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Changes in bone density after cemented total knee arthroplasty: influence of stem design
J H Lonner1, M Klotz, C Levitz
1Penn Orthopaedic Institute, Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
The Journal of Arthroplasty
|February 15, 2001
Summary
Total knee arthroplasty with cemented tibial stems significantly reduces bone density in the proximal tibia over the long term, potentially increasing loosening risks. Alternative designs may improve implant survivorship.
Area of Science:
- Orthopedic surgery
- Biomaterials science
- Bone physiology
Background:
- Total knee arthroplasty (TKA) demonstrates high short-term survivorship.
- Aseptic loosening is a primary cause of TKA failure with longer follow-up.
- Stress shielding, indicated by reduced bone density, is linked to altered mechanical loading after TKA.
Purpose of the Study:
- To investigate the long-term effects of tibial stem design on proximal tibial bone density.
- To compare bone density changes between cemented stems and pegged prostheses.
Main Methods:
- Dual-energy x-ray absorptiometry (DXA) was used to assess bone density.
- Bone densities were compared between operated and contralateral tibias at an average of 94 months post-surgery.
- Evaluated Miller-Galante I (pegged) and Press-Fit Condylar (stemmed) prostheses.
Main Results:
- Cemented tibial stems showed significantly reduced bone density in the tibial metaphysis.
- The pegged prosthesis group did not exhibit significant changes in proximal bone density.
- No significant bone density changes were observed in the diaphyseal bone for either group.
Conclusions:
- Cemented stems may lead to proximal bone resorption due to reduced stress transfer.
- Proximal bone loss associated with stemmed components could contribute to tibial loosening and complicate revision surgery.
- Consideration of shorter stems, reduced cement usage, or alternative designs is recommended to mitigate bone loss and improve long-term TKA survivorship.