Position and anatomical landmarks
The anatomical site of infiltration depends on the location of the scar. The scar is palpated to find its most painful spot(s), recognised by the patient as a sharp pain.
The surrounding area is disinfectedand covered with sterile drapes. A needle ((22-G, 5 cm, 1 cm active tip) is inserted (under ultrasound guidance) into the scar's most painful spot(s). The correct spot is confirmed when the patient experiences reproducible paresthesia in the scar by stimulation with 50 Hz, 0,5 V. Then, a pulsed radio-frequency current of 45 V lasting for 120 seconds is administered with no preceding local anaesthetic. The maximum temperature should not exceed 42°C, but if this occurs the output should be reduced. If necessary, a second treatment period of 120 seconds can be administered if the impedance is above 500 Ω, prior to injection of 1 ml NaCl 0.9% solution.
- The most serious complication of the injection is infection.
- Small subcutaneous bleedings may result in a temporary increase in pain after the injection.