Annette Pantall, DO(UK), PhD; David Ewins, PhD

1. Muscle activity during stance phase of walking: Comparison of maleswith transfemoral amputation with osseointegrated fixations tonondisabled male volunteers Annette Pantall, DO(UK), PhD; David Ewins, PhD

2. Aim • Examine surface electromyography (sEMG) activity of hip joint muscles, vertical ground reaction force (GRF), and hip joint angles during stance phase of walking in individuals with transfemoral amputation (TFA) with osseointegrated fixations (OFs). • Relevance • OFs may improve comfort, fatigue, hip movement, and ease of prosthetic attachment but little information is available regarding muscle function.

3. Method • 5 males with TFA with OFs. • Recorded GRF, lower-limb kinematics, and sEMG from residual-limb muscles. • 10 nondisabled male subjects. • Collected sEMG data. Placement of electrodes on right lower limb.

4. Results • Hip muscles displayed cyclical patterns of sEMG activity suggestive of functional ability to contract and exert moment about hip joint. • Patterns of sEMG recordings were broadly similar between TFA and nondisabled groups. • Main difference was phase of maxima and minima. • Variability of muscle activity was greater in individuals with OFs than in subjects with intact limbs.

5. Conclusion • Muscles in residual limb retain aspects of their previous functional pattern. • Viability of myoprocessor in TFA. • Normalized amplitude is too variable to permit single muscles to be used. • Features like temporal occurrence of local minima or maxima that relate to loading and hip kinematics should be explored. • Microprocessor-controlled prostheses may modulate neurolocomotor signals, resulting in signal that could function as myoprocessor.