Here, we'll describe the surgical technique for performance of the agonist-antagonist mononeural interface procedure at the time of an elective below-knee amputation. A residual tibial length of approximately 15 to 16 centimeters is elected based on the height of the patient. The anterior fasciocutaneous tissues of the lower extremity are then incised and elevated to afford exposure of the distal musculotendinous structures. Here, an anterior periosteal flap of approximately 8 to 10 centimeters is elevated off of the anterior tibia. This will be used for coverage of the AME constructs after creation. The saphenous nerve and vein are identified. Here, the tibialis anterior and peroneus lungus muscle and tendons have been identified and are transposed proximally. The superficial peroneal nerve is then identified within the lateral compartment and then tagged for later neuroma prevention using an RPNI technique. The anterior tibial vessels are then ligated. Again, the superficial peroneal nerve is being tagged for later RPNI. The musculature of the anterior and lateral compartment is then resected. And a standard myocutaneous flap is then elevated. Here, the serral nerves are being identified, running immediately deep to the creal fascia of the posterior myocutaneous flap. The lateral gastroc muscle tendinous gastroc muscle tendinous unit is then dissected free from the underlying soleus and then mobilized for later transposition to the medial aspect of the residual limb. Here, the serral nerve is being further identified and tagged for later management with RPNI. An interval between the medial gastroc and the underlying soleus is developed so as to preserve this perforator here to the posterior fasciocutaneous flap. We'll transpose the lateral gastrocnemius musculotendinous unit through this interval between the medial gastroc and the soleus in order to preserve blood supply to the posterior flap. The lateral gastroc is then being delivered to the medial side of the residual limb, where it will then be paired with the tibialis anterior musculotendinous unit, which is coming from lateral to medial. Posterior tibial vessels are then ligated and a standard amputation is performed with anterior bevel of the tibia and a standard fashioning of the fibula. The musculotendinous unit is stripped so as to provide proximal tendon with which to create the AME constructs. Of note, the tendon travels for a significant length within the muscle, which affords a very proximal creation of these agonist-antagonist mononeural interfaces. Here, the extensor retinaculum and two tendons have been harvested and will be used for creation of the AME pulleys. A suture-only anchor is then used to secure the pulley structures to the anterior tibia. The excess retinaculum is then resected, and the agonist-antagonist mononeural interfaces are then created, with tendon repairs performed on each side of the pulleys so as to decrease the likelihood of significant scarring within the pulley. RPNI are then created and then delivered deep within the posterior flap. A drain is placed here. Antibiotic powder is also being used. And a standard soleal myodesis is then being performed. One of the things you'll note is that the previously elevated periosteal flap has been transposed over the AME constructs prior to definitive myodesis of the soleus. There you see the periosteal flap. Standard amputation closure is then performed. And here you see the function of the AME constructs in the early postoperative time frame.

agonist-antagonist mononeural interface

below-knee amputation

RPNI technique

neuroma prevention

soleal myodesis