Targeted Muscle Reinnervation: Surgical Protocol for a Randomized Controlled Trial in Postamputation Pain

The scope of this research is on surgical treatments for post-amputation pain after major limb loss. We're trying to answer the question of whether surgical procedures in which nerves are allowed to reinnervate muscles again are more effective in treating post-amputation pain than simply pouring them in already innervated muscles. The number of limb amputation is limited within any given hospital, and these are often performed for different reasons.

Therefore, obtaining a uniform patient population is challenging. Additionally, achieving consistency in surgical procedure poses practical challenges due to variations in the level of amputation and traumatic damage, resulting in diverse anatomical structures of residual limbs. This protocol provides a standardized method to perform the targeted muscle reinnervation technique, which was agreed upon by a large consortium of experienced surgeons.

This standardization will minimize bias in our randomized control trial and would allow the technique to be used and implemented in other clinics conducting amputation care. To begin, evaluate the flexibility of the soft tissue surrounding the nerve of the neuroma. Plan skin incisions based on the findings from the physical assessment and EMG evaluation.

Perform the skin incision with the scalpel at the location of the painful neuroma. Identify the donor nerve through blunt dissection, then isolate the donor nerve along with the neuroma using loop magnification and microsurgical instruments. Mobilize the donor nerve as needed to reach the recipient site.

Transect the neuroma using a commercial nerve cutting set and repeat for each nerve with an identified painful neuroma in the current exposed area. Next, perform a blunt dissection to identify all motor nerve branches to the target muscle. Set the handheld nerve stimulator between 0.5 to 1 milliamperes and put it in contact with each of the nerve branches to stimulate them.

Identify the nerve causing the largest muscle contraction to be the recipient nerve. Denervate the target muscle completely when possible. Once active contraction is confirmed, use straight microscissors to transect the nerve without tension near its entry point, aiming for less than 1 centimeter.

Transpose the proximal stump of the transected donor nerve proximally away from the coaptation site without specific management. Next, perform nerve-to-nerve coaptation by suturing the donor nerve to the recipient residual or target motor nerve with an 8-0 non-resorbable monofilament suture. Place the stitch in the center of the donor nerve.

Reinforce the suture with additional stitches to secure the donor nerve epineurium to the surrounding fascia and epimysium of the recipient nerve. Ensure the coaptation is tension-free and without excess redundancy.