• Journal of Institute of Control, Robotics and Systems
• /
• v.21 no.10
• /
• pp.944-950
• /
• 2015

Recent studies on ankle-foot prostheses used for transtibial amputees have focused on the adaptation of the ankle angle of the prosthesis according to ground conditions. For adaptation to various ground conditions (e.g., incline, decline, and step conditions), ankle-foot prostheses should first recognize the ground conditions as well as the current human motion pattern. For this purpose, the ground reaction forces and orientation angle of the tibia provide fundamental information. The measurement of the orientation angle, however, creates a challenge in practice. Although various sensors, such as accelerometers and gyroscopes, can be utilized to measure the orientation angles of the prosthesis, none of these sensors can be solely used due to their intrinsic drawbacks. In this paper, a time-varying complementary filtering (TVCF) method is proposed to incorporate the measurements from an accelerometer and a gyroscope to obtain a precise orientation angle. The cut-off frequency of TVCF is adaptively determined according to the human gait phase detected by a fuzzy logic algorithm. The performance of the proposed method is verified through experiments.

• Journal of Korean Foot and Ankle Society
• /
• v.25 no.3
• /
• pp.111-116
• /
• 2021

Purpose: Variations in the preferred conservative and operative treatment methods for ankle arthritis may be observed in the practice of orthopedic surgeons. This study is based on the Korean Foot and Ankle Society (KFAS) member survey and aims to report the current trend and changes in the management of ankle arthritis over the last few decades. Materials and Methods: A web-based questionnaire containing 24 questions was sent to all KFAS members in July 2021. The questions were mainly related to the preferred techniques and clinical experience in osteotomy, arthrodesis, and total ankle arthroplasty (TAA) for patients with ankle arthritis. Results: Sixty-three out of 550 surgeons (11.5%) responded to the survey. The responses to 6 out of the total of 24 questions (25.0%) achieved the levels needed to reflect a tendency. Answers that showed a tendency were related to the following: a surgical approach for arthrodesis (anterior approach), use of auto-bone graft for arthrodesis (iliac bone), a nonunion rate of more than 10% following arthrodesis, main reason related to unsatisfactory results after arthrodesis (nonunion or delayed union), the main reason to change total ankle prosthesis (unstable supply of prosthesis), the unusualness of revision TAA and conversion of fusion to TAA. Diversity was found in several aspects of treatment (degree of experience and satisfaction in supramalleolar osteotomy, fixation method for arthrodesis, preferred TAA prosthesis and longevity, degree of experinece, annual number of TAA operation. Conclusion: This study proposes updated information with regard to the current trends in the management of ankle arthritis in Korea. Both consensus and variations in the approach to patients with ankle arthritis were identified through this survey. With an increasing preference for TAA, the need for the development of a prosthesis optimized for Koreans and a stable supply of prostheses were the suggestions made by the study.

• Journal of Korean Foot and Ankle Society
• /
• v.11 no.1
• /
• pp.18-22
• /
• 2007

Purpose: To provide basic data on anatomy of the ankle joint in adults using magnetic resonance imaging as well as to compare measurements with available data of corresponding dimension in the different sizes of the total ankle replacements design ($HINTEGRA^{(R)}$). Materials and Methods: Magnetic resonance (MR) sagittal and coronal images from one hundred-forty nine were studied. Post traumatic, arthritic, or grossly deformed ankles at any reason were excluded. Lengths, widths of the main parts of this articulation and also the radius of curvature of talar dome were measured in the MR images. Statistical analysis was performed on these measurements. Results: On MR coronal image data, average tibial width was $30.0{\pm}4.1\;mm$ and talar width was $27.0{\pm}3.4\;mm$. On sagittal image date, average anteroposterior length of the distal tibia was $39.0{\pm}4.2\;mm$, average anteroposterior length of the talus was $31.3{\pm}2.8\;mm$, and average sagittal radius of curvature of talar dome was $20.1{\pm}2.9\;mm$. All measurements in male were significantly larger than in female (p<0.01), but a significant difference according to age was not found. Conclusion: Ankle morphometric data define a basis of size, particularly useful in the design of ankle prostheses.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.10 no.4
• /
• pp.305-313
• /
• 2016

Movements of the lower limb are important for normal walking and smooth oscillation of the center of gravity. The ankle rotations such as dorsi-flexion, plantar-flexion, inversion and eversion allows the foot to accommodate to ground during level ground walking. Current below knee (B/K) prostheses are used for replacing amputated ankle, and make it possible for amputees to walk again. However, most of amputees with B/K prostheses often experience a loss of terrain adaptability as well as stability because of limited ankle rotation. This study is focused on the development of multi-rotational prosthetic foot for lower limb amputee. Our prosthesis is possible for amputees to easily walk in level ground by rotating ankle joint in sagittal plane and adapt to the abnormal terrain with ankle rotation in coronal plane. The resistance of ankle joint in the direction of dorsi/plantar-flexion can be manually regulated by hydraulic damper with controllable nozzle. Furthermore, double layered rubber induce the prosthesis adapt to irregular ground by tilting itself in direction of eversion and inversion. The experimental results highlights the potential that our prosthesis induce a normal gait for below knee amputee.