Selection of optimal muscle set for 16-channel standing neuroprosthesis

J Rehabil Res Dev, 2006 · DOI: 10.1682/JRRD.2007.10.0162 · Published: January 1, 2006

Spinal Cord Injury Neurology Rehabilitation

Simple Explanation

This study explores how to best use a 16-channel neuroprosthesis to help people with paraplegia stand. It uses a computer model to figure out which muscles to stimulate for the best balance and posture control. The goal is to identify the optimal set of muscles to activate with electrical stimulation, allowing users to maintain a wider range of stable standing positions without needing as much support from their arms or external devices. The model helps determine which muscles are most important for controlling movement in both sideways (coronal) and forward/backward (sagittal) directions, ultimately improving the neuroprosthesis's effectiveness.

Study Duration

Not specified

Participants

Not specified

Evidence Level

Not specified

Key Findings

1
The prime muscle targets should be the medial gastrocnemius, tibialis anterior, vastus lateralis, semimembranosus, gluteus maximus, gluteus medius, adductor magnus, and erector spinae.
2
Coactivation of the lateral gastrocnemius and peroneus longus with the medial gastrocnemius and of the peroneus tertius with the tibialis anterior increased the percentage of feasible postures to 71 percent.
3
The adductor magnus is very important in providing hip adduction moments in sideways leaning postures and together with the gluteus medius helps stabilize postures in the coronal plane.

Research Summary

This study used a musculoskeletal model of the legs and trunk to determine which muscles to target with the new system in order to maximize the range of postures that can be statically maintained, which should increase the system’s ability to provide adequate support to maintain standing when the user’s posture moves away from a neutral stance. The results show that the prime muscle targets should be the medial gastrocnemius, tibialis anterior, vastus lateralis, semimembranosus, gluteus maximus, gluteus medius, adductor magnus, and erector spinae. The single best electrode combination suggested by this study consists bilaterally of the gastrocnemii coactivated with the peroneus longus (using a branched intramuscular electrode), the tibialis anterior coactivated with the peroneus tertius (via stimulation of the deep peroneal nerve), all of the vasti coactivated with the rectus femoris (via stimulation of the femoral nerve), and intramuscular electrodes in the semimembranosus, gluteus maximus, gluteus medius (with emphasis on the anterior portion), adductor magnus (with emphasis on the superior portion), and erector spinae.

Practical Implications

Improved Neuroprosthesis Design

The identified optimal muscle set can be used to design more effective 16-channel neuroprostheses for standing, providing better balance and stability for users with paraplegia.

Reduced Reliance on Assistive Devices

By targeting the right muscles, the new system can potentially reduce the need for external orthoses and upper-body effort, allowing for more independent standing.

Enhanced Rehabilitation Outcomes

The study provides a theoretical basis for muscle selection, which can guide clinical implementation and lead to improved rehabilitation outcomes for individuals with spinal cord injuries.

Study Limitations

1
The present study focuses only on static postures, the results should apply to situations in which the disturbances to posture are small or the changes in posture are slow, thus allowing any dynamic effects to be neglected.
2
The number of electrodes that can be implanted in a functional neuromuscular stimulation system is necessarily limited by both technological and surgical constraints.
3
Real-world systems come with many other considerations, such as individual user needs, desires, and functional limitations caused by the level of SCI, muscle spasticity, and muscle atrophy.

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