Shusaku Kanai

Effects of methods of descending stairs forwards versus backwards on knee joint force in patients with osteoarthritis of the knee: A clinical controlled study

BackgroundThe aim of this study was to investigate the kinetic characteristics of compensatory backward descending movement performed by patients with osteoarthritis of the knee.MethodsUsing a three-dimensional motion analysis system, we investigated lower extremity joint angles, joint moments, joint force of the support leg in forward and backward descending movements on stairs, and joint force of the leading leg at landing in 7 female patients with osteoarthritis of the knee.ResultsCompared with the forward descending movement, knee joint angle, joint moment and joint force of the support leg all decreased in the backward descending movement. Joint force of the leading leg at landing was also reduced in the backward descending movement. In addition, we confirmed that the center of body mass was mainly controlled by the knee and ankle joints in the forward descending movement, and by the hip joint in the backward descending movement.ConclusionsSince it has been reported that knee flexion angle and extensor muscle strength are decreased in patients with osteoarthritis of the knee, we believe that backward descending movement is an effective method to use the hip joint to compensate forthese functional defects. In addition, due to the decreased knee joint force both in the leading and support legs in backward descending movement, the effectiveness of compensatory motion for pain control and knee joint protection was also suggested.

The effect of additional activation of the plantar intrinsic foot muscles on foot dynamics during gait

BACKGROUND The plantar intrinsic foot muscles (PIFMs) contribute to support the medial longitudinal arch. But the functional role of the PIFMs during dynamic activities is not clear. The purpose of this study was to examine the change in the foot dynamics during gait accompanied with the change in the PIFMs activity to determine the functional role of the PIFMs during gait. METHODS Twenty healthy male subjects were randomly assigned to the electrical stimulation group (ESG) or control group (CG). In the ESG, the electrical stimulation to the PIFMs was provided from mid-stance to pre-swing using surface electrodes to simulate reinforcement of the PIFMs. The foot dynamics during the stance phase of gait was measured using a 3D motion analysis, and the amount of change from baseline (electrical stimulation was not provided) was compared between groups using an independent sample t-test. RESULTS In the ESG, the timing for the navicular height to reach the minimum value was significantly later, and the vertical ground reaction force (2nd peak) significantly decreased more. There were no group differences in the amount of change from baseline on gait velocity, stance phase duration, minimum navicular height and ground reaction force in other directions. CONCLUSION Results from this study showed that the functions of the PIFMs most likely include shock absorption and facilitation of efficient foot ground force transmission during the stance phase of gait.

Does the weakening of intrinsic foot muscles cause the decrease of medial longitudinal arch height

[Purpose] There are no reliable evidences that the weakening of intrinsic foot muscles causes the decrease of the medial longitudinal arch (MLA) height. The purpose of this study was to confirm whether the fatigue of intrinsic foot muscles decrease the MLA height during standing and gait using 3D motion analysis system. [Subjects and Methods] Twenty healthy male subjects participated in this study. Foot kinematics was measured using an Oxford Foot Model before and after fatigue-inducing exercises of the abductor hallucis and flexor hallucis brevis muscles. [Results] Following fatigue-inducing exercise, in both standing and gait, the MLA height did not decrease but slightly increased. In addition, the reduction of a rear foot eversion angle was noted. [Conclusion] Fatigue of the abductor hallucis and flexor hallucis brevis muscles did not cause a change associated with collapsing of the MLA during both standing and gait. This suggested that the MLA support force from these muscles would be compensated by other MLA support structures, such as extrinsic foot muscles.

Analysis of Gait with One Crutch and One Ankle Immobilized

片側足関節ギプス固定時の「歩きにくさ」を調査する目的で，三次元動作解析装置を用い裸足時および足関節ギプス固定時の下肢関節モーメント・角度を計測し，運動学・運動力学的な検討を加えた。また，足関節固定時の歩行について被験者の感想を聴取したところ，「膝が止められるよう」「踏み返しが難しい」等の「歩きにくさ」に関する意見が聴取された。足関節ギプス固定時において，立脚中の膝関節伸展角度のピーク値が増加し，制動力としての膝関節屈曲モーメントの発生が示唆された。実験結果より足関節固定中の「歩きにくさ」には立脚中期付近に発生する膝関節の過度な伸展と伸展制動力としての膝関節屈曲モーメントが影響すると考えられた。