Effect of an unrestricted knee-ankle-foot orthosis on the stance phase of gait in healthy persons

Orthotic walking outcome of persons with motor complete low thoracic spinal cord injury-a retrospective study

STUDY DESIGN

Retrospective study.

OBJECTIVE

To analyse the orthotic walking outcome of patients with Low Thoracic Spinal Cord Injury (LT-SCI).

SETTING

The Rehabilitation Institute at Christian Medical College, Vellore, India.

METHODS

Data between January 2005 and June 2015 were retrospectively collected from electronic medical reports of patients with motor complete LT- SCI who were admitted for the comprehensive rehabilitation program. The orthotic walking outcome of these patients was measured by the Walking index for SCI version II (WISCI II). Demographical and clinical parameters were measured and their association with the walking outcome was analyzed using regression analysis.

RESULTS

A total of 430 patients were identified within the study period. Eighty-five percent of people (n = 365) achieved walking at the time of discharge (WISCI II level 12 = 260 and level 9 = 105). Out of 11 demographical and clinical parameters considered, eight of them were found to be significant predictors of walking in the univariate analysis. Age less than 30 years had the highest odds of predicting WISCI II level 9 and level 12 than those older in the multivariate analysis (OR 17.58; 95% CI 7.35-42.03). Single neurological level T12 increased the chance of achieving WISCI II level 12 by 10 times (OR 10.2; 95% CI 3.8-27.36).

CONCLUSIONS

Orthotic walking for persons with motor complete low thoracic spinal cord injury is an achievable goal through a comprehensive rehabilitation program. The factors identified in this study will help rehabilitation professionals strategically select the ideal candidate for orthotic gait training.

Role and Significance of Trunk and Upper Extremity Muscles in Walker-Assisted Paraplegic Gait: A Case Study

Background and Purpose: Understanding the role and significance of trunk and upper extremity muscles in paraplegic gait can help in designing more effective assistive devices for these patients and also provides valuable information for improving muscle strengthening programs. Methods: In a patient with a spinal cord injury (SCI) who could walk independently (rating scale of ambulatory capacity, 9) with the aid of bilateral ankle-foot orthosis and a walker, the kinematics, kinetics and electromyographic (EMG) activities of 16 muscles from the trunk and upper and lower extremities were recorded during gait. The onset, cessation, and duration of the EMG signal were associated with the 4 phases of each step, distinguished based on the kinematics results. Results: It was found that the reciprocating activation pattern of the quadratus lumborum, latissimus dorsi, pectoralis major, and lower trapezius is responsible for trunk extension during the balance adjustment phase, leg unload and foot clearance creation during the leg raising phase, and propulsion force generation during the leg swing phase. Conclusion: The continuous activation of the rectus abdominis and erector spinae within the gait cycle helps stabilize the thorax and acts in reverse, that is, fixes the proximal joint and moves the distal limb. The shoulder girdle muscles contribute to the leg's unloading and then smooth landing during leg raising and leg swing phases, respectively.

Studying the effect of kinematical pattern on the mechanical performance of paraplegic gait with reciprocating orthosis

Paraplegic users of mechanical walking orthoses, e.g. advanced reciprocating gait orthosis (ARGO), often face high energy expenditure and extreme upper body loading during locomotion. We studied the effect of kinematical pattern on the mechanical performance of paraplegic locomotion, in search for an improved gait pattern that leads to lower muscular efforts. A three-dimensional, four segment, six-degrees-of-freedom skeletal model of the advanced reciprocating gait orthosis-assisted paraplegic locomotion was developed based on the data acquired from an experimental study on a single subject. The effect of muscles was represented by ideal joint torque generators. A response surface analysis was performed on the model to determine the impact of the kinematical parameters on the resulting muscular efforts, characterized by net joint torques. Results indicated that a lateral bending manoeuvre at the trunk would facilitate the foot clearance by reducing the torque requirement of the whole body lateral tilting. For swing leg advancement, the trunk posterior bending manoeuvre was found to be more effective and efficient than the whole body axial rotation, owing to the coupled reciprocal action of the advanced reciprocating gait orthosis. It was hypothesized that a modified gait pattern, with larger trunk movements and no axial rotation, could improve the energy expenditure and upper body loading during advanced reciprocating gait orthosis-assisted locomotion. More detailed modelling and experimental studies are needed to verify this hypothesis and evaluate its potential effects on the soft tissue strains.

Design, construction and evaluation of an electromechanical stance-control knee-ankle-foot orthosis

A new electromechanical Stance-Control Knee-Ankle-Foot Orthosis (SCKAFO) was designed to provide improved gait for people with knee-extensor weakness. This SCKAFO inhibits knee flexion at any knee angle while allowing knee extension during weight bearing. During swing or other non-weight bearing activities, the SCKAFO allows free knee motion. A prototype joint was mechanically tested to determine the moment at failure, loading behaviour, and device safety. Quantitative kinematic gait analysis of three able-bodied subjects and three knee-ankle-foot-orthosis (KAFO) users showed that the new SCKAFO had a desired minimal effect on able-bodied walking gait. The SCKAFO permitted a mean increase in sagittal knee motion (488%) during swing for the three KAFO users and a reduction in pelvic obliquity and hip abduction angle abnormalities during terminal stance and swing for two KAFO users.

