Hi, this is Jason Sousa. I'm going to talk about some of the technical aspects of target muscle renovation, regenerative peripheral nerve interface techniques for neuroma management in the bologna amputee. So here, a longitudinal six to eight centimeter incision is made halfway between the expected location of the tibial nerve and the common peroneal nerve. The sural nerve is then identified. This is the peroneal contribution to the sural nerve. Tissues are swept medially and the common peroneal nerve is then identified and dissected free laterally. Both nerves are then surrounded with the vessel loops. This is the tibial contribution to the sural nerve. You can see a large neuroma in that branch of the sural nerve. At this point, the inner space between the heads of the medial and lateral gastrocnemius muscles is entered and then dissected bluntly to identify the tibial nerve. Here, a motor branch to the lateral gastroc muscle is identified. It's then stimulated with a handheld nerve stimulator. An additional motor branch to the soleus is also identified emanating from the tibial nerve. These two branches will serve as the recipient nerves for target and muscle re-innervation. So lateral gastroc and then soleus branch. At this point, the tibial nerve is delivered into the field and transected. It is not entirely necessary to deliver the entirety of the distal neuroma into the field, but it is critical that resection is performed or transection is performed proximally enough that there are healthy nerve fascicles available for coaptation. Part of the benefit attributed to TMR is based on the concept of fostering coordinated regeneration. And so in order to get that coordinated regeneration, there need to be healthy donor nerve fascicles. So here you'll see the distal portion of the nerve has significant scar and fibrosis as illustrated there. And then more approximately, there are healthy nerve fascicles that can be then guided into the recipient motor nerve. So this is the motor branch to the soleus muscle that's going to serve as the recipient for the tibial nerve. The motor branch is then delivered into the central portion of the much larger tibial nerve. This is the size mismatch that's commonly discussed in the context of targeted muscle re-innervation. So here, one of the ways that this is accounted for is with the use of a centralizing suture. So this is an 8-0 proline suture. And the goal of this suture is to simply centralize the recipient motor branch into the mid portion of the tibial nerve. If a standard epineurial coaptation was performed, it would place the recipient nerve eccentrically into the tibial nerve. Here, the goal is to put the recipient nerve in the mid portion of this donor tibial nerve. This is performed with a mattress style suture as shown here. And then we're careful not to overly tighten this approximating stitch. In this case, given that there is a relatively large recipient nerve, we're going to reinforce this coaptation with two epineurial sutures from the donor nerve to the recipient nerve. This is not always possible in the setting of a more significant size mismatch. In the setting of a more significant size mismatch, the reinforcing sutures would be placed between the epineurium of the donor nerve and epimysium of the recipient or target muscle, as will be shown for the common peroneal nerve.

neuromas

regenerative peripheral nerve interface

below-knee amputees

targeted muscle re-innervation

nerve coaptation