The Walch type B humerus

glenoid retroversion is associated with torsional differences in the humerus

Sumit Raniga, Nikolas K. Knowles, Emily West, Louis F. Ferreira, George S. Athwal

Research output: Contribution to journalArticle

Abstract

Background: The Walch type B glenoid has the hallmark features of retroversion, joint subluxation, and bony erosion. Although the type B glenoid has been well described, the morphology of the corresponding type B humerus is poorly understood. As such, the aim of this imaging-based anthropometric study was to investigate humeral torsion in Walch type B shoulders. Methods: Three-dimensional models of the full-length humerus were generated from computed tomography data for the Walch type B group (n = 59)and for a control group of normal nonarthritic shoulders (n = 59). An anatomic humeral head-neck plane was created and used to determine humeral torsion relative to the epicondylar axis. Measurements were repeated, and intraclass correlation coefficients were calculated. Results: The type B humeri had significantly (P <.001)less retrotorsion (14° ± 9°)than the control group (36° ± 12°)relative to the epicondylar axis. Male and female individuals within the control group showed statistically significant differences in humeral torsion (P =.043), which were not found in the type B group. Inter-rater reliability showed excellent agreement for humeral torsion (intraclass correlation coefficient, 0.962). A subgroup analysis between Walch type B2 and B3 shoulders showed no significant differences in any of the humeral or glenoid parameters. Conclusion: The Walch type B humerus has significantly less retrotorsion than non-osteoarthritic shoulders. At present, it is unknown whether the altered humeral retrotorsion is a cause or effect of the type B glenoid. In addition, it is unknown whether surgeons should be reconstructing type B2 humeral component version to pathologic torsion or to nonpathologic population means to optimize arthroplasty survivorship.

Original languageEnglish
Pages (from-to)1801-1808
Number of pages8
JournalJournal of Shoulder and Elbow Surgery
Volume28
Issue number9
DOIs
Publication statusPublished - 1 Sep 2019
Externally publishedYes

Keywords

  • Anatomy Study
  • B2
  • B3
  • Imaging
  • retroversion
  • shoulder arthroplasty
  • shoulder osteoarthritis
  • Walch

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