Targeted Muscle Reinnervation: Surgical & Functional Outcomes - 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.

Surgical and Functional Outcomes of Targeted Muscle Reinnervation

Surgical Outcomes

Surgical Outcomes

TMR is now an established procedure that has been performed on more than 100 patients in hospitals worldwide, including the San Antonio Military Medical Center (SAMMC, formerly the Brooke Army Medical Center), the Walter Reed National Military Medical Center, and Northwestern Memorial Hospital (NMH) in Chicago.

The following data are based on surgical outcomes from TMR procedures performed from 2002 to 2012 at NMH and SAMMC [1]. All data were obtained under approved protocols from the Institutional Review Boards of the appropriate institutions.

Patient Population

27 patients underwent TMR at NMH or SAMMC (17 subjects with transhumeral amputations; 10 subjects with shoulder disarticulation amputations).

Subjects ages ranged from 18-55, and average duration between amputation and TMR surgery was 16 months, with a range of 4 months to 6 years. Neither age nor time since amputation had any noticeable effect on outcomes.

All of these subjects had TMR performed on one side, although several patients had bilateral amputations.

Since publication of Targeted Muscle Reinnervation: A Neural Interface for Artificial Limbs, bilateral TMR has been performed on a patient with a right-side transhumeral amputation and a left-side shoulder disarticulation amputation.

Acute Surgical Outcomes

Mean operative time for transhumeral surgeries was 3 hours, 22 minutes; for shoulder disarticulation surgeries, the mean duration was 5 hours, 37 minutes. Surgical time was most likely longer for shoulder disarticulation surgeries because of the challenges imposed by altered anatomy due to high-impact injuries.

  • 90% of patients were in the hospital for one night following surgery.
  • 3 out of the 27 patients experienced delayed healing of the surgical incision; however, all patients went on to heal without the need for revision procedures.
  • Mean duration of follow-up was 28 months.

In all, a total of 79 nerve transfers were performed, yielding robust EMG signals in 75 target muscle – a 95% success rate. However, not all signals were suitable for prosthesis control due to cross talk or difficulty in maintaining adequate electrode contact with skin.

Of the 27 patients who underwent TMR at NMH/RIC and SAMMC, 25 (93%) were subsequently fit with TMR-controlled myoelectric devices.

Postsurgical Pain Outcomes

  • 15 of 19 patients who presented with phantom limb pain experienced an exacerbation of phantom limb pain symptoms following the procedure; however, pain returned back to pre-surgery levels 4-6 weeks later.
  • Of 14 patients with neuroma pain, neuroma pain persisted in only 2 patients following TMR surgery.

Since publication of Targeted Muscle Reinnervation: A Neural Interface for Artificial Limbs, TMR has been performed on an individual during acute amputation of the arm at the shoulder disarticulation level. This resulted in successful nerve transfers and no evidence of neuroma pain [2].


  1. Souza JM, Cheesborough JE, Ko JH, Cho MS, Kuiken TA, Dumanian GA. Targeted Muscle Reinnervation: A Novel Approach to Postamputation Neuroma Pain. Clinical orthopaedics and related research. Feb 22 2014.
  2. Cheesborough JE, Souza JM, Dumanian GA, Bueno RA, Jr. Targeted muscle reinnervation in the initial management of traumatic upper extremity amputation injury. Hand. Jun 2014;9(2):253-257.

Functional Outcomes

Functional Outcomes

We used three objective outcome measures to evaluate the success of TMR in six individuals:

Box and Block test.
(Click image to enlarge)

1. Box and Block test [1] – Subjects move one-inch blocks from one side of a box, over a partition, to the other side of the box. A higher score indicates improvement.

After TMR, individuals could move an average of 323% more blocks in the given time than they could before TMR.

Clothespin relocation test.
(Click image to enlarge)

2. Clothespin Relocation test [2] – Subjects are timed as they move three clothespins from a horizontal bar, rotate them, and place them on a vertical bar. Adapted from the Rolyan Graded Pinch Exerciser, this test requires control of all three available degrees of freedom of the prosthesis, including wrist rotation. A lower score indicates improvement.

After TMR, subjects could manipulate and relocate clothespins on average of 49% more quickly than they could before TMR.

