Quantitative analysis of human ankle characteristics at different gait phases and speeds for utilizing in ankle-foot prosthetic design.

BACKGROUND: Ankle characteristics vary in terms of gait phase and speed change. This study aimed to quantify the components of ankle characteristics, including quasi-stiffness and work in different gait phases and at various speeds. METHODS: The kinetic and kinematic data of 20 healthy participants were collected during normal gait at four speeds. Stance moment-angle curves were divided into three sub-phases including controlled plantarflexion, controlled dorsiflexion and powered plantarflexion. The slope of the moment-angle curves was quantified as quasi-stiffness. The area under the curves was defined as work. RESULTS: The lowest quasi-stiffness was observed in the controlled plantarflexion. The fitted line to moment-angle curves showed R2 > 0.8 at controlled dorsiflexion and powered plantarflexion. Quasi-stiffness was significantly different at different speeds (P = 0.00). In the controlled dorsiflexion, the ankle absorbed energy; by comparison, energy was generated in the powered plantarflexion. A negative work value was recorded at slower speeds and a positive value was observed at faster speeds. Ankle peak powers were increased with walking speed (P = 0.00). CONCLUSIONS: Our findings suggested that the quasi-stiffness and work of the ankle joint can be regulated at different phases and speeds. These findings may be clinically applicable in the design and development of ankle prosthetic devices that can naturally replicate human walking at various gait speeds.

Gait evaluation of new powered knee-ankle-foot orthosis in able-bodied persons: a pilot study.

BACKGROUND: Knee-ankle-foot orthoses are utilized for walking by patients with lower limb weakness. However, they may be rejected by patients due to the lack of knee flexion available when using them for walking activities. AIM: The aim of this study was to perform a pilot study investigating the effect of a new powered knee-ankle-foot orthosis on walking in healthy persons before testing with patients with lower limb weakness. METHODS: Walking evaluation was performed on five healthy subjects (mean age: 26 ± 5.6 years). Walking trials were randomly performed in three test conditions: normal walking without an orthosis, walking with a conventional knee-ankle-foot orthosis unilaterally, and also with a new powered knee-ankle-foot orthosis applied to the same leg. RESULTS: The means of walking speed, cadence, and knee flexion during swing and step length were all decreased. Compensatory motions were increased by both orthoses compared to normal walking. More knee flexion was observed in both swing and stance phases when walking with the powered knee-ankle-foot orthosis compared to the conventional knee-ankle-foot orthosis. CONCLUSION: The results demonstrated the potential of a powered orthosis in providing improvements in gait parameters compared to a conventional device in healthy subjects but are yet untested in subjects with lower limb weakness. CLINICAL RELEVANCE: The results of this study demonstrated that a powered knee-ankle-foot orthosis could lock the knee during stance and provide active knee flexion during swing to potentially reduce the tripping during ambulation.

The effect of a knee ankle foot orthosis incorporating an active knee mechanism on gait of a person with poliomyelitis.

BACKGROUND: The aim of this case study was to identify the effect of a powered stance control knee ankle foot orthosis on the kinematics and temporospatial parameters of walking by a person with poliomyelitis when compared to a knee ankle foot orthosis. CASE DESCRIPTION AND METHODS: A knee ankle foot orthosis was initially manufactured by incorporating drop lock knee joints and custom molded ankle foot orthoses and fitted to a person with poliomyelitis. The orthosis was then adapted by adding electrically activated powered knee joints to provide knee extension torque during stance and also flexion torque in swing phase. Lower limb kinematic and kinetic data plus data for temporospatial parameters were acquired from three test walks using each orthosis. FINDINGS AND OUTCOMES: Walking speed, step length, and vertical and horizontal displacement of the pelvis decreased when walking with the powered stance control knee ankle foot orthosis compared to the knee ankle foot orthosis. When using the powered stance control knee ankle foot orthosis, the knee flexion achieved during swing and also the overall pattern of walking more closely matched that of normal human walking. The reduced walking speed may have caused the smaller compensatory motions detected when the powered stance control knee ankle foot orthosis was used. CONCLUSION: The new powered SCKAFO facilitated controlled knee flexion and extension during ambulation for a volunteer poliomyelitis person.

