Abstract

Background: The ankle (talocrural) joint is composed of a superior mortise, formed by the weight-bearing inferior surface of the tibia and the two malleoli, which receive the trochlea of the talus. The ankle joint is maintained medially by a strong, medial (deltoid) ligament, and a much weaker lateral ligament. On rocky surfaces, the natural ankle will initiate ground contact with reduced dorsiflexion to provide a relatively flatter foot. Patients wearing prosthesis attempt to replicate this strategy but are unable to mimic the ankle angle to match the terrian, presumably due to the reduced range of motion available from the ankle and foot. Therefore, the desing of a prosthetic foot and ankle mechanism with expanded ranges of ankle motion presents an opportunity to restore vital functions among amputees using lower limb prosthesis and this forms the bases of this study. This design and fabrication of a below-knee prosthesis followed standard protocols in prosthetics and orthotics with the inclusion of ankle joint.
Objectives: The aim of the study is to make accurate and proper assessments/measurements of the amputee which will help to design and fabricate different components of the prosthesis, including the devised ankle joint, then assemble the components and fit the below-knee prosthesis on the amputee in other to achieve a better ambulation and rehabilitation of the amputee.
Materials and method: The methods followed in the fabrication of the device include: Assessment, Impression/measurement taking, Modification, Lamination of test/check socket, Lamination of a new positive cast/model, Formation of liners/inserts, Lamination of a definitive socket, Attachment of socket to pylon and ankle joint (bench alignment), Prosthesis finishing, Amputee’s training and follow-up. The below-knee prosthesis consists of a socket, metal pylon and ankle joint component, padding/suspension materials, screws, bolts and nuts. The materials used for fabricating these components and the below knee prosthesis as a whole included: Plaster of Paris (POP) bandage and powder, Plastic polymer laminate, Reinforcement textile, Padding/suspension materials, Metals, Cosmetic finishing materials, and Adhesives.
Results: The ankle joint in the design resulted in minimal energy expenditure, no pain, improved number of steps and strides per minute by the amputee than the use of the conventional prosthesis. From a paired t-test conducted for the improved and conventional prostheses in steps and strides, there was significant difference between the improved and the conventional prostheses at 5% level (p value

Key words: Ankle joint, Amputee’s Rehabilitation, Below-knee prosthesis, functionality.