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Purpose: To determine the impact of axial traction during high resolution 3.0T MR imaging of the ankle on morphological assessment of articular cartilage and quantitative cartilage imaging parameters., Materials and Methods: MR images of n=25 asymptomatic ankles were acquired with and without axial traction (6kg). Coronal and sagittal T1-weighted (w) turbo spin echo (TSE) sequences with a driven equilibrium pulse and sagittal fat-saturated intermediate-w (IMfs) TSE sequences were acquired for morphological evaluation on a four-point scale (1=best, 4=worst). For quantitative assessment of cartilage degradation segmentation was performed on 2D multislice-multiecho (MSME) SE T2, steady-state free-precession (SSFP; n=8) T2 and SSFP diffusion-weighted imaging (DWI; n=8) images. Wilcoxon-tests and paired t-tests were used for statistical analysis., Results: With axial traction, joint space width increased significantly and delineation of cartilage surfaces was rated superior (P<0.05). Cartilage surfaces were best visualized on coronal T1-w images (P<0.05). Differences for cartilage matrix evaluation were smaller. Subchondral bone evaluation, motion artifacts and image quality were not significantly different between the acquisition methods (P>0.05). T2 values were lower at the tibia than at the talus (P<0.001). Reproducibility was better for images with axial traction., Conclusion: Axial traction increased the joint space width, allowed for better visualization of cartilage surfaces and improved compartment discrimination and reproducibility of quantitative cartilage parameters., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To investigate whether the static knee alignment affects articular cartilage ultrastructures when measured using T2 relaxation among asymptomatic subjects., Methods: Both knee joints (n = 96) of 48 asymptomatic volunteers (26 females, 22 males; 25.4 ± 1.7 years; no history of major knee trauma or surgery) were evaluated clinically (Lysholm, Tegner) and by MRI (hip-knee-ankle angle, standard knee protocol, T2 mapping). Group (n = 4) division was as follows: neutral (<1° varus/valgus), mild varus (2°-4° varus), severe varus (>4° varus) and valgus (2°-4° valgus) deformity with n = 12 subjects/group; n = 24 knees/group. Regions of interest (ROI) for T2 assessment were placed within full-thickness cartilage across the whole joint surface and were divided respecting compartmental as well as functional joint anatomy., Results: Leg alignment was 0.7° ± 0.5° varus among neutral, 3.0° ± 0.6° varus among mild varus, 5.0° ± 1.1° varus among severe varus and 2.5° ± 0.7° valgus among valgus group subjects and thus significantly different. No differences between the groups emerged from clinical measures. No morphological pathology was detected in any knee joint. Global T2 values (42.3 ± 2.3; 37.7-47.9 ms) of ROIs placed within every knee joint per subject were not different between alignment groups or between genders, respectively., Conclusion: Static frontal plane leg malalignment does not affect cartilage ultrastructure among young, asymptomatic individuals as measured by T2 quantitative imaging., Level of Evidence: Cross-sectional study, Level II-III.

Articular cartilage, once damaged, has very low regenerative potential. Various experimental approaches have been conducted to enhance chondrogenesis and cartilage maturation. Among those, non-invasive electromagnetic fields have shown their beneficial influence for cartilage regeneration and are widely used for the treatment of non-unions, fractures, avascular necrosis and osteoarthritis. One very well accepted way to promote cartilage maturation is physical stimulation through bioreactors. The aim of this study was the investigation of combined mechanical and electromagnetic stress affecting cartilage cells in vitro. Primary articular chondrocytes from bovine fetlock joints were seeded into three-dimensional (3-D) polyurethane scaffolds and distributed into seven stimulated experimental groups. They either underwent mechanical or electromagnetic stimulation (sinusoidal electromagnetic field of 1 mT, 2 mT, or 3 mT; 60 Hz) or both within a joint-specific bioreactor and a coil system. The scaffold-cell constructs were analyzed for glycosaminoglycan (GAG) and DNA content, histology, and gene expression of collagen-1, collagen-2, aggrecan, cartilage oligomeric matrix protein (COMP), Sox9, proteoglycan-4 (PRG-4), and matrix metalloproteinases (MMP-3 and -13). There were statistically significant differences in GAG/DNA content between the stimulated versus the control group with highest levels in the combined stimulation group. Gene expression was significantly higher for combined stimulation groups versus static control for collagen 2/collagen 1 ratio and lower for MMP-13. Amongst other genes, a more chondrogenic phenotype was noticed in expression patterns for the stimulated groups. To conclude, there is an effect of electromagnetic and mechanical stimulation on chondrocytes seeded in a 3-D scaffold, resulting in improved extracellular matrix production., (© 2013 Wiley Periodicals, Inc.)

Objective: Both, matrix-assisted chondrocyte transplantation (MACT) and osteochondral autograft transplantation (OCT), are applied for treatment of articular cartilage defects. While previous clinical studies have compared the respective outcome, there is no such information investigating the ultrastructural composition using T2 mapping comparing cartilage T2 values of the repair tissue (RT)., Methods: Eighteen patients that underwent MACT or OCT for treatment of cartilage defects at the knee joint (nine MACT, nine OCT) were matched for gender (one female, eight male pairs), age (33.8), body mass index (BMI) (28.3), defect localization, and postoperative interval (41.6 months). T2 assessment was accomplished by T2 maps, while the clinical evaluation included the Lysholm and Cincinnati knee scores, a visual analogue scale (VAS) for pain, the Tegner activity scale, and the Short Form-36., Results: Global T2 values of healthy femoral cartilage (HC) were similar among groups, while T2 values of the RT following MACT (46.8ms, SD 8.6) were significantly lower when compared to RT T2 values after OCT (55.5ms, SD 6.7) (P=0.048). MACT values were also significantly lower in comparison to HC (52.5ms, SD 7.9) within MACT patients (P=0.046), while OCT values were significantly higher compared to HC (49.9ms, SD 5.1) within OCT patients (P=0.041). The clinical outcome following MACT was consistently superior to that after OCT while only the Lysholm score reached the level of significance (MACT 77.0, OCT 66.8; P=0.04)., Conclusion: These findings indicate that MACT and OCT result in a different ultrastructural outcome, which is only partially represented by the clinical picture.