I. Pain Characteristics: Shortened standing phase time, shortened stride length and decreased gait speed of the affected lower limb. 1. Hip pain: compensatory movements such as lowering of the shoulder joint on the affected side, elevation of the opposite shoulder joint, and excessive tilting of the trunk to the opposite side allow the body weight to cross over the painful joint to reduce the mechanical pressure on the joint surface to alleviate the pain. 2. Knee pain: mild flexion of the knee joint can reduce the tension of the joint capsule and toe landing instead of foot following the ground. Zhang Jiankui, Department of Pediatrics, The First Affiliated Hospital of Henan College of Traditional Chinese Medicine 3. anterior foot pain: reduced plantarflexion of the ankle joint and loss of toe off the ground movement. 4. ankle or posterior foot pain: when landing for the first time, the foot follows the ground disappears and is replaced by the tip of the foot or the medial or lateral side of the foot. II. muscle weakness (a) gluteus maximus muscle weakness 1. gluteus maximus muscle role: hip extension and spinal stabilizing muscle (prevent the body weight from falling excessively forward when the foot touches the ground.) 2. performance when muscle strength decreases: the trunk always remains posteriorly inclined throughout the standing phase, and the bilateral shoulder joints are withdrawn, thus forming the gluteus maximus gait with a raised chest and convex abdomen. 3. mechanism: when the gluteus maximus muscle strength is reduced, its action is compensated by the paraspinatus muscle, resulting in the contraction of the paraspinatus muscle to pull the hip joint backward after the foot follows the ground in order to prevent falling, so that the line of gravity of the body falls on the back of the hip joint and locks the hip joint in the extended position. 4. Compensate: Simple weakness of the gluteus maximus muscle can be compensated by the contraction of the N cord muscle to make the gait close to normal. Clinically, if the S1 nerve root is damaged, both the N cord and gluteus maximus muscles are damaged. (2) gluteus medius weakness 1. role of gluteus medius: hip joint abduction, play the role of stabilizing and supporting the pelvis. 2. 2. When the muscle strength decreases, it shows: unilateral: Trendelenberg gait, i.e. when the affected side is in the standing phase, the pelvis on the healthy side decreases, the pelvis on the affected side protrudes to the side, the trunk tilts to the affected side compensatingly, the shoulder joint on the affected side is down, the hip and knee flexion increases, and the ankle dorsiflexion increases. Bilateral: up and down swaying from side to side, so called duck walk. (c) Hip flexor muscle weakness The flexor hip muscle is the main accelerator muscle in the swing phase, and its muscle strength is reduced causing the lack of power for limb travel in the swing phase, which can only be compensated by the trunk swinging backward at the end of the support phase and suddenly swinging forward at the early stage of the swing phase, and the stride length on the affected side is obviously shortened. (D) quadriceps palsy 1. three periods of quadriceps involvement: end of the striding phase DD extension of the lower leg standing phase DD eccentric contraction, control of knee flexion toe off the ground DD start the lower limb forward stride 2. quadriceps palsy, mainly for the impact of the foot following the ground phase. At this time, the gluteus maximus muscle contracts to maintain the proximal femur position and the triceps calf muscle contracts to maintain the distal femur position, thus locking the knee joint in the hyperextended position. 3. If hip extensor weakness is also present, some patients lean over and press the thigh with their hands during the first heel landing phase and during the standing phase to help extend the knee. Repeated hyperextension of the knee joint will greatly increase the load on the knee ligaments and joint capsule, resulting in injury and pain. (E) Anterior tibial muscle weakness 1. Role of anterior tibial muscle: Ankle dorsiflexion. 2. When the anterior tibial muscle is weak, the support phase is shortened in the early phase after the foot touches the ground because the ankle joint cannot control plantarflexion, so it rapidly enters the middle support phase. In anterior tibial muscle palsy, the patient develops foot drop in the swing phase, resulting in functional hyperextension of the lower extremity, often compensated by excessive hip flexion and knee flexion (cross-threshold gait), while the early phase of the support phase is preceded by full-foot or toe-to-toe contact with the ground, mostly in patients with common peroneal nerve palsy. ② Simultaneous and combined hip flexor weakness or lower extremity spasticity is manifested as toe dragging walking, accompanied by abduction and external rotation of the hip joint. (F) gastrocnemius muscle weakness 1. gastrocnemius muscle role: stirrup action at the end of the standing phase, prompting the leg to swing forward. 