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T. Shiroshita1
1Gunma Paz University, School of Physiotherapy Faculty of Heath Science, Gunma, Japan
Background: Jacquelin Perry introduced and categorized the concept of rocker function in walking: a first rocker occurring at the start of the walking cycle, followed by second and third rockers carrying the gravity forward. However, the kinematic role of rocker function and how to perceive each rocker clinically are not clear.
Purpose: The purpose of this study is to clarify the kinematic role of the second and third rockers to assist with clinical gait analysis in physical therapy.
Methods: Twenty healthy subjects (14 male, 6 female) participated in this study. They had no difficulties with toe movements and had not needed medical care due to injury around the ankle in the past 6 months. The average age of the subjects was 21.2 ± 0.4 years, their average height was 166.4 ± 6.6 cm, and their average weight was 59.4 ± 6.1 kg. The subjects’ gait was measured with a 3 dimensional-motion analyzer (Vicon MX), 9 infrared cameras, and 3 floor reaction-force meters.
Subjects were measured during free walking five times, and mean values were calculated. The plantar flexion moment and ankle dorsiflexion angle were measured and the values at 12%, 31%, and 50% of the gait cycle were calculated, as these are the points in the cycle delineating the three rockers as defined by Perry. The second rocker value was calculated as the amount of change from 12% to 31% and the third rocker from 31% to 50%. These change amounts were compared using a t-test with IBM SPSS Statistics 21 software.
Subjects were measured during free walking five times, and mean values were calculated. The plantar flexion moment and ankle dorsiflexion angle were measured and the values at 12%, 31%, and 50% of the gait cycle were calculated, as these are the points in the cycle delineating the three rockers as defined by Perry. The second rocker value was calculated as the amount of change from 12% to 31% and the third rocker from 31% to 50%. These change amounts were compared using a t-test with IBM SPSS Statistics 21 software.
Results: The mean values of the 12%, 31% and 50% plantar flexion moments in the ankle joint were 1.52 ± 1.49 Nm, 6.26 ± 1.73 Nm, and 13.33 ± 1.13 Nm, respectively. The second rocker value was 4.74 ± 1.61 Nm and the third rocker value was 7.06 ± 2.03 Nm. The third rocker value was significantly higher than the second (p = 0.000, <0.01).
On the other hand, the mean values of the ankle dorsiflexion angle at 12%, 31% and 50% were 1.0 ± 2.9°, 8.3 ± 4.0°, and 12.1 ± 5.8°, respectively. The second rocker value of the dorsiflexion angle was 7.3 ± 3.3°, and the third rocker value was 3.8 ± 2.6°. The second rocker value was significantly higher than the third (p = 0.007, <0.01).
On the other hand, the mean values of the ankle dorsiflexion angle at 12%, 31% and 50% were 1.0 ± 2.9°, 8.3 ± 4.0°, and 12.1 ± 5.8°, respectively. The second rocker value of the dorsiflexion angle was 7.3 ± 3.3°, and the third rocker value was 3.8 ± 2.6°. The second rocker value was significantly higher than the third (p = 0.007, <0.01).
Conclusion(s): In this study, we analyzed the kinematic role of the changes in the angle and moment occurring during the second and third rockers of the walking gait cycle. We found that the ankle dorsiflexion angle in the second rocker is higher than in the third rocker and the ankle joint moment in the third rocker is higher than in the second.
Implications: From these results, it is clear that the second and third rockers do not function equally. Our findings suggest that the clinical focus for patients with limited range of motion should be the second rocker, and for patients with muscle activity and output impairments it should be the third rocker.
Funding, acknowledgements: I would like to thank Gunma Paz University for a grant that made it possible to complete this study.
Keywords: gait analysis, roker function, clinical evaluation
Topic: Musculoskeletal
Did this work require ethics approval? Yes
Institution: Gunma Paz University
Committee: Ethics Committee for Human Research of Gunma Paz University
Ethics number: PAZ14-22
All authors, affiliations and abstracts have been published as submitted.
