Received May 22, 2021, accepted May 30, 2021, date of publication June 7, 2021, date of current version June 21, 2021. Digital Object Identifier 10.1109/ACCESS.2021.3086807 Advancements, Trends and Future Prospects of Lower Limb Prosthesis MUHAMMAD ASIF 1,2 , MOHSIN ISLAM TIWANA 1,2 , (Member, IEEE), UMAR SHAHBAZ KHAN 1,2 , WAQAR SHAHID QURESHI 1,2 , JAVAID IQBAL 1,2,3 , (Member, IEEE), NASIR RASHID 1,2 , AND NOMAN NASEER 4 , (Senior Member, IEEE) 1 Department of Mechatronics Engineering, National University of Sciences and Technology (NUST), Islamabad 44000, Pakistan 2 National Centre of Robotics and Automation (NCRA), College of Electrical and Mechanical Engineering (CEME), National University of Sciences and Technology, Islamabad 44000, Pakistan 3 School of Mechanical and Manufacturing Engineering (SMME), National University of Sciences and Technology, Islamabad 44000, Pakistan 4 Department of Mechatronics Engineering, Air University Islamabad, Islamabad 44000, Pakistan Corresponding author: Muhammad Asif (m.asif@ceme.nust.edu.pk) This work was supported in part by the National Centre of Robotics and Automation (NCRA) through the Robot Design and Development Laboratory (RDDL), College of Electrical and Mechanical Engineering, NUST, Islamabad, Pakistan, and in part by the Higher Education Commission of Pakistan through grant titled ‘‘Establishment of National Centre of Robotics and Automation’’ under Grant DF-1009-31. ABSTRACT Amputees with lower limb loss need special care during daily life activities to make the movement natural as before amputation. No such work exists covering the main aspects from causes of amputation to the psycho-social impact of the amputees after using the prosthetic device. This review presents for lower limb prosthesis; the study of lower limb amputation, design & development, control strategies & machine learning algorithms, the psycho-social impact of prosthetic users, and design trends in patents. Research articles, review papers, magazines, letters, study reports, surveys, and patents, etc. have been used as sources for this review. Traumatic injuries and different diseases have been found as common causes of amputation. Design & development section illustrates design mechanisms, the categories of passive, active, & semi-active prostheses, an overview of a subset of commercially available prosthetic devices, and 3D printing of the accessories. The control section provides information about control techniques, sensors used, machine learning algorithms, and their key outcomes. Quality of life, phantom limb pain, and psycho-social impact of prosthetic users have been summarized for different countries that are believed to attract the interest of the readers. We have also developed an open-source database ‘‘FAKH-50’’ for patents to emphasize the design trends and advancements in lower limb prostheses from 1970 to 2020. Overall trend analysis determined is in the descending order as the knee (48%) > ankle (28%) > foot (22%) > hip (2%) patents in the current version of our database. The forthcoming section highlights the challenges and prospects of the domain. A mutual observation demands the design of a bio-compatible, lightweight, and economic prosthesis to track the normal human gait by eliminating phantom limb pain. This will empower the amputees to live a quality life in society. This work may be beneficial for researchers, technicians, clinicians, and amputees. INDEX TERMS Causes of amputation, lower limb amputation, lower limb prosthesis, design mechanisms, semi-active prosthesis, human gait cycle. I. INTRODUCTION Natural systems are the ample sources of stimulation for humans to lead technological developments. In recent decades advances in biomedical engineering empowers the community to develop artificial limbs to mimic the mobility of amputees. Lower limb amputation is common in humans and prosthesis restores the mobility for the lost limb to The associate editor coordinating the review of this manuscript and approving it for publication was G. R. Sinha . enhance the quality of life. Amputation is the loss of one or multiple human body parts due to some etiology. Limb loss often occurs due to traumatic injuries, certain diseases, and forced amputation due to surgery [1]. According to a new study, more than one million amputations occur globally that is one every ‘‘30’’ second [2]. Transfemoral amputees spent about 60% and transtibial amputees spent about 30% extra metabolic energy during the walk when compared with unimpaired persons. Similarly, walking speed may be 10% to 65% slower as compared to 85956 This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ VOLUME 9, 2021