No abstract

Flatfoot deformity is characterized by loss of the medial longitudinal arch, forefoot abduction, hindfoot eversion, and often Achilles tendon contracture. Our objectives were to validate a cadaveric flatfoot model that involves selective ligament attenuation and to determine if Achilles tendon overpull is associated with increased pes planus severity. We measured the three-dimensional (3D) orientation of the bones of interest in the unloaded, loaded, and Achilles tendon overpull conditions. A flatfoot model was created by attenuating ligaments involved in the pes planus deformity followed by cyclic axial loading, and bone orientations were acquired in the three conditions. Significant differences seen between normal feet and flat feet were consistent with those seen with the pes planus deformity. The first metatarsal dorsiflexed and abducted relative to the talus. The navicular abducted relative to the talus. The calcaneus everted relative to the tibia. The talus plantar flexed and adducted. Achilles overpull resulted in first metatarsal-to-talus dorsiflexion and navicular-to-talus abduction. Thus, selective ligament attenuation followed by cyclic axial loading can create a cadaveric flatfoot model consistent with the in vivo deformity. Longitudinal arch depression, hindfoot eversion, talonavicular joint abduction, forefoot abduction, and talar plantar flexion were seen. Simulated Achilles tendon contracture increased the severity of the deformity, particularly in arch depression and forefoot abduction.

Amputees who wear prosthetic limbs often experience discomfort from blisters and sores due to mechanical insult; these skin conditions are exacerbated by elevated skin temperatures and excessive perspiration within the prosthetic socket. The goal of this study was to create a tool for developing new prostheses that accommodate varying thermal loads arising from everyday activities. A three-dimensional thermal model of a transtibial residual limb and prosthesis was constructed using the finite element (FE) method. Transverse computerized tomography (CT) scans were used to specify the geometry of the residual limb and socket. Thermal properties from the literature were assigned to both biological tissue and prosthetic socket elements. The purpose of this work was to create a model that would aid in testing the effect of new prosthesis designs on skin temperature. To validate its output, the model was used to predict the skin temperature distribution in a common prosthetic socket system (silicone liner, wool sock, and carbon fiber socket) at rest with no mechanical loading. Skin temperatures were generally elevated near muscle and decreased anteriorly and at the distal end. Experimental temperature measurements taken at the skin-prosthesis interface of five human subjects were used to validate the model. Data extracted from the thermal model at anterior, posterior, lateral, and medial locations were typically within one standard deviation of experimental results; the mean temperatures were within 0.3 degree C for each section and were within 0.1 degree C overall.

demonstrated improved structural properties including energy to failure (LV: 2.018, Ad: 1.343 N∑m∑deg), stiffness (LV: 0.076, Ad: 0.056 N∑m/deg; p < .05), maximum torque (LV: 0.363, Ad: 0.293 N∑m), and degree to failure (LV: 8.14, Ad: 7.08 deg). Micro CT analysis showed a statistically significant higher proportion of bone volume to total volume (BV/TV) in group LV versus group AV. Conclusion: RBMCs transfected with LV-BMP are more effective at healing a critical size rat femoral defect than Ad-BMP. Luciferase expression was noted at a later time point for those animals in group LV compared to group AV. Gene therapy using a LV vector is a novel and efficient technique for the delivery of osteoinductive growth factor BMP to a site of significant bone loss associated with trauma, revision joint arthroplasty, pseudoarthrosis of the spine, and tumor resection.