Gait Analysis of Hip Disarticulation Amputees Based on Kinematic Parameters and Plantar Pressure Measurement / 医用生物力学

Objective To analyze the gait characteristics of hip disarticulation amputees, and analyze the reasons for their differences from normal gait, so as to assist clinical diagnosis and evaluation. Methods Through the portable human motion capture device and plantar pressure analysis system, the kinematics and plantar pressure information of 5 hip amputees were collected and compared with 15 healthy volunteers in control group. Gait differences between the amputees and normal subjects and between the affected leg side and the healthy leg side of the amputees were compared. Results The proportion of double-support period for hip amuptees was higher than that of normal gait. Step length, step time, loading response period, mid support period, pre-swing period, proportion of the swing period for the affected leg side and healthy leg side of hip amputees showed significant differences with those of control group. The relative symmetry index of the gait for hip amputees was 0.60±0.05. Compared with the affected leg side, the support period of the healthy leg side was extended, the step length was shortened, the ground reaction force was greater than that of the affected leg side, and the center of pressure trajectory shifted to the affected leg side. Conclusions The gait of hip amputees is significantly different from that of normal people. Hip amputees have weak walking ability, poor gait symmetry, and they lack of continuity in the body’s center of gravity. The results provide experimental basis and theoretical analysis for the design of mechanical structure and control system of novel hip prosthesis.

Design and simulation of dynamic hip prosthesis based on remote motion center mechanism / 生物医学工程学杂志

The rotation center of traditional hip disarticulation prosthesis is often placed in the front and lower part of the socket, which is asymmetric with the rotation center of the healthy hip joint, resulting in poor symmetry between the prosthesis movement and the healthy lower limb movement. Besides, most of the prosthesis are passive joints, which need to rely on the amputee's compensatory hip lifting movement to realize the prosthesis movement, and the same walking movement needs to consume 2-3 times of energy compared with normal people. This paper presents a dynamic hip disarticulation prosthesis (HDPs) based on remote center of mechanism (RCM). Using the double parallelogram design method, taking the minimum size of the mechanism as the objective, the genetic algorithm was used to optimize the size, and the rotation center of the prosthesis was symmetrical with the rotation center of the healthy lower limb. By analyzing the relationship between the torque and angle of hip joint in the process of human walking, the control system mirrored the motion parameters of the lower on the healthy side, and used the parallel drive system to provide assistance for the prosthesis. Based on the established virtual prototype simulation platform of solid works and Adams, the motion simulation of hip disarticulation prosthesis was carried out and the change curve was obtained. Through quantitative comparison with healthy lower limb and traditional prosthesis, the scientificity of the design scheme was analyzed. The results show that the design can achieve the desired effect, and the design scheme is feasible.

Static Finite Element Analysis on Hip Disarticulation Prosthesis Socket-Residual Limb in Stance Phase / 医用生物力学

Objective To study mechanical properties of the interface between hip residual limb and hip socket during the stance phase by using the finite element analysis (FEA) method, so as to provide the theoretical basis for structure optimization and design of hip socket, as well as the research basis for comfort evaluation of hip socket. Methods According to CT scan images of the patient’s residual limb, the model of bone, soft tissues and socket was reconstructed by reverse modeling. The distribution of normal stress and shear stress on the interface between hip residual limb and hip socket was analyzed and a pressure acquisition module system was designed to verify the stress distribution condition. Results The interfacial stress between hip residual limb and hip socket was mainly distributed in the waist and the bottom of the residual limb, and the interfacial stress was more evenly distributed in the rest of the residual limb. The results of finite element calculation were in good agreement with the system measurement results of pressure acquisition module. Conclusions In order to improve force transfer and safety and comfort of the hip socket, it is necessary to fully consider stress condition of the waist and bottom of the residual limb, as well as the coordination degree between residual limb and hip socket.

Advance in Bilateral Hip Disarticulation Prosthesis (review) / 中国康复理论与实践

@#With the development of the industry, all the parts of bilateral hip disarticulation prosthesis have been improved. The patients with bilateral hip disarticulation prosthesis can achieve the swing-to gait or swing-through gait, even the reciprocal gait.

Design of Reciprocal Gait Prosthesis for Bilateral Hip Disarticulation / 中国康复理论与实践

@#ObjectiveTo design a reciprocal gait prosthesis connecting with the other prosthetic accessories for the bilateral hip disarticulation amputees.MethodsThe principle of reciprocal gait orthosis for paraplegia was used in the design, fitting reciprocal gait prosthesis for an amputee, which was compared with an ordinary bilateral Canadian type hip disarticulation prosthesis in the walking velocity and energy expenditure.ResultsThe amputee walked at lower energy expenditure and more like normal gait with reciprocal gait prosthesis while the walking velocity decreased, compared with the conventional prosthesis.ConclusionThis reciprocal gait prosthesis for bilateral hip disarticulation amputee needs less energy expenditure during walking like normal gait.

Bilateral hip disarticulation in paraplegics

Background: Decubitus ulcers are severe challenges to paraplegic patients, as well as to the medical providers caring for such disabled persons. Severe, chronic infection often can lead to death, especially in developing countries. Sometimes, hip disarticulation is the most appropriate surgical response to chronic ulceration. Objective: Report the results of bilateral disarticulations in 3 patients, one in Cambodia, and two in Australia. Methods: Chart reviews, examinations, and interviews with the patients were conducted to identify appropriate details of the indications and results. Results: Severe decubitus ulcers were successfully treated using the technique, without undue surgical complications. The general health of the patients was much improved. Conclusion: Bilateral hip disarticulations were performed as last stage salvage operations in three patients, who expressed satisfaction with the results, even though some problems with balance and recurrent ulceration persisted.

Gait Analysis for Prosthetic Ambulation of Hip Disarticulation: A case report

There have been a many reports of observational analysis on hip disarticulation prosthetic ambulation, but not a scientific analysis by a computerized motion analyzer. We present to share with our professional colleague our invaluable experience gained from the study on the gait analysis of a left hip disarticulation prosthetic gait. Using a Vicon 370 three dimensional gait analysis system, the gait analysis was performed in a left hip disarticulation patient fitted with a left Canadian type hip disarticulation prosthesis. In linear parameters, the cadence showed 79 steps/min, the gait speed was 0.68 m/sec, and the double support phase was 25.27% of a total gait cycle. In kinematics, the maximal pelvic tilt angle showed 29.92o at pre-swing phase, and significantly increased as compared with normal person. Hip motion change remained flexed, and maximal knee flexion angle disclosed 22.07o at the terminal stage of initial swing phase. In kinetics, the hip extension moment on initial contact stage was 0.089 NM/kg, which was impaired being compared with normal person. In conclusion, the increased pelvic tilt which implies that initiation of a prosthetic gait for hip disarticulation comes from a forward swing of the pelvis on the affected side, and an overall decrease of gait parameters accounts for the degree of disability of hip disarticulation amputee.