Design, construction and evaluation of an electromechanical stance-control knee-ankle-foot orthosis

A new electromechanical Stance-Control Knee-Ankle-Foot Orthosis (SCKAFO) was designed to provide improved gait for people with knee-extensor weakness. This SCKAFO inhibits knee flexion at any knee angle while allowing knee extension during weight bearing. During swing or other non-weight bearing activities, the SCKAFO allows free knee motion. A prototype joint was mechanically tested to determine the moment at failure, loading behaviour, and device safety. Quantitative kinematic gait analysis of three able-bodied subjects and three knee-anklefoot-orthosis (AFO) users showed that the new SCKAFO had a desired minimal effect on able-bodied walking gait. The SCKAFO permitted a mean increase in sagittal knee motion (488%) during swing for the three KAFO users and a reduction in pelvic obliquity and hip abduction angle abnormalities during terminal stance and swing for two KAFO users.

Immediate and long-term effects of ankle-foot orthosis on muscle activity during walking: a randomized study of patients with unilateral foot drop

OBJECTIVES

To determine (1) whether use of an ankle-foot orthosis (AFO) by patients with ankle dorsiflexor paresis leads to decreased muscle activity, immediately or 6 weeks after AFO use, and (2) whether this decrease (if present) differs between healthy and paretic subjects.

DESIGN

Cross-sectional and longitudinal randomized case-control study.

SETTING

Rehabilitation research center in the Netherlands.

PARTICIPANTS

Fourteen healthy persons and 29 patients with foot drop.

INTERVENTIONS

Muscle activity was measured by surface electromyography. Electromyographic reproducibility was tested in 14 healthy volunteers walking with and without AFO. Acute changes in muscle activity from AFO use were compared between the 14 healthy persons and the 29 patients with foot drop. Adaptation effects of AFO use after 6 weeks were studied in 29 patients, randomly chosen 16 of whom had started using an AFO at the first measurement.

MAIN OUTCOME MEASURES

Amount of change in mean rectified electromyographic activity (delta value) between walking with and without AFO. Follow-up measurements were conducted after 3 and 6 weeks.

RESULTS

Correlation coefficients, reflecting within-subject reproducibility, varied between.68 and.96 (mean,.86). In patients and healthy subjects, tibialis anterior muscle activity decreased by 7% and 20% (P = .01, P = .04), respectively, when using an AFO. In patients, this decrease was measured in the overall activity during the gait cycle; in healthy subjects, it was measured in the first 15% of the gait cycle. Overall electromyographic activity did not change during 6 weeks; delta values per muscle did not change during follow-up in the AFO group.

CONCLUSION

AFO use immediately reduced muscle activity of the ankle dorsiflexors. However, using an AFO for 6 weeks did not lead to a generally lower electromyographic activity level nor did the amount of activity reduction accumulate in comparison with patients who did not use an AFO. It is, therefore, safe to use an AFO, even with recently paretic patients.

The influence of flexed-knee gait on the energy cost of walking in children

There is an understanding that walking with flexed knees contributes to the increased energy cost of walking found in children with neurological conditions. To determine the influence of flexed-knee gait on energy cost of walking in a group of children without neurological abnormality, the gait patterns of 10 normal children were studied using a Vicon system and standard marker set. A telemetric system (Cosmed K2) was then used to measure the oxygen cost of walking of the same children. The tests were repeated restricting the subjects' knee extension bilaterally, using hinged braces, set to 0, 15, 30, and 45 degrees of flexion. Although the braces themselves caused a significant increase in O2 cost (mL/kg/m) (P < 0.05), due to a decrease in walking speed, no further significant increase in oxygen cost was demonstrated regardless of the degree of knee flexion imposed, despite a significant increase in measured hip flexion and ankle dorsiflexion at the 45 degrees of knee flexion setting (P < 0.05). We propose that moderate flexed-knee gait does not of itself cause an increase in the energy cost of walking and that other factors present in the physically disabled child are likely to be implicated.

Effects of joint motion constraints on the gait of normal subjects and their implications on the further development of hybrid FES orthosis for paraplegic persons

In this study the effects of angular motion constraints of the lower limbs on the gait of normal subjects were investigated. An assessment orthosis was developed with a new hip coupling mechanism which allows its ratio of reciprocal flexion to extension to be altered. The knee and ankle joints of the orthosis could also be set to be free or locked in specific directions of angular motion in the sagittal plane. A total of 12 different orthosis configurations was tested on three normal subjects. The kinematic, kinetic and electromyographic (EMG) data were collected using the VICON system, two Kistler forceplates, foot switches and an eight channel EMG system. The physiological cost index of walking was assessed by measuring the heart rate and walking speed. It was found that (1) a higher hip flexion-extension ratio was associated with lower energy cost and faster walking; (2) allowing the knee to flex significantly reduced the energy cost and increased the walking speed; (3) allowing the ankle to plantarflex during early stance phase reduced the knee flexing moment. The implications of these effects on the further development of hybrid functional electrical stimulation orthotic systems are discussed.

Adaptations during the stance phase of gait for simulated flexion contractures at the knee

Adaptations in the stance phase of gait to knee flexion contractures simulated by a knee-ankle-foot orthosis were studied in 20 healthy women (mean age: 25 +/- 3.6 years). Stride characteristics, joint postures, floor reactions, and indwelling electromyographic activity of the lower gluteus maximus, vastus lateralis, long head of the biceps femoris, and soleus muscles were measured during walking with the orthosis, with and without contracture simulation. Simulated knee flexion contracture resulted in decreased stride length and velocity and increased forefoot weight bearing and flexion posture in stance. Increases were also seen in magnitude and/or duration of flexion floor reaction torques and gluteus maximus, vastus lateralis, and soleus muscle activity. The addition of a restriction of plantar flexion resulted in a further decrease in velocity and stride length and a small increase in hip extension posture. These results show that knee flexion contractures, simulated in healthy subjects, cause a decrease in gait function with a simultaneous increase in muscular demand.