title: Generic targeting guides place revision glenoid components in more anatomic version than traditional techniques.
abstract: BACKGROUND
  Glenoid component positioning in revision shoulder arthroplasty is difficult because of distorted anatomic landmarks and scarring in and around the glenoid vault. This study compared glenoid component version in revision total shoulder arthroplasty (TSA) and reverse TSA (RTSA) using traditional instrumentation vs. a generic glenoid targeting guide.
  
  
  METHODS
  Radiographs of 50 shoulders undergoing revision arthroplasty were reviewed by an independent reviewer. Twenty-one components were placed using traditional instrumentation and 29 with a generic targeting guide. Glenoid component version was measured on axillary lateral radiographs, and absolute deviation from anatomic version was calculated.
  
  
  RESULTS
  The average deviation in version from anatomic was 8° (range, 0°-21°) with the traditional technique and 5° (range, 0°-18°) with the targeting guide (P = .03). In revision to TSA, the average deviation was 10° with the traditional technique and 3° with the targeting guide (P = .01). There was no significant difference in revision to RTSA (average deviation was 8° with traditional technique and 6° with the targeting guide). Glenoid components in obese patients (body mass index  >30 kg/m2) had less deviation (5°) with the targeting guide technique than with the traditional technique (9°, P = .04). No significant differences were found between techniques in glenoids with more than 15° of preoperative retroversion, TSA conversion to RSTA, or arthroplasty after proximal humeral fixation.
  
  
  CONCLUSIONS
  For revision arthroplasty, glenoid components placed with the generic targeting guide were significantly more accurate in version than with traditional instrumentation, particularly with revision to anatomic TSA. The targeting guide was useful in obese patients.
authors.affiliation: University of Tennessee-Campbell Clinic Department of Orthopaedic Surgery & Biomedical Engineering, Memphis, TN, USA.
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Mulligan
authors.affiliation: University of Tennessee-Campbell Clinic Department of Orthopaedic Surgery & Biomedical Engineering, Memphis, TN, USA.
authors.forename: Frederick M
authors.initials: FM
authors.lastname: Azar
authors.affiliation: University of Tennessee-Campbell Clinic Department of Orthopaedic Surgery & Biomedical Engineering, Memphis, TN, USA. Electronic address: tthrockmorton@campbellclinic.com.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Throckmorton
mesh_terms: D000368:Aged; D059925:Anatomic Landmarks; D000072228:Arthroplasty, Replacement, Shoulder / Q000295:instrumentation* / Q000379:methods; D005260:Female; D062785:Hemiarthroplasty / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008297:Male; D017755:Prosthesis Fitting / Q000295:instrumentation*; D012086:Reoperation; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D000072227:Shoulder Prosthesis
keywords: Revision shoulder arthroplasty; accuracy; generic targeting guide; glenoid component version; revision reverse total shoulder arthroplasty; traditional instrumentation