First, we will review tibialis posterior anatomy. It originates at the interosseous membrane, the posterior surface of the tibia inferior to the soleal line, and the posterior surface of the fibula. It then travels to its insertion at the tuberosity of the navicular, cuneiform, and cuboid, and the basis of the second through the fourth metatarsals. The tibialis posterior muscle is innervated by the tibial nerve. Its function is to plantar flex the ankle and invert the foot. Now we will review the cross-sectional anatomy of the tibialis posterior muscle. The tibialis posterior muscle is highlighted here. It is located posterior to the interosseous membrane. Located posteriorly are the posterior tibial neurovascular bundle and fibular vascular bundle. Again, the interosseous membrane is located anterior to the tibialis posterior muscle, as well as the anterior tibial artery. Up to this point, we have presented the cross-sectional anatomy of the leg in the supine position. We will perform the tibialis posterior injection in the prone position. The leg is now oriented in the prone position so that the anterior aspect is located at the bottom of the screen. Here, the tip of the needle has been placed in the tibialis posterior muscle, traveling from medial to lateral. It has traveled through the soleus muscle and the flexor digitorum longus muscle between the tibia and the posterior tibial neurovascular bundle. Note the lateral location of the fibular vascular bundle that should be avoided. Also note the interosseous membrane here that serves as an important landmark to avoid injury to the anterior neurovascular bundle. Let's discuss the anatomy we expect to see on ultrasound. Outlined here is the soleus muscle. Medial and posterior to the tibia is the flexor digitorum longus muscle, and lateral to that is the tibialis posterior muscle. Outlined in red is the posterior tibial neurovascular bundle. Outlined in blue is the fibular vascular bundle. Several steps should be carried out prior to injection to ensure patient safety and procedure success. Explain the procedure to the patient. After explaining the risks and benefits of the procedure, obtain informed consent. Check for contraindications. Examine the patient to determine the appropriate muscular targets and dosing plan following manufacturer recommendations. Take time before the procedure to set up the room and make sure that you have adequate assistance. Depending on skill level and comfort with ultrasound-guided injections, one to two assistants may be required for this procedure. Assistants may help with operation of the ultrasound machine and the handheld device for electromyography and electrical stimulation. Gather the necessary equipment as described earlier in this video. Position the patient to optimize patient comfort and provider ergonomics. Disinfect the target site per institutional protocol. Select a timeout per institutional protocol prior to starting the procedure. You will first need to orient yourself by scanning the target muscle region. The target muscle, tibialis posterior, is circled in red here. This muscle can be seen between the tibia and fibula, but is posterior to the interosseous membrane. In ColorFlo Doppler imaging, identify the vasculature to avoid during the injection. Here, the needle is being inserted from medial to lateral through the flexor digitorum longus muscle and between the tibia and the posterior tibial neurovascular bundle. Electrical stimulation can now be used to ensure proper needle tip positioning. Needle position is confirmed when isolated movement of the tibialis posterior muscle is seen on ultrasound. In some cases you may also see ankle plantarflexion and inversion of the foot. Three key images are needed to confirm needle placement. These include the cross-sectional view of the target muscle, cross-sectional view of the vasculature adjacent to the target muscle, and length of the needle traversing to the target muscle. Once needle position is confirmed, botulinum toxin is injected into the target muscle. Finally, the needle is withdrawn. www.ottobock.com

tibialis posterior muscle

anatomy

injection procedure

ultrasound guidance

botulinum toxin