Lower limb amputation is a permanent disability, which results in lower life quality, limited mobility, and engagement of the person in social activities (
1). Lower-limb amputation can occur in the battlefield or surgically at a hospital (
2). Lower-limb loss has a higher occurrence rate compared to upper-limb loss, as a study of amputees in Iran-Iraq war showed that from each 200 amputees in the war, only 25 had upper body limb loss while the rest had limb loss in their lower body parts (
3). Other studies have shown that the most widespread lower body limb loss is the below-knee limb loss (
4) and the rehabilitation process for these individuals is accompanied by major difficulties (
5). These peoples, due to difficulty in adapting to their situation, are stricken with psychological and social disorders, such as depression, desperation, lower confidence level, anxiety, and suicide attempts, and they develop other disorders, such as addiction to drugs, alcohol, psychedelics or decreased functionality in the society (
6).In addition, quality of life in lower-limb amputees decreases due to their immobility issues (
7,
8). Therefore, in the rehabilitation process of amputees, prosthesis usage can help with mobility dysfunctions and improve personal and social functionality (
9). For this reason, one of the important factors in rehabilitation of lower-limb amputee people can be the prescription of a prosthesis, which can act as a substitute for the lost limb (
10). Age, Gender, and scale and reason of amputation are also influential in prosthesis usage (
11). Studies have shown that quality of life in unilateral trans-femoral amputee prosthesis users have been improved in psychosocial adjustments and athletic activity restrictions (
12). Overall, what is prominent is that the quality of life in amputees is drastically reduced, and can be observed and monitored in forms of depression, scale of engagement in social activities, problems with prosthesis and mobility characteristics of prosthesis. However, many of these problems can be solved by prescribing a suitable prosthesis (
3,
13,
14). Due to the importance of life quality in the amputee, many studies have been carried out in this regard. Sinha et al. by using the short form-36 (SF-36) and mental component summary (MCS), studied affecting factors regarding quality of life in lower-limb amputee and found that employment status, phantom-limb pain, use of assistive devices, and prosthesis have the most impact in determining quality of life in this population (
14). In another study, Mousavi et al. assessed the quality of life in war-related bilateral lower limb amputees of Iranian disabled war veterans using SF-36 survey form and discovered that this group of patients had significantly lower quality of life. Out of different parameters, history of hospitalization and salary satisfaction were the key factors in quality of life in this group of patients. This study also revealed that improvement of supportive services and rehabilitation, including encouragement to exercise, leisure events, and control and treatment of amputation side-effects can increase quality of life in this group (
3). Deans et al. investigated the relationship between physical activity and quality of life in lower-limb amputees to determine the important aspects of physical activity on quality of life factors in this group and found that implementing supportive changes in the environment can contribute to quality of life for this group (
15). Asano et al. conducted a study to predict quality of life in individual lower limb amputees. They found that social activity in amputees has a very important effect on regaining and maintaining quality of life in this group (
13). The goals of rehabilitation of amputees are improvement in mental, physical, social, and economic functioning and bringing back this group to the society (
16). Therefore, to reduce disorders that result from amputation and increase adjustment of amputee with prosthesis, it should be emphasized that parts of prosthesis, such as ankle and knee parts, should have high degree of similarity and adjustment to the natural limb with ability of performing the same movements that a natural limb can perform to reduce problems, which are caused by amputation and prosthesis usage (
17). In this regard, it seems that ankle transverse plane motion plays a major role. This motion can be beneficial in easing up performing actions, such as putting on socks and shoes (
18). This motion can also assist the patient in cross-legged sitting and kneeling positions and also helps the patient maintain a more natural posture (
19). For these reasons and the perceived necessities, an attempt was made to design a unit that can provide ankle motion in the transverse plane. Therefore, the aim of this study was to investigate of the effects of ankle turner unit on the quality of life of unilateral below knee amputees. Therefore, the aim of this study was to investigate the effects of ankle turner unit on the quality of life of unilateral below knee amputees.