2. Gastrocnemius muscle weakness: the explosiveness of the stirrup action is weakened, and the forward movement of the body is reduced and slowed down, which slows down the forward movement of the lower limbs, resulting in a shortened stride length and reduced walking speed. Deformity 1. Hip flexion deformity In the middle and late support phase: if the deformity is unilateral, the contralateral lower limb shows functional overgrowth, using hip lift or trunk tilt to compensate for the contouring function of the swing phase, and the stride length is shortened. 2. Knee flexion is less common and is usually caused by osteoarthritic deformities or lesions. The patient maintains a flexed knee position in both the support and swing phases. Patients must use compensatory mechanisms to stabilize the knee joint during the brace phase. Because the patient is unable to extend the knee at the end of the swing phase, the stride length is shortened. 3. Knee stiffness The angle of joint flexion in the late brace phase and early swing phase is <40 degrees (normal is 60 degrees), while the hip flexion is delayed in both the posterior and the later phases. Knee flexion in the swing phase is driven by hip flexion, and reduced hip flexion will reduce knee flexion, resulting in foot dragging. Patients often compensate in the swing phase by adopting a circle gait, lifting the hip as much as possible or tiptoeing on the opposite lower limb. If the ankle joint is plantar flexion deformed, the patient will walk with the toes or forefoot on the ground, tilt the trunk forward, shift the body weight forward, and increase hip and knee flexion during the striding phase. The proprioception provides information on the position and movement of the joint during joint activity and plays an important role in muscle tone regulation and muscle control; at the same time, the feedback mechanism of proprioception is also important in maintaining the stability of joint function. 2. lower limb extensor synergistic pattern: hip extension, internal retraction and internal rotation, knee extension, ankle plantarflexion and internal rotation. 3. Slowed walking speed, shortened stride length on the healthy side, disappearance of the foot following the ground on the first landing, and knee reversion. 4. The standing phase of the affected side is shortened, and the knee flexion angle is significantly reduced or disappeared due to the spasm of quadriceps muscle during the swing phase. (3) Scissor gait Cause: Spasm of the hip adductor group, commonly found in patients with spastic cerebral palsy or traumatic brain injury. Performance: when stepping phase, the lower limb steps forward medially, accompanied by N cord muscle spasm and knee flexion; ankle plantar flexor spasm appears with the front of the foot on the ground, the lower limb swings forward when the toes drag the ground; excessive hip and knee flexion, prolonging the standing phase, shortening the stepping phase time, reducing the step base (support surface), reducing the stride length, and slowing the step speed. (d) Parkinson's gait lesion site: basal ganglia. Performance characteristics: bilateral motor control disorders and dysfunction, characterized by lack of movement and stiffness of the muscles of the face, trunk, upper and lower extremities. Gait performance: difficulty in starting walking, prolonged double support phase, forward tilt of trunk during walking, mild hip and knee flexion, reduced joint range of motion, no plantar flexion at ankle stride phase, shortened stride length and stride stride length, thin stride, almost disappearance of upper limb swing, easy to fall. Panic gait: Patients walk rapidly forward with small steps, although it is difficult to start walking, and once started and difficult to stop walking, can not stop or turn at will, showing a forward or panic gait. (E) Ataxic gait (ataxic gait) Causes: damage to the cerebellum or its conduction pathways; impaired sensation in the lower extremities. Typical features: walking with two upper limbs abducted to maintain body balance, step base widening, high leg lift, foot landing heavy; can not walk in a straight line, but in a curve or in a "Z" shape; because walking is not easy to control, so walking swaying instability, like a drunkard, so also known as Moet gait or drunkard gait. Lower extremity sensory impairment: The patient's gait is characterized by widening of the step base and rapid gait frequency (stumbling); at the same time, due to the lack of proprioceptive feedback, the patient often needs to look down at his or her feet when walking, thus making it difficult to walk in the dark.