Clear plastic is used so the prosthetist may evaluate the intimate fit of the interface. The patient stands on the prosthesis and walks on it. Things like height, toe in-toe out, and walking dynamics are all visually inspected. The prosthesis may be positioned differently to allow better walking. The toe may be lowered or raised or moved medially or laterally The dynamic movement of the prosthetic foot greatly affect the performance of the Below Knee prosthesis.
Some feet look like feet, some look more functional.
Some feet try to mimic the springlike effect of the foot in their design by using a composite or plastic leaf spring or keel. Some feet mimic the anatomic structure of the foot. All of the feet attempt to replace lost muscle function with cushions, bumpers, and springs. After the evaluation interface has been fitted and align a definitive prosthesis may be made. The endoskeletal design has a soft outer foam covering that may be shaped to match the patients sound side.