Comparison of the effects of solid versus hinged ankle foot orthoses on select temporal gait parameters in patients with incomplete spinal cord injury during treadmill walking.

BACKGROUND: Ankle foot orthoses (AFOs) are usually used for patients with incomplete spinal cord injury (ISCI) to provide support in walking. OBJECTIVES: The aim of this study was to compare the effect of AFOs, with and without ankle hinges, on specific gait parameters during treadmill training by subjects with ISCI. STUDY DESIGN: Quasi-experimental. METHODS: Five patients with ISCI at the thoracic level participated in this study. Gait evaluation was performed when walking 1) barefoot 2) wearing a solid AFO and 3) wearing a hinged AFO. RESULTS: The mean step length when walking barefoot was 26.3 ± 16.37 cm compared to 31.3 ± 17.27 cm with a solid AFO and 28.5 ± 15.86 cm with a hinged AFO. The mean cadence for walking barefoot was 61.59 ± 25.65 steps/min. compared to 50.94 ± 22.36 steps/min. with a solid AFO and 56.25 ± 24.44 steps/min with a hinged AFO. Significant differences in cadence and step length during walking were only demonstrated between the barefoot condition and when wearing a solid AFO. Significant difference was not observed between conditions in mean of ankle range of motion. CONCLUSION: The solid AFO was the only condition which improved cadence and step length in patients during ISCI gait training. Clinical relevance A solid AFO could be used permanently to compensate for impaired ankle function or it could be used while retraining stepping.

Comparison of the efficacy of laterally wedged insoles and bespoke unloader knee orthoses in treating medial compartment knee osteoarthritis.

BACKGROUND: Patients suffering from medial compartment knee osteoarthritis (OA) may be treated with unloader knee orthoses or laterally wedged insoles. OBJECTIVES: The aim of this study was to identify and compare the effects of them on the gait parameters and pain in these patients. STUDY DESIGN: Quasi-experimental. METHODS: Volunteer subjects with medial compartment knee OA (n = 24, mean age 59.29 ± 2.23 years) were randomly assigned to two separate groups and evaluated when wearing an unloader knee orthosis or insoles incorporating a 6° lateral wedge. Testing was performed at baseline and after six weeks of each orthosis use. A visual analog scale score was used to assess pain and gait analysis was utilized to determine gait parameters. RESULTS: Both orthoses improved all parameters compared to the baseline condition (p = 0.000). However, no significant differences in pain (p = 0.649), adduction moment (p = 0.205), speed of walking (p = 0. 056) or step length (p = 0.687) were demonstrated between them. The knee range of motion (p = 0.000) were significantly different between the two interventions. CONCLUSION: Both orthoses reduced knee pain. Maximum knee range of motion was increased by both interventions although it was 3 degrees less when wearing the knee orthosis. Clinical relevance Both orthoses reduce pain and improve gait anomalies in medial compartment knee OA. Our results suggest a laterally wedged insole can be an alternative conservative approach to unloader knee orthosis for treating symptoms of medial compartment knee OA.

The effect of an isocentric reciprocating gait orthosis incorporating an active knee mechanism on the gait of a spinal cord injury patient: a single case study.

OBJECTIVE: The aim of this study was to identify the effect of induced knee flexion during gait on the kinematics and temporal-spatial parameters during walking by a patient with spinal cord injury (SCI) through the application of an isocentric reciprocating gait orthosis (IRGO) with a powered knee mechanism. METHODS: Two orthoses were considered and evaluated for an ISCI subject with a T8 level of injury. An IRGO was initially manufactured by incorporating drop lock knee joints and was fabricated with custom molded AFOs to block ankle motion. This orthosis was also adapted with electrically-activated knee joints to provide active knee extension and flexion when disengaged. RESULTS: Walking speed, stride length and cadence were increased 37.5%, 11% and 26%, respectively with the new orthosis as compared to using the IRGO. The vertical and horizontal compensatory motions reduced compared to mechanical IRGO. At end of stance phase, knee joint flexion was 37.5° for the AKIRGO compared to 7° of movement when walking with the IRGO. The overall pattern of walking produced was comparable to that of normal human walking. CONCLUSION: Knee flexion during swing phase resulted in an improved gait performance and also reduction in compensatory motions when compared to a mechanical IRGO.

