Study Design. A cross-sectional study based on an online questionnaire.Objective. The aim was to investigate the prevalence and intensity of low back pain (LBP) in people with lower limb amputation (LLA) and to analyze the association factors that can influence the genesis of LBP. Summary of Background Data. It is still unclear whether LBP is more prevalent in the amputated population than in its nonamputated counterpart. Given the multifactorial nature of LBP, it is necessary to explore possible factors that can influence its presence and intensity, to build a solid background to define a better rehabilitation pathway for the management of these people. Methods. The online questionnaire included six sections. informed consent of the study, demographic information, comorbid conditions, history of LLA, history of LBP, and acceptance of the amputation. Results. Between March and June 2021, 239 participants [mean age (SD). 49.2 (11.5); female 11%] completed the survey (response rate: 32%). From the results of this study, LBP in LLA showed a prevalence of 82% postamputation and 70% in the last year. A logistic regression with a backward method showed that participants who had problems in the not affected leg presented 1.58 (95% confidence interval: 0.70; 2.45) times higher odds to have LBP after the amputation. Conclusion. This study shows that the prevalence of LBP in lower limb amputees appears to be higher than in the general population, with similar levels of pain intensity and frequency. The highest percentage of people with a sedentary lifestyle not practicing any kind of sports emphasizes the importance of educating this population on the importance of physical activity. New strategies to invest in the education of this population in terms of physical activity are needed.

Lower limbs position sense is a complex yet poorly understood mechanism, influenced by many factors. Hence, we investigated the position sense of lower limbs through feet orientation with the use of Immersive Virtual Reality (IVR). Participants had to indicate how they perceived the real orientation of their feet by orientating a virtual representation of the feet that was shown in an IVR scenario. We calculated the angle between the two virtual feet (α-VR) after a high-knee step-in-place task. Simultaneously, we recorded the real angle between the two feet (α-R) (T1). Hence, we assessed whether the acute fatigue impacted the position sense. The same procedure was repeated after inducing muscle fatigue (T2) and after 10 min from T2 (T3). Finally, we also recorded the time needed to confirm the perceived position before and after the acute fatigue protocol. Thirty healthy adults (27.5 ± 3.8: 57% women, 43% men) were immersed in an IVR scenario with a representation of two feet. We found a mean difference between α-VR and α-R of 20.89° [95% CI: 14.67°, 27.10°] in T1, 16.76° [9.57°, 23.94°] in T2, and 16.34° [10.00°, 22.68°] in T3. Participants spent 12.59, 17.50 and 17.95 s confirming the perceived position of their feet at T1, T2, T3, respectively. Participants indicated their feet as forwarding parallel though divergent, showing a mismatch in the perceived position of feet. Fatigue seemed not to have an impact on position sense but delayed the time to accomplish this task.