Hybrid Assistive Limb Training: A Walking Aid after Total Knee Arthroplasty

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Hybrid Assistive Limb Training: A Walking Aid after Total Knee Arthroplasty

Total knee arthroplasty (TKA) is surgery recommended for severe osteoarthritis (OA) and rheumatoid arthritis (RA). Physical function and quality of life (QOL) is reported to be decreased immediately after the TKA. Results of the previous studies state the rehabilitation period of about one year is required for proper walking speed and walking ability. 

Moreover, knee extension lag occurs early after surgery.  Therefore, walking function is particularly important for patients after TKA. The Hybrid Assistive Limb (HAL) is a wearable robot that provides motion according to the wearer’s voluntary drive. Most other exoskeleton devices are also used to generate predefined movement. In contrast, HAL delivers mobility in response to the wearer’s voluntary drive. The wearer operates HAL by adjusting his or her muscle activity. Various clinical trials have been conducted and confirmed the safety of HAL for patients with stroke, spinal cord injury, cerebral palsy, and neuromuscular diseases. Tanaka et al. did an RCT study that compared the efficacy of HAL and conventional therapy after TKA on the lower limb function. The improvement was observed within 1 week with the use of HAL. This study was a conducted for a short-term evaluation (3 weeks) after surgery and did not measure the improvement in range of motion (ROM). Moreover, in this study, the two-legged HAL was used and includes only OA patients. Therefore, the present study ascertained and compared the effect of single leg version of HAL on walking ability, knee ROM, muscle strength, pain, and physical function with the conventional therapy for up to 8 weeks after TKA for OA and RA patients.

None of the patients in the HAL group has reported any serious adverse events. At week 4 and 8, the HAL group shows significant improvement (P < 0.05) in the walking speed and step length in the self-selected walking speed condition, and the walking speed. At 2, 4 and 8 weeks, the HAL group shows greater step length in the maximum walking speed condition than in the control group (P < 0.05). At 2 weeks, the HAL group lowered the extension lag and knee pain (P < 0.05) and also significantly raised the muscle strength of knee extension at 8 weeks (P < 0.05).

In conclusion, the author revealed that after the TKA, the HAL training helps in the improvement of walking ability, ROM, and muscle strength as compared to conventional physical therapy for up to 8 weeks. The findings of this study also demonstrated that the HAL training after TKA could be considered a safe and effective rehabilitation intervention.


Journal of Orthopaedic Surgery and Research

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Original title of the article:

Training with Hybrid Assistive Limb for walking function after total knee arthroplasty


Kenichi Yoshikawa et al

Therapeutic, Hybrid Assistive Limb, Arthritis, Knee, Comparative study, Efficacy, Safety, Walking ability
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