3. Assessment of Motor and Process Skills (AMPS) [3-5] – Subjects choose from a list of familiar, relevant activities of daily living, such as making a sandwich.

This test evaluates motor skills, in particular how effectively and efficiently the subjects moves when grasping and manipulating objects during the task. The process skills evaluates the subject for task organization, planning, problem solving. Similar to the Box and Block test, a higher score indicates improvement.

After TMR, most subjects showed increased scores in both motor and process skills, and four out of five subjects demonstrated significant improvements in motor scores.

In addition, we used the Disabilities of the Arm, Shoulder, and Hand (DASH) [6, 7] outcome measure to evaluate subjective responses to TMR. The DASH consists of 30 scored questions on physical function, symptoms, and social functioning; the higher the score, the higher the level of disability experienced.

Of the three subjects tested, all scored lower on the DASH after TMR.


  1. Mathiowetz V, Volland G, Kashman N, Weber K. Adult norms for the Box and Block Test of manual dexterity. The American journal of occupational therapy : official publication of the American Occupational Therapy Association. Jun 1985;39(6):386-391.
  2. Kuiken TA, Dumanian GA, Lipschutz RD, Miller LA, Stubblefield KA. The use of targeted muscle reinnervation for improved myoelectric prosthesis control in a bilateral shoulder disarticulation amputee. Prosthetics and orthotics international. Dec 2004;28(3):245-253.
  3. Fisher AG. The assessment of IADL motor skills: an application of many-faceted Rasch analysis. The American journal of occupational therapy : official publication of the American Occupational Therapy Association. Apr 1993;47(4):319-329.
  4. A. G. Fisher, "Development of a functional assessment that adjusts ability measures for task simplicity and rater leniency," in Objective measurement: Theory into practice. vol. 2, M. Wilson, Ed., ed Norwood, NJ: Ablex, 1994, pp. 145-175.
  5. A. G. Fisher, AMPS Assessment of Motor and Process Skills, 5th Edn. Fort Collins, CO: Three Star Press, 2003.
  6. Hudak PL, Amadio PC, Bombardier C. Development of an upper extremity outcome measure: the DASH (disabilities of the arm, shoulder and hand) [corrected]. The Upper Extremity Collaborative Group (UECG). American journal of industrial medicine. Jun 1996;29(6):602-608.
  7. Beaton DE, Katz JN, Fossel AH, Wright JG, Tarasuk V, Bombardier C. Measuring the whole or the parts? Validity, reliability, and responsiveness of the Disabilities of the Arm, Shoulder and Hand outcome measure in different regions of the upper extremity. Journal of hand therapy : official journal of the American Society of Hand Therapists. Apr-Jun 2001;14(2):128-146.

Patients' Experience

Patients' Experience

Several patients reported that tasks, including yard work, cleaning, and cooking were easier, and that they were able to perform more tasks after TMR. Additionally, some patients said that operation of the prosthesis was smoother after TMR and that they used their prosthesis more frequently, and for longer periods.

Below are some comments from TMR patients, describing their experience with TMR prosthesis control

Individuals with Shoulder Disarticulation TMR

“You don’t have to think about it, it’s there. I move my phantom limb—that’s how I operate it. I move my phantom limb and it responds.”; “I guess in my mind my hand is still there, when I open that I’m literally opened [sic] my hand … and when I close it, I literally close my hand.” –Subject 1

“I can pick up objects … like a quarter. I can pick it up flat off the floor or a table … I can pick up an object like a round ball or something like that. I can actually snatch it up in a short time.”

–Subject 1

“It doesn’t change the way I do things, but it is faster and this prosthesis is easier to control.” – Subject 3

Individuals with Transhumeral TMR

“It changes the way I do things because it is more efficient. It is easier to control than the previous prosthesis.” –Subject 2

“Moving elbow and hand—it’s become a very natural thing. This prosthesis is more effective and easier to control. To be able to think ‘open your hand’ and your hand opens, rather than using your elbow, which is so unnatural—I wouldn’t change it for anything.”-Subject 3

More TMR patient stories can be read at RIC’s Patient Stories homepage:

Zac Vawter

Amanda Kitts

Glen Lehman

Further follow up is needed to determine whether improved control provided by TMR translates into increased prosthesis usage in the long term. Problems such as discomfort and weight are not mitigated by TMR and frequently cause individuals to abandon their prostheses—several TMR patients commented that prosthesis weight limited their use of the device.

