Lower Limb Nerve Injuries and Gait Abnormalities Flashcards
What is the basis of walking? What is the external force acting on you to move you in desired direction? How do you use the ground to create external force?
Shifiting one’s center of gravity from one place to another. The ground’s force = external force. If you press (plantarflex) against the floor downwards and backwards, floor will push you forwards and upwards.
Ambulation
Walking
What is the gait cycle’s goal? Describe hip motion. What clinical issue screws this up? What does leg do to prevent up and down motion of center of gravity?
Minimize movement of center of gravity in directions that are not desired (more forward, not upward). Want to maintain balance and use the least amount of energy as possible. This is done by moving the center of gravity in a straight line (place one foot in front of the other). Opposing hip acts as pivot point. You rotate AROUND it with the other femor. The Moving femor’s hip internally rotates. You alternate between internal and external rotation. Osteoarthritis screws this up by preventing the alternating internal and external hip rotation. Leads to swaying since you cannot rotate. Up and down motion is prevented by slight flexion at knee joint (avoid walking with fully extended knee).
Describe stance phase of gait cycle.
- Heel strike. Note foot is dorsiflexed
- Flatten foot (plantar flex)
- Midstance….you need to bring trunk of body over supporting base.
- Plantar flex again. This allows foot to leave ground
- Toe off. Limb is now behind you trunk
Describe swing phase of gait cycle.
- Acceleration: you need to accelerate the leg you shot backward form the stance phase. Bring it to the trunk.
- Midswing: brings lag to center of gravity
- Deceleration: Your leg has overshot your center of gravity. Decelerate it so that you can heel strike and start the stance cycle.
Describe relationship between speed and percentage of stance and swing phases
Stance phase normally takes up 60% of the walking period. Swing space is 40%. The quicker you move, the lower you stance percentage becomes. 50%-50% = goal. Running = 0% stance (Usain Bolt)
When you walk, what double period exists? When you run, what double period exists?
Double stance and double swing respectively
When standing, what is the tendency of the force vector on the hip, knee, and ankle joint? What resists each movement?
- Behind the hip: extend (iliofemoral and ischiofmeoral ligaments resit this.
- In front of the knee: extend (posterior knee joint capsule opposes this)
- In front of the ankle: dorsiflexion (opposed by gastrocnemius and solius)
Upon heel strike, where is the force vector passing? What muscles resist the flexion of the hip during heel strike? What weakens the gluteal nerve? What paralyzes the gluteal nerve? What do patients with Gluteus maximus gait do in order to avoid needing to extend (glute max) at the hip?
Vector passes infront of the hip (flex), behind the knee and behind the heel. Resisted by the gluteus maximus (Innervated by inferior gluteal nerve. Causes extension). Gluteus maximus is paralyzed by sevoring inferior gluteal nerve and paralyzed by sevoring L5, S1, or S2. APtient swith issues with these nerves shift their center of gravity posterior to the hip joint to encourage extension at the hip and eliminate need to extend via gluteus maximus. Patients shift shoulders backwards (exterior lurch on weakened side).
What doe sth eknee what to do during the heel strike? What resists this action? What innervates the quads. What action results of quads of patient is weakened/paralyzed?
- Knee wants to flex.
- Action resisted by thigh leg extensor (quadraceps, innervated by femoral nerve). If quads are weakened (cut :2, 3, or 4) or paralyzed (cut femoral) The patient will trying to move knee joint behind the force line so that they do not need to use the knee extensor. This results in the patient moving the axis of rotation behind the knee since you cannot move the force line in front of the knee (You dine yourself leaning yourself forward and putting hand on leg each time you heel-strike affected leg. The goal of the hand is to help push back the femur.)
During heel-strike, what is your foot naturally going to do? What does your body do to resist this? What happens if tibialis anterior is weakened (and what do you haev to cut to get this to happen)? What happened if tibialis anterior is completely cut off of innervation. How is foot slap related to walking speed?
Naturally, foot plantarflexes due to the ground;s reaction…the flow of the force on impact. So your body activates dorsiflexors (tibialis anterior) in order to avoid foot-slapping the ground. Note that a weakened tibialis anterior (cutting L4) will lead to a foot-flap on impact with the affected tibialis anterior leg. In the case of a tibialis anterior with no innervation (cut off deep fibular nerve) you will have to literally drag your foot. Those who walk fast have increased rate of foot-slap. since you are increasing stress on tibialis anterior.
When in midstance position, where does your forceline travel? What is the other foot doing when one foot is in midstance? What are the natural tendencies of the leg during midstance and what muscles counter this??
Forceline travels through hip, behind knee, and infront of foot. Note that the other foot is swinging (midstance = single stance!!!). During midstance, nautrally leg is partially flexed (resisted by quads = knee extensor) and ankle is in dorsiflexion (resisted by plantar flexion muscle….Gastrocnemius and solius)
While foot is in singe stance, what is the natural tendency of the body at the hip? What muscles counter this, and their innervation? What test tests for this? Patients with weakened gluteus medius and minimus do what tto counter ths need tio use leg abductors? What is a positive trendelenburg sign +gait name??
Naturally in midstace, body wanted to lean towards floating side (adduct). Adduction is avoided with abductors (gluteus medius and minimus muscles, innervated by superior gluteal nerve). Use trandelenberge test for this. When these 2 muscles are weak (cut l3, l4, or l5) or paralyzed (cut superior gluteal nerve), patients will shift force line outside the hip (otuside the spporting base, and TOWARDS THE WEAKER MUSCLES) to make the hip and abductor and eliminate the need to use the glute minimus and medius. Positive trendelenburg sign = unsupported side of the pelvis drops…trendelenburg gait.
During midswing, what is the natural tendency of the body? What happens if anterior tibial muscles are paralyzed? What gait is associated with weakend tibia anterior is lateral compartment is also weakened?
Normally in midswing, gravity causes extension at knee (flexion caused by hamstrings for resistance) and plantarflexion at ankle (dorsiflexion provided by tibialis anterior). If tibialis anterior is weakend or noninnervated, you would need to increase flexion of knee in order to clear the foot from the ground. If one struggles with this, you will notice a toe-strike action. Weakend tibius anterior can lead to circumducted gait (and need for a cane) if lateral compartment is also weakend, which will also help clear foot from the ground
