Biomechanics II Lecture 8 (P11) PDF

‫السالم عليكم و رحمه الله و بركاته‬  Ahmed Torad, PhD, PT, Cairo university, 2020 Presente lecturer, Basic Science department, d by Faculty of Physical Therapy, Kafrelsheik Week Lecture Practical Wee Mid-term Exam...

‫السالم عليكم و رحمه الله و بركاته‬  Ahmed Torad, PhD, PT, Cairo university, 2020 Presente lecturer, Basic Science department, d by Faculty of Physical Therapy, Kafrelsheik Week Lecture Practical Wee Mid-term Exams k8 Gait 6 Applications on Abnormal gait Wee Abnormal gait due to muscle due to muscle weakness weakness k9 Stress-strain curve Wee Applications on stress- Stress –strain curve k 10 strain curve application on stress- Wee Applications on stress- strain curve (Bone strain curve k 11 loading and fractures ) Wee k 12 Revision Causes of pathological gait Pathological Gait Due To Muscle Weakness  Causes of pathological gait 1- Deformity 2- Impaired Motor Control (Spasticity) 3- Sensory Loss 4- Pain 5- muscle weakness  Weakness of Pretibial Group (dorsi flexors) A- normal function: 1- Controls plantar flexion moment from heel strike to foot flat because GRFV pass posterior to the ankle. 2- Dorsiflexes the ankle in initial swing. 3- maintain ankle in dorsiflexion in midswing, terminal swing and heel strike. B- effect of weakness on gait: 1- Inability to counteract plantar flexion moment so there is excessive plantar flexion from heel strike to foot flat. 2- The entire foot or toes would strike the floor at initial contact. 4- Toe drag during swing phase and lack of normal heel strike. C- Possible compensation: In stance phase: 1- Forward lean of the trunk with anterior pelvis tilt. 2- Knee hyperextension 3- the toes positioned first at heel strike to eliminate the need for dorsiflexion. This position C- Possible compensation: In swing phase: 1- Functional shortening of the affected limb can be produced by increased hip flexion to lift the limb and the foot to prevent toe drag “high steppage gait”. 2- Shortening of the limb can be done also by hip hiking. C- Long term effects of compensation: 1- Genurecurvatum may occur as a result of prolonged knee hyperextension. 2- Low back pain results from compensatory forward trunk leaning. 3- Easy fatigue due to increase amount of energy expenditure as a result of previous compensation.  Weakness of Calf Muscles (PLANTAR FLEXORS) A- normal function: GRFV passes anterior to the ankle joint in midstance, terminal stance and preswing creating dorsiflexion moment, this is compensated by action of plantar flexors. B- Effect of weakness on gait: Inability to counteract dorsiflexion moment leading to Excessive ankle dorsiflexion. C- POSSIBLE COMPENSATION: 1- Delay heel rise (prolonged heel contact) during stance phase (terminal stance and preswing). 2- Decrease in propulsive force due to lack of plantar flexion. 3- Short steps and slower walking speed.  Other causes of pathologic al gait  Impaired Motor Control (Spasticity) Soleus and gastrocnemius spasticity: leads to persistent ankle plantar flexion and inability to rise on the metatarsal heads. Hamstring spasticity: leads to persistent knee flexion which limits the effectiveness of terminal swing and restricts thigh advancement in stance. Lack of motor control causes the patient to use mass flexion pattern: That is, the hip and knee flex simultaneously while the ankle dorsiflexes with inversion. Stance stability is attained by mass extensor pattern: That is the hip and knee extensors and ankle plantarflexors act  sensory Loss Sensory loss obstructs walking as it prevents the patient from knowing the position of the hip, knee, and ankle or foot. Moderate sensory loss causes slow walking, while greater loss causes the patient to be unable to use his available motor control because he cannot trust the motions that occur.  Pain The main causes of musculoskeletal pain are: Excessive tissue tension. Joint effusion due to trauma or arthritis  deformity contracture is the most common cause of deformity. For example In swing a plantar flexion contracture: inhibits floor clearance, so increased hip flexion is needed for floor clearance. knee flexion contracture: blocks progression during stance because it: 1- inhibits the A hip flexion contracture: impairs hip stability during stance. the trunk lean forward of the vertical line. This introduces additional strain on the back and hip extensors.