Our hope is that TMR will provide the impetus for development of improved prostheses that will enable users to benefit from improved control.


Laura A. Miller, PhD, CP

Laura A. Miller, PhD, CP, received a BS in biomedical engineering from Tulane University, New Orleans, LA and MS and PhD degrees in biomedical engineering, from Northwestern University, where she also obtained certification in prosthetics. She works as a Research Prosthetist for the Center for Bionic Medicine at the Rehabilitation Institute of Chicago and is an Associate Professor in Physical Medicine and Rehabilitation at Northwestern University. Her research interests include fitting and evaluation of new advanced prosthetic devices. Dr. Miller is a member of the International Society of Prosthetics and Orthotics and the American Academy of Orthotists and Prosthetists.

Kathy A. Stubblefield, BSKathy A. Stubblefield, BS, received a BS degree in occupational therapy from the University of Kansas. Ms. Stubblefield worked as a Research Therapist for the Center for Bionic Medicine at the Rehabilitation Institute of Chicago until her retirement in May 2012. She has more than 35 years of experience and expertise in the treatment of patients with stroke, spinal cord injury, and upper limb amputation. In addition, Ms. Stubblefield has participated in research, training, and testing of TMR patients using conventional and experimental prosthetic components and control schemes.

Robert D. Lipschutz, BS, CPRobert D. Lipschutz, BS, CP, received a BS in mechanical engineering from Drexel University, and received a certificate in prosthetics and orthotics from the Post Graduate Medical School, New York University. He completed his prosthetics training at the Shriner’s Hospital for Crippled Children in Springfield, MA and continued his clinical work at Newington Children’s Hospital in Newington, CT. He worked as a Research Prosthetist for the Center for Bionic Medicine, and is currently Director of Prosthetics and Orthotics Education for the Prosthetics and Orthotics Clinical Center at the Rehabilitation Institute of Chicago, as well as an assistant professor in the Department of Physical Medicine and Rehabilitation at Northwestern University. His current research interests include fitting and evaluation of new advanced prosthetic devices.

Blair A. Lock, MSBlair A. Lock, MS, received BS and MS degrees in electrical engineering and a diploma in technology management and entrepreneurship from the University of New Brunswick, Fredericton, NB, Canada. Mr. Lock is a collaborator with the Center for Bionic Medicine at the Rehabilitation Institute of Chicago. He is also managing partner of Coapt LLC, a company specializing in upper-extremity control technology. His research interests include pattern recognition for improved control of powered prostheses and user experience in rehabilitation technologies. Mr. Lock is a registered professional engineer with the Association of Professional Engineers and Geoscientists of New Brunswick, Canada.

Jason M. Souza, MDJason M. Souza, MD, received a ScB in neuroscience from Brown University, Providence, RI and an MD from Harvard Medical School. Dr. Souza is currently completing an integrated residency in plastic and reconstructive surgery at Northwestern Feinberg School of Medicine, and is a Lieutenant Commander in the Medical Corps of the United States Navy. Dr. Souza has participated in numerous TMR procedures.

Greg Dumanian

Gregory A. Dumanian, MD, is Chief and Program Director of the Division of Plastic Surgery at the Northwestern Feinberg School of Medicine, and holds professorships in Surgery, Neurosurgery, and Orthopedic surgery. Dr. Dumanian obtained a BA in Chemistry from Harvard and an MD from the University of Chicago Pritzker School of Medicine. After a residency in general surgery at the Massachusetts General Hospital, Dr. Dumanian completed plastic surgery training at the University of Pittsburgh and a fellowship in hand surgery at the Curtis Hand Center in Baltimore, Maryland, and is board certified in surgery, plastic surgery, and hand surgery. His specialties include state-of-the-art reconstructive breast surgery after cancer treatment, aesthetic surgery, abdominal wall reconstruction, peripheral nerve surgery, hand surgery, and reconstructive microsurgery. Dr. Dumanian co-developed the TMR procedure and performed the first TMR surgery in a human amputee in 2002.

Todd KuikenTodd A. Kuiken, MD, PhD, 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.

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.