The knee joint of a conventional knee-ankle-foot orthosis (KAFO) is locked during walking. This study aims to evaluate the effects of stance phase knee flexion on the kinematics, spatiotemporal parameters, and energy consumption of KAFO users.
A retrofitting drop lock that allows 12° of stance flexion in a single-axis knee joint was developed (called the semiflexion knee joint). Four subjects with quadriceps weakness volunteered to participate in the study. Gait analysis was conducted for the locked knee and the semiflexion knee orthosis using a calibrated eight-camera three-dimensional motion capture system. Preceding each trial, participants were given 5 days of gait training with the corresponding KAFO. Subjective feedback about the performance of the new KAFO was collected.
Walking with the semiflexion KAFO did not significantly improve the speed (p = 0.161), cadence (p = 0.232), and stride length (p = 0.95) compared with walking with a locked KAFO. Although not significant (p = 0.132), trends of Physiological Cost Index (PCI) seemed to reduce in all subjects while walking with the semiflexion knee.
Using the KAFO with stance flexion did not significantly improve any of the locked knee gait parameters. However, there was a trend of reduction in the PCI score while walking with the semiflexion KAFO, and it also improved the ease of doing some activities of daily living.
GANESH M. BAPAT, PhD, and S. Sujatha, PhD, are affiliated with the Department of Mechanical Engineering, IIT Madras, Chennai, India.
RAJDEEP OJHA, PHD, is affiliated with the Department of Bioengineering, Christian Medical College, Vellore, India.
PRASHANTH CHALAGERI, MD, is affiliated with the Department of Physical Medicine and Rehabilitation, Christian Medical College, Vellore, India.
Disclosure: A patent application has been filed for the design of the drop lock mentioned in this paper by Indian Institute of Technology Madras, Chennai, India. The authors declare no conflict of interest.
Correspondence to: S. Sujatha, PhD, TTK Center for Rehabilitation Research and Device Development, Department of Mechanical Engineering, IIT Madras, Chennai 600036, India; email: firstname.lastname@example.org