1 3 J Anesth DOI 10.1007/s00540-016-2223-0 ORIGINAL ARTICLE A nomogram for predicting the need for sciatic nerve block after total knee arthroplasty Rovnat Babazade 1,2 · Thilak Sreenivasalu 2,3 · Pankaj Jain 4 · Matthew T. Hutcherson 4 · Amanda J. Naylor 4 · Jing You 4,5 · Hesham Elsharkawy 4,6 · Ali Sakr Esa Wael 4,6 · Alparslan Turan 4 Received: 28 December 2015 / Accepted: 20 July 2016 © Japanese Society of Anesthesiologists 2016 nonlinear association between continuous predictors and SNB was assessed using the restricted cubic spline model. Results In total 6279 TKA cases involving 2329 patients with complete datasets were used for building the predic- tion model, including 276 (12 %) patients who received a postoperative SNB and 2053 (88 %) patients who did not. The estimated C statistic of the prediction model was 0.64. The nomogram is used by first locating the patient position on each predictor variable scale, which has corresponding prognostic points. The cut-off of 11.6 % jointly maximizes the sensitivity and specificity. Conclusion This is the first study to be published on SNB prediction after TKA. Our nomogram may prove to be a useful tool for guiding physicians in terms of their deci- sions regarding SNB. Keywords Nomogram · Sciatic nerve block · Postoperative pain · Total knee arthroplasty Introduction Total knee arthroplasty (TKA) is a commonly performed procedure in the USA, with the primary aims of relieving knee pain and improving the quality of life of patients with end-stage arthritis. An estimated 718,000 procedures were carried out in 2011 [1, 2], and the demand for primary TKA is expected to grow in the coming years [3]. TKA causes severe postoperative pain in 60 % of patients and moderate pain in 30 % of patients [4]. Therefore, pain management remains one of the major challenges for anesthesiologists following TKA. Postoperative knee pain interferes with physical ther- apy, mobilization [5], and patient satisfaction, which in turn results in delayed recovery and higher hospital costs Abstract Purpose Sciatic nerve block (SNB) is commonly per- formed in combination with femoral nerve block (FNB) for postoperative analgesia following total knee arthroplasty (TKA). Despite the fact that 10–20 % of TKA patients require SNB for postoperative posterior knee pain, there are no existing studies that suggest a model to predict the need for SNB. The aim of our study was to develop a pre- diction tool to measure the likelihood of patients undergo- ing TKA surgery requiring a postoperative SNB. Methods With institutional review board approval, we obtained data from the electronic medical record of patients who underwent TKA at the Cleveland Clinic. A multivari- able logistic regression was used to estimate the probabil- ity of requiring a postoperative SNB. Clinicians selected potential predictors to create a model, and the potential This report was previously presented, in part, at the American Society of Anesthesiologists, 2014 Meeting, New Orleans. * Alparslan Turan alparslanturan@yahoo.com http://www.OR.org 1 Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX, USA 2 Outcomes Research Consortium, Cleveland, OH, USA 3 Department of Anesthesiology, Saint Louis University Hospital, Saint Louis, MO, USA 4 Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic, Cleveland, OH, USA 5 Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH, USA 6 Anesthesiology, Cleveland Clinic, Lerner College of Medicine, Cleveland Clinic, Cleveland, OH, USA