Tibial nerve block: evaluation of a novel midleg approach in 241 patients

Several techniques of tibial nerve (TN) block have been described but require mobilization of the patient. We describe a new landmark, along the internal tibial shaft edge at the midleg level, that allows to block the TN and to insert a catheter with the patient lying supine.

241 ASA physical status I to III awake, supine patients were studied prospectively. Cutaneous projections of the internal tibial condyle and the internal malleolus were marked and the needle was inserted 45 degrees cephalad in an antero-posterior plane, midway on the line between those two points, 1 cm posterior to the tibial shaft's internal edge. The catheter was introduced in the peri-nervous space using nerve stimulation (< 0.5 mA) on both the Tuohy needle and catheter. Ten millilitres of 2% lidocaine were injected through the catheter. Cutaneous and dermatomal sensory blockade were assessed using cold and pinprick tests while motor block was assessed using a modified Bromage scale. Satisfaction and analgesia scores were noted after surgery for 48 hr. Adverse events were recorded.

The TN was always blocked, matching the distal L5 cutaneous nerve supply. Blood reflux was present in five patients (needle or catheter). No additional adverse events were noted. During the initial postoperative 48 hr, 0.2% ropivacaine was infused through the catheter (5 mL.hr(-1)) which always provided effective pain relief.

The midleg technique of TN anesthesia and catheter insertion allows patients to remain in the supine position and results in a high rate of homogeneous anesthesia, a low incidence of side effects and effective continuous analgesia.