The paper
"The Hybrid Humerus Reverse Shoulder Arthroplasty: A prospective study of bone grafting and metaphyseal fixation with undersized stem in the assessment of proximal humeral stress shielding and associated clinical outcome", published in Seminars in Arthroplasty: JSES on 22 June 2024.
What stress shielding is
When a metal stem is fixed inside a bone, it carries load that the bone would otherwise carry. Bone responds to the load placed on it, so bone that is no longer loaded gradually thins. This is stress shielding, and in the upper humerus it is relevant because thinned bone is weaker, is more prone to fracture, and leaves less to work with if the replacement ever needs revising.
The technique studied
The study examines a technique using an undersized humeral stem in a Grammont-style implant, combined with bone grafting and fixation in the metaphysis, the flared upper part of the bone. The aim is to have the bone continue to carry load rather than the stem taking it, and so to reduce stress shielding.
The paper reports the rates of stress shielding and implant loosening observed, together with functional outcomes. Those figures are in the published paper. Individual results vary, and a prospective single-technique study of this kind describes what the approach achieved rather than establishing that it is better than the alternatives.
Authors
Roberto Pareyon Valero (first author), Ashish Gupta, Helen Ingoe, Dr Mohammad Jomaa, Kristine Italia, Jashint Maharaj and Sarah Whitehouse.
Affiliations: St Andrew's War Memorial Hospital, QUASR, the ARC Training Centre for Joint Biomechanics, QUT and The University of Queensland.
Read it
The paper is available on ScienceDirect.
Related information
See our reverse total shoulder replacement page, and our post on stemless bone-preserving shoulder replacement, which addresses the same problem differently.