Repair of osteochondral defects with recombinant human type II collagen gel and autologous chondrocytes in rabbit

SummaryObjectiveRecombinant human type II collagen (rhCII) gels combined with autologous chondrocytes were tested as a scaffold for cartilage repair in rabbits in vivo.MethodAutologous chondrocytes were harvested, expanded and combined with rhCII-gel and further pre-cultivated for 2 weeks prior to transplantation into a 4 mm diameter lesion created into the rabbit's femoral trochlea (n = 8). Rabbits with similar untreated lesions (n = 7) served as a control group.ResultsSix months after the transplantation the repair tissue in both groups filled the lesion site, but in the rhCII-repair the filling was more complete. Both repair groups also had high proteoglycan and type II collagen contents, except in the fibrous superficial layer. However, the integration to the adjacent cartilage was incomplete. The O'Driscoll grading showed no significant differences between the rhCII-repair and spontaneous repair, both representing lower quality than intact cartilage. In the repair tissues the collagen fibers were abnormally organized and oriented. No dramatic changes were detected in the subchondral bone structure. The repair cartilage was mechanically softer than the intact tissue. Spontaneously repaired tissue showed lower values of equilibrium and dynamic modulus than the rhCII-repair. However, the differences in the mechanical properties between all three groups were insignificant.ConclusionWhen rhCII was used to repair cartilage defects, the repair quality was histologically incomplete, but still the rhCII-repairs showed moderate mechanical characteristics and a slight improvement over those in spontaneous repair. Therefore, further studies using rhCII for cartilage repair with emphasis on improving integration and surface protection are required

Going carless in different urban fabrics : socio-demographics of household car ownership

Diverse physical features of urban areas alongside socio-demographic characteristics affect car ownership, and hence the daily mobility choices. As a case of sustainable mobility, we explore how various urban environments and socio-demographics associate with the spatial and social distribution of household car ownership and carlessness in the Helsinki Metropolitan Area, Finland. Three urban fabrics characterizing the study area are established based on the transportation mode (walking, public transportation, or automobile) the physical urban environment primarily supports. The national level Monitoring System of Spatial Structure and Urban Form database, and the National Travel Survey (2016) are utilized to further include spatial and socio-demographic variables into our analysis across these fabrics. Our results show that households with and without cars differ in terms of residential distance to the city center, neighborhood density, house type, and socio-demographic profiles. Single pensioners and students are most likely to be carless, whereas families represent the opposite. Within the carless households the differences are also evident between different groups. For the more affluent households residing in dense and well-connected areas, and mostly possessing driver's licenses, carlessness is presumably a choice. Contrarily, many other carless households represent the less affluent often located in the more distant, low-density, and less accessible areas, while also possessing less driver's licenses, making carlessness more of a constraint, as the local urban fabric does not support such lifestyle. Consequently, carless households should be increasingly recognized as a focus group in sustainable urban planning in terms of identifiable best practices and potential vulnerability.Peer reviewe

Estimation of articular cartilage properties using multivariate analysis of optical coherence tomography signal

SummaryObjectiveThe aim was to investigate the applicability of multivariate analysis of optical coherence tomography (OCT) information for determining structural integrity, composition and mechanical properties of articular cartilage.DesignEquine osteochondral samples (N = 65) were imaged with OCT, and their total attenuation and backscattering coefficients (μt and μb) were measured. Subsequently, the Mankin score, optical density (OD) describing the fixed charge density, light absorbance in amide I region (Aamide), collagen orientation, permeability, fibril network modulus (Ef) and non-fibrillar matrix modulus (Em) of the samples were determined. Partial least squares (PLS) regression model was calculated to predict tissue properties from the OCT signals of the samples.ResultsSignificant correlations between the measured and predicted mean collagen orientation (R2 = 0.75, P < 0.0001), permeability (R2 = 0.74, P < 0.0001), mean OD (R2 = 0.73, P < 0.0001), Mankin scores (R2 = 0.70, P < 0.0001), Em (R2 = 0.50, P < 0.0001), Ef (R2 = 0.42, P < 0.0001), and Aamide (R2 = 0.43, P < 0.0001) were obtained. Significant correlation was also found between μb and Ef (ρ = 0.280, P = 0.03), but not between μt and any of the determined properties of articular cartilage (P > 0.05).ConclusionMultivariate analysis of OCT signal provided good estimates for tissue structure, composition and mechanical properties. This technique may significantly enhance OCT evaluation of articular cartilage integrity, and could be applied, for example, in delineation of degenerated areas around cartilage injuries during arthroscopic repair surgery

