## 5 Conclusions  
A comprehensive analysis of stress and displacement behaviors in limb lengthening device components has been undertaken, focusing particularly on pitch sizes and material compositions. The findings from extensive SolidWorks simulations offer valuable insights, leading to strategic recommendations aimed at optimizing device performance and ensuring the reliability of threads. Material selection plays a crucial role in determining stress and displacement outcomes. Stainless Steel Austenitic AISI 316L (annealed) exhibited potential deformation risks, with stress surpassing its yield strength. Titanium Commercial Purity Grade 4 (annealed) showed susceptibility to deformation, while Titanium Alpha-Beta Alloy Ti-6 Al-4V (annealed) emerged as a promising option, displaying lower stress levels and enhanced resistance to deformation. Moreover, the 20-thread engagement configuration consistently demonstrated the most stable displacement across various pitch sizes, indicating reliability and potential suitability for limb-lengthening device designs. The study suggests Titanium Alpha-Beta Alloy Ti-6 Al-4V (annealed) as the preferred material due to its favorable stress and displacement characteristics, highlighting enhanced resistance to deformation. The universally recommended 20-thread engagement configuration offers stable displacement performance across diverse pitch sizes, although it is acknowledged that the associated cost may be considerably higher. To validate and confirm the reliability and accuracy of SolidWorks simulations, future research could incorporate physical testing, providing an additional layer of assurance regarding device safety and performance. Furthermore, research should focus on exploring innovative design configurations to optimize stress distribution and minimize deformation risks, ultimately leading to more robust and reliable limb-lengthening devices [32; 33; 34; 35]. This dual focus on experimental validation and advanced design exploration has the potential to significantly contribute to continual improvements in safety and efficacy in limb lengthening procedures. The study's findings have significant implications for these procedures, prioritizing material strength and appropriate thread configurations to enhance device safety and reliability. In conclusion, this study offers a thorough analysis of stress and displacement behaviors in limb-lengthening device components, providing practical recommendations for material selection and optimal thread configurations. These insights contribute to ongoing efforts to improve the safety and reliability of limb lengthening procedures. The proposed enhancements in materials, thread design, and testing methodologies aim to advance the overall design and performance of motorized intramedullary leg-lengthening devices. These improvements are poised to enhance the safety and efficacy of medical devices used in limb-lengthening procedures, ultimately benefiting patients by minimizing complications and optimizing outcomes. The project will progress to the manufacturing phase, where the test rig will undergo tensile loading with torque. This practical phase, following the initial Finite Element Analysis (FEA) simulation stages, offers a real-world assessment of the designed limb lengthening device. Tensile loading with torque serves as a critical evaluation, providing insights into the device's structural integrity, durability, and performance under the conditions simulating those encountered during limb lengthening procedures. This hands-on approach will significantly contribute to understanding the device's mechanical behavior and inform potential refinements for improved safety and reliability in limb lengthening procedures. To provide a detailed illustration and description of the devices used in the patients for the motorized intramedullary lengthening nail, I have summarized the following explanation below. 1.