Location of the entry point of the muscular branch of the nerve to vastus medialis

Editor—Blocking the nerve to vastus medialis can be cause of occasional motor weakness identified after adductor canal block (ACB), a common procedure for pain control knee and leg surgery. Although it results in less quadriceps muscle compared with femoral block, significant is occasionally seen.1Lynch J.R. Okoroha K.R. Lizzio V. Yu C.C. Jildeh T.R. Moutzouros Adductor versus anterior cruciate ligament reconstruction: prospective randomized trial.Am J Sports Med. 2019; 47: 355-363Crossref PubMed Scopus (27) Google Scholar,2Koh H.J. Koh I.J. Kim M.S. Choi K.Y. Jo H.U. In Y. Does patient perception differ following total arthroplasty? A simultaneous bilateral study.J Arthroplasty. 2017; 32: 1856-1861Abstract Full Text PDF (13) Scholar The observed ACB may related spread local anaesthetics proximally, nerve, or as result medialis. However, proximal was not found correlated changes strength.3Jaeger P. Jenstrup M.T. Lund J. et al.Optimal volume anaesthetic block: using continual reassessment method estimate ED95.Br Anaesth. 2015; 115: 920-926Abstract (28) Thus, blocking emerges possible origin ACB, would totally blocked given its close location injection site. By comparison, exposed smaller amount that insufficient this large nerve. from courses lateral saphenous vessels, then divides into posteromedial (mainly sensory) anterolateral (muscular) branches; one four terminal muscular branches enter provide innervation.4Tran Chan V.W.S. Peng P.W.H. Agur A.M.R. Evaluation injectate spread: cadaveric study.Reg Anesth Pain 2020; 45: 124-130Crossref (7) current study set out determine entry point so avoided when performing an ACB. An enhanced understanding help refine approach minimise femoris weakness. sample included 22 cadavers (44 lower limbs). This granted exemption status institutional review board at Boston University School Medicine. thigh length superior iliac spine base patella measured. emerging branch followed muscle. distance measured, ratio calculated. average 44 limbs 43 (2.9) cm. entered 19.2 (1.9) cm patella, which slightly below mid-thigh, 55% (4%) patellar (Fig. 1). Previous work showed starts ∼60% ∼4.6–6.5 inferior mid-thigh.5Tubbs R.S. Loukas M. Shoja M.M. Apaydin N. Oakes W.J. Salter E.G. Anatomy potential clinical significance vastoadductor membrane.Surg Radiol Anat. 2007; 29: 569-573Crossref (39) Anaesthesiologists typically perform anatomically triangle. cadaver studies dye, mid-thigh (femoral triangle) consistently stained medialis.6Johnston D.F. Black N.D. Cowden R. Turbitt L. Taylor S. Spread dye distal triangle canal: 44: 39-45Crossref (11) contrast, end anatomical (sensory) medialis, but spared branches.4Tran only nerve.6Johnston Based on above, optimal sensory while sparing fibres. findings suggest laterally, canal. Clinical area supports above findings, difficult produce injecting volumes ACB.7Johnston Sondekoppam R.V. Giffin Litchfield Ganapathy Determination ED50 ED95 0.5% ropivacaine weakness: dose-finding 42: 731-736Crossref (8) comparison vs mid resulted lowest morphine consumption, no difference strength.8Abdallah F.W. Mejia Prasad G.A. al.Opioid- motor-sparing proximal, mid-, locations trial.Anesthesiology. 131: 619-629Crossref (17) subsartorial rather than other used continuous infusion (low concentration 0.2% 8 ml h−1), usually single-shot injections did measure strength specifically.8Abdallah Scholar,9Chuan A. Lansdown Brick K.L. al.Adductor catheter analgesia arthroplasty: multicentre randomised controlled study.Br 123: 360-367Abstract (20) conclusion, mid-thigh. finding clinicians technique maximise analgesic benefits. authors declare they have conflicts interest. Supplementary data article: Download .docx (.01 MB) Help docx files Multimedia component 1 2