Stress shielding of the proximal humerus

Last revised by Henry Knipe on 22 Mar 2023

Citation, DOI, disclosures and article data

Citation:

Nicoletti D, Knipe H, Najjar R, et al. Stress shielding of the proximal humerus. Reference article, Radiopaedia.org (Accessed on 23 May 2024) https://doi.org/10.53347/rID-161371

DOI:

https://doi.org/10.53347/rID-161371

Permalink:

https://radiopaedia.org/articles/161371

rID:

161371

Article created:

1 Feb 2023, Domenico Nicoletti ◉

Disclosures:

At the time the article was created Domenico Nicoletti had no financial relationships to ineligible companies to disclose.

View Domenico Nicoletti's current disclosures

Last revised:

22 Mar 2023, Henry Knipe ◉

Disclosures:

At the time the article was last revised Henry Knipe had the following disclosures:

Integral Diagnostics, Shareholder (ongoing)
Micro-X Ltd, Shareholder (ongoing)

These were assessed during peer review and were determined to not be relevant to the changes that were made.

View Henry Knipe's current disclosures

Revisions:

10 times, by 4 contributors - see full revision history and disclosures

Systems:

Musculoskeletal

Tags:

cases, orthopaedics, orthopedic hardware, ortho, orthopedics, case2

Stress shielding of the proximal humerus after total shoulder arthroplasty (TSA) is a bone resorption around the proximal prosthesis stem.

According to Wolff's Law, bone remodels in response to stress. After a TSA or shoulder hemiarthroplasty, intact bone previously responsible for bearing mechanical load is replaced with a metallic humeral implant more rigid than intact cortical bone, which causes a change in the distribution of loading that leads to remodeling with resorption of bone in the affected regions. This bone volume reduction after arthroplasties leads to implant loosening and periprosthetic fracture.

Polyether-ether-ketone (PEEK) is an excellent alternative to titanium alloys. The stiffness of PEEK closely matches that of cortical bone and acts as a load sharing device, as opposed to a weight bearing device with the advantage that in dynamic areas of the body, such as the hands and feet, it prevents stress shielding after fracture fixation.

Radiographic features

Radiographic signs of stress shielding are more present with press-fit components associated with increasing relative stem diameter.

Plain radiograph

The postoperative assessment is usually done using AP, Grashey and axillary views. The transition from good bone stock postoperatively, to osteopenia, and eventually collapse of the bone down to the prosthesis requires careful comparison with serial x-rays.