Tibial nerve blockade is useful as a diagnostic, prognostic, or therapeutic procedure in painful disorders involving the ankle and foot.
After informed consent is obtained, the patient is placed in the prone position. The knee is flexed to allow palpation of the superior popliteal fossa borders and identification of the skin crease behind the knee joint. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 1½-in. (3- to 4-cm), 21- to 23-gauge needle is inserted just above the crease line in the middle of the popliteal fossa. A nerve stimulator is used to identify the tibial nerve by eliciting plantar flexion of the foot. The average depth from skin to nerve in adults is 1.5 to 2 cm. After negative aspiration, 5 mL of local anesthetic is injected to block the tibial nerve (Fig. 67-17).
FIGURE 67-17. Tibial and common peroneal nerve block at the knee. Approach for tibial and common peroneal nerve injection and neural blockade at the knee. Tibial and common peroneal (lateral popliteal) nerve.
The tibial nerve is the larger of the two branches of the sciatic nerve and supplies motor innervation to the flexor muscles at the back of the knee joint and calf. The cutaneous innervation supplies the skin overlying the popliteal fossa and down the back of the leg to the ankle. It travels through the center of the popliteal fossa as it proceeds distally down the leg.
Hematoma and intravascular injection are possible, owing to the close proximity of the popliteal vessels. If an arterial puncture occurs, prolonged direct pressure is usually adequate to prevent the development of a hematoma.