4.3. Response Rate and Mortality
At the time of the evaluation, two to five years after the amputation had passed. Mortality rates after major limb amputations for nontraumatic amputations show rates up to 70% at 5 years follow-up [
22] as major limb amputation is mainly a symptom of a systemic disease; thus, the mortality rate ranging between 32 and 59% in this study population is representative. One limitation within this study remains, which is that this study lacks a time-based analysis of the measured parameters.
The response rate to the questionnaire after five months was lower than expected (27 amputees, 16%). A total of 25% of the responders were traumatic amputees representing the 12% of traumatic amputees of the original cohort. A total of 75% of the 27 responding amputees were nontraumatic. The low response rate might be explained by the high abovenamed mortality rates among nontraumatic amputations.
Another reason could be the conception of the study. We tried to reduce conceptual limitations such as overall length and design of the questionnaire (see below). We limited the questionnaire to 13 pages by concentrating on relevant questions to QoL instead of standardized questionnaires, and we used a comfortable font size (Arial 14).
The study’s findings are constrained by the small cohort size (N = 27), which limits the scope of interpretations. However, it should be noted that the participants, who were at least two years into their rehabilitation process, may offer a somewhat representative sample as they were unbiased by past experiences. It should be noted that this study did not include an intervention arm.
4.4. Prosthetic Supply, Assistive Devices, and Mobility
All responding amputees were fitted with a prosthesis. Almost all amputees (N = 26) needed one further assistive device in addition to their prosthesis. The additional need for assistive devices could be due to the overall rather low level of mobility. Other studies reported comparable dependency on further assistive devices to achieve independence and safety in everyday life locomotion [
23]. Those results affirm the importance of the supply beyond the prosthetic device.
The association between prosthetic use and physical activity is an important subject to discuss [
24]. Herein, 55% (N = 15) of the amputees used their prosthesis up to eight hours a day and 8% (N = 2) did not use the prosthesis at all. Other investigations report that 40% of patients used their prosthesis between 6 and 16 h a day [
23] and less than 20% of the study participants did not use prosthetic provision at all, or only rarely [
25]. Even though the overall mobility of both patient groups decreased after the amputation, the regained mobility in trauma patients was higher. Although four out of seven patients had reached a mobility level of K2 after amputation, none dropped below that level. In contrast, four patients (20%) with a nontraumatic cause of amputation were no longer able to walk at all after the amputation (K-level 0), most probably limited by their accompanying comorbidities and age. Therefore, mobility post-amputation is mainly related to, or even determined by, mobility prior to amputation, and this implies accompanying underlying systemic disease [
26,
27]. Thus, those determining factors should be identified, and other medical disciplines, such as internal medicine, should be involved in amputation care to address the underlying pathologies limiting mobility. Furthermore, concepts described as prehabilitation might be integrated in an amputee care concept. The term prehabilitation describes all interventions aiming to improve a person’s functional capacity, as well as tolerance to possible future physiological stress, such as surgical interventions [
28]. Prehabiliation has not yet been a focus of research regarding major lower-limb amputation [
19].
The finding that there was no relationship between the final K-level and the time that passed until prosthetic fitting was quite unexpected. We expected a strong correlation between a high K-level and shorter time until prosthetic supply, since reports in the literature have shown that earlier prosthetic fitting can lead to quicker ambulation and walking ability [
29,
30]. Again, this study lacks a time-based analysis of the measured parameters, especially mobility outcome parameters, which can change over time during rehabilitation.
4.5. Relations of Quality of Life, Adaption to the New Life Situation, Mobility, and Satisfaction with the Assistive Devices (QUEST)
Even though we found that self-rated QoL was mostly reported to be severely limited due to the amputation, the self-rated adaptation to the new situation was mostly satisfactory in the analyzed cohort (largely adapted, 74%, N = 27).