Going carless in different urban fabrics: socio-demographics of household car ownership

Diverse physical features of urban areas alongside socio-demographic characteristics affect car ownership, and hence the daily mobility choices. As a case of sustainable mobility, we explore how various urban environments and socio-demographics associate with the spatial and social distribution of household car ownership and carlessness in the Helsinki Metropolitan Area, Finland. Three urban fabrics characterizing the study area are established based on the transportation mode (walking, public transportation, or automobile) the physical urban environment primarily supports. The national level Monitoring System of Spatial Structure and Urban Form database, and the National Travel Survey (2016) are utilized to further include spatial and socio-demographic variables into our analysis across these fabrics. Our results show that households with and without cars differ in terms of residential distance to the city center, neighborhood density, house type, and socio-demographic profiles. Single pensioners and students are most likely to be carless, whereas families represent the opposite. Within the carless households the differences are also evident between different groups. For the more affluent households residing in dense and well-connected areas, and mostly possessing driver's licenses, carlessness is presumably a choice. Contrarily, many other carless households represent the less affluent often located in the more distant, low-density, and less accessible areas, while also possessing less driver's licenses, making carlessness more of a constraint, as the local urban fabric does not support such lifestyle. Consequently, carless households should be increasingly recognized as a focus group in sustainable urban planning in terms of identifiable best practices and potential vulnerability

Simultaneous ultrasound measurement of articular cartilage and subchondral bone

SummaryObjectiveIn osteoarthritis (OA), subchondral sclerosis takes place during cartilage degeneration. High frequency ultrasound (12–55MHz) has been shown to diagnose degenerated articular cartilage, while 0.1–1MHz ultrasound has been applied for clinical characterization of bone and diagnostics of osteoporosis. The aim of the study is to investigate, for the first time, the feasibility of 5MHz ultrasound for simultaneous analysis of articular cartilage and subchondral bone.MethodsOsteochondral samples (n=10) were prepared from fresh and visually normal bovine medial tibial plateaus. Acoustic properties of the cartilage and subchondral bone were measured with a scanning ultrasound system using the pulse-echo geometry and compared with biomechanical, histological and compositional reference data.ResultsThe apparent integrated backscatter (AIB) from internal cartilage showed significant partial correlations with hydroxyproline (Hypro) (r=0.58, P=0.000), water content (r=−0.52, P=0.001) and dynamic modulus (r=0.57, P=0.000) of the tissue. Weak but statistically significant correlation was found between the bone AIB and mineral density of the subchondral plate (r=−0.34, P=0.041). Topographical variations in cartilage thickness could be detected using ultrasound. Composition, thickness and mechanical properties of the cartilage varied significantly across the tibial plateau. For the calculated ultrasound parameters, the variation was significant only between a few locations.ConclusionsPulse-echo ultrasound geometry at 5MHz was feasible for simultaneous measurement of the acoustic properties of articular cartilage and subchondral bone. However, the relationships between the ultrasound parameters and properties of cartilage and bone were not as strong as reported earlier in studies focusing only either on bone or cartilage. Simultaneous measurement of both tissues compromises, due to natural curvature of articulating surfaces, the perpendicularity of the incidence of the ultrasound pulse. Obviously, this source of uncertainty should be minimized in order to enable effective clinical use of ultrasound in simultaneous measurement of articular cartilage and subchondral bone

