1. Incorrect cut: see above - one of the most frequent reasons for complaints.
2. Incorrect choice of model: e.g. if the activity level is too high. Gel liners in particular are intended for rather low walky classes in order to embed sensitive leg stumps. If the activity level is too high, the liner material can wear out prematurely, but also the muscle force transferred by the user is absorbed by the soft liner material.
3. Incorrect size: e.g. too wide or too tight. Due to the size run, attention must be paid to the correct liner size. With silicone liners, the residual limb circumference must be measured approx. 4 cm above the distal tip of the residual limb in a circular fashion. For initial fittings, the size equal to the measured residual limb circumference is often used, for subsequent fittings use one size smaller. Two circular residual limb measurements are necessary to determine the size of gel liners. One is taken at the distal end of the residual limb, about 4 cm above the tip of the residual limb, and the second is taken about 30 cm from the distal end of the residual limb.
Generally, experience is required when determining the size, as a liner that is chosen too narrow can be very uncomfortable or even painful for the amputee. If the liner size is too wide, air may be trapped, which leads to increased sweating at the end of the residual limb. The body sweat that builds up reacts aggressively to the residual limb skin and in combination with pressure and friction can lead to further residual limb skin problems.
4. Incorrect or improper tightening of a liner. Each silicone or gel liner must be turned completely inside out, centred on the distal end of the residual limb and unrolled slowly. When the liner is unrolled at the level of the knee, it is advisable to slightly flex the knee to minimise contact pressure on prominent kneecaps. Removal is done in reverse order.
5. Incorrect cleaning or disinfection not only leads to possible skin problems, but can also change the material composition in the silicone or TPE gel. The consequences are known to be premature wear, brittleness, cracking or a decrease in the cushioning effect of the liner material.