Gait evaluation of the advanced reciprocating gait orthosis with solid versus dorsi flexion assist ankle foot orthoses in paraplegic patients.

BACKGROUND: Mechanical orthoses are used for standing and walking after neurological injury. Most orthoses such as the advanced reciprocating gait orthosis typically use solid ankle-foot orthoses. OBJECTIVES: The goal of this study was to test the effects of ankle dorsiflexion assistance in patients with spinal cord injury when ambulating with an advanced reciprocating gait orthosis compared to walking with fixed ankles. STUDY DESIGN: Quasi-experimental. METHODS: Four patients with spinal cord injury were fitted with an advanced reciprocating gait orthosis equipped with solid and dorsiflexion assist-type ankle-foot orthoses and walked at their self-selected speed. Joint angles and spatial-temporal parameters were measured and analyzed. RESULTS: The mean walking speed and stride length were both significantly increased along with cadence by the volunteer subjects when ambulating using the advanced reciprocating gait orthosis fitted with dorsiflexion assist ankle-foot orthoses compared to the advanced reciprocating gait orthosis with solid ankle-foot orthoses. The mean ankle joint ranges of motion were significantly increased when walking with the advanced reciprocating gait orthosis with dorsiflexion assist ankle-foot orthoses compared to when using the advanced reciprocating gait orthosis with the solid ankle-foot orthoses. Knee joint ranges of motion were reduced, and hip joint ranges of motion were increased but not significantly. CONCLUSION: The advanced reciprocating gait orthosis fitted with the dorsiflexion assist ankle-foot orthoses had the effect of improving gait parameters when compared to the advanced reciprocating gait orthosis with solid ankle-foot orthoses. Clinical relevance The advanced reciprocating gait orthosis with dorsiflexion assist ankle-foot orthoses has the potential to improve hip and ankle joint kinematics and the temporal-spatial parameters of gait in spinal cord injury patients' walking.

Design and simulation of a new powered gait orthosis for paraplegic patients.

BACKGROUND AND AIM: This article describes the development and testing of a new powered gait orthosis to potentially assist spinal cord injury patients to walk by producing synchronized hip and knee joint movements. TECHNIQUE: The first evaluation of the orthosis was performed without users, and was followed by evaluation of the orthosis performance using three healthy subjects to test the structure under weight-bearing conditions. The orthosis was primarily evaluated to ascertain its ability to generate appropriate hip and knee motion during walking. The walking experiments replicated the flexion and extension of both the hip and knee produced by the actuators which had previously been demonstrated during the initial computer simulations. DISCUSSION: The results suggest that this new orthosis could be used to assist paraplegic subjects who have adequate ranges of motion and also with weakness or reduced tone to ambulate, and may also be suitable for other subjects with impaired lower limb function (e.g. stroke, poliomyelitis, myelomeningocele and traumatic brain injury provided they do not have increased tone or movement disorders.

Evaluation of a novel powered hip orthosis for walking by a spinal cord injury patient: a single case study.

BACKGROUND: The aim of this case study was to identify the effect of a powered hip orthosis on the kinematics and temporal-spatial parameters of walking by a patient with spinal cord injury (SCI). CASE DESCRIPTION AND METHODS: Two orthoses were evaluated while worn by an incomplete SCI subject with a T-8level of injury. Gait evaluation was performed when walking with an Isocentric Reciprocating Gait Orthosis (IRGO) and compared to that demonstrated by a newly powered version of the orthosis; based on the IRGO superstructure but incorporating powered hip joints using an electrically motorized actuator that produced active hip joint extension and flexion. FINDINGS AND OUTCOMES: The powered hip orthosis, when compared to the IRGO, increased the speed of walking, the step length and also the cadence demonstrated by this subject. Vertical and horizontal compensatory motions with new orthosis decreased. Hip angles when walking with this orthosis were comparative to those demonstrated by normal walking patterns. CONCLUSIONS: The hip actuator produced positive effects on the kinematics and temporal-spatial parameters of gait during level-ground walking trials, resulting in an alternative approach to walking by SCI patients.