Efficacy of an ultrasound-guided subsartorial approach to saphenous nerve block: a case series

Abstract

Purpose The saphenous nerve, a branch of the femoral nerve, is a pure sensory nerve that supplies the anteromedial aspect of the lower leg from the knee to the foot. There is limited evidence of the effectiveness of ultrasoundguided techniques to block the saphenous nerve. We therefore undertook a retrospective case series to investigate the efficacy of an ultrasound-guided subsartorial approach to saphenous nerve block. Methods During a four-month period, all patients receiving a subsartorial saphenous nerve block for lower extremity surgery at our institution had their medical records reviewed. Patient demographics and data were recorded, including block characteristics, intraoperative anesthetic management, pre-block, post-block, and postoperative pain scores, as well as postoperative analgesic dosing. Preoperative block success was defined by minimal intraoperative analgesic administration and a pain score of 0 in the postanesthesia care unit not requiring analgesic supplementation. Postoperative block success was defined by reduction of pain score to 0 without need for additional analgesic dosing. Results Thirty-nine consecutive patients were identified as receiving an ultrasound-guided subsartorial saphenous nerve block. Overall, this ultrasound-guided technique was found to have a 77% success rate.Conclusion This case series shows that an ultrasoundguided subsartorial approach to saphenous nerve blockade is a moderately effective means to anesthetize the anteromedial lower extremity. The success rate is based on stringent criteria with an endpoint of postoperative analgesia. A randomized prospective study would provide a more definitive answer regarding the efficacy of this technique for surgical anesthesia. RésuméObjectif Le nerf saphe`ne interne, une branche du nerf fe´moral, est un nerf purement sensitif qui innerve la partie ante´rome´diale de la jambe, du genou jusqu'au pied. Il existe peu de preuves quant a`l'efficacite´des techniques guide´es par ultrason pour l'anesthe´sie du nerf saphe`ne interne. Nous avons donc entrepris une revue re´trospective d'une se´rie de cas afin d'examiner l'efficacite´d'une approche sous-sartoriale guide´e par ultrason pour l'anesthe´sie du nerf saphe`ne interne. Méthodes Pendant une pe´riode de quatre mois, les dossiers me´dicaux de tous les patients ayant be´ne´ficie´d'un bloc sous-sartorial du nerf saphe`ne interne pour une chirurgie du membre infe´rieur a`notre institution ont e´teŕ evus. Les donne´es de´mographiques et des renseignements sur ces patients ont e´te´recueillis, dont les caracte´ristiques du bloc, la prise en charge de l'anesthe´sie perope´ratoire, les scores de douleur pre´-anesthe´sie, postanesthe´sie et postope´ratoire, ainsi que la posologie analge´sique postope´ratoire. La re´ussite du bloc en pe´riode pre´ope´ratoire a e´te´de´finie par une administration perope´ratoire minime de substances analge´siques et un score de douleur a`0 ne nécessitant aucun apport analge´sique supple´mentaire a`la salle de re´veil. La re´ussite du bloc en pe´r...

Ultrasound-guided adductor canal block for arthroscopic medial meniscectomy: a randomized, double-blind trial

“…This is similar to other ultrasound-guided approaches to the saphenous nerve block. 23 A limitation of this study was not taking this relatively low success rate into consideration when powering the study. The inclusion of the perceived block failures in the overall statistical analysis gives a true clinical reflection of the ability of this block to reduce postoperative pain scores in the PACU.…”

The Effects of Ultrasound-Guided Adductor Canal Block Versus Femoral Nerve Block on Quadriceps Strength and Fall Risk

“…This block is frequently used for anesthesia and analgesia of the medial calf and ankle. 6 Recent case reports and a randomized trial have demonstrated superior analgesia after total knee arthroplasty (TKA) in patients receiving ACB compared with parenteral opioids. [7][8][9] Our objective was to determine if an ultrasound-guided ACB can preserve quadriceps strength, thus minimizing weakness of knee extension compared with ultrasound-guided FNB.…”

Effect of Nerve Stimulation Use on the Success Rate of Ultrasound-Guided Subsartorial Saphenous Nerve Block

“…1,2 However, in part owing to its small caliber, the saphenous nerve is more difficult to reliably block than the sciatic nerve in the popliteal fossa (ie, with success rates reliably exceeding 95%). [3][4][5] As the terminal branch of the femoral nerve, the saphenous nerve provides sensory innervation to the anteromedial aspect of the lower leg, including the medial ankle joint capsule and distal tibia. 6 Extending proximally from the femoral triangle, it descends within the adductor canal, accompanying the femoral artery and nerve of vastus medialis beneath the sartorius muscle, and continues its course underneath the sartorius muscle until it penetrates the connective tissue between the tendons of the sartorius and gracilis muscles on the medial side of the knee.…”