (Regenos spacer, not approved by the FDA). To assess the short-term bone bonding capacity of Regenos spacer used in a double-door laminoplasty, including displacement, deformation, and absorption after implantation. Fifty patients underwent a double-door laminoplasty using Regenos spacers, with computed tomography (CT) images obtained at 2-4 weeks and 6-12 months, post-surgery, in 30 patients. Bone bonding rate, amount of displacement, and the incidence of deformation and absorption were evaluated from the early and late postoperative CT images. Bone bonding rate for Regenos spacers, using our modified classification, was 48.9% at 6 months, post- surgery, and 67.0% at 12 months. The change in anterior-posterior diameter of the spinal canal (ΔH) was significantly greater for Regenos spacers than for autologous bone spacers (p < 0.05). There was no difference in the change in angle between the vertebral arch and the posterior wall of the vertebral body (ΔR) between the Regenos and autologous bone spacers. Deformation was identified in 21.3% (10/47). Though, no evidence of breakage along their long axis was identified among these 10 cases on axial CT images with passable clinical results. Regenos spacers lowered the risk of early dislocation after implantation and facilitated bone bonding due to infiltration of surrounding tissue. However, the deformation and absorption was observed at high rates because of their insufficient mechanical strength, we need to require a longer term follow-up to more clearly evaluate their adverse impact in clinically.

Unidirectional porous ß-tricalcium phosphate induces bony fusion in lateral lumbar interbody fusion.

Lateral lumbar interbody fusion (LLIF) often requires the use of allograft or artificial bone. We used ß-tricalcium phosphate artificial bone with a porosity of 57% consisting of a novel unidirectional porous structure (Affinos®) in patients (5 male and 9 female) who underwent LLIF from August 2015 as a substitute for autologous bone. We evaluated 60 graft windows in the cages at 30 intervertebral levels. To evaluate interbody bony fusion, CT multi-planar reconstruction coronal and sagittal images obtained 1 year after surgery were assessed. Intra-cage bony fusion was observed in 39 of 60 graft windows and so total bony fusion rate was 65%. Intra-cage bony fusion was confirmed in 17 of 29 (58.6%) graft windows with autologous bone and 22 of 31 (70.9%) graft windows with Affinos®. There was no significant difference in the rate of bony fusion between autologous bone and Affinos® (p = 0.418). In conclusion, the rate of bony fusion using Affinos® in LLIF cages was not inferior to that using autologous bone graft. Affinos® is a candidate for graft material in LLIF surgery and further exploration is warranted.

SEM and TEM analysis of water degradation of human dentinal collagen.

Recently several long-term studies have reported evidence of the hydrolytic degradation of collagen fibrils based on fractured surface observations after bond testing. Those studies suggested that one cause of the decline in the bond strength was the degradation of the collagen fibrils within the bonds. However, one concern has been raised that the dentinal collagen fibrils may be stable in water that does not contain oral bacteria or enzymes. Therefore, the present study aimed to clarify the micromorphological change in naked collagen fibrils after 500 days of water storage. To prepare exposed collagen fibrils, sectioned and polished human dentin surfaces were acid conditioned for 15 s with the use of two commercially available acid conditioners: All-Etch (10% phosphoric acid) and Uni-Etch (32% phosphoric acid) (Bisco, Inc.). Those specimens were stored in distilled water at 37 degrees C for 1 day (control) for 500 days. After the storage periods, the samples were examined with the use of SEM and TEM. Under SEM and TEM examination, micromorphological alterations (disarrangement of collagen web, widening the interfibrillar space, and the thinning diameter of collagen fibrils) were found in the specimens after 500 days in water.