胸椎側彎青少年行走與跨越障礙時平衡控制與運動學策略之研究

Abstract

青少年原發性脊椎側彎為青少年時期最常見的脊椎側彎。青少年原發性脊椎側彎為矢狀面、額狀面和橫切面三維的變形，患者常伴隨著本體感覺和感覺統合的問題，此綜合神經肌肉骨骼系統的問題可能會導致日常生活功能性動作控制不佳，行走較不穩定甚至是改變動作控制策略。走路為人體神經肌肉骨骼系統以最低層級之自主認知控制下，整合失狀面與額狀面之控制所達成之動態平衡，臨床亦常使用步態評估個人動作控制以及肢段調節能力的方法。然而，在日常生活中，除了平地行走，因障礙物而絆倒為日常生活環境跌倒的危險因子之一，因此，跨越障礙物為一需要高度協調能力的動作，且需要精準的動作控制以及維持全身的平衡，系統性整合下動態平衡之能力以成功且有效的跨越。有鑒於此，過去研究經常透過人體質量中心相對於足底壓力中心之傾角與傾角變化速率描述人體平衡控制，可用於評估動態穩定性之指標參數。因此，本研究以傾角與傾角變化速率比較走路與跨越障礙物平衡控制，評估脊椎側彎對人體肢段協調及平衡控制之影響。過去文獻對於原發性脊椎側彎患者平地走路研究結果一致性低，且對於患者和健康受試者平衡之差異性尚未有一致看法，更缺乏文獻針對跨越障礙物下肢運動學和平衡控制的影響。另一方面，過去研究指出，脊椎側彎亦可能影響身體質量分布，因此脊椎側彎對人體平衡控制之影響亦尚待釐清。 本研究收取青少年原發性脊椎側彎患者和年紀、性別和身體質量指數相仿的健康青少年受試者，分別以自選行走速度於測力板步道執行平地行走和跨越障礙物試驗，其中跨越障礙物包含10%、20%和30%腿長三個高度。其結果顯示，不論是靜態站立、或是平地行走脊椎的側彎會造成患者軀幹、骨盆以及下肢姿勢上的調整，且患者凸側和凹側之間亦有所差異，易造成患者在重心轉換時平衡控制較差。根據跨越障礙物結果顯示，患者於凹側腳跨越障礙物，因牽涉較多的關節改變，導致縮短跨越腳和障礙物之間的距離，絆倒的風險因而上升，不僅絆倒風險增加，基於人體質量中心相對於足底壓力中心之傾角與傾角變化速率之平衡控制發現，脊椎側彎影響平衡控制導致患者跨越障礙物以較不穩定的控制策略，患者以較差的平衡控制與協調模式行走於平地與跨越障礙物。基於本研究之發現，脊椎側彎主要發生在額狀面，但無論是姿勢的調整，協調和平衡控制皆會造成全身性的影響。因此，了解原發性脊椎側彎患者對於姿勢、平衡控制、協調與動態穩定性之影響，有助於臨床人員對疾病判斷和未來治療成效的評估以降低因疾病所帶來的風險。

Adolescent idiopathic scoliosis (AIS) is the most common three-dimensional spinal deformity pathology during adolescence, often accompanied with sensory integration and proprioception problems, which may lead to postural control problems with compromised postural stability and altered end-point control during functional activities. Walking ability is critical for an independent life. The integrated performance of joint movements is reflected in the stability of one’s position control ability. Among the activities of daily living, negotiating obstacles places more neuromechanical demand on the locomotor system than level walking does, and has been identified as an environmental risk factor for falling. A safe and efficient obstacle-crossing task requires precise end-point (foot) position control while maintaining body balance through highly coordinated joint movements of the stance and swing limbs. Describing the position and velocity of the body’s center of mass (COM) with respect to the center of pressure (COP), in terms of COM-COP inclination angles (IAs) and their rate of change (RCIA), provides useful information to investigate dynamic balance control during movements. Identifying the postural adjustments or changes for different phases and events is needed for developing programs to improve the AIS gait, but such information has been limited. Therefore, the purposes of the current dissertation were to fill the gap via three-dimensional motion analysis of quiet standing, level walking and obstacle crossing in patients with AIS; to identify the effects of AIS on the end-point control and on angular kinematics of the trunk and pelvis-leg apparatus during level walking and obstacle-crossing for both the concave- and convex-side limb leading; to identify the effects of Lenke 1 AIS on whole-body balance control during obstacle-crossing. Adolescents with AIS and sex-, age- and BMI-matched healthy controls participated in the current study with informed written consent. The kinematic and kinetic changes between the trunk, pelvis, and lower limb segments, and toe-obstacle clearances at different gait events were measured during quiet standing, level walking and obstacle crossing. Each level walked and crossed obstacles of 3 heights with either the concave- (AIS-A) or convex-side (AIS-V) limb leading. The current findings suggested that postural adjustments involving the trunk, pelvis and lower limb segments were needed in severe thoracic AIS during both quiet standing and level walking, and differed between concave and convex sides at different key gait events during level walking. Patients with AIS adopted different crossing strategies. During AIS-A, additional kinematic modifications were observed, with significantly decreased leading toe-clearance, increasing the risk of tripping. The patients with Lenke 1 thoracic AIS were also found to cross obstacles with altered, compromised COM-COP control in both sagittal and frontal planes when compared to healthy controls. The current findings suggested that although scoliotic spinal deformity occurred mainly in the frontal plane, postural adjustments in all three planes were present at key events during level walking with associated joint loading changes in patients with severe thoracic AIS. With the concave-side limb leading, more joint kinematic modifications with reduced toe-clearance were found when compared to those during the convex-side limb leading, suggesting an increased risk of tripping. Monitoring of such adjustments and the associated joint kinematic changes will be helpful for assessing the disease and treatment outcomes. The results also suggest that the thoracic spinal deformity in Lenke 1 AIS affects the whole-body balance control during obstacle-crossing, which should be monitored for signs of increased risk of loss of balance in the management of such patient groups.