The correlation analysis revealed overall high satisfaction for both traumatic and nontraumatic patients with the devices and service, indicating higher adaptation to the new situation if good service and satisfying assistive devices were received. The correlation analysis for QoL correlated negatively with K-level, adaptation to the new life situation, and satisfaction with the device and services. Within this study, for amputees with AKA and knee disarticulations, impact on QoL was not relevant when compared to amputees at more distal amputation levels. This is congruent to other studies showing no correlation between satisfaction measured by the QUEST questionnaire and amputation levels [
31]. Due to the limited number of study participants, it was not possible to discern possible reasons. Maybe this could be explained by the finding that advanced mobility skills including outdoor walking could still be reached using a reliable, safe prosthesis and required assistive. As for additional therapies, all were regarded as helpful; 74% of the study cohort received physiotherapy but only 33% participated in rehabilitation sport. However, the presence and characteristics of a specific prosthetic rehabilitation protocol were not assessed in this study, which might be a further important factor influencing the overall (functional) outcome [
4,
5,
7]. Even if our data consisted of discrete variables, we decided to use linear regression lines, without forecasting character but aiming for better visualization of the degree of correlation. Generally, there are many possible scores that can be used to measure QoL, with high variations due to complex interactions of physical function and psychological comorbidities [
6,
7,
32]. It is important to note that even though 44% stated to be severely limited in the QoL, the majority of participants (96%) felt largely or even completely adapted to the new life situation after amputation.
There are multiple questionnaires with different approaches to assess satisfaction with the prosthetic devices [
33,
34,
35]. The herein used QUEST 2.0 questionnaire evaluates the degree of satisfaction with assistive technology devices from the user’s perspective [
11]. Overall satisfaction is the result of multidimensional, dynamic constructs. The subjective evaluation of a limb replacement, including the emotional perception, seems to be influenced by factors like appearance, properties, fit, use, and interaction with the residual limb, as well as pre-existing emotional predispositions of the amputee. Therefore the satisfaction with the prosthesis can be described as a bio–psycho–social construct, contributing to the overall quality of care [
31,
32,
35,
36,
37,
38,
39,
40,
41]. Furthermore, amputees’ satisfaction is the offset of their continuous experience and their expectations of healthcare services, including experienced management of the healthcare budget [
31,
32,
33,
34,
35,
36,
37,
38]. Interestingly, amputees were generally more satisfied with the services than with the prosthetic devices.
The German guidelines for rehabilitation after major lower-limb amputation defines minimum goals 14 days after the prosthetic fitting, such as independent ability of donning the prosthesis, pain-free fitting, and safe and independent mobilization with an assistive device [
41]. This is congruent to other investigations using the QUEST and highlighting comfort, effectiveness, and ease of use [
42]. We agree that those goals allow for satisfaction, mobility, and safety and are fundamental for the acceptance of the physical impairment, but also for the long-term rehabilitation, including adaptation at a satisfying QoL. Worse outcomes in overall mobility have been associated not only with a worse QoL, but with preceded cognitive concerns and overall activity [
43]. One of the main objectives in rehabilitation is regaining mobility, in which satisfaction with the prosthetic device is a major factor as it enables mobility [
33]. From the previous literature, we know that the higher the mobility of amputees, for example, due to participation in mobility programs [
44] or even due to more advanced prostheses [
45], the higher the satisfaction in the QUEST questionnaire is stated to be. It has been shown, furthermore, that independence is very valued and expressed by activities, commonly regarded as mundane, such as being able to go for a walk or driving a car [
15]. The design of this study placed the focus on substantial mobility and patients’ evaluation of their assistive-device-related quality of care, which is why our QoL questionnaire was adapted to the ability of mundane but elementary activities (go for a walk, driving a car), kind and frequency of support by caregivers, and overall self-rated degree of adaption to the new life situation [
31,
32,
33,
34,
35,
36,
37,
38].
Furthermore, the social impact (e.g., return to work) of amputation and its influence on satisfaction and the rehabilitation process should be assessed and addressed in the future [
8]. The discussion underlines, once more, the importance of comprehensive prosthetic and assistive device supply after amputation and [
20,
40] the necessary paradigm shift in lifelong amputee care. Lately, we are observing the transition to an interdisciplinary care model for amputees’ that recruits services focused on functional and psychosocial rehabilitation to offer comprehensive care by addressing the needs of a challenging patient population [
46,
47].