The effective heel height is obtained by subtracting the thickness of the sole of the shoe from the apparent heel height as shown below. For the same reason, the heels of the shoes should be replaced frequently so that wear will not result in alignment changes. Also, a badly worn shoe will increase the wear on a prosthetic foot. Prostheses should not be worn without shoes. Not only will it cause excessive stress on the stump and knee joint, but the wear on the foot will result in permanent malalignment.
Most prostheses are water-resistant but few are waterproof.
If the foot becomes wet, the shoe should be removed as soon as possible to facilitate drying. If the amputee has any doubt about the fit, alignment, or condition of the prosthesis or stump, he should consult his prosthetist immediately. Maintenance requirements for knee units vary. Prosthetists will give instructions for maintenance except for hydraulic units which must be taken care of by the prosthetist or manufacturer. An exchange unit can be provided when a hydraulic unit has to be removed for repair.