Stair ascent with an innovative microprocessor-controlled exoprosthetic knee joint.

Climbing stairs can pose a major challenge for above-knee amputees as a result of compromised motor performance and limitations to prosthetic design. A new, innovative microprocessor-controlled prosthetic knee joint, the Genium, incorporates a function that allows an above-knee amputee to climb stairs step over step. To execute this function, a number of different sensors and complex switching algorithms were integrated into the prosthetic knee joint. The function is intuitive for the user. A biomechanical study was conducted to assess objective gait measurements and calculate joint kinematics and kinetics as subjects ascended stairs. Results demonstrated that climbing stairs step over step is more biomechanically efficient for an amputee using the Genium prosthetic knee than the previously possible conventional method where the extended prosthesis is trailed as the amputee executes one or two steps at a time. There is a natural amount of stress on the residual musculoskeletal system, and it has been shown that the healthy contralateral side supports the movements of the amputated side. The mechanical power that the healthy contralateral knee joint needs to generate during the extension phase is also reduced. Similarly, there is near normal loading of the hip joint on the amputated side.

Immediate effects of a new microprocessor-controlled prosthetic knee joint: a comparative biomechanical evaluation.

OBJECTIVE: To investigate the immediate biomechanical effects after transition to a new microprocessor-controlled prosthetic knee joint. DESIGN: Intervention cross-over study with repeated measures. Only prosthetic knee joints were changed. SETTING: Motion analysis laboratory. PARTICIPANTS: Men (N=11; mean age ± SD, 36.7±10.2y; Medicare functional classification level, 3-4) with unilateral transfemoral amputation. INTERVENTIONS: Two microprocessor-controlled prosthetic knee joints: C-Leg and a new prosthetic knee joint, Genium. MAIN OUTCOME MEASURES: Static prosthetic alignment, time-distance parameters, kinematic and kinetic parameters, and center of pressure. RESULTS: After a half-day training and an additional half-day accommodation, improved biomechanical outcomes were demonstrated by the Genium: lower ground reaction forces at weight acceptance during level walking at various velocities, increased swing phase flexion angles during walking on a ramp, and level walking with small steps. Maximum knee flexion angle during swing phase at various velocities was nearly equal for Genium. Step-over-step stair ascent with the Genium knee was more physiologic as demonstrated by a more equal load distribution between the prosthetic and contralateral sides and a more natural gait pattern. When descending stairs and ramps, knee flexion moments with the Genium tended to increase. During quiet stance on a decline, subjects using Genium accepted higher loading of the prosthetic side knee joint, thus reducing same side hip joint loading as well as postural sway. CONCLUSIONS: In comparision to the C-Leg, the Genium demonstrated immediate biomechanical advantages during various daily ambulatory activities, which may lead to an increase in range and diversity of activity of people with above-knee amputations. Results showed that use of the Genium facilitated more natural gait biomechanics and load distribution throughout the affected and sound musculoskeletal structure. This was observed during quiet stance on a decline, walking on level ground, and walking up and down ramps and stairs.

Biomechanical influences of shoulder disarticulation prosthesis during standing and level walking.

BACKGROUND: Modern prosthetic systems with more degrees of freedom offer the patient clearly improved functions. However, the influence of functional arm prostheses on body posture and gait have never been quantified. OBJECTIVES: The purpose of this investigation was to observe the impact of a functional arm prosthesis on body posture and gait of shoulder disarticulation patients. STUDY DESIGN: Experimental, biomechanical. METHODS: Eight patients with unilateral shoulder disarticulation were enrolled. Static posture and gait analyses were conducted with and without using a functional arm prosthesis. Static posture analysis using the L.A.S.A.R. Posture device as well as kinematic and kinetic gait analysis using an optoelectronic camera system combined with force plates were conducted with and without prosthesis in eight unilateral shoulder disarticulation patients. RESULTS: Static analysis confirmed that an arm prosthesis improves body posture of amputees. Gait analysis revealed that compensatory movements during walking as well as external knee moments on the prosthetic side leg are significantly reduced when using a free swinging shoulder joint. CONCLUSIONS: An arm prosthesis does not only offer functional and cosmetic benefits. The results confirm that unilateral shoulder disarticulation patients benefit from a functional arm prosthesis with a free swinging shoulder joint in terms of optimized posture and gait dynamics. CLINICAL RELEVANCE: This study demonstrates that shoulder disarticulation patients benefit from a functional prosthesis with a free swinging shoulder joint. Such prosthesis significantly improves body posture and gait characteristics, reduces compensatory movements and relieves distress to the musculoskeletal system. This should be considered when prescribing a prosthesis for shoulder disarticulation amputees.

Biomechanical differences between two exoprosthetic hip joint systems during level walking.

Previous studies have shown low end-user acceptance of a hip disarticulation style prosthesis and that the limitations of such prostheses, including poor gait pattern, socket discomfort, weight of the prosthesis, loss of mobility, instability and high energy consumption are a contributing factor. This study was initiated to determine if a new style of prosthetic hip joint could help to overcome some of the limitations concerning the gait pattern. The present study analyzed the gait pattern of six hip disarticulation amputee subjects. The objective was to compare two different prosthetic hip joints, both from Otto Bock HealthCare: The new Helix(3D) and the 7E7, which is based on the Canadian model proposed by McLaurin (1954). Kinematics and kinetics were recorded by an optoelectronic camera system with six CCD cameras and two force plates. During weight acceptance, the Helix(3D) extends considerably slower and reaches full extension later than the 7E7. The increased range of pelvic tilt observed with hip disarticulation amputees is significantly reduced (by 5 ±â€Š3 degrees) when using the Helix(3D) Hip Joint. In addition, this system showed increased stance phase knee joint flexion as well as increased maximum swing phase knee flexion angles compared to the 7E7. These motion analysis results show that the Helix(3D) Hip Joint can reduce gait abnormalities compared to the uniplanar design of the 7E7 hip joint.