About TMR Surgery
- Targeted muscle reinnervation (TMR) is a procedure that redirects the electrical impulses in
the nerve stumps at the end of your residual limb, into new muscles.
- It can relieve neuroma pain, as well as phantom limb pain. It can also be used to improve a person’s control over their myoelectric prosthesis.
- You can have TMR surgery only, or you can combine it with other procedures such as
The benefits of TMR surgery
Many amputees experience neuroma or phantom limb pain after an amputation. Neuroma pain (NP) arises in the nerve stumps while phantom limb pain (PLP) arises in your mind, although it feels like it comes directly from your absent limb. Both can be debilitating. Despite the large variety of surgical treatments that surgeons have proposed to address both types of pain, the only method that has shown consistent results is TMR surgery.
In one study of TMR surgery performed by the Relimb™ team (published in JPRAS - 2021), 90% of upper limb neuroma patients experienced more than 90% relief from NP more than 12 months after
their procedure. There were similar improvements in PLP over the same period.
The TMR procedure
During a TMR procedure, your surgeon will transfer the nerves that previously controlled your absent limb into a “target” muscle. An ideal target muscle is one in the residual limb that no longer has a function due to your amputation. For example, a surgeon might select the biceps as the target muscle for an above elbow amputee.
After TMR surgery
Within days of the surgery, your nerves will begin growing into their target muscles. This process is known as reinnervation. Full reinnervation takes from 12-18 months, but you will notice changes in
your NP immediately and may start to notice changes in your PLP as soon as 3-6 months after
Once the reinnervation process is complete, you will regain the ability to make the target muscles contract just by “thinking it”. For example, if we target the biceps muscle, this now contracts when you
imagine moving your thumb or fingers. The muscles also provide the nerves with the electrical feedback that they lost due to your amputation.
As a result, you will start to experience less sensitivity and reduced PLP. The feedback also instructs the nerves not to reform a new neuroma, preventing a recurrence of the NP.
TMR and myoelectric prostheses
TMR can also help you to control your myoelectric prosthesis more intuitively, faster and with greater precision.
Myoelectric prosthetic devices are usually controlled using the electrical signals generated when you contract a muscle in your residual limb. Often, there may be only two sites of muscle control. This means that you can only perform simple functions, like opening and closing your prosthetic hand.
With TMR, it is possible to create multiple control sites. For example, in the upper limb, we can sometimes create 6 (or more) muscle control sites. As a result, you may be able to develop better control over your prosthesis, with the ability to perform advanced movements in your prosthetic fingers, wrist and elbow.
To achieve the best results, we work closely with our rehabilitation partners at Dorset Orthopaedic, a leading clinic with expertise in prosthetics and post-TMR
38 years ago, I was involved in a motorcycle accident and lost my left arm above the elbow. In the same accident, I also suffered a severe brachial plexus injury, which left me suffering from intense PLP. Over the years, I tried everything you can think of for the pain: pregabalin, opiates, mirror therapy, hypnosis, you name it. Nothing worked. Eventually, I just learnt to live with the pain.
Unfortunately, I then developed increasing problems with severe back pain. The rehabilitation doctors said that the loss of my left arm meant that the weight across my shoulders was uneven and I had developed a significant scoliosis (twisting) of the spine. To address this, I needed to wear a heavier socket-fitted prosthesis on my left side. To make things worse, the brachial plexus injury meant that my residual limb was very sensitive when touched. So, wearing a heavier prosthesis would also mean having to suffer more pain.
I was sure that there must be a better solution and did some internet research. I discovered that a better solution to my problem might be to undergo a combined TMR and osseointegration (OI) procedure. The OI surgery would allow me to wear a heavier prosthesis and the TMR procedure would help to deal with my phantom limb pain. Surgery was not available on the NHS, so I approached the team at Relimb. They felt that I was a suitable candidate for the surgery, and we went ahead with this at the Royal Free in April 2018.
It has been 3 years since I underwent the surgery, and I am so grateful for what the team at Relimb have been able to do for me. Having the bone-anchor in place in my left arm means that I can now wear a prosthesis that is the right weight for me, without having to disturb the soft-tissues of my residual limb. As a result, my scoliosis has gone and my back pain with it.
The TMR surgery did result in significant worsening of my phantom limb pain for a few months. However, eventually, the nerves grew through and, with a lot of help from the team at Dorset Orthopaedic, I was able to regain voluntary control over the reinnervated muscles. As this happened, it suddenly felt as though my amputated left arm was back again. Over a few weeks, I suddenly noticed that the PLP was also beginning to occur less frequently and at lower intensity.
Nowadays, I don’t have any PLP at all. Since I have undergone the TMR surgery, it has also been possible to increase the number of activation sites that I can use to control my myoelectric prosthetic limb. This has improved my ability to use the prosthesis, and this has allowed me to return to the hobbies I enjoy most – like riding my motorcycle!
*Name changed to respect our patient’s privacy.
Aftercare and Pain Control FAQs
Do I need to stay in overnight for TMR?
If you choose TMR only (i.e. not in combination with osseointegration), you will generally be able to go home on the same day as your surgery. Some patients with more complex needs, such as TMR for a through-shoulder amputation, may need to stay overnight to receive support with pain control.
What kind of rehabilitation do I need?
If you are having TMR surgery to improve your control over a bionic limb, you must undergo rehabilitation with a specialist that is experienced in the use of computerised feedback techniques, such as Dorset Orthopaedic.
If you are undergoing TMR surgery to deal with neuroma pain only, you do not need specialised rehabilitation. However, many of our patients who engage in specialist rehabilitation after surgery also learn to use their reinnervated muscles more quickly and observe more rapid resolution of their pain.
Can I shower after surgery?
After TMR surgery, your incision will be closed (typically) with absorbable sutures, which do not need to be removed. You may wash and shower with running water immediately after surgery.
How long until I can start using my prosthesis again?
We recommend that you avoid any heavy use of your limb for 2-3 weeks. You should not use your prosthesis until your wound has healed (3-6 weeks – longer for lower limb TMR) and any associated soft-tissue swelling has resolved.
What type of medications should I be taking to manage my pain?
We advise you to continue taking your normal anti-neuroma or anti-phantom pain medications before surgery.
We may also advise you to begin increasing your dose of these medications a few days before your surgery is performed. This is because you may experience a temporary, but significant, increase in PLP. This may last for around 3-6 months after the procedure.
The wound pain after this surgery is usually minimal and easily controlled with standard pain medication, which you will only need to take for a few days.