title: Clinical effectiveness of the obturator externus muscle injection in chronic pelvic pain patients.
abstract: BACKGROUND
  Because of its anatomical location and function, the obturator externus (OE) muscle can be a source of pain; however, this muscle is understudied as a possible target for therapeutic intervention in pain practice. In this retrospective observational study, we evaluated the clinical effectiveness of the OE muscle injection with a local anesthetic in chronic pelvic pain patients with suspected OE muscle problems.
  
  
  METHODS
  Twenty-three patients with localized tenderness on the inferolateral side of the pubic tubercle accompanied by pain in the groin, anteromedial thigh, or hip were studied. After identifying the OE with contrast dye under fluoroscopic guidance, 5 to 8 mL of 0.3% lidocaine was injected. Pain scores were assessed before and after injection; patient satisfaction was also assessed.
  
  
  RESULTS
  Mean pain score decreased by 44.7% (6.6 ± 1.8 to 3.5 ± 0.9, P < 0.001) 2 weeks after OE muscle injection as compared with pain score before injection. In addition, 82% of patients (19 of 23 patients) reported excellent or good satisfaction during 2 weeks after injection. No patients reported complications from OE muscle injection.
  
  
  CONCLUSIONS
  Fluoroscopy-guided injection of the OE muscle with local anesthetic reduced pain scores and led to a high level of satisfaction at short-term follow-up in patients with suspected OE muscle problem. The results of this study suggest that OE muscle injection may be a valuable therapeutic option for a select group of chronic pelvic pain patients who present with localized tenderness in the OE muscle that is accompanied by groin, anteromedial thigh, or hip pain.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Shin Hyung
authors.initials: SH
authors.lastname: Kim
authors.forename: Do Hyeong
authors.initials: DH
authors.lastname: Kim
authors.forename: Duck Mi
authors.initials: DM
authors.lastname: Yoon
authors.forename: Kyung Bong
authors.initials: KB
authors.lastname: Yoon
mesh_terms: D000328:Adult; D000368:Aged; D000779:Anesthetics, Local / Q000627:therapeutic use*; D059350:Chronic Pain / Q000188:drug therapy*; D003287:Contrast Media; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D007273:Injections, Intramuscular; D008012:Lidocaine / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal; D009776:Obturator Nerve; D010147:Pain Measurement; D017060:Patient Satisfaction; D017699:Pelvic Pain / Q000188:drug therapy*; D010388:Pelvis; D012189:Retrospective Studies; D016896:Treatment Outcome; D061028:Trigger Points; D055815:Young Adult
chemical_list: D000779:Anesthetics, Local; D003287:Contrast Media; D008012:Lidocaine
keywords: chronic pain; hip joint; injections; intramuscular; myofascial pain syndromes; obturator externus; obturator nerve; pelvic pain