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Total elbow prosthesis loosening caused by ulnar component pistoning.
Emilie V Cheung1, Shawn W O'Driscoll
1Mayo Clinic, Rochester, Minnesota 55905, USA.
Summary
Linked total elbow prostheses can loosen due to ulnar component pistoning. Surgeons must prevent intraoperative anterior impingement and distal insertion to avoid this preventable failure mechanism.
Area of Science:
- Orthopedic Surgery
- Biomedical Engineering
- Implant Design
Background:
- Linked semiconstrained total elbow prostheses are widely used but may have a higher risk of implant loosening.
- A novel, preventable cause of mechanical loosening in the ulnar component of linked total elbow prostheses is described.
Purpose of the Study:
- To identify and describe a previously unreported cause of mechanical loosening of the ulnar component in linked total elbow prostheses.
- To evaluate clinical and radiographic findings in patients experiencing painful pistoning of the ulnar component.
Main Methods:
- Clinical and radiographic evaluation of ten patients with painful pistoning of polymethylmethacrylate-coated ulnar components in Coonrad-Morrey linked total elbow prostheses.
- Intraoperative assessment for anterior impingement and component positioning during revision arthroplasty.
Main Results:
- All ten patients presented with elbow pain and sensation of ulnar component movement; six reported squeaking.
- Radiographic evidence included radiolucent lines around the ulnar component/cement mantle (n=10) and gaps between cement and prosthesis tip (n=6).
- Revision surgery confirmed loose ulnar components in all patients, with successful revision in nine out of ten cases at follow-up.
Conclusions:
- Ulnar component pistoning within the cement mantle can lead to pullout failure in Coonrad-Morrey total elbow prostheses.
- Preventative measures include intraoperative checks for anterior impingement and avoiding distal insertion of the ulnar component.
- This failure mechanism should inform the design of future total elbow arthroplasty implants.
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