Related Experiment Video
Updated: Mar 21, 2026
Individualized Stem-positioning in Calcar-guided Short-stem Total Hip Arthroplasty
Published on: February 27, 2018
An explorative time-elapsed μCT-based cadaveric study on humeral stem stability in reverse shoulder arthroplasty
Dermot O'Rourke1, Xiaolong Fan2, Ashish Gupta3
1ARC ITTC for Joint Biomechanics, Queensland University of Technology, Brisbane, Australia; Queensland Unit for Advanced Shoulder Research, Brisbane, Australia; School of Mechanical, Medical, and Process Engineering, Queensland University of Technology, Brisbane, Australia.
Smaller humeral implants in reverse shoulder arthroplasty may increase complications. This study found implant design significantly impacts stability, especially in smaller humeri, suggesting tailored approaches are needed for better patient outcomes.
Area of Science:
- Orthopedic surgery
- Biomechanical engineering
- Medical device design
Background:
- Reverse shoulder arthroplasty (RSA) complications are higher with smaller humeral implants.
- Reduced bone stock in smaller humeri compromises implant stability.
- Bone-preserving hybrid onlay-Grammont stems aim to improve cortical engagement, but evidence is limited.
Purpose of the Study:
- To evaluate the biomechanical stability of different humeral implant designs in large and small humeri.
- To compare the effects of implant size and placement (inlay vs. hybrid onlay-Grammont) on implant stability.
Main Methods:
- A 2x2 factorial design study using paired large (male) and small (female) humeri.
- Implantation with inlay and hybrid onlay-Grammont designs.
- Testing under physiological and compressive failure loads using a μCT-compatible rig.
- Quantification of stiffness, displacement, and cortical failure via 3D μCT imaging and force-displacement data.
Main Results:
- In large humeri, the hybrid onlay-Grammont showed greater stiffness and failure load, causing cortical opening.
- In small humeri, the inlay implant had significant distal migration without cracking.
- The onlay design in small humeri resulted in controlled radial cortical failure.
Conclusions:
- Reduced bone stock in small humeri can alter implant failure mechanisms, preventing full cortical loading.
- Implant design choice is critical for stability, particularly in smaller bone dimensions.
- Further research is needed on patient, surgical, and loading factors influencing implant stability in RSA.
