(natural, toe-in, toe-out). The knee kinetics and kinematics during landing were evaluated 5 using a motion analysis system. Results under three toe conditions were compared using 6 a one-way repeated-measures analysis of variance and a post-hoc Bonferroni test. Results: Toe-in landing was associated with a significantly greater knee abduction angle, 8 tibial internal rotation angle, and knee abduction moment than the natural and toe-out 9 conditions. Toe-out landing was associated with significantly greater tibial internal 10 rotational angular velocity.

The data support the clinical reality of 1-step minimally invasive cartilage-reparative medicine with UPAL gel without harvesting donor cells.

Objective Osteoarthritis is a progressive joint disease characterized by cartilage degradation and synovial inflammation. Presence of cartilage fragments in the joint due to degradation of cartilage is thought to be associated with local inflammatory response and progressive osteoarthritic process. Understanding the mechanism by which cartilage fragments elicit this destructive process should aid in designing novel therapeutic approaches. Therefore, objective of current study is to establish an in vitro model to examine the cross-talk between chondrocytes and cartilage fragments–stimulated macrophages. Design Cartilage fragments were prepared from femoral head cartilages of mice and analyzed using a scanning electron microscope and particle size analyzer. Bone marrow–derived macrophages were co-cultured with cartilage fragments and chondrocytes using transwell co-culture system. Macrophage inflammatory mediators in supernatant of cultures were determined by ELISA and gene expression of macrophages and chondrocyte were quantified by qRT-PCR. Results Shapes of cartilage fragments were irregular with sizes ranged between 0.54 and 55 μm. Macrophages cultured with cartilage fragments released significantly higher concentrations of TNF-α, IL-6, and NO than those of mock and control. Consistently, gene expressions of TNF-α, IL-6, and MMP-9 were significantly increased in stimulated macrophages. The elevation in production of pro-inflammatory molecules in stimulated macrophages cultures were coincident with an increase in gene expression of chondrocyte MMP-13, iNOS, and IL-6. Conclusion We developed an in vitro co-culture model to study the impact of stimulation of macrophage by cartilage fragments on the expression of chondrocyte carbolic factors. Our results revealed that cartilage fragments triggered macrophages inflammatory response that enhanced the production of chondrocyte catabolic factors.

Background: Many tissue-engineered methods for meniscal repair have been studied, but their utility remains unclear. Hypothesis: Implantation of low-endotoxin, ultra-purified alginate (UPAL) gel without cells could induce fibrocartilage regeneration on meniscal defects in rabbits. Study Design: Controlled laboratory study. Methods: Forty-two mature Japanese White rabbits were divided into 2 groups of 21 animals each. In each animal, a cylindrical defect measuring 2 mm in diameter was created with a biopsy punch on the anterior horn of the medial meniscus. In the control group, no treatment was applied on the left medial meniscal defect. In the UPAL gel group, the right medial meniscal defect was injected with the UPAL gel and gelated by a CaCl2 solution. Samples were evaluated at 3, 6, and 12 weeks postoperatively. For biomechanical evaluation, 6 additional samples from intact animals were used for comparison. Results: The macroscopic score was significantly greater in the UPAL gel group than in the control group at 3 weeks (mean ± SE: 5.6 ± 0.82 vs 3.4 ± 0.83, P = .010), 6 weeks (5.9 ± 0.72 vs 2.5 ± 0.75, P = .026), and 12 weeks (5.2 ± 1.21 vs 1.0 ± 0.63, P = .020). The histological score was significantly greater in the UPAL group than in the control group at 3 weeks (2.1 ± 0.31 vs 1.2 ± 0.25, P = .029) and 12 weeks (2.2 ± 0.55 vs 0.3 ± 0.21, P = .016). The mean stiffness of the reparative tissue in the UPAL gel group was significantly greater than that in the control group at 6 weeks (24.325 ± 3.920 N/mm vs 8.723 ± 1.190 N/mm, P = .006) and at 12 weeks (27.804 ± 6.169 N/mm vs not applicable [because of rupture]). Conclusion: The UPAL gel enhanced the spontaneous repair of fibrocartilage tissues in a cylindrical meniscal defect in rabbits. Clinical Relevance: These results imply that the acellular UPAL gel may improve the repair of traumatic meniscal injuries.