Neuromusculoskeletal interfacing of lower limb prostheses
Doctoral thesis, 2021

The method of bone-anchored attachment of limb prostheses via a percutaneous skeletal extension was developed to circumvent commonly reported problems associated with the conventional method of socket attachment. In addition to the direct structural connection, the percutaneous implant may serve as a conduit for bidirectional communication between muscles and nerves within the residual limb and the prosthesis. Implanted electrodes recording myoelectric activity within the residual limb can be used to infer the user’s movement intent and may thus be used to provide intuitive control of the prosthesis in real time. Sensory feedback from the prosthesis can be provided back to the user by neurostimulation via implanted neural electrodes, thus closing the control loop. Together the skeletal, neural, and muscular interfaces form a neuromusculoskeletal interface. This technology is currently being evaluated in a clinical trial on individuals with upper limb amputation, but it has not yet been used in the lower limb.

The aim of this thesis has been to translate the concept of neuromusculoskeletal interfacing to the lower limb. An additional aim has been to reduce the limitations on high impact activities, that exist on current available systems for bone-anchored attachment of limb prostheses. To achieve these aims, a new design of the neuromusculoskeletal interface was developed where the structural capacity was increased with respect to current versions of the implant system to accommodate increased loads for highly active usage by individuals with lower limb amputation. In order to set adequate design requirements, investigations were conducted to determine the load exposure of bone-anchored implant systems during a number of loadbearing activities. Structural verification of the neuromusculoskeletal interface has been performed using numerical simulations as well as physical testing in static and dynamic conditions. The first steps towards clinical implementation of the lower limb neuromusculoskeletal interface have been taken by the development of a clinical research protocol that has been approved by the Swedish Ethical Review Authority.

direct skeletal attachment

Osseointegrated Prostheses for the Rehabilitation of Amputees (OPRA)

neuromusculoskeletal interface

OPRA

Osseointegration

Enhanced Osseointegrated Prostheses for the Rehabilitation of Amputees (e-OPRA).

bone-anchored attachment

Enhanced Osseointegrated Prostheses for the Rehabilitation of Amputees (e-OPRA).

OPRA

Opponent: Prof. Helen Huang, North Carolina State University & University of North Carolina at Chapel Hill Joint Department of Biomedical Engineering, North Carolina, USA

Author

Alexander Thesleff

Chalmers, Electrical Engineering, Signal Processing and Biomedical Engineering, Biomedical Signals and Systems

Loads at the implant-prosthesis interface during free and aided ambulation in osseointegrated transfemoral prostheses

IEEE Transactions on Medical Robotics and Bionics,; Vol. 2(2020)p. 497-505

Journal article

Load exposure of osseointegrated implants for transfemoral limb prosthesis during running

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS,; Vol. 2018-July(2018)p. 1743-1746

Paper in proceeding

Thesleff, A., Ortiz-Catalan, M., Brånemark, R., The effect of cortical thickness and thread profile dimensions on stress and strain in bone-anchored implants for amputation prostheses

Thesleff, A., Ortiz-Catalan, M., Brånemark, R., Low plasticity burnishing improves fretting fatigue resistance in bone-anchored implants for amputation prostheses

Thesleff, A., Ahkami, B., Anderson, J., Hagberg, K., Ortiz-Catalan, M. Design of a stepwise safety protocol for lower limb prosthetic risk management in a clinical investigation

Lower limb prostheses are far behind their upper limb counterparts in terms of human-device interaction. Whereas it is common for upper limb prostheses to record signals from the remaining muscles in the residual limb and use them for controlling the prosthesis, this feature is absent in all clinically available lower limb prostheses. This means that despite the fact that the muscles and the nerves above the amputation site are mostly intact, this source of control information is left unused.

To address this problem, an interface which provides a direct connection between a prosthesis and the skeleton, muscles, and nerves has been developed. The skeletal interface provides a stable and comfortable mechanical connection between the prosthesis and the residual limb. The muscular interface allows for the recording of bioelectric signals from the musculature within the residual limb. The signals can then be used to provide intuitive control of the prosthesis. The neural interface allows for the stimulation of peripheral nerves. Such stimulation can generate sensations which the user perceives as coming from the missing limb. Combined with external sensors placed on the prosthesis, neurostimulation can therefore be used to provide sensory feedback from the prosthesis back to the user.

In this thesis this interface has been redesigned for usage with lower limb prostheses. It is believed that this technology will allow for long-term, robust and intuitive control of lower limb prostheses using bioelectric signals and sensory feedback via neurostimulation. What is unique with this interface is that it will not be restricted to usage in controlled laboratory environments but may function equally well during everyday use in home environments. The interface therefore has a great potential of providing actual functional improvements in the daily life for its users and thereby reduce the disability associated with a lower limb amputation.

Neural styrning av benproteser

Swedish Foundation for Strategic Research (SSF) (ID15-0089), 2016-01-01 -- 2020-12-31.

Neural control of bionic legs

VINNOVA (2018-03235), 2018-11-26 -- 2020-10-31.

Neurally controlled robotic leg prostheses

VINNOVA (2017-01471), 2017-06-01 -- 2018-05-31.

Areas of Advance

Health Engineering

Subject Categories

Medical Materials

ISBN

978-91-7905-494-6

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4961

Publisher

Chalmers University of Technology

Online

Opponent: Prof. Helen Huang, North Carolina State University & University of North Carolina at Chapel Hill Joint Department of Biomedical Engineering, North Carolina, USA

More information

Latest update

5/12/2021