In Vivo contrast-enhanced cone beam CT provides quantitative information on articular cartilage and subchondral bone

In post-traumatic osteoarthritis, both articular cartilage and subchondral bone undergo characteristic pathological changes. This study investigates potential of delayed cone beam computed tomography arthrography (dCBCTa) to simultaneously detect variations in cartilage and subchondral bone. The knees of patients (n\ua0=\ua017) with suspected joint injuries were imaged using a clinical CBCT scanner at 5 and 45\ua0min after the intra-articular injection of anionic contrast agent (Hexabrix™) with hydroxyapatite phantoms around the knee. Normalized attenuation (i.e., contrast agent partition, an indicator of tissue composition) in cartilage, bone mineral density (BMD) in subchondral bone plate (SBP), subchondral bone and trabecular bone, and thicknesses of SBP and cartilage were determined. Lesions of cartilage were scored using International Cartilage Repair Society (ICRS) grading. Normalized attenuation in the delayed image (t\ua0=\ua045\ua0min) increased along the increase of ICRS grade (p\ua0=\ua00.046). Moreover, BMD was significantly higher in SBPs under damaged cartilage (ICRS\ua0=\ua01–2 or ICRS\ua0≥\ua03; p\ua0=\ua00.047\ua0and p\ua0=\ua00.038, respectively) than in SBP under non-injured tissue (ICRS\ua0=\ua00). For the first time, dCBCTa enabled the detection of articular cartilage injuries and subchondral bone alterations simultaneously in vivo. Significant relations between ICRS grading and both cartilage and bone parameters suggest that dCBCTa has potential for quantitative imaging of the knee joint

Short-term exercise-induced improvements in bone properties are for the most part not maintained during aging in hamsters.

Physical exercise during growth affects composition, structure and mechanical properties of bone. In this study we investigated whether the beneficial effects of exercise during the early growth phase have long-lasting effects or not. Female Syrian golden hamsters (total n=152) were used in this study. Half of the hamsters had access to running wheels during their rapid growth phase (from 1 to 3months of age). The hamsters were sacrificed at the ages of 1, 3, 12, and 15months. The diaphysis of the mineralized humerus was analyzed with microCT and subjected to three-point-bending mechanical testing. The trabecular bone in the tibial metaphysis was also analyzed with microCT. The collagen matrix of the humerus bone was studied by tensile testing after decalcification. The weight of the hamsters as well as the length of the bone and the volumetric bone mineral density (BMDvol) of the humerus was higher in the running group at the early age (3months). Moreover, the mineralized bone showed improved mechanical properties in humerus and had greater trabecular thickness in the subchondral bone of tibia in the runners. However, by the age of 12 and 15months, these differences were equalized with the sedentary group. The tensile strength and Young's modulus of decalcified humerus were higher in the runners at early stage, indicating a stronger collagen network. In tibial metaphysis, trabecular thickness was significantly higher for the runners in the old age groups (12 and 15months). Our study demonstrates that physical exercise during growth improves either directly or indirectly through weight gain bone properties of the hamsters. However, the beneficial effects were for the most part not maintained during aging