Creation and finite-element analysis of multi-lattice structure design in hip stem implant to reduce the stress-shielding effect

Mustafa Guven Gok

Full text link: https://journals.sagepub.com/doi/abs/10.1177/14644207211046200

Creation and Finite-Element Analysis of Multi-Lattice Structure Design in Hip Stem Implant to Reduce the Stress-Shielding Effect

1. Scientific Reference

• Study Title: Creation and Finite-Element Analysis of Multi-Lattice Structure Design in Hip Stem Implant to Reduce the Stress-Shielding Effect
• Author: Mustafa Güven Gök
• Journal: Proceedings of the Institution of Mechanical Engineers Part L: Journal of Materials: Design and Applications
• Year of Publication: 2022
• DOI: 10.1177/14644207211046200

2. Scientific Background

One of the long-standing biomechanical challenges in total hip arthroplasty is the phenomenon known as stress shielding. This occurs when a metallic implant possesses substantially greater stiffness than the surrounding bone, resulting in an uneven distribution of mechanical loads. Over time, reduced mechanical stimulation may contribute to bone remodeling and localized bone loss around the implant.

Recent advances in additive manufacturing have enabled the production of highly complex porous structures that can modify the mechanical behavior of orthopedic implants. Lattice-based architectures are particularly attractive because they allow engineers to reduce implant stiffness while maintaining structural integrity.

Within this context, the present study investigates whether combining different lattice geometries within a single femoral stem design can improve load transfer to the surrounding bone and reduce stress-shielding effects. The work contributes to the growing field of topology-optimized and additively manufactured orthopedic implants intended to achieve a more physiological mechanical response.

3. Study Objective

The primary objective of this study was to design and evaluate femoral hip stems incorporating multi-lattice architectures in the proximal region of the implant.

The authors sought to determine whether different combinations of cubic lattice structures could reduce implant stiffness, improve load transmission to the femur, and consequently decrease the stress-shielding effect when compared with a conventional solid hip stem design.

4. Methodology

This investigation was a preclinical computational study based on finite-element analysis (FEA).

A conventional Ti6Al4V femoral stem served as the reference model. Three alternative multi-lattice configurations were developed:

• Design 1: Simple Cubic (SC)-based lattice architecture
• Design 2: Body-Centered Cubic (BCC)-based lattice architecture
• Design 3: Face-Centered Cubic (FCC)-based lattice architecture

The proximal portion of each stem was divided into three sections, with additional internal horizontal and vertical reinforcement beams incorporated into the lattice structures.

Virtual implantation was performed using a femoral model reconstructed from computed tomography data. Mechanical simulations were conducted under loading conditions representative of normal walking for a 700 N individual. Stress distribution, strain energy density, displacement behavior, and stress-shielding signals were analyzed throughout multiple femoral regions.

No clinical subjects, animal models, or in vivo experiments were included in this study.

5. Main Findings

The incorporation of multi-lattice structures substantially altered the mechanical response of the femoral stems.

The conventional stem exhibited a maximum von Mises stress of approximately 289 MPa, whereas the lattice-based designs reduced peak stresses to values ranging from approximately 189 MPa to 221 MPa, depending on the architecture evaluated.

A notable reduction in implant weight was also observed:

• Design 1: approximately 25.9% weight reduction
• Design 2: approximately 18.8% weight reduction
• Design 3: approximately 18.3% weight reduction

The stress-shielding analysis demonstrated improved load transfer to the proximal femur for all multi-lattice designs. Compared with the conventional stem, stress-shielding signal improvements varied according to anatomical location and reached a maximum increase of 150.47%.

Among the three evaluated configurations, the simple cubic-based design produced the most favorable biomechanical performance, combining lower stress concentrations with improved transmission of mechanical loads to the surrounding bone.

6. Clinical Interpretation

Although this study is computational rather than clinical, its findings provide valuable insight into the design principles that may influence the long-term biomechanical behavior of orthopedic implants.

The results suggest that reducing implant stiffness through strategically engineered lattice architectures can promote a more physiological distribution of mechanical loads. This is particularly relevant because stress shielding remains one of the major contributors to peri-implant bone remodeling and potential implant failure over time.

The superiority of the simple cubic configuration observed in this investigation highlights the importance of lattice geometry, not merely porosity level, in determining biomechanical performance. The way loads are transmitted through the lattice network appears to play a crucial role in maximizing load sharing between implant and bone.

From a broader perspective, the concepts explored in this study extend beyond hip arthroplasty. Similar principles are increasingly relevant in dental implantology, maxillofacial reconstruction, patient-specific implants, and CAD/CAM-guided implant manufacturing, where balancing mechanical stability with biological adaptation remains a critical objective.

Nevertheless, these findings should be interpreted cautiously. Computational simulations cannot fully reproduce the complexity of biological healing, osseointegration, bone remodeling, or long-term clinical performance.

7. Clinical Applications

The outcomes of this research may be relevant for:

• Development of next-generation orthopedic implants manufactured through additive manufacturing technologies.
• Design optimization of load-sharing femoral stems.
• Research involving porous titanium biomaterials and lattice-based implant structures.
• Patient-specific implant engineering.
• Biomechanical optimization of implant-supported rehabilitation systems.

The concepts described may also provide useful insights for researchers investigating porous implant designs in dental implantology and bone reconstruction applications, although direct clinical extrapolation should be avoided.

8. Level of Evidence, Limitations and Transparency

This publication represents a preclinical finite-element simulation study.

Consequently, the level of evidence is limited compared with clinical investigations, prospective cohorts, or randomized controlled trials. The findings primarily demonstrate biomechanical feasibility under controlled computational conditions.

Several limitations should be considered:

• Absence of clinical validation.
• No experimental mechanical testing reported.
• Dependence on numerical modeling assumptions.
• Evaluation performed under specific loading scenarios.

The authors indicate that future experimental investigations would be valuable to validate the proposed implant designs.

Regarding transparency, the author reported no financial support for the study and declared no conflicts of interest. The acknowledgments section notes institutional access to software resources but does not identify any commercial sponsorship.

9. Key Study Highlights

• Study Type: Finite-element computational study
• Level of Evidence: Preclinical biomechanical investigation
• Population: Not applicable
• Number of Patients: None
• Follow-Up Duration: Not applicable
• Material Evaluated: Ti6Al4V titanium alloy
• Primary Outcome: Stress-shielding behavior and load transfer
• Main Result: Multi-lattice stems improved proximal femoral load sharing compared with a conventional stem
• Best Performing Design: Simple Cubic (Design 1)
• Maximum Reported Improvement: 150.47% increase in stress-shielding signal relative to the conventional design in specific femoral regions
• Main Conclusion: Multi-lattice architectures significantly reduced the stress-shielding effect in simulated hip stem implants
• Limitations: Computational study without clinical validation

10. Scientific Impact

This study contributes to the evolving body of research focused on biomechanically optimized orthopedic implants. While porous and lattice-based implant concepts have been investigated previously, the present work explores the use of multiple lattice configurations within a single femoral stem, providing a novel design approach.

The findings reinforce the concept that implant architecture can be as influential as material selection in determining biomechanical performance. By demonstrating improved load transfer and reduced stress shielding through multi-lattice designs, the study supports continued exploration of additive manufacturing technologies for orthopedic applications.

Importantly, the research highlights how structural engineering can be used to tailor implant behavior to better match the mechanical environment of bone. This represents a meaningful step toward more personalized and biologically compatible implant solutions.

11. Editorial Conclusion

This finite-element investigation demonstrates that incorporating multi-lattice architectures into Ti6Al4V femoral stems can improve load transfer to the surrounding bone while reducing indicators associated with stress shielding. Among the evaluated designs, the simple cubic lattice configuration achieved the most favorable biomechanical performance. Although these results are promising from an engineering perspective, they remain limited to computational modeling and require experimental and clinical validation before their potential clinical significance can be fully established.