A reliable method of determining glenohumeral offset in anatomic total shoulder arthroplasty

J Shoulder Elbow Surg. 2019 Aug;28(8):1609-1616. doi: 10.1016/j.jse.2018.12.019. Epub 2019 Mar 28.

Abstract

Background: Glenohumeral offset (GHO) may change from the preoperative state after anatomic total shoulder arthroplasty (TSA), and has been identified as a factor that may affect shoulder mechanics, strength, and function. The primary objective was (1) to establish a reliable method of measuring GHO with standardized computed tomography (CT) imaging planes and (2) to determine whether an association exists between GHO and functional outcomes in TSA.

Methods: Thirty-seven patients underwent TSA for glenohumeral osteoarthritis. Preoperative and postoperative CT scans were reformatted along standardized measurement planes for the glenoid and humerus separately. Inter-rater and intrarater reliability was determined for 3 methods to measure humeral offset and 2 methods to measure glenoid offset. Univariate regression analysis was used to determine the association between GHO and functional outcomes including the Constant score and strength.

Results: Of all methods tested, the highest preoperative and postoperative inter-rater reliability was r = 0.84 and r = 0.8, and r = 0.7 and r = 0.8 for humeral and glenoid offset, respectively. Intrarater reliability was >0.94. There was a mean increase of 4.3 mm (standard deviation, 4.6; range, -10.6 to 10.8) in combined GHO from preoperative to postoperative time points. No associations were observed between change in offset and functional or strength scores.

Discussion: A reliable approach to measure prearthroplasty and postarthroplasty GHO with CT plane standardization has been described. A net increase in GHO was observed after TSA. No associations were found between change in offset after TSA and functional scores or strength up to 2 years postoperatively.

Keywords: Glenohumeral offset; lateral humeral offset; shoulder arthroplasty; shoulder offset.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Arthroplasty, Replacement, Shoulder / methods*
  • Female
  • Humans
  • Humerus / diagnostic imaging*
  • Humerus / surgery
  • Male
  • Osteoarthritis / diagnosis
  • Osteoarthritis / physiopathology
  • Osteoarthritis / surgery*
  • Osteotomy / methods
  • Postoperative Period
  • Prospective Studies
  • Range of Motion, Articular / physiology
  • Reproducibility of Results
  • Shoulder Joint / diagnostic imaging
  • Shoulder Joint / physiopathology
  • Shoulder Joint / surgery*
  • Tomography, X-Ray Computed / methods*