An Initial Assessment of the Correlation Between Virtual Reality and Paper and Pencil Line Bisection Test Results.

Objective: To make an initial assessment of the correlation between immersive virtual reality-based (ILBT) line bisection testing and paper-and-pencil-based line bisection (PLBT) testing in healthy subjects. Design: Diagnostic study. Setting: Research laboratory. Participants: Twenty healthy adults (51.5 [11.0] years old, 55% women; N=20). Interventions: Participants underwent an ILBT and a conventional PLBT in near space (NS) and more distant space (MDS). Correlations between the ILBT and PLBT, deviation rates in the NS and MDS, horizontal gaze distribution, and presence of virtual reality sickness (VRS) were evaluated. Main Outcome Measures: Correlation between the deviation rates of the PLBT and ILBT. Results: There was no significant correlation between the ILBT and PLBT for evaluating the deviation rate of the line bisection test (LBT). There was no significant difference in the deviation rate of the LBTs between the NS and MDS, but there was a significant difference in the horizontal line-of-sight distribution. VRS was not observed as an adverse event. Conclusions: In healthy adult subjects, our results suggested that there was no significant correlation between the deviation rates of the ILBT and PLBT. We also found that the ILBT is a useful and safe method for evaluating the horizontal line-of-sight distribution and percentage deviation of line segments from the center in the NS and MDS without inducing VRS.

Bone bonding strength of diamond-structured porous titanium-alloy implants manufactured using the electron beam-melting technique.

The present study examined the bone bonding strength of diamond-structured porous titanium-alloy (Porous-Ti-alloy) manufactured using the electron beam-melting technique in comparison with fiber mesh-coated or rough-surfaced implants. Cylindrical implants with four different pore sizes (500, 640, 800, and 1000µm) of Porous-Ti-alloy, titanium fiber mesh (FM), and surfaces roughened by titanium arc spray (Ti-spray) were implanted into the distal femur of rabbits. Bone bonding strength and histological bone ingrowth were evaluated at 4 and 12weeks after implantation. The bone bonding strength of Porous-Ti-alloy implants (640µm pore size) increased over time from 541.4N at 4weeks to 704.6N at 12weeks and was comparable to that of FM and Ti-spray implants at both weeks. No breakage of the porous structure after mechanical testing was found with Porous-Ti-alloy implants. Histological bone ingrowth that increased with implantation time occurred along the inner structure of Porous-Ti-alloy implants. There was no difference in bone ingrowth in Porous-Ti-alloy implants with pore sizes among 500, 640, and 800µm; however, less bone ingrowth was observed with the 1000µm pore size. These results indicated Porous-Ti-alloy implants with pore size under 800µm provided biologically active and mechanically stable surface for implant fixation to bone, and had potential advantages for weight bearing orthopedic implants such as acetabular cups.

Carboxymethyl-chitin promotes chondrogenesis by inducing the production of growth factors from immune cells.

Many techniques have been tested for their ability to restore cartilage defects, but several problems still remain in the complete healing of injured cartilage. In our previous study, we found that a carboxymethyl-chitin/beta-tricalcium phosphate (CM-chitin/beta-TCP) composite induced cartilage regeneration in the osteochondral defects of rabbits in vivo. We also found that CM-chitin stimulated peritoneal exudate cells (PEC) in mice and induced several kinds of inflammatory cytokines and transforming growth factor beta-1 (TGF-beta1). In this study, we examined whether CM-chitin is responsible for the induction of chondrogenesis via the production of TGF-beta1 in vitro. The murine pluripotent cell line C3H10T1/2 was maintained as a micromass culture in conditioned medium prepared from PEC stimulated with and without CM-chitin. CM-chitin-conditioned medium induced RNA expression of the chondrogenic-factor Sox9 and the matrix proteins aggrecan, Col2a1, and Comp. Their expression levels were decreased in the presence of anti-TGF-beta1 antibody. The micromass tissues cultured in CM-chitin conditioned medium at day 21 were clearly stained by Toluidine blue or Alcian blue (histological staining) and collagen II antibody (immunohistological staining), showing the expression of acidic glycosaminoglycan and type II collagen. Similar results were observed in micromass tissue stimulated with TGF-beta1 as a positive control. However, no chondrogenesis occurred when CM-chitin was added directly to a C3H10T1/2 cell culture. These results indicated that CM-chitin is a potent inducer of chondrogenesis via the induction of TGF-beta1 in immune cells.