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Periprosthetic bone mineral density changes after unicondylar knee arthroplasty
Tarja A Soininvaara1, Kristiina A L Harju, Hannu J A Miettinen
1North Karelia Central Hospital, Joensuu Finland. Tarja.Soininvaara@uef.fi
The Knee
|November 17, 2012
Summary
Unicompartmental knee arthroplasty (UKA) did not preserve bone mineral density (BMD) in the distal femur. However, tibial BMD changes were minor, suggesting a balanced mechanical load distribution after UKA surgery.
Area of Science:
- Orthopedic surgery
- Biomedical engineering
- Bone metabolism
Background:
- Unicompartmental knee arthroplasty (UKA) offers a less invasive surgical option for knee osteoarthritis (OA).
- UKA aims to preserve knee anatomy and kinematics, potentially maintaining patellofemoral joint function.
- The preservation of bone mineral density (BMD) around the implant is a key consideration for long-term implant survival.
Purpose of the Study:
- To investigate the effect of medial compartment UKA on periprosthetic bone mineral density (BMD).
- To assess changes in BMD in the distal femur and proximal tibia up to 7 years post-surgery.
- To determine if UKA preserves BMD, particularly in the patellofemoral joint's weight-bearing areas.
Main Methods:
- A prospective study of 21 osteoarthritis patients undergoing medial UKA.
- Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DEXA).
- Measurements were taken at baseline and at regular intervals up to 7 years post-surgery.
Main Results:
- Significant periprosthetic bone loss was observed in the distal femoral metaphysis within the first 3 months post-UKA.
- BMD in the distal femur showed an average loss of 4.4% to 11.9%, though changes were non-significant between 2 and 7 years.
- The medial tibial metaphysis showed a significant BMD increase of 8.9% at 1 year, while lateral tibial regions showed no significant change.
Conclusions:
- Unicompartmental knee arthroplasty (UKA) did not preserve BMD in the distal femoral metaphysis.
- Minor BMD changes in the tibial metaphysis suggest a mechanical balance between compartments post-UKA.
- The findings indicate that while distal femoral BMD decreases, tibial BMD remains relatively stable, warranting further investigation into long-term implications.