Kinesiology RoR 10, 11, 12

How many bones comprise the knee joint? What are they called?

Three bones

Femur, Tibia, Patella

Why is the knee joint frequently injured?

It’s positioned between two bony levers

What is the significance of the tibial tuberosity?

All four quadriceps insert on the tibial tuberosity

What is the function of the patella and what kind of bone is it?

The patella is a sesamoid bone

-Increase internal movement arm of quadriceps

-Centralize force of quadriceps pull

-Reduce tendon and friction forces

-Contribute to overall knee stability

-Provide bony protection

How many degrees of freedom does the knee have? In what planes??

Two degrees of freedom

Flexion/extension-sagittal plane (largest motion)

Rotation-transverse plane (smallest motion)

What do the menisci do?

Fibrocartilaginous- attached to the tibia to deepen the joint’s socket

-Promote lubrication of joint

-Prevent joint capsule from intruding into joint space

-Partially protect against excessive motion

What does ACL stand for and what does it do?

Anterior Collateral ligament (ACL)- resists tibia from going forward (anterior) it’s like a band stopping the tibia pushing forward

What does PCL stand for and what does it do?

Posterior Collateral Ligament (PCL)- resits tibia from going backward (posterior) its another band that protects the leg going too far backward

What does MCL stand for and what does it do?

Medial Collateral Ligament (MCL)- stop us from knees from collapsing inward

What does LCL stand for and what does it do?

Lateral Collateral Ligament (LCL)- help stop the knees and leg going outward

What does the tibiofemoral joint capsule do?

Forms a sleeve around the knee Helps stabilize the knee

If we have edema about the knee where will it collect?

Suprapatellar pouch- pouch area above the knee

What are the norms for knee extension/flexion?

Flexion- 135 degree

Extension- 0 degrees; sometimes hyperextend but not past 15 degrees

Explain the screw home mechanism?

Tibia stays locked and the femur sits on it when coming extended; when we go into full extension the tibia will rotate medially and lock in place like a key lock (closed kinetic chain)

Which muscle serves as the primary medial stabilizer of the patella?

Vastus medialis oblique (VMO)

At what degree of flexion does the patella have the most contact with the femur?

90 degrees of flexion because it is a lot of weight bearing positions

At what degree of flexion does the patella have the least contact with the femur?

Full extension

What is patella baja?

Patella baja is the knee sitting lower (patella lays lower on the femur)

What is patella alta?

Patella Alta is the knee sitting higher up (patella lays higher on the femur)

Knee extensor (quad) function is to?

Stabilize: isometric (on a bus were using our quads to stay steady when being moved)

Decelerate: eccentric (stop knee flexion when landing)

Accelerate: concentric (box jump)

Knee flexor (hamstring) function is to?

little force required by these muscles in open chain

Closed chain- great forces required particularly by hip

Dynamically restrain anterior tibial translation

Function to assist and decelerate rotation

Why is hip flexion with knee extension inefficient?

Hamstrings- passive insufficiency

Rectus Femoris(Quad)- active insufficiency

Why is hip extension with knee flexion inefficient?

Hamstrings will have active insufficiency( too short to force)

Rectus Femoris (Quad) -passive insufficiency (too tight to stretch over hip and knee

Why is knee flexion with plantar flexion inefficient?

Gastrocnemius- shortened at knee and ankle

Which knee compartment absorbs more weight : medial or lateral? How much weight?

Medial compartment absorbs 60% of forces

People with patellofemoral pain syndrome report most pain at what degree of knee flexion?

90 degrees

What are the two reasons for extensor lag at the knee?

Weakness

Pain

Why does swelling in the joint capsule impact proprioception?

Our ligaments(ACL, PCL, MCL, LCL), Capsule/synovial lining, and Menisci all have mechanoreceptors that are embedded within the area, and when the area is injured we have less proprioception

Which long bone bears 90% of the weight at the ankle?

Tibia

Which is the largest and strongest tarsal bone?

Calcaneus

What protects the calcaneus?

Thick fat pad

Which of the metatarsals is thick and shortest?

1st metatarsal

Which of the metatarsals is thin and longest?

2nd metatarsal

The metatarsal shafts are concavely arched: what does this help with?

Shock absorption

What do sesamoid bones do in our body? What is their purpose?

absorb weightbearing forces and reduce friction

Name the motions that the ankle moves in?

Dorsiflexion/plantarflexion

Abduction/adduction

Eversion/Inversion

What three motions does pronation of the foot include?

Dorsiflexion

Abduction

Eversion

What three motions does supination of the foot include?

Plantarflexion

Adduction

Inversion

What is a mortise joint (describe the motions) : give an example?

Horseshoe shape of two things together and it widens or closes in depending on how you move

the ankle bones are an example the horseshoe widens or closes in when foot moves up and down

Which “ray” is used as a central reference in foot & a stable platform for push off during locomotion

(ray refers to the cuneiform, metatarsal, and respective phalanges)

Second ray

What is the minimum degrees of MTP extension required