Simultaneous ultrasound measurement of articular cartilage and subchondral bone

Objective: In osteoarthritis (OA), subchondral sclerosis takes place during cartilage degeneration. High frequency ultrasound (12-55. MHz) has been shown to diagnose degenerated articular cartilage, while 0.1-1. MHz ultrasound has been applied for clinical characterization of bone and diagnostics of osteoporosis. The aim of the study is to investigate, for the first time, the feasibility of 5. MHz ultrasound for simultaneous analysis of articular cartilage and subchondral bone. Methods: Osteochondral samples (n=10) were prepared from fresh and visually normal bovine medial tibial plateaus. Acoustic properties of the cartilage and subchondral bone were measured with a scanning ultrasound system using the pulse-echo geometry and compared with biomechanical, histological and compositional reference data. Results: The apparent integrated backscatter (AIB) from internal cartilage showed significant partial correlations with hydroxyproline (Hypro) (r=0.58, P=0.000), water content (r=-0.52, P=0.001) and dynamic modulus (r=0.57, P=0.000) of the tissue. Weak but statistically significant correlation was found between the bone AIB and mineral density of the subchondral plate (r=-0.34, P=0.041). Topographical variations in cartilage thickness could be detected using ultrasound. Composition, thickness and mechanical properties of the cartilage varied significantly across the tibial plateau. For the calculated ultrasound parameters, the variation was significant only between a few locations. Conclusions: Pulse-echo ultrasound geometry at 5. MHz was feasible for simultaneous measurement of the acoustic properties of articular cartilage and subchondral bone. However, the relationships between the ultrasound parameters and properties of cartilage and bone were not as strong as reported earlier in studies focusing only either on bone or cartilage. Simultaneous measurement of both tissues compromises, due to natural curvature of articulating surfaces, the perpendicularity of the incidence of the ultrasound pulse. Obviously, this source of uncertainty should be minimized in order to enable effective clinical use of ultrasound in simultaneous measurement of articular cartilage and subchondral bone

Detection of mechanical injury of articular cartilage using contrast enhanced computed tomography

Objective: Osteoarthritic degeneration may be initiated by mechanical overloading of articular cartilage. Mechanical injury increases the permeability of tissue, thereby probably affecting the diffusion of contrast agents in articular cartilage. We investigated whether it is possible to detect acute cartilage injury by measuring contrast agent diffusion into articular cartilage using contrast enhanced computed tomography (CECT). Methods: Osteochondral plugs (Ø= 6.0. mm, n= 36) were prepared from intact bovine patellae (n= 9). Two of the adjacent samples were injured by impact loading, using a drop tower, while the others served as paired controls. The samples were imaged before immersion in contrast agent solution [ioxaglate (Hexabrix™) or sodium iodide (NaI)] and 1, 3, 5, 7, 10, 15, 20 and 25. h after immersion using a MicroCT-instrument. Contrast agent content, diffusion coefficient and diffusion flux were determined for each sample. Results: Already after 1. h the penetration of contrast agents into cartilage was significantly (P< 0.05) greater in the injured samples. The diffusion coefficient was not altered by the injury, which suggests that reaching the diffusion equilibrium takes the same time in injured and intact cartilage. However, the diffusion flux of ioxaglate through the articular surface was significantly higher in injured samples at 30-60. min after immersion. Conclusions: To conclude, CECT could diagnose articular cartilage injuries, and determination of the diffusion flux of ioxaglate helped to detect tissue injury without waiting for the diffusion equilibrium. These results are encouraging, however, in vivo application of CECT is challenging and systematic further studies are needed to reveal its clinical potential

Associations of neighborhood-level socioeconomic status, accessibility, and quality of green spaces in Finnish urban regions

Highlights • Fair access to green spaces with varying qualities was analyzed in Finland. • Most of the Finnish urban population lives within 300 m from any green space. • Large green areas and forests were more accessible to high SES areas. • Green areas with facilities and routes were more accessible to low SES areas. • Quality of green spaces should be better considered in accessibility analyses. Abstract Ensuring fair access to urban green spaces is a constant challenge for planning in densifying cities. Moreover, the quality of green spaces that determines their usability is often insufficiently considered in accessibility research. We examined residents’ accessibility to different types of green spaces also by neighborhood-level socioeconomic status (SES) in the seven largest urban regions in Finland. We identified eight different green space types, and high and low SES neighborhoods using income, education, and unemployment rate. We calculated network-based accessibility to the different types of green spaces and compared areas with a high and low SES using ANOVA. 90% of the urban residents lived within 300 meters of any green space. However, inclusion of the quality factors decreased accessibility of the green spaces from 34% to 75%. Residents living in high and low SES areas had different quality features in their nearest green spaces. Recreation facilities and routes were closer to low SES areas, whereas areas of high SES were associated with better accessibility to large green areas, and forests. This pattern recurred in most individual cities with varying distance differences. Our results emphasize the importance of considering the quality of green spaces in urban planning