The T2 value changes reflected histologic tendon healing. While T2 and Bonar grade were lower at all time points in tendons treated with PRP, there was no significant difference between the treatment and control tendons.

IAI-HA prevented gait disturbances in the DMM model, but did not prevent histological changes associated with OA progression.

Quantitative elastography using an acoustic coupler is a reproducible technique for measuring the elasticity of the Achilles tendon. It may detect early tendon degeneration that is not depicted on B-mode imaging.

Level IV, case series.

Knees with osteophyte formation at the IC, even those of K/L severity grade 0/1, are at risk for the development of radiographic OA by 48 months.

The findings of this study suggest that ultrasound examination may be suitable for screening for meniscal tears. The fact that almost 10% of the lateral menisci could not be evaluated because of poor images appears to be a weakness of ultrasound.

ObjectivesThe aim of this study was to investigate the effect of granulocyte-colony stimulating factor (G-CSF) on mesenchymal stem cell (MSC) proliferation in vitro and to determine whether pre-microfracture systemic administration of G-CSF (a bone marrow stimulant) could improve the quality of repaired tissue of a full-thickness cartilage defect in a rabbit model.MethodsMSCs from rabbits were cultured in a control medium and medium with G-CSF (low-dose: 4 μg, high-dose: 40 μg). At one, three, and five days after culturing, cells were counted. Differential potential of cultured cells were examined by stimulating them with a osteogenic, adipogenic and chondrogenic medium.A total of 30 rabbits were divided into three groups. The low-dose group (n = 10) received 10 μg/kg of G-CSF daily, the high-dose group (n = 10) received 50 μg/kg daily by subcutaneous injection for three days prior to creating cartilage defects. The control group (n = 10) was administered saline for three days. At 48 hours after the first injection, a 5.2 mm diameter cylindrical osteochondral defect was created in the femoral trochlea. At four and 12 weeks post-operatively, repaired tissue was evaluated macroscopically and microscopically.ResultsThe cell count in the low-dose G-CSF medium was significantly higher than that in the control medium. The differentiation potential of MSCs was preserved after culturing them with G-CSF.Macroscopically, defects were filled and surfaces were smoother in the G-CSF groups than in the control group at four weeks. At 12 weeks, the quality of repaired cartilage improved further, and defects were almost completely filled in all groups. Microscopically, at four weeks, defects were partially filled with hyaline-like cartilage in the G-CSF groups. At 12 weeks, defects were repaired with hyaline-like cartilage in all groups.ConclusionsG-CSF promoted proliferation of MSCs in vitro. The systemic administration of G-CSF promoted the repair of damaged cartilage possibly through increasing the number of MSCs in a rabbit model.Cite this article: T. Sasaki, R. Akagi, Y. Akatsu, T. Fukawa, H. Hoshi, Y. Yamamoto, T. Enomoto, Y. Sato, R. Nakagawa, K. Takahashi, S. Yamaguchi, T. Sasho. The effect of systemic administration of G-CSF on a full-thickness cartilage defect in a rabbit model MSC proliferation as presumed mechanism: G-CSF for cartilage repair. Bone Joint Res 2017;6:123–131. DOI: 10.1302/2046-3758.63.BJR-2016-0083.

Purpose To determine the time-dependent change in strain ratios (SRs) at the healing site of an Achilles tendon rupture in a rabbit model of tendon transection and to assess the correlation between SRs and the mechanical and histologic properties of the healing tissue. Materials and Methods Experimental methods were approved by the institutional animal care and use committee. The Achilles tendons of 24 New Zealand white rabbits (48 limbs) were surgically transected. The SRs of Achilles tendons were calculated by using compression-based quantitative ultrasonographic elastography measurements obtained 2, 4, 8, and 12 weeks after transection. After in vivo elastography, the left Achilles tendon was harvested for mechanical testing of ultimate load, ultimate stress, elastic modulus, and linear stiffness, and the right tendons were harvested for tissue histologic analysis with the Bonar scale. Time-dependent changes in SRs, mechanical parameters, and Bonar scale scores were evaluated by using repeated-measures analysis of variance. The correlation between SRs and each measured variable was evaluated by using the Spearman rank correlation coefficient. Results Mean SRs and Bonar scale values decreased as a function of time after transection, whereas mechanical parameters increased (P < .001). SR correlated with ultimate stress (ρ = 0.68, P <.001,) elastic modulus (ρ = 0.74, P <.001), and the Bonar scale (ρ = 0.87, P <.001). Conclusion Quantitative elastography could be a useful method with which to evaluate mechanical and histologic properties of the healing tendon. RSNA, 2017 Online supplemental material is available for this article.