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There is increasing use of digital technologies in urban planning, including in the generation of designs and the participative side of planning. We examine this digital planning by reporting on the application of an experimental online participatory platform in the regeneration of a London housing estate, enabling reflection on participation processes and outcomes. Drawing on lessons learned, the paper synthesises a conceptual representation of online participation and a relational framework for understanding the participatory platform and its context. We subsequently develop a ‘matrix of participative space’, building on Arnstein’s ‘ladder of participation’, to present a two-dimensional framework of online participation, identifying cases of ‘participative deficit’ and ‘democratic deficit’. We conclude with implications for future digital participation in urban planning and design.

Introduction/Purpose: The aim was to compare different bone marrow stimulation techniques and consequent fluid permeability of subchondral bone by assessing flow of radiopaque contrast agent using μCT image analysis and 3D modelling. Methods: Donated human tali specimens (n=12) were prepared by creating separate matched 10mm diameter chondral defects in each. Each defect underwent one of three surgical techniques: fine wire drilling, nanofracture or microfracture, addition of radiopaque contrast agent and imaged using a clinical μCT scanner. Using Slicer 3D software each μCT scan was segmented for bone and contrast agent regions in each surgical site of each sample. Each site was resolved into a cylinder and the ratio of segmented pixels of contrast agent against bone calculated. Results: μCT analysis indicated that 8/12 nanofracture regions demonstrated enhanced flow of contrast to at least the depth of the fracture site, with some additional lateral flow also observed. 8/12 microfracture regions demonstrated flow of contrast agent localised to the fracture site and preferential flow laterally. Only 1/12 samples with fine wire drilling demonstrated any fluid flow. In 11/12 samples that showed no permeation of contrast agent, a residual layer of contrast agent on the chondral surface was seen. Segmentation of each sample site showed a significant increase (n=12, p< 0.05) in fluid flow of the contrast agent in the nanofracture sites (11%) compared to microfracture (5%) and fine wire drilling (2%). Conclusion: Nanofracture showed significantly improved fluid permeability throughout the surrounding trabecular structure, when compared to microfracture and fine wire drilling. Microfracture allowed some fluid flow, but only confined to the immediate area around the fracture site, while fine wire drilling allows very little fluid flow at all. This study suggests that nanofracture should perhaps be the preferred mode of subchondral bone preparation for osteochondral lesions of the talus. Quantitative measurement of contrast permeability into talar subchondral bone by technique Nanofracture showed significantly improved fluid permeability throughout the surrounding trabecular structure, when compared to microfracture and fine wire drilling

Category: Basic Sciences/Biologics; Ankle; Arthroscopy; Sports Introduction/Purpose: Current surgical practice for the treatment of osteochondral lesions in the ankle involves using one of three techniques to promote blood flow from subchondral bone tissue to the defect site, improving the rate of healing. These different techniques: - fine-wire drilling, nanofracture and microfracture, involve disrupting the trabecular bone. However, the size and method of these techniques means this varies in terms of penetration depth and diameter. Additionally, each technique causes differing degrees of damage to the trabecular structure, and the ability of fluid to flow through the porous structure. The aim of this study was to compare the influence of the different techniques on the fluid permeability of the tissue following by assessing the flow of radiopaque contrast agent using μCT image analysis. Methods: Fresh-frozen cadaveric tali specimens (n=12) were prepared through creating a 10mm diameter chondral defect in three different regions of each talus. Each region then underwent one of three surgical techniques: 1) Fine wire drilling, 2) Nanofracture or 3) Microfracture, undertaken by a single surgeon.0.1 ml radiopaque contrast agent (Omnipaque TM 300) was then added to each region and imaged using a clinical μCT scanner (SCANCO Medical AG, 73.6 μm resolution) The amount of contrast agent that permeated through each different region was assessed through imaging processing. Results: The μCT analysis indicated that across the 12 samples, eight nanofracture regions demonstrated flow of contrast agent to the depth of the fracture site or deeper. Some lateral flow was also observed in these sites. Eight microfracture regions demonstrated that the flow of contrast agent was localised to the fracture site and a preferential flow laterally. In only one sample, did a fine wire drilling region demonstrate any fluid flow. In this sample, contrast agent had permeated through the drilling site to the bottom and some sub-site permeation was observed. However, in all samples that showed no permeation of contrast agent through the fracture site, there was a layer of contrast agent on the chondral surface or minor permeation through to the sub- chondral surface. Conclusion: Nanofracture showed improved fluid permeability throughout the surrounding trabecular structure, when compared to microfracture and fine wire drilling. Microfracture appears to allow some fluid flow, but this is confined to the immediate area around the fracture site, while fine wire drilling appears to allow almost no fluid flow through the surrounding trabecular tissue. This conclusion is reinforced by previous literature that concluded the damage to the structure of the trabecular tissue is reduced when using nanofracture, compared to the other two techniques.

Category: Basic Sciences/Biologics; Ankle; Ankle Arthritis Introduction/Purpose: Osteochondral lesions of the talus commonly occur because of traumatic injury. These lesions can affect the biomechanical behaviour of the ankle joint resulting in further degradation of the tissue and development of osteoarthritis. However, little is known about the impact of such lesions to the biomechanical behaviour of the natural ankle joint, in particular changes to the tribology of the joint due to their introduction. The aim of this study was to develop a tribological simulation of the natural tibiotalar joint to assess frictional changes due to the introduction of chondral lesion and to further assess the impact of current treatment modalities such as AMIC techniques (Nanofracture with Chondro-Gide membrane) and osteochondral allograft cores (OCA). Methods: A healthy left cadaveric tibiotalar joint (n =1) was cemented into a custom-made jig; to preserve centre of rotation (COR). The sample was loaded into a ProSim Pendulum Friction simulator and tested using the following loading conditions. Simulations were run at 1-Hertz frequency for 3600 cycles with a constant load of 640 N applied through the tibia through a +- 10° flexion and extension (F/E) angle. Data was normalised using a mean frictional offset value calculated through a 2-minute pre- and post-test to account for additional frictional torque and changes to friction factor was assessed. Cartilage was assessed for changes in tissue appearance and damage. Following this, a 10-mm circular, chondral defect was introduced to talar dome and testing was repeated under the same conditions. The defect was repaired with a 10-mm Chondro-Gide patch and then 10-mm OCA before being subsequently tested using the same methods. Results: No visible changes were seen to the cartilage during testing for the healthy, defected and Chondro-Gide treated conditions. Some damage could be seen on the reciprocal tibial cartilage after testing with the OCA repair. Assessment of normalised friction factors showed that while testing, for each condition, the frictional output remained stable with a reduction in the mean friction factor seen due to the introduction of a defect. This was maintained with Chondro-Gide. A return to normal was seen in the OCA treatment with the overall mean values for the healthy and OCA repair were 0.0301 and 0.0329, respectively. In addition, overall mean frictional factor values in the presence of a defect and Chondro-Gide repair showed reduced frictional values of 0.0119 and 0.0103, respectively. Conclusion: This method will allow for potential preclinical evaluation of treatments for OLTs in an appropriately simulated environment to assess tribological changes. The values obtained for the frictional factor all sit within the expected range for friction between two cartilage surfaces that has been reported in the literature 0.003 and 0.08. Thus, providing a reliable platform for comparing different methods of osteochondral defect repair in the tibiotalar joint.

Category: Basic Sciences/Biologics; Ankle; Sports Introduction/Purpose: The management of osteochondral lesions of the talus (OLTs) provides a challenging predicament for clinicians; with an increased array of treatment options available. In many cases, the management strategy used is dependent on both the size and location of the lesion. One of the current treatments used for mid-sized (10-20 mm) lesions is Chondro-Gide membrane. To apply this therapy, the defect site is debrided into a shape of the clinicians' preference with a template being used to prepare the Chondro-Gide matrix to the correct size and shape. However, there is some debate within the clinical community as to which shape allows for improved treatment. In this study we aim to assess whether a square or circular scaffold repair provided improved treatment when tested tribologically. Methods: 16-mm circular chondral defects were introduced to the talar dome of cadaveric donor tissue (n = 3). The tibiotalar joints were cemented with the centre of rotation preserved. The ankle joint was loaded into a ProSim Pendulum Friction simulator and tested using the following loading and motor conditions. Simulations were run at a 1-Hertz for 3600 cycles with a constant tibial load of 640 N and 20° sweep arc through flexion and extension. Data was normalised using a mean frictional offset value calculated using 2 minute pre- and post- test to account for additional frictional torque. Nanofracture was performed on the defect site and a circular Chondro-Gide patch was fixed using a synthetic fibrin glue before testing using the same conditions. The circular defect site was modified to create a 16-mm square defect which was repaired with a square patch in the same manner and tested as described. Results: The overall mean frictional factors over the 1-hour test for the defect, circular and square repairs were 0.039, 0.042 and 0.026, respectively. These values are within the expected range for in vitro testing of two cartilage surfaces previously reported in the literature of 0.003 and 0.08, suggesting that frictional values did not differ between the samples. However, visual changes to the stability of the repair and the reciprocal tibial cartilage could be seen post testing. In all cases the circular repair remained in the defect site. In comparison, for 2 out of 3 of the defects repaired with a square Chondro-Gide patch did not remain stable within the defect site. In both cases further delamination was seen on the reciprocal tibial cartilage tissue. Conclusion: This method will allow for potential preclinical evaluation of treatments for OLTs in an appropriately simulated environment to assess tribological changes. The values obtained for the frictional factor all sit within the expected range for friction between two cartilage surfaces that has been reported in the literature 0.003 and 0.08. Thus, providing a reliable platform for comparing different methods of osteochondral defect repair in the tibiotalar joint.