Surface and form alterations in retrieved shoulder hemiarthroplasty

Area of Science:

• Orthopedic surgery
• Biomaterials science
• Medical device analysis

Background:

• Shoulder hemiarthroplasty is a treatment for shoulder arthritis with intact glenoid.
• Glenoid erosion is a frequent reason for revision surgery.
• The study investigates changes in retrieved shoulder hemiarthroplasty implants.

Purpose of the Study:

• To compare the metallic articular surface of retrieved shoulder hemiarthroplasty implants with new ones.
• To determine if surface roughness increases due to articulation.
• To detect metallic wear on retrieved implants.

Main Methods:

• Analysis of 13 retrieved and 3 new shoulder hemiarthroplasties.
• Measurement of surface roughness at the head's dome and rim.
• Use of coordinate measuring machine for volumetric wear and geometric alterations.
• Scanning electron microscopy for wear analysis.

Main Results:

• Retrieved implants exhibited significantly increased surface roughness compared to new implants.
• Roughness was generally higher at the dome than the rim, though not significantly.
• No volumetric wear was detected, but shape deviations due to deformation were observed.

Conclusions:

• Implant surface roughness and shape changes occur in vivo due to articulation with cartilage or bone.
• The metallic humeral component's increasing roughness may cause glenoid erosion.
• These findings highlight in vivo material degradation in shoulder hemiarthroplasty.