Control systems for powered prosthetic legs typically divide the gait cycle into several periods with distinct controllers, resulting in dozens of control parameters that must be tuned across users and activities. To address this challenge, this paper presents a control approach that unifies the gait cycle of a powered knee-ankle prosthesis using a continuous, user-synchronized sense of phase. Virtual constraints characterize the desired periodic joint trajectories as functions of a phase variable across the entire stride. The phase variable is computed from residual thigh motion, giving the amputee control over the timing of the prosthetic joint patterns. This continuous sense of phase enabled three transfemoral amputee subjects to walk at speeds from 0.67 to 1.21 m/s and slopes from -2.5 to +9.0 deg. Virtual constraints based on task-specific kinematics facilitated normative adjustments in joint work across walking speeds. A fixed set of control gains generalized across these activities and users, which minimized the configuration time of the prosthesis.

Background: Articulated or hinged ankle-foot orthosis (AFO) allow more range of motion. However, quantitative investigation on articulated AFO is still sparse. Objective: The objective of the study was to quantitatively investigate effects of alignment and joint types on mechanical properties of the thermoplastic articulated AFO. Study design: Tamarack dorsiflexion assist flexure joints with three durometers (75, 85 and 95) and free motion joint were tested. The AFO joint was aligned with the center of the motor shaft (surrogate ankle joint), 10 mm superior, inferior, anterior and posterior with respect to the motor shaft center. Methods: The AFO was passively moved from 20 plantar flexion to 15 dorsiflexion at a speed of 10 /s using a motorized device. Mechanical properties including index of hysteresis, passive resistance torque and quasi-static stiffness (at neutral, 5, 10 and 15 in plantar flexion) were quantified. Results: Significant effects of joint types and joint alignment on the mechanical properties of an articulated thermoplastic AFO were revealed. Specifically, center alignment showed minimum resistance and stiffness while anterior and posterior alignment showed significantly higher resistance and stiffness. The dorsiflexion assist torques at neutral position ranged from 0.69 AE 0.09 to 1.88 AE 0.10 Nm. Conclusions: Anterior and posterior alignment should be avoided as much as possible. Clinical relevanceThe current study suggested that anterior and posterior alignment be avoided as much as possible in clinical practice due to potential skin irritation and increase in stress around the ankle joint.

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BACKGROUND: This exploratory study was conducted in an effort to demonstrate that bioelectrical impedance analysis (BIA) phase angle measurement is a novel tool for monitoring the effectiveness of a wound care regimen at a regional level and is valuable in comparing that status with the overall metabolic health of the patient. Isolating and measuring the extent to which nutritional supplementation contributes to the healing process is difficult and confounded by the many treatment modalities patients undergo.OBJECTIVE: The authors conducted a limited exploratory study to determine whether regional phase angle measurements accurately reflected the status of chronic nonhealing wounds. This information would potentially provide the ability to quantitatively evaluate of the role of nutritional supplementation in wounds of varying etiologies by comparing regional BIA phase angle measurement with overall BIA phase angle measurement.METHODS: Eleven patients with wounds of varying etiologies were selected to participate. Each patient underwent a treatment regimen specific to his or her condition, and all patients were given JUVEN Ò nutritional supplement.RESULTS AND CONCLUSION: In all patients, the BIA phase angle measurement mirrored the health of the wound and provided an accurate tool for assessing the regional tissue health, a valuable insight in measuring the effectiveness of a systemic treatment.