# Impact of Gait-Synchronized Vibrotactile Sensory Feedback on Gait in Lower Limb Amputees
## 4 Discussion
In the TUG, the cohort's median improvement in performance time was 0.39 s, falling below the minimal detectable change (MDC) reference value for the TUG [38; 39]. Although a statistically significant change in the TUG was observed, determining the exclusive attribution of this change to the intervention remains uncertain. Regarding the FSST, the cohort exhibited a median improvement of 2.18 s, surpassing the established MDC reference value, suggesting intervention-based improvement for the entire cohort. Additionally, three subjects in the TUG (27%; subjects 5, 8, and 10) and four subjects in the FSST (36%; p# 1, 8, 10, and 11) demonstrated improvements that exceeded the minimal detectable change (MDC) values, indicating potential intervention-based benefits for these individuals. It is important to note the lack of established minimal clinically important difference (MCID) values for the TUG and FSST in the literature, which raises uncertainty about the final clinical significance of these changes. The 10 MWT and the 2 MWT are commonly used functional assessments for evaluating an individual's gait speed and walking endurance, which are indicative of their physical functionality and ability to use prosthetics [41; 42]. [PERSON] et al. previously established normative values for the 10 MWT and 2 MWT in unilaterally amputated subjects, with an average walking speed of 72.1 \(\pm\) 18.8 m/min (equivalent to 1.20 \(\pm\) 0.31 m/s) and an average walking distance of 143.8 \(\pm\) 37.5 m [35]. In our study, the cohort's median walking speed remained within these ranges at both the initial and follow-up measurements, indicating normative values for amputated subjects (see Figure 8). For the 2 MWT, the cohort's median walking distance was initially below the normative value but increased to fall within the normative range after the intervention (see Figure 9). On an individual level, two subjects (18%; p# 2 and 11) exhibited walking speeds below the norm, while four subjects (36%; p# 3, 6, 7 and 9) even exceeded the norm after the intervention with the VTFS. In terms of walking distance, six subjects (55%; p# 1, 2, 5, 8, 10 and 11) initially fell below the established standard (see Figure 9). However, the intervention improved endurance to within the normative range for three of these subjects (27%; p# 5, 8 and 10). These absolute improvements suggest that the intervention with the VTFS enhanced the parameters of walking speed, distance, and gait stability in the amputated cohort. To evaluate the clinical significance of the observed changes in the 10 MWT and the 2 MWT, we referenced the minimal clinically important difference (MCID) values as outlined in Table 1[40]. Surprisingly, the cohort's median walking speed slightly decreased following the intervention (\(-0.02\) m/s). However, it should be noted that five subjects (45%; pH 3, 5, 6, 7 and 10) experienced clinically relevant improvements in walking speed as a result of the VTFS intervention, as illustrated in Figure 8. Conversely, no clinically significant improvement was observed in walking distance for the overall cohort, with only one subject (9%; pH 10) achieving a clinically relevant increase in this parameter, as depicted in Figure 9.  
Studies could not show a clear correlation between the 10 MWT and 2 MWT [40; 43]. Our findings may suggest that supplementary feedback had a more pronounced impact on fast movements, such as walking speed, coordination and balance, as opposed to endurance, which is predominantly an individual achievement of long-term rehabilitation. Two subjects (pH 2 and 4) showed an absolute decrease in performance across all four gait tests. Subject 2 suffered from a Complex Regional Pain Syndrome (CRPS) before his below-knee amputation, and unfortunately, although the CRPS reduced, it persisted after the amputation. During the intervention time the contralateral knee arthrosis pain of subject 2 increased, which most probably reduced the overall walking ability.