## 5 Conclusions  
In this work, a methodology to design a personalized transtibial prosthesis using an analytical method was developed. Furthermore, the analytical results were validated by means of finite element analysis, obtaining errors no greater than 6.5%. The main difference between commercial and customized prostheses is the efficiency and comfort they provide to the patient. The methodology provided herein allows the geometric model of the prosthesis to be approximated, so as to be able to determine stresses and deformations associated with its operating conditions. Therefore, the selection of adequate construction materials is easier, achieving an operational design. Furthermore, the usage of the videometry technique has been proven to be a successful method for studying the biomechanics of the human gait, simplifying the process due to the ease of implementation. Of interest is the analysis of the articulated area in the prosthesis design, which allows the impact produced in the foot during the contact phase of the walking cycle to be partially absorbed. The weight of the prosthesis is also considered in order to provide comfort and adaptation for the patient. In this sense, the designed prosthesis has a smaller weight than the patient's healthy foot, which allows the weight in the socket to be adjusted, maintaining the stability of both lower limbs. This paper presents limitations based on four important aspects. Firstly, in terms of methodological limitations, the sample size was only one test subject; however, the test subject had a 50 th percentile anatomy. This allows us to estimate that 50% of the world's population will be able to use this research to design a custom Flex-Foot(r) prosthesis. Secondly, the software used to capture the test subject's gait could present errors due to shutter delay, so it is necessary to carry out many tests until the repeatability of the experiment is greater than 90%. Thirdly, the lack of previous research studies on this subject prevents a comparison of the results obtained. However, this research supports the use of an analytical method and numerical method for prosthesis design. Finally, one of the greatest limiting factors is the longitudinal effects that occur in the prosthesis when it is used by a patient with a lower limb amputation. The time available to investigate a problem and measure change or stability over time is, in most cases, very limited. This bias may reflect its dependence on research, since it is not possible to estimate data on the evolution of the anatomy of the subject using the implant. These limitations of our study may inspire other researchers to return to custom prosthesis design. Figure 24: Analytically and numerically computed stresses and deformations for the complete prosthesis model. (**A**) Case 3.1. (**B**) Case 3.2. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Prosthesis Section**} & \multicolumn{3}{c}{**Deformations in m**} \\ \cline{2-4}  & **Analytical Method** & **Numerical Simulation** & **Error Rate** \\ \hline Foot module & \(1.02\times 10^{-3}\) & \(9.9866\times 10^{-4}\) & 2.0914\% \\ Heel module & \(2.64\times 10^{-3}\) & \(2.5819\times 10^{-3}\) & 2.2\% \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Comparison of analytically and numerically computed deformations. **Author Contributions**: Conceptualization, C.R.T.-S.; methodology, G.U.-S.; software, A.J.P.-D.; validation, L.A.A.-P.; formal analysis, M.A.H.-A. ; investigation, J.C.P.-R.; resources, C.R.T.-S.; data curation, M.A.H.-A. ; writing--original draft preparation, M.A.H.-A. ; writing--review and editing, A.J.P.-D.; visualization, G.U.-S.; supervision, C.R.T.-S.; project administration, M.A.H.-A. ; funding acquisition, M.A.H.-A..\". All authors have read and agreed to the published version of the manuscript. **Funding:** This research received no external funding.