Targeted Muscle Reinnervation: Selection & Evaluation of Patients - Rehabilitation Institute of Chicago

Skip to Content

Targeted Muscle Reinnervation: A Neural Interface for Artificial Limbs

Targeted Muscle Reinnervation: A Neural Interface for Artificial Limbs (CRC Press, 2013) can be purchased at the CRC Press website or on Amazon.

RIC Center for Bionic Medicine

TMR research was pioneered at the Center for Bionic Medicine (CBM). The CBM combines science, engineering, and clinical skill to improve function and life quality for persons with limb loss.

Development of this website was supported by the National Library of Medicine of the National Institutes of Health, Award Number G13LM011221. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Rehabilitation of the Targeted Muscle Reinnervation Patient

Patient Evaluation

Selection and evaluation of TMR candidates

TMR involves elective surgery followed by a long post-surgical reinnervation period, as well as a significant time commitment for prosthetic fitting and occupational therapy training. Successful outcomes depend on careful screening of potential candidates, together with a comprehensive, team-based approach to rehabilitation.

Prior to TMR surgery, patients should undergo a thorough medical exam, an assessment of emotional and mental health, and an evaluation of likely compliance with the requirements for successful rehabilitation.

Presurgical evaluation

This video was produced thanks to generous support
from the McCormick Foundation.

Appropriate patient selection can determine the success or failure of TMR surgery. In order to be considered a candidate for TMR, patients must:

  • Have a shoulder disarticulation or transhumeral amputation - TMR has only been performed on patients with these type of amputations; however, researchers are currently investigating how individuals with transradial and transfemoral amputations may benefit from TMR.
  • Be willing to live without their prosthesis for 3 to 6 weeks after surgery until their soft tissues heal.
  • Be motivated enough to follow a lengthy recovery and training process.

The health and viability of residual musculature and nerves should be assessed. Brachial plexopathy is a contraindication for TMR, as healthy nerves and muscles are necessary for robust reinnervation. In addition, the examination should evaluate:

  • Proximal injury to shoulder complex—common in traumatic amputation.
  • Impairments to the sound limb, which may be exacerbated due to overuse injuries.
  • Core strength and posture.
  • Soft tissue deficits, bony prominences, split-thickness skin grafts or scars, which may impede prosthesis wear, but may be surgically addressed during the TMR procedure.
  • A cognitive and emotional assessment as many individuals with amputations struggle with emotional health issues, depression, or anxiety [1, 2], which may affect success of the TMR procedure. Such issues must be monitored by the clinical team and addressed before surgery. Consultation with a psychologist is recommended.
  • Traumatic brain injury (TBI) is possible following a traumatic amputation.
    • If TBI is suspected, cognitive screening is recommended to ensure that the patient is able to follow directions and comply with treatment.
    • TMR should be delayed to allow patients to recover from mild or moderate TBI.

Evaluation of likely compliance

  • To maximize the likelihood of compliance, the patient must thoroughly understand the TMR procedure, the timeframes involved, and the rehabilitation process.
  • The patient must understand what TMR will do for them: it will not make their prosthesis more comfortable or less heavy. Previous abandonment of a prosthesis for these reasons may suggest that improved control may not result in the patient using the device.
  • A history of noncompliance with treatment may indicate lower likelihood of compliance with the TMR process.

Patient and team education

Patient and team education is vital so that informed medical decisions can be made to ensure the success of the procedure and that patients receive the full benefits of TMR.

The TMR surgery is only the initial part of a multi-step recovery process. Pre- and post-surgery, patients should be educated on the specific details of their TMR procedures, as well as expectations for recovery and any other potential complications.

This video was produced thanks to generous support
from the McCormick Foundation.

In addition, all members of the rehabilitation team—surgeons, physiatrists, occupational therapists, prosthetists—must understand which nerve transfers will be performed during surgery so successful rehabilitation recommendations and timelines can be created.

After TMR, prosthetic fitting should be delayed pending complete reinnervation and achievement of adequate strength in reinnervated muscles.

Potential surgical complications

TMR surgery has the same risk of infection as any other soft tissue surgery. However, some potential complications specific to TMR include:

  • Risk of target muscle paralysis.
  • Neuroma pain (although evidence suggests that TMR may prevent or treat neuroma pain, any cut nerve has the potential to develop painful end-neuromas).
  • Phantom limb pain
  • Transfer sensation—if skin is denervated during the TMR procedure, sensory afferents from transferred nerves may reinnervate this skin. Touching the reinnervated skin may allow the patient to feel sensations, often described as a “tingling feeling,” which seem to come from their missing limb. Although patients should be aware of this possibility, most patients have not found this to be burdensome.

Further information for patients is available on RIC’s TMR page.

References

  1. Copuroglu C, Ozcan M, Yilmaz B, Gorgulu Y, Abay E, Yalniz E. Acute stress disorder and post-traumatic stress disorder following traumatic amputation. Acta orthopaedica Belgica. Feb 2010;76(1):90-93.
  2. Desmond DM. Coping, affective distress, and psychosocial adjustment among people with traumatic upper limb amputations. Journal of psychosomatic research. Jan 2007;62(1):15-21.

Author

RIC's Todd Kuiken Todd A. Kuiken, MD, PhD, began studying nerve transfers with the intention of producing new EMG signals for control of myoelectric prosthetic arms while in graduate school. Years of animal work and EMG simulation studies resulted in the first human nerve transfer surgery intended to improve prosthesis control, in 2002. The technique, called targeted muscle reinnervation (TMR), was successful and has since become an established clinical procedure, benefiting many patients across the US and overseas.

Dr. Kuiken leads an interdisciplinary team that includes physicians, prosthetists, therapists, neuroscientists, engineers, software developers, graduate students, and post-doctoral researchers at the Center for Bionic Medicine within the Rehabilitation Institute of Chicago. This combination of clinical and research expertize provides a unique environment in which to understand and develop TMR and to translate research data into clinical applications. Four integrated research groups within the Center for Bionic Medicine seek to study the functional and sensory benefits of TMR, to develop lighter, more functional prosthetic devices, and to design control systems to capitalize on the vast neural information made available by TMR. TMR has continued to evolve and improve, in particular with recent collaborative research on pattern recognition control. Dr. Kuiken has continued to lead efforts to understand and capitalize on the potential of TMR to provide improved prosthetic function.

Dr. Kuiken received a BS in biomedical engineering from Duke University, and a PhD in biomedical engineering and an MD from Northwestern University. He completed a residency in physical medicine and rehabilitation at the Rehabilitation Institute of Chicago and Northwestern University Medical School. In addition to leading the Center for Bionic Medicine, Dr. Kuiken is Director of Amputee Services at the Rehabilitation Institute of Chicago. He is also a Professor in the Departments of Physical Medicine and Rehabilitation, Surgery, and Biomedical Engineering at Northwestern University. Dr. Kuiken is the recipient of many awards and honors for his work on TMR and is an internationally respected leader both in research and the clinical care of people with limb loss.