Neuroma – RPNI vs TMR

Neuromas are one of the biggest long term debilitating issues for post-trauma and surgery patients. The development of painful neuroma or phantom limb can force patients to remain in wheelchairs, use large amounts of drugs and prevent the wearing of prosthetics. This can prevent patients getting back to their normal life, back to a job, or just back to enjoying what makes them happy. The prevention of this phenomena is a clinical focus for the team at Brisbane Hand and Plastic Surgery and the RBWH as we are passionate about doing relatively simple operations to dramatically improve patients lives.

The world of neuroma pain management is changing rapidly. Neuromas are small scars / growths at the end of damaged nerves after trauma or deliberate transection from amputation. When amputations were first performed on the battlefield in late 1800s Europe or the American Civil War, little consideration was made to nerves and chronic pain, as the priority was keeping soldiers alive. Nowadays survival from amputation is almost a foregone conclusion, and patients suffer long term consequences if nerves are not managed appropriately in trauma or elective surgery scenarios.

The primary management of nerves in amptuations revolved around initially burying nerves in muscle or bone to prevent neuroma formation. Recent ideological changes conceptualized by Dumanian et al suggested that nerves need ‘…somewhere to go, and something to do’. This led to the inception of Targeted Muscle Reinnervation (TMR) wherein a transected major nerve is coapted to a distal muscle target, to reinnervate a small portion of muscle and basically switch it off. More recently, the idea of wrapping a muscle or dermal graft around nerve stumps (Regenerative Peripheral Nerve Interface, RPNI) have presented reasonably comparable results in pain outcomes. The choice between each technique is a source of surgeon preference and much contention in the scientific literature at present. The idea conceptualised by Dumanian rings true, that if a surgeon is thinking ahead and giving the nerve something to do, they will have better outcomes than if no consideration is given at all. Our approach at BHAPS and RBWH is to use TMR where muscle nerves are available and for large mixed / motor nerve transections, and RPNI for smaller peripheral sensory nerves.

The number needed?

As many as we can possibly find to prevent even the smallest painful neuroma. As local clinical experience evolves, we will publish our data, however the results in the literature speak for themselves.

Is one better than the other? Kind of… TMR is a better option for re-innervating a small muscle (or piece of muscle) for functional prosthetic rehabilitation (read – robot arm/leg). However for post-operative pain medicine requirements, phantom limb sensation and pain scores – there is minimal difference between the two techniques.

Compared to nothing though?

A study from the USA by Kubiak et al in 2019 comparing RPNI with no nerve management for Below Knee Amputations, controls had 13% neuroma formation vs RPNI with 0% neuroma formation and 50% less patients displayed phantom limb symptoms than in the control group. For patients with amputations that had painful neuromas, revision with RPNI demonstrated a 71% reduction in pain, and 56% of patients reduced their pain medications to nothing. Importantly – nonones pain got worse after their procedures.

The important thing about this? There is a surgical option that can offer patients with pain a chance to reduce or stop their analgesic medications and improve their mobilisation on prosthesis. This improvement to quality of life is greatly promising for patients suffering pain.