title: Does Reducing the Concentration of Bupivacaine When Performing Therapeutic Shoulder Joint Injections Impact the Clinical Outcome?
abstract: OBJECTIVE
  Mixtures of local anesthetics and steroids are routinely injected intraarticularly to temporarily relieve joint pain, even though local anesthetics have been reported to cause chondrocyte death in a dose- and time-dependent manner. This study aimed to determine if intraarticular injections of bupivacaine 0.5% and bupivacaine 0.25% would provide similar pain relief.
  
  
  METHODS
  All fluoroscopically guided glenohumeral joint injections performed using 2.5 mL of bupivacaine and 0.5 mL (20 mg) of triamcinolone acetonide over a 42-month period were included if a pain score was recorded before, 5-10 minutes after, and 1 week after injection. Pain reduction of more than 2 points was considered much improved clinically with pain reduction of more than 1 point considered the minimum clinically important difference (MCID) threshold.
  
  
  RESULTS
  Statistically significant and much improved pain reduction was achieved using both bupivacaine 0.5% and 0.25% 5-10 minutes (-3.7 points; 95% CI, -3.4 to -4.0 points; p ≤ 0.001; and -3.3 points; 95% CI, -3.0 to -3.5 points; p ≤ 0.001) and 1 week (-2.5 points; 95% CI, -2.2 to -2.9 points; p ≤ 0.001; and -2.1 points; 95% CI, -1.8 to -2.3 points; p ≤ 0.001) after injection, respectively. Adjusting for age, sex, pain score before injection, and indication, the mean decrease in pain was greater in the bupivacaine 0.5% group by 0.30 points 5-10 minutes after injection (95% CI, -0.03 to 0.63 points; p = 0.08) and 0.46 points 1 week after injection (95% CI, 0.13-0.77 points; p = 0.01).
  
  
  CONCLUSIONS
  Both bupivacaine 0.5% and bupivacaine 0.25% provide statistically significant and much improved pain relief 5-10 minutes and 1 week after intraarticular glenohumeral injections. Bupivacaine 0.5% provided greater pain relief than bupivacaine 0.25%, but the difference was less than 0.5 points and therefore did not meet the MCID threshold.
authors.affiliation: 1 Department of Radiology and Medical Imaging, University of Virginia, 1218 Lee St, Box 800170, Charlottesville, VA 22908.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fox
authors.affiliation: 2 Department of Public Health Sciences, University of Virginia, Charlottesville VA.
authors.forename: James T
authors.initials: JT
authors.lastname: Patrie
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002045:Bupivacaine / Q000008:administration & dosage*; D005260:Female; D005471:Fluoroscopy; D005938:Glucocorticoids / Q000008:administration & dosage*; D006801:Humans; D007270:Injections, Intra-Articular; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D012189:Retrospective Studies; D012785:Shoulder Joint; D020069:Shoulder Pain / Q000188:drug therapy*; D016896:Treatment Outcome; D014221:Triamcinolone / Q000008:administration & dosage*
chemical_list: D000779:Anesthetics, Local; D005938:Glucocorticoids; D014221:Triamcinolone; D002045:Bupivacaine
keywords: bupivacaine; intraarticular injections; local anesthetics; pain; shoulder joint