헛디딤 인식 유무에 따른 보행특성 분석

Abstract

[한글]본 연구에서는 보행 중 발생할 수 있는 여러 돌발적인 상황에서 헛디딤을 유도하여 동작특성 및 균형회복 기전에 대해 정량적인 자세균형 평가를 수행하였다. 헛디딤 인식의 유무에 따라 보행인자, 관절각도, 지면반발력, 근전도, 모멘트와 일률, 압력중심 등과 같은 동작특성을 분석하였다./헛디딤 인식보행은 하강된 지면을 내려와 닿는 발의 위치에 따라 발 앞부분이 닿는 헛디딤 인식보행 Ⅰ과 발뒤꿈치로 닿는 헛디딤 인식보행 Ⅱ로 구분할 수 있다. 헛디딤 인식보행 Ⅰ의 경우, 발목관절이 저굴하고 엉덩관절이 신전하며 하강된 지면을 내려온다. 반대쪽 발의 발목관절은 말기입각기에 배굴되며 무릎관절은 유각기동안 굴곡하였다. 또한 전유각기동안 추진력이 감소하여 발목 모멘트와 일률이 크게 감소되었다. 지면과 닿은 이후, 입각기동안 발목관절 배굴은 증가하였으며 제동력은 증가, 추진력은 감소하였으며 하중수용기동안 발목 저굴모멘트 정점이 발생하며 에너지 흡수가 증가하였다. /헛디딤 인식보행 Ⅱ의 경우, 지면을 내려오는 동안 발목관절이 배굴되며 엉덩관절이 신전하였다. 반대쪽 발은 헛디딤 인식보행 Ⅰ과 유사하였다. 입각기동안 전후방향에서 제동력과 추진력이 증가하고 외측의 힘이 증가하였다. 지면을 인식하고 내려온 이후, 입각기동안 발목관절 배굴이 감소하였다. 발뒤꿈치로 지면과 닿은 후 헛디딤 인식보행 Ⅰ보다 큰 충격으로 초기정점이 발생하며 제동력이 증가하고 추진력이 감소하였다. 하중수용기동안 무릎과 엉덩관절은 에너지 흡수가 증가하였다. /한편 헛디딤 보행의 경우는 헛디딤이 발생할 때 유각기 말기동안 발목이 배굴되어 지면과 닿은 직후 발바닥 전체로 빠르게 접촉하였다. 엉덩관절은 헛디딤을 인식한 보행에 비해 크게 신전하였다. 이때 반대쪽 발은 유각기에 골반을 크게 들어올리고 발목이 배굴 후 저굴되어 발 앞부분으로 지면과 닿는다. 또한 무릎관절 굴곡이 크게 발생하며 엉덩관절은 굴곡 후 신전하였다. 전유각기 이후 앞정강근의 활성화로 발목관절이 배굴되며 중간볼기근의 활성화로 엉덩관절은 외전하였다. 전유각기가 짧아짐에 따라 지면을 충분히 추진해주지 못하여 전유각기동안 에너지 생성이 감소하였다. 헛디딤 이후 큰 충격이 발생하여 제동력이 급격한 증가를 보이며 발목관절은 급격히 배굴하여 발목 저굴모멘트가 최대정점이 보인다. 이때 앞정강근과 가자미근의 모두 수축되어 발목 일률은 흡수되나, 헛디딤 인식보행 Ⅰ보다 작게 흡수되었다. 이후 입각기동안 관절 움직임이 작았으며 전유각기에서 넙다리곧은근과 넙다리두갈래근이 수축하여 하지가 무너지는 것을 방지하고, 중간볼기근을 수축하여 엉덩관절은 외전하였다. 이때 추진력이 크게 감소하여 발목 저굴모멘트와 에너지 생성이 감소하였다. /본 연구 결과를 이용하여 향후 노약자와 보행장애자에 대한 임상적인 실험을 통하여 넘어짐을 예방하고 치료할 수 있는 기초자료로 이용할 수 있을 것으로 기대한다.

[영문]Falls are a serious problem among the elderly, frequently resulting in physical injury and significant costs for health care and the unexpected walking is the most frequently mentioned cause of falls in the elderly. To understand unexpected walking and develop methods for avoiding falls that it is important to find the postural recovery mechanism. /The purpose of the present study was to examine the recovery strategy during recognized and unexpected step-down walkings. To investigate the stability of gait in healthy subjects, we designed a movable platform to apply a perturbation during gait. The platform could be moved in the vertical direction by a hydraulic pump controlled an AC servo motor. Three-dimensional motion analyses were performed to determine biomechanical characteristics of the lower extremity during both recognized and unexpected step-down walking in ten young healthy volunteers. Kinematics of the lower extremity, three-dimensional ground reaction forces, electromyography and COP displacements were analyzed before and after step-down. Two types of recognized walking were considered. In recognized walking I forefoot contact was made during stair descent, and in recognized walking II heel contact was found at the same period. /Firstly, in recognized walking I, ankle plantarflexion and hip extension were noted during terminal swing. On the opposite foot, at the same time, ankle dorsiflexion in terminal stance and knee flexion in swing were significant. In addition, ankle moment and power were significantly reduced, since the propulsive force decreased during pre-swing. Right after the forefoot contact during the step-down, a significant dorsiflexion was observed with increased breaking force. However, the propulsive force during pre-swing significantly decreased. Especially, ankle plantarflexion moment increased, which made a significant energy absorption in loading response. /Secondly, in recognized walking II, ankle dorsiflexion and hip extension were observed during stair-descent. The opposite foot showed similar motions to those in recognized walking I. Both breaking and propulsive forces increased, and significant lateral forces were developed in mid-stance. Right after the heel contact during the step-down, ankle dorsiflexion was reduced during stance period. A strong impact was generated due to heel contact, which resulted in significant increases in breaking force. However, propulsive forces during pre-swing decreased. Significant energy absorptions at both knee and hip were observed during loading response. /Finally, in unexpected step-down walking, the whole plantar surface of the foot or the heel contacted to the ground. A rapid ankle dorsiflexion was found right after the unexpected step-down and increased plantarflexion moment was generated during loading response. After the unexpected situation, the break force was rapidly showed the increase. At this time, both tibialis anterior and soleus were simultaneously activated. Less energy was consumed than in recognized walking I. Moreover, the range of motion at ankle, knee and hip were significantly small during stance period. In pre-swing, rectus femoris and biceps femoris prevented the collapse of the lower limbs. As gluteus medius was activated in swing phase, hip adduction and internal rotation of the thigh were noted. During late stance, propulsive forces decreased and thus, both plantarflexion moment and power generation were significantly reduced. On the opposite side, compared with both recognized walkings, hip extension and pelvic upward motion during terminal swing were significant. The opposite foot showed forefoot contact due to ankle plantarflexion in swing phase with significant knee and hip flexions. Due to the shortened pre-swing, the energy generation at the ankle to push sufficiently off the ground was greatly reduced. /In summary, in this study provided kinematic and kinetic results in recognized and unexpected step-down walkings were presented. This preliminary study will be helpful to understand the biomechanics of unexpected dynamic perturbations and valuable to prevent frequent falling of the elderly and patients with gait disorders.