It has proven to be a difficult task to design and provide an ankle-foot orthosis (AFO) that enables the client to walk securely and comfortably without bearing weight through the lower leg and foot skeletal parts. Although it is widely acknowledged that the patella tendon weightbearing (PTB) ankle-loot orthosis only partially unweights the lower tibia, ankle, and foot, it is nevertheless frequently prescribed for this purpose. In this work, two ankle foot orthoses of the AFO PTB type of Calf-Corset were manufactured using a vacuum molding technique based on two kinds of materials as composite material reinforcement. The first AFO material was based on 8 layers of Perlon, while the second was based on 8 layers of fiberglass. A tensile and a fatigue test had been used to investigate the mechanical properties of the AFOs' material. The findings revealed that the yield strength (Ϭy) is 42.897 MPa, the tensile strength (Ϭult) for Perlon is 42.993 MPa, and the elongation at break is 1.138 mm, whereas fiber glass has a tensile strength (Ϭult), yield strength (Ϭy), and elongation at break of 224 MPa, 170 MPa, and 2.17 mm, respectively. Additionally, the gait cycle and the collected data on distributed pressure are measured using force plates and F-socket devices. The patellar tendon-bearing model was constructed using the SolidWorks software tool. In addition, for the fiber glass and Perlon PTB orthosis models, the total deformation, safety factor of fatigue, and Von-Mises stress were calculated using the FEM (ANSYS). The safety factor of fatigue values for the material PTBO with 8 layers of fiber glass was 2.2895, and for 8 layers of Perlon, it was 0.083515.