## 4 Discussion  
The general health status and the state of the stump have an effect on the correctness and efficiency of the gait after a double transfemoral amputation [21]. The properly hardened stump allows for the painless axial load to which it is subjected in the prosthesis funnel. A particularly important element is also the fitting of a prosthesis funnel and full mobility of the hip joint. In many people who have undergone double amputation, flexion-abduction contractures are observed in the hip joint. These contractures can significantly limit the learning of proper gait. A multi-stage rehabilitation process, maintaining normal movement ranges and scar treatment means that the time of actually learning to walk with a prosthesis is sometimes reduced. In addition, the fear of falling and the ability to find oneself in a different situation can prolong the prosthesis fitting process. The first step in improvement is changing position--from a sitting position to a standing one. In many cases, this stage is difficult to achieve due to a fear of falling. Stubby prostheses (stubbies) ensure gradual adaptation to the use of standard prostheses by lowering the center of body mass, which improves coordination and balance. The current limb prosthesis market offers a whole range of products tailored to the patient's needs. Advances in prosthetics are centered around improved materials and designs that increase the performance of a given prosthesis and improve mobility, and a gait analysis makes it possible to create a product that will successfully reproduce a physiological gait. The definite advantage of using stubbies is the reduction of the center of body mass. This allows many people who have had a double amputation above the knee joints to be more active. This concerns both home activities as well as outdoor ones. In this case study, the pelvis and trunk were bent while the cadence had to be increased to maintain gait speed. In their research on people have had a double amputation, [PERSON] et al. also observed a higher cadence than in non-disabled participants (107.7 \(\pm\) 14.0 step/min for the users of stubby prostheses and 104.4 \(\pm\) 8.0 step/min for the users of full-length prostheses) [15]. In the studies by [PERSON] et al., the cadence in people who have had a double amputation was lower than in both participants who had had a unilateral amputation above the knee joint and in non-disabled people, where it was 96 step/min [14]. However, it should be noted that in this group the reason for the amputation was an improvised explosive device that usually causes additional injury. In cases where people have had an amputation as the result of an explosive device, the fitting of a prosthetic socket is sometimes impossible due to accompanying tissue injuries. In these cases, the DSF becomes an alternative to the traditional prosthetic socket. In the studies of [PERSON] et al. and [PERSON] et al. the DSF suspension method turned out to be safe and the percentage of periprosthetic fractures was between 2 and 3% [17; 18]. In our study, the GRF measurement was used to determine the magnitude of force transferred to the thigh stumps. In the above case, the GRF did not reach higher rates than in the other samples. Compared to healthy people, the values achieved by the subject were slightly higher (120% BW for healthy people and 130% BW of stubby prosthesis). It can therefore be assumed that in people who have had DSF in the process of gait rehabilitation, gait training without the use of traditional prostheses does not generate GRF higher than in the case of a stubby prosthesis. Another element discussed in articles concerning the gait after having undergone a double amputation is step width. [PERSON] et al. and [PERSON] et al. have shown that the step width affects the energy expenditure of gait. As the stride width increases, the energy expenditure increases [6; 11]. Step width was the smallest when walking with stubby prostheses. For this reason, the involvement of muscles bending the hip joint is increased.