Long-term implant of intramuscular sensors and nerve transfers for wireless control of robotic arms in above-elbow amputees.

Targeted muscle reinnervation (TMR) amplifies the electrical activity of nerves at the stump of amputees by redirecting them in remnant muscles above the amputation. The electrical activity of the reinnervated muscles can be used to extract natural control signals. Nonetheless, current control systems, mainly based on noninvasive muscle recordings, fail to provide accurate and reliable control over time. This is one of the major reasons for prosthetic abandonment. This prospective interventional study includes three unilateral above-elbow amputees and reports the long-term (2.5 years) implant of wireless myoelectric sensors in the reinnervation sites after TMR and their use for control of robotic arms in daily life. It therefore demonstrates the clinical viability of chronically implanted myoelectric interfaces that amplify nerve activity through TMR. The patients showed substantial functional improvements using the implanted system compared with control based on surface electrodes. The combination of TMR and chronically implanted sensors may drastically improve robotic limb replacement in above-elbow amputees.

[Exoprosthetic Replacement of the Upper Extremity]. / Exoprothetischer Ersatz bei Amputationen der oberen Extremität.

During the last years, the prosthetic replacement in upper limb amputees has undergone different developments. The use of new nerve surgical concepts improved the control strategies tremendously, especially for high-level amputees. Technological innovation in the field of pattern recognition enables the control of multifunctional myoelectric hand prostheses in a natural and intuitive manner. However, the different levels of amputation pose different challenges for the therapeutic team which concern not only the prosthetic attachment; also the expected functional outcome of prosthetic limb replacement differs greatly between the individual levels of amputation. Therefore, especially in partial hand amputations the indication for prosthetic fitting has to be evaluated critically, as these patients may benefit more from biologic reconstructive concepts. The value of the upper extremity, in particular of the hand, is undisputable and, as such represents the driving force for the technological and surgical developments within the exoprosthetic replacement. This article discusses the possibilities and limitations of exoprosthetic limb replacement on the different amputation levels and explores new developments.

[Prosthetic reconstruction of the upper extremity]. / Prothetische Rekonstruktion der oberen Extremität.

BACKGROUND: Prosthetic replacement after amputation or loss of function of the upper extremity has gained therapeutic value over the last years. The control of upper arm prostheses has been refined by the use of selective nerve transfers, and the indication for prosthetic replacement has been expanded. OBJECTIVES: Overview regarding surgical, therapeutic and prosthetic options in upper extremity amputations or their loss of function. METHODS: Selective literature research including the authors' own experience in everyday clinical practice, as well as a review of medical records. RESULTS: Selective nerve transfers of the amputated nerves of the brachial plexus to the remaining stump muscles can create up to six myosignals for intuitive and simultaneous control of the different prosthetic joints. This way, an efficient and harmonious control of the prosthetic device is possible without the need to change between the different control levels. The prosthetic replacement, with consequent elective amputation, represents a new approach in the functional reconstruction of the upper extremity, especially in patients with a functionless hand after massive soft tissue or nerve damage.

Hand Transplantation Versus Hand Prosthetics: Pros and Cons.

Composite tissue transplantation and new developments in the field of prosthetics have opened new frontiers in the restoration of function among upper limb amputees. It is now possible to restore hand function in affected patients; however, the indications, advantages, and limitations for either hand transplantation or prosthetic fitting must be carefully considered depending on the level and extent of the limb loss. Hand transplantation allows comprehensive hand function to be restored, yet composite tissue transplantation comes with disadvantages, making this method a controversial topic in the hand surgical community. Alternatively, prosthetic limb replacement represents the standard of care for upper limb amputees, but results in the known limitations of function, sensation, and usage. The indication for hand transplantation or prosthetic fitting strongly depends on the level of amputation, as well as on the extent (unilateral/bilateral) of the amputation. In this review, we discuss the advantages and disadvantages of hand transplantation and prosthetic replacement for upper limb amputees in general, as well as in regard to the different levels of amputation.

Prosthetic reconstruction to restore function in transcarpal amputees.

Mutilated hands at the distal level may pose a challenge for reconstruction. Biological treatment options may require multiple surgical interventions and a long rehabilitation course with little hope of good functional outcome. Standard hand prostheses are also not an ideal solution, as they are too long and cumbersome for partial hand injuries. This paper outlines the functional outcomes of prosthetic reconstruction with devices customized for the transcarpal amputation levels. The functional outcome was evaluated with the Action Research Arm Test (ARAT), Southampton Hand Assessment Procedure (SHAP), and the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH). Functional evaluation was performed at least 12 months after final fitting. Psychological assessment was performed with the Short Form-36. The three patients achieved a mean ARAT score of 35.67 ± 0.58. The average SHAP score was 74 ± 7.81. The average DASH score was found to be 16.11 ± 12.03. The reconstructed hand achieved a score of 75.27 ± 8.16% in SHAP and 62.57 ± 1.02% in ARAT in relation to the healthy hand. All patients exhibited average physical and mental component summary scales in the Short Form-36. The majority of transcarpal amputations are seen in manual laborers due to work-related trauma. Returning to work is the main goal in such young and otherwise-healthy patients. As shown with this study, prosthetic fitting results in quick and reliable functional reconstruction. Therefore, this treatment should be considered as an option during the initial decision-making process of reconstructing difficult traumatic injuries of the hand.

[Prosthetic reconstruction in high amputations of the upper extremity]. / Prothetische Rekonstruktion hoher Amputationen der oberen Extremität.

BACKGROUND: Conventional upper arm prostheses are controlled via two surface electrodes that measure motor activity of two separately innervated muscle groups. The various prosthetic joints are chosen by co-contractions and controlled linearly by these two muscles. A harmonious and natural course of movements is not possible in this way. OBJECTIVES: Overview regarding surgical, therapeutical and prosthetic options in high amputations of the upper extremity. METHODS: Selective literature research including the authors' own experience in everyday clinical practice as well as a review of medical records. RESULTS: Selective nerve transfers of the amputated nerves of the brachial plexus to the remaining stump muscles can create up to six myosignals for intuitive and simultaneous control of the different prosthetic joints. In this way, an efficient and harmonious control of the prosthetic device is possible without the need to change between the different control levels. At the same time, possible neuromas are treated and painless wear of the prosthesis is achieved. Due to the resulting extended use of the prosthetic device, the demands regarding stump quality are increased. Thus, both surgically and by the means of the orthopedic technician a stable stump-socket connection should be achieved to enable optimal prosthetic function.