Louise Keating

Reliability of three-dimensional gait analysis in cervical spondylotic myelopathy

BACKGROUND Gait impairment is one of the primary symptoms of cervical spondylotic myelopathy (CSM). Detailed assessment is possible using three-dimensional gait analysis (3DGA), however the reliability of 3DGA for this population has not been established. The aim of this study was to evaluate the test-retest reliability of temporal-spatial, kinematic and kinetic parameters in a CSM population. METHODS Twelve patients with CSM (mean age 54 years) were consecutively recruited from a neurosurgery clinic. 3DGA was conducted on 2 separate days, less than 1 week apart, using the VICON(®) 250 Motion Analysis. The average of 10 gait cycles was analysed. Reliability was assessed using the one-way random intraclass correlation coefficient (ICC), the standard error of measurement (SEM), and Bland-Altman limits of agreement (LOA). RESULTS Temporal-spatial parameters showed excellent reliability, with ICCs above 0.9 for speed, cadence, stride length, double support time, and step width. ICCs for kinematic parameters ranged from acceptable (0.62, peak knee flexion in stance) to excellent (0.95, total hip sagittal plane motion). The SEM for all kinematic parameters was below 4°, with the exception of peak hip internal rotation (5.8°). Peak values were less reliable than the total range of motion in a plane. The majority of kinetic parameters showed excellent reliability (ICCs>0.85), with the exception of peak medio-lateral ground reaction force (ICC 0.12). CONCLUSIONS This information will enhance the interpretation of gait scores for CSM patients, as an estimate of the change required to exceed measurement error is now available.

Footwear Antennas for Body Area Telemetry

Antennas designed to link footwear sensors within body centric networks are introduced with two small UWB antennas, one directional and another quasi-omnidirectional. The radiating characteristics are evaluated for three positions on a sample sports shoe using a detailed simulation model and measurements with a homogenous foot phantom. Antenna performance is assessed for resilience to close proximity loading by the footwear materials and the phantom foot.

Improved harness crutch to reduce upper limb effort in swing-through gait

A novel crutch, the harness crutch, is described which reduces loading on the arms during the swing phase of swing-through gait. The device was fabricated by attaching a modified mountaineering harness by two side straps, to modified axillary crutches. The harness crutch was compared with the saddle crutch, described by Taylor in 1883. The saddle crutch produced pressures in excess of 500 mmHg in the perineal area; no pressures were produced in this area with the harness crutch. Ischial pressures produced by both systems were similar. In six out of eight non-impaired subjects, significantly more force was transmitted to the harness crutch (an average 47% of body weight) than to the saddle crutch (an average 40% of body weight). A comparison of the oxygen cost of swing-through gait was made between the harness crutch and unmodified axillary crutches; with the harness crutch oxygen cost was significantly lower (p < 0.01) and there were no significant differences in speed and stride length.

An Antenna for Footwear

Antenna design for footwear is an essential part of enabling reliable wireless links with lower-limb sensors used in body centric networks. Sensors can report biomechanical pressure data to analyse kinematic and posture parameters for a range of medical and sporting applications. Consideration is given to antenna shapes, the fit with shoe shapes, the positioning on the shoe and the radiation patterns suited to on body and off-body communications.

Insole Antenna for On-Body Telemetry

A 433-MHz antenna is proposed for integration with the insole of footwear for a body-area network. The folded dipole design with an asymmetric groundplane radiates from its edges and considers the close proximity of the human foot and ground surfaces. It functions for different ground conductivity conditions and an on-body communication link with an inverted-F antenna in the upper body area was evaluated on a static and dynamic human subject. The antenna solution was compliant with specific absorption rate (SAR) requirements, remains matched and links with upper body nodes regardless of the body posture and node location.

Anatomical loading on a UWB antenna for shoe toe box

A UWB 6.0-8.5 GHz monopole antenna for mounting on the toe-box area of footwear is designed using a detailed model of a running shoe and a foot-shaped phantom. Variation of anatomical features between individual people gives rise to different proximity and permittivity loads on the antenna. To take account of environment, the antenna design optimization considers different proximity distances for impact on the reflection coefficient and on the radiation efficiency.