Purpose : To analyze the clinical effect and results of patients that underwent lower extremity surgery under ultrasound-guided nerve block by orthopeadic surgeon.
Material and methods : 3312 cases (2597 patients) that underwent surgery of the lower extremity under ultrasound guided nerve block performed by an orthopeadic surgeon from January 2010 to April 2015 were prospectively analyzed. The group consisted of 2043 male and 1269 female and the mean age was 50 (11~95) years old. A single orthopeadic surgeon performed ultrasound guided lateral femoral cutaneous nerve (LFCN, 630 cases), femoral nerve (FN, 2503 cases), obturator nerve (ON, 366 cases), sciatic nerve (SN, 3271 cases), or posterior femoral cutaneous nerve (PFCN, 222 cases) block on a case-by-case basis. 1:1 mixture of 1% lidocaine and 0.75% ropivacaine was used as anesthetics for every case. Average of 16 (10~20) ml was used for femoral nerve block, 18 (15~20) ml for sciatic nerve block, 9 (7~10) ml for obturator nerve block, and 6 (5~7) ml each for lateral and posterior femoral cutaneous nerve block. For antianxiety purpose, average of 2.0 (1.5~2.5) mg of Benzodiazepine (Midazolam®) was intramuscularly injected before surgery to patients who met the criteria. If patient i nsisted to be sedated, average of 2.4 (2.0~3.0) mg of additional Midazolam® was intravenously injected mixed with 100ml normal saline.
Matching between surgical category and nerve block, time required for nerve block, anesthesia induction time, anesthetic duration, analgesic duration, tolerable tourniquet time, VAS satisfaction score, preference of anesthesia method for future surgery, and anesthetic and sedative related complication were analyzed.
Result : 12 cases underwent FN block only, 1762 cases underwent FN and SN block, 317 cases underwent FN, SN, LFCN, and ON block, 163 cases underwent FN, SN, LFCN block, 127 cases underwent FN, SN, and PFCN block, 77 cases underwent FN, SN, LFCN< and PFCN block, 18 cases underwent FN, LFN, and ON block, 765 cases underwent SN block, 25 cases underwent SN and PFCN block, 11 cases underwent all 5 nerve block, and 35 cases had different combination of block.
530 cases (16%) underwent ASO and DM foot surgery including amputation, 1350 cases (41%) underwent fixation surgery for fracture of foot and ankle, tibia, knee, and femur or metal removal. 54 cases (1.6%) had ankle arthroscopic surgery and 196 cases (6%) had knee arthroscopic surgery. Other surgery consisted of hallux valgus (172 cases), Achilles tendon (92 cases), lateral ankle instability (110 cases), and other surgery of the foot and ankle or lower leg (742 cases, 22%). Other knee and femur surgery was performed in 66 cases (2%).
Average of 2.5 minutes (2~6) was required for FN and SN block (1762 cases), 4.8 minutes (4~12) for FN, SN, LFCN, and ON block, and 1.1 minutes (1~3) for SN block. Total anesthesia induction time was 48 minutes (20~100) on average. The anesthesia duration time until the patient feels pain by pin prick test was 4.5 hours (4~6) for femoral nerve dermatome and 5.6 hours (5~7) for sciatic nerve dermatome. Duration time until the analgesic effect of anesthetic is disappears and patient feels pain even without pin prick was average of 11.5 hours (6~19).
The tolerable tourniquet time after sciatic nerve block was average of 35 minutes (0~50). When blocking femoral and sciatic nerve, tourniquet on the mid-thigh was tolerable for 51 minutes (0~90) on average and when the FN, SN, LFCN, and ON were blocked, patients were tolerable for 84 minutes (50~120) on average.
VAS satisfaction score was 9.3 (5~10) and for preference of anesthesia method assuming that the patient undergo the same surgery in the future, 95% (3149 cases) chose nerve block instead of general, spinal anesthesia, etc. 1271 cases (556 patients) that had surgery at least 2 time for the lower extremity underwent all surgeries under nerve block.
52 cases (2.9%) among 1762 cases that had FN and SN block suffered from mild pain during incision of the ankle or medial side of the lower leg. For such cases, additional saphenous nerve blockade was performed on the proximal medial lower leg.
No complication such as infection, hematoma, paralysis or nerve irritation occurred. However, though not included in this study, there was 2 cases, one case with conversion disorder and the other case of mental retardation underwent surgery under general anesthesia due to failure of controlling anxiety and sedation. 7 cases (0.5%) out of 1324 cases that Benzodiazepine (Midazolam®) were injected intravenously showed paradoxical excitation and received antidote, Flumazenil (Flunil®). Except a case who had a history of dementia suffered from postoperative short term dementia, no other anesthetic and sedative related complication occurred.
Conclusion : Regional anesthesia through ultrasound guided nerve block for femur, knee, lower leg, foot and ankle is a safe, easy, and fast procedure that can be done by an orthopedic surgeon. In addition, since the nerves can be selectively blocked and precisely injected, the amount of anesthetics could be minimized and thus the complication could be decreased. It seems that in the future, ultrasound guided nerve block could replace general and spinal anesthesia for lower extremity surgery.