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Individualized Stem-positioning in Calcar-guided Short-stem Total Hip Arthroplasty
Published on: February 27, 2018
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Effect of stem position and length on bone-stem constructs after cementless hip arthroplasty
Dae-Kyung Kwak1, Sun-Hee Bang2, Sung-Jae Lee2
1Department of Orthopaedic Surgery, Hallym University Sacred Heart Hospital, Anyang, South Korea.
Bone & Joint Research
|April 6, 2021
Summary
Short stems in cementless hip arthroplasty increase stress and micromotion, particularly with varus insertion. Neutral positioning and avoiding stair-climbing post-surgery are recommended for better initial stability and reduced thigh pain.
Area of Science:
- Orthopedic surgery
- Biomechanical engineering
- Finite element analysis
Background:
- Concerns exist regarding initial stability and early periprosthetic fractures with cementless hip arthroplasty using short stems.
- Understanding stress distribution and micromotion is crucial for optimizing implant design and surgical technique.
Purpose of the Study:
- To investigate the biomechanical effects of femoral stem length and positioning on cortical bone stress and stem-bone micromotion.
- To compare these effects under different physiological loading conditions.
Main Methods:
- Construction of 12 femoral finite element models (FEMs) with press-fit fixation.
- Simulation of three different stem lengths and two insertion positions (neutral and varus).
- Analysis of cortical bone stress and stem-bone micromotion during simulated walking and stair-climbing.
Main Results:
- Stress concentration observed at medial and lateral bone-stem interfaces, increasing with shorter stems and varus insertion.
- Maximum stress occurred at the lateral interface with a varus-inserted short stem.
- Higher stress and micromotion were recorded during stair-climbing compared to walking, and with shorter/varus-inserted stems.
Conclusions:
- Neutral stem insertion is recommended to minimize stress and micromotion.
- Avoiding strenuous activities like stair-climbing in the early postoperative period is advised.
- These measures are particularly important when using shorter stems to enhance initial stability and reduce thigh pain.
