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Individualized Stem-positioning in Calcar-guided Short-stem Total Hip Arthroplasty
Published on: February 27, 2018
Partially cemented AncaDualFit hip stems do not fail in simulated active patients
Luca Cristofolini1, Paolo Erani, Amelia Saponara Teutonico
1Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Via di Barbiano, 1/10, 40136 Bologna, Italy. cristofolini@tecno.ior.it
Clinical Biomechanics (Bristol, Avon)
|October 31, 2006
Summary
The AncaDualFit partially cemented hip stem demonstrated excellent long-term endurance under simulated severe cyclic loading, showing minimal cement damage and stable migration. This implant is safe for active patients, offering reliable fixation.
Area of Science:
- Orthopedic biomechanics
- Biomaterials engineering
- Implant design and performance
Background:
- Partially cemented hip stems aim to combine short-term benefits of cemented and long-term advantages of cementless designs.
- The AncaDualFit stem was previously validated under average loads, but concerns existed regarding its long-term performance in active patients subjected to high cyclic loads.
- Potential fixation failure due to cyclic loading in demanding patients was a key concern for this implant type.
Purpose of the Study:
- To evaluate the long-term in vitro performance and endurance of the AncaDualFit partially cemented hip stem under simulated severe loading conditions.
- To assess micromotion and cement damage of the AncaDualFit stem and compare it to established cemented and cementless hip stems.
- To determine the implant's suitability for active patients by analyzing its response to prolonged, high-magnitude cyclic loads.
Main Methods:
- An in vitro validated protocol simulating 24 years of cyclic loading in active patients was employed.
- Inducible and permanent micromotions were measured for five AncaDualFit specimens.
- Micromotion and cement damage (fatigue cracks) were quantified and compared against two cemented and one cementless stem.
Main Results:
- The AncaDualFit stem exhibited slightly higher inducible and permanent micromotions than cemented stems but significantly less than the cementless stem.
- Implant migration showed a clear trend towards stabilization over the simulated period.
- Minimal cement damage was observed, comparable to highly successful cemented stems, with cracks limited to the cement inlet and not propagating.
Conclusions:
- The AncaDualFit partially cemented stem demonstrates robust performance and can withstand severe cyclic loading without significant damage, attributed to its cement pocket design.
- Comparative analysis with other successful designs indicates reassuring results for the AncaDualFit stem.
- The study concludes that the AncaDualFit stem is safe for use, even in active patients requiring high implant endurance.
