title: The anterior approach for a non-image-guided intra-articular hip injection.
abstract: OBJECTIVE
  The purpose of this study was to investigate and validate the accuracy and safety of a technique using an anterior approach for non-image-guided intra-articular injection of the hip by use of anatomic landmarks.
  
  
  METHODS
  We enrolled 55 patients. Injections were performed before supine hip arthroscopy after landmarking and before application of traction. After the needle insertion, success was confirmed with an air arthrogram and by direct visualization after arthroscope insertion. Accuracy and difficulty achieving correct needle placement were correlated with age, weight, height, body mass index, body type, gender, and surgical indication, as well as femoral and pelvic morphology. Forty-five patients who underwent injection in the office were followed up separately to document injection side effects. Needle placement accuracy was correlated to patients' demographics. All statistical tests with P values were 2 sided, with the level of significance set at P < .05.
  
  
  RESULTS
  There were 51 correct needle placements and 4 misses, yielding a 93% success rate. The most common location for needle placement was the upper medial head-neck junction. Female gender was correlated with a more difficult needle placement and misses in relation to group size (P = .06). The reasons for misplacements of the needle were a high-riding trochanter, increased femoral version, thick adipose tissue over the landmarks, and variant of ilium morphology. Of 45 patients in the side effect study arm, 3 reported sensory changes of the lateral femoral cutaneous nerve that resolved within 24 hours.
  
  
  CONCLUSIONS
  Hip injections by use of the direct anterior approach, from the intersection of the lines drawn from the anterior superior iliac spine and 1 cm distal to the tip of the greater trochanter, are safe and reproducible. Patient characteristics, such as increased subcutaneous adipose tissue or osseous anatomic variants, can lead to difficulty in placing the needle successfully. These characteristics can be predicted with the aid of physical examination and careful study of the pelvic radiographs.
  
  
  METHODS
  Level IV, therapeutic case series.
authors.affiliation: Department of Orthopaedics, Division of Sports Medicine and Hip Preservation, University of Colorado, Denver, CO, USA. omer.meidan@ucdenver.edu
authors.forename: Omer
authors.initials: O
authors.lastname: Mei-Dan
authors.forename: Mark O
authors.initials: MO
authors.lastname: McConkey
authors.forename: Brian
authors.initials: B
authors.lastname: Petersen
authors.forename: Eric
authors.initials: E
authors.lastname: McCarty
authors.forename: Brett
authors.initials: B
authors.lastname: Moreira
authors.forename: David A
authors.initials: DA
authors.lastname: Young
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000367:Age Factors; D000368:Aged; D059925:Anatomic Landmarks; D001182:Arthroscopy / Q000379:methods; D001827:Body Height; D001835:Body Weight; D005260:Female; D005269:Femur; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D007270:Injections, Intra-Articular / Q000009:adverse effects / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D009339:Needles; D011859:Radiography; D012449:Safety; D012737:Sex Factors; D013008:Somatotypes