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H. K. Ramakrishnan

Bio: H. K. Ramakrishnan is an academic researcher from York University. The author has contributed to research in topics: Gait analysis & Gait (human). The author has an hindex of 4, co-authored 4 publications receiving 4250 citations.

Papers
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TL;DR: The relatively small number of body surface markers used in the VICON system render it easy to implement for use in routine clinical gait evaluations and should be a useful reference for describing and comparing pathologic gait patterns.

2,953 citations

Journal ArticleDOI
TL;DR: The results demonstrate that with the subjects walking at their natural or preferred spped, the gait variables are quite repeatable, and suggest that it may be reasonable to base significant clinical decisions on the results of a single gait evaluation.

1,415 citations

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TL;DR: The persistent gait abnormalities of patients implanted with posterior-stabilized prostheses (posterior cruciate substituting) are comparable to those of patients surgically implanted withcruciate-retaining prostheses and superior to cruciates-sacrificing prostheses.
Abstract: Sixteen patients implanted with a posterior-stabilized prosthesis (Insall-Burstein PS II, Zimmer, Warsaw, IN) and 32 age-matched control subjects were evaluated by isokinetic muscle testing and comprehensive gait analysis at a mean 46 months following the index arthroplasty. The contralateral knee was normal in 13 patients and an asymptomatic total knee arthroplasty in 3 patients. No significant differences (P > .05) were found between the study and control groups in spatiotemporal gait parameters nor were there isokinetic strength deficits. A prolonged firing of the vastus medialis was observed in some patients. Knee range of motion during level walking and stair descent was decreased significantly (P < .05) in the study group. There was no significant difference for knee range of motion between the study and control groups during stair ascent. Spatiotemporal gait parameters in the total knee arthroplasty patients show no significant differences from the control subject at nearly 4 years after surgery. However, other gait abnormalities are present and cannot be accounted for on the basis of muscle weakness, abnormal phasic muscle activity, or inadequate knee range of motion. With reference to historic control subjects, the persistent gait abnormalities of patients implanted with posterior-stabilized prostheses (posterior cruciate substituting) are comparable to those of patients implanted with cruciate-retaining prostheses and superior to cruciate-sacrificing prostheses.

152 citations

Journal ArticleDOI
TL;DR: Frequently, the knee of the limb that was affected by Paget disease was flexed during stance and flexed less during swing and had an increased adduction moment, which may be related to the bowing deformity.
Abstract: Eighteen patients who had Paget disease were evaluated in our gait-analysis laboratory. The results were compared with those of ten healthy age-matched control subjects in order to quantitate the biomechanical changes and to describe the specific patterns of walking that occur secondary to bowing of a lower extremity. Kinetic and kinematic data were acquired using infrared video cameras and force platforms; electromyographic data were obtained using surface electrodes. Velocity and cadence were decreased and stride time and double-limb support time were increased in the patients who had Paget disease compared with the control subjects. Frequently, the knee of the limb that was affected by Paget disease was flexed during stance and flexed less during swing. When the involved knee was in varus angulation it also had an increased adduction moment, which may be related to the bowing deformity. Although the patterns of ground-reaction force were similar in the patients and the control subjects, the magnitudes of forces were reduced in the patients. Phasic muscle activity was similar in the two groups.

16 citations


Cited by
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Journal ArticleDOI
TL;DR: The gait analysis laboratory provides quantified assessments of human locomotion which assist in the orthopaedic management of various pediatric gait pathologies by utilizing a video-based data collection strategy similar to commercially available systems for motion data collection.

2,684 citations

Journal ArticleDOI
TL;DR: This paper deals with methodological problems related to the reconstruction of the position and orientation of the human pelvis and the lower limb bones in space during the execution of locomotion and physical exercises using a stereophotogrammetric system.

1,513 citations

Journal ArticleDOI
TL;DR: The modelling method presented represents a good way to estimate in vivo muscle forces during movement tasks and changing the muscle model to one that is more physiologically correct produced better predictions.

1,049 citations

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TL;DR: In this study, the individual contributions of the ankle plantar flexors to the body segment energetics are examined using a musculoskeletal model and optimization framework to generate a forward dynamics simulation of normal walking at 1.5 m/s.

1,025 citations

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TL;DR: The literature reviewed shows that gait symmetry has often been assumed, to simplify data collection and analysis, and asymmetrical behavior of the lower limbs during able-bodied ambulation was addressed in numerous investigations and was found to reflect natural functional differences between the lower extremities.

921 citations