## 4 Conclusions  
To address the relatively low mechanical properties and elastic moduli of polyetheretherketone material, which can pose challenges for its application as bone prosthetics material, we prepared a multi-walled carbon nanotube/nanohydroxyapatite/carbon fiber ternary composite by using a wet blending technique, then examined its surface energy and thermal properties. We also prepared a multi-walled carbon nanotube/nanohydroxyapatite/carbon fiber/polyetheretherketone quaternary composite material using the ball mill blending technique and examined its mechanical properties and surface wettability. The following conclusions can be drawn:  
1. Due to the addition of multi-walled carbon nanotubes and nanohydroxyapatite, the surface energy of the ternary composites increases, the contact angle decreases, and the hydrophilicity is enhanced. The CF2 composites exhibited better heat resistance than the original carbon fibers. The de-sized carbon fibers were prepared to meet the requirements of the hot compression molding process. Additionally, the surface roughness of the carbon fiber in the CF2 composites increased.
2. The MHCP2 composite tensile strength was 123.5 MPa, which was 17.62% higher than the CP tensile strength and 75.82% higher than pure PEEK. The MHCP2 elastic modulus was 11.73 GPa, which is close to that of human cortical bone. The compressive strength of the MHCP2 composite was 191 MPa, which was 5.82% higher than the compressive strength of CP and 25.39% higher than pure PEEK. Reducing the friction coefficient and density of the composite material can reduce energy loss and wear, resulting in characteristics such as light weight, high strength, and high elastic modulus. The hydrophilicity of the tetrameric composite material was improved, consequently leading to faster absorption or spreading of liquid onto the solid surface.  
However, this study still experienced some limitations. The mechanical properties and elastic moduli of the quaternary composites are close to those of human skin and bone. However, the biocompatibility of quaternary composites has yet to be verified. The biocompatibility should be verified through experiments such as in vitro cell cultures, animal experiments, and biochemical analyses. If quaternary composites exhibit high biocompatibility, they can satisfy the requirements for use in implants. The MWCNTs/HA/CF/PEEK femur shank prosthesis tested in this study was prepared through hot compression molding  
Figure 4: Contact angles. (**a**) CF/PEEK; (**b**) MWCNT/HA/CF/PEEK.  
technology. The MWCNTs/HA/CF/PEEK femur shank, along with a traditional titanium alloy femoral stem for the femoral prosthesis replacement simulation, was subjected to static, dynamic, and torsion loads, verifying the stability of the two materials prepared for the prosthetic replacement of the femoral stem. This research lays the foundation for the traditional bone prosthetics material.  
[PERSON] and [PERSON] conceived and designed the experiment; [PERSON] and [PERSON] performed the experiment; [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] analyzed the data and prepared the manuscript. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Youth Fund Project of the Science and Technology Research Project of Colleges and Universities in Hebei Province (QN2024222), the Natural Science Foundation of Hebei Province, the Beijing-Tianjin-Hebei Basic Research Cooperation Project (H202208073), and the Hebei Provincial Department of Human Resources and Social Security, Hebei Province Three Talent Funding Project (B20221004).  
Not applicable.  
Data Availability Statement: Data are contained within the article.  
The authors declare no conflicts of interest.