Background Establishing gait symmetry is a major aim of amputee rehabilitation and may be more attainable with powered prostheses. Though, based on previous work, we postulate that users transfer a previously-learned motor pattern across devices, limiting the functionality of more advanced prostheses. The objective of this study was to preliminarily investigate the effect of increased stance time via visual feedback on amputees’ gait symmetry using powered and passive knee prostheses. Methods Five individuals with transfemoral amputation or knee disarticulation walked at their self-selected speed on a treadmill. Visual feedback was used to promote an increase in the amputated-limb stance time. Individuals were fit with a commercially-available powered prosthesis by a certified prosthetist and practiced walking during a prior visit. The same protocol was completed with a passive knee and powered knee prosthesis on separate days. We used repeated-measures, two-way ANOVA (alpha = 0.05) to test for significant effects of the feedback and device factors. Our main outcome measures were stance time asymmetry, peak anterior-posterior ground reaction forces, and peak anterior propulsion asymmetry. Results Increasing the amputated-limb stance time via visual feedback significantly improved the stance time symmetry (p = 0.012) and peak propulsion symmetry (p = 0.036) of individuals walking with both prostheses. With the powered knee prosthesis, the highest feedback target elicited 36% improvement in stance time symmetry, 22% increase in prosthesis-side peak propulsion, and 47% improvement in peak propulsion symmetry compared to a no feedback condition. The changes with feedback were not different with the passive prosthesis, and the main effects of device/ prosthesis type were not statistically different. However, subject by device interactions were significant, indicating individuals did not respond consistently with each device (e.g. prosthesis-side propulsion remained comparable to or was greater with the powered versus passive prosthesis for different subjects). Overall, prosthesis-side peak propulsion averaged across conditions was 31% greater with the powered prosthesis and peak propulsion asymmetry improved by 48% with the powered prosthesis. Conclusions Increasing prosthesis-side stance time via visual feedback favorably improved individuals’ temporal and propulsive symmetry. The powered prosthesis commonly enabled greater propulsion, but individuals adapted to each device with varying behavior, requiring further investigation.
Articular cartilage has unique load-bearing properties but has minimal capacity for intrinsic repair. Here, we used three-dimensional weaving, additive manufacturing, and autologous mesenchymal stem cells to create a tissueengineered, bicomponent implant to restore hip function in a canine hip osteoarthritis model. This resorbable implant was specifically designed to function mechanically from the time of repair and to biologically integrate with native tissues for long-term restoration. A massive osteochondral lesion was created in the hip of skeletally mature hounds and repaired with the implant or left empty (control). Longitudinal outcome measures over 6 months demonstrated that the implant dogs returned to normal preoperative values of pain and function. Anatomical structure and functional biomechanical properties were also restored in the implanted dogs. Control animals never returned to normal and exhibited structurally deficient repair. This study provides clinically relevant evidence that the bicomponent implant may be a potential therapy for moderate hip osteoarthritis.
T he 3-D geometry of bones and joints can be determined from MRI or CT images, and MRI-based 3-D models of articular surfaces have been reported. 1,2 Geometric accuracy of CT images have been described in several studies, including studies that focused on cortical thickness 3 and geometry of the articular surface. 4-7 Accuracy of CT, cone-beam CT, and micro-CT is influenced by several factors, including beam orientation relative to the scan surface and slice thickness. 3 An increase in the popularity of additive manufacturing has led to the common use of CT data to create 3-D or physical models. Accuracy of additive manufacturing models produced from CT-derived 3-D models has been evaluated with a focus on CT scan variables and CT scan segmentation variables. 8,9 Imaging with CT has been used to assess the shape and relative position of bones, 10 estimate joint loads, 11-13 conduct computational modeling of articular contact, 14,15 assess pathological changes in joints, 16,17 and plan surgical procedures. 18 Evaluation of the geometric accuracy of computed tomography and microcomputed tomography of the articular surface of the distal portion of the radius of cats
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