Effect of a rigid ankle foot orthosis and an ankle foot orthosis with an oil damper plantar flexion resistance on pelvic and thoracic movements of patients with stroke during gait

Abstract

Background: Impairments of trunk movements in gait of stroke are often reported. Ankle foot orthosis (AFO) is commonly used to improve gait of stroke; however, the effect of different types of AFOs on the pelvic and thoracic movements during gait in stroke has not been clarified.

Methods: Thirty-four patients with stroke were randomly allocated to undergo 2 weeks of gait training by physiotherapists while wearing a rigid AFO (RAFO) with a fixed ankle or an AFO with an oil damper (AFO-OD) that provides plantarflexion resistance and free dorsiflexion. A motion capture system was used for measurements of shod gait without AFO at baseline and with and without AFO after gait training. Two-way repeated ANOVA, Wilcoxon signed-rank test, and Mann-Whitney U test were performed for the data after the gait training to know the effect of different kinds of AFOs.

Results: Twenty-nine patients completed the study (AFO-OD group: 14, RAFO group: 15). Interactions were found in pelvic rotation angle, change of shank-to-vertical angle (SVA) in the stance, and paretic to non-paretic step length, which increased in AFO-OD group with AFOs (p < 0.05), while the SVA decreased in RAFO group with AFOs (p < 0.05). The main effects were found in pelvic rotation at the contralateral foot off, and thoracic tilt at foot off when an AFO was worn. The change of SVA in stance was positively correlated with the pelvic rotation in the AFO-OD group (r = 0.558). At initial contact, pelvic rotation was positively correlated with thoracic rotation in both groups.

Conclusions: The findings in 29 patients with stroke showed that pelvic and thoracic movements especially the rotation were affected by the type of AFOs. Pelvic rotation and lower limb kinematics exhibited significant improvements with AFO-OD, reflecting more desirable gait performance. On the other hand, the increase in thoracic in-phase rotation might expose the effect of insufficient trunk control and dissociation movement. Trial registration UMIN000038694, Registered 21 November 2019, https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_his_list.cgi?recptno=R000044048 .

Keywords: Ankle–foot orthosis; Biomechanics; Gait; Rehabilitation; Stroke; Trunk movement.

Fig. 1

Flow diagram for patient’s selection process

Fig.2

Correlation coefficient between parameters: a AFO-OD group; b RAFO group. ICPz: pelvic rotation angle at initial contact; ICTz: thoracic rotation angle at initial contact; CFOPx: pelvic tilt angle at contralateral foot off; CICPx: pelvic tilt angle at contralateral initial contact; PSstep: paretic to non-paretic step length; ShankCIC: shank vertical angle at contralateral initial contact; ShankFO: shank vertical angle at foot off; ShankST: the change of shank vertical angle in the stance

Fig. 3

AFOs used in this study. a AFO-OD: AFO with an oil damper; b RAFO: plastic customized rigid AFO

Fig. 4

A schematic design of the AFO with oil damper unit. The oil damper unit consists of a hydraulic cylinder(1), a ring portion metal plate (2), and a metal plate (3). An adjustment screw (4) controls the flow rate of the oil by varying the orifice diameter; the smaller the orifice diameter, the lower the flow rate, allowing for greater resistance to plantarflexion of the ankle joint at heel strike. A spring (5) assists with dorsiflexion. The rod cap (6) is used to set the initial angle of the ankle joint