Related Experiment Videos
The use of constrained components in total hip arthroplasty
Paul F Lachiewicz1, Scott S Kelley
1Department of Orthopaedics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
The Journal of the American Academy of Orthopaedic Surgeons
|April 20, 2004
Summary
Constrained components can treat hip dislocation after total hip arthroplasty. However, these devices have a significant failure rate, ranging from 4% to 29%.
Area of Science:
- Orthopedic surgery
- Biomedical engineering
- Materials science
Background:
- Recurrent dislocation after total hip arthroplasty (THA) can result from soft-tissue insufficiency.
- Constrained components are designed to prevent dislocation by securing the prosthetic femoral head within the acetabular liner.
- Two FDA-approved constrained component designs exist: S-ROM and Howmedica Osteonics.
Purpose of the Study:
- To evaluate the appropriateness and outcomes of constrained components in surgical treatment for recurrent hip dislocation post-THA.
- To describe the mechanisms and potential failure modes associated with constrained acetabular components.
Main Methods:
- Review of existing literature and FDA-approved prosthetic designs (S-ROM and Howmedica Osteonics).
- Analysis of how constrained components function to maintain stability.
- Examination of force transfer pathways within the constrained implant system.
Main Results:
- Constrained components utilize locking mechanisms to maintain femoral head position.
- These components transfer forces to the locking mechanism, liner-shell, or bone-prosthesis interface.
- Reported failure rates range from 4% to 29% in short-term follow-up studies.
Conclusions:
- Constrained components may be indicated for recurrent dislocation post-THA.
- Potential failure modes include loosening, dissociation, breakage, and recurrent dislocation.
- The inherent design may lead to stress concentrations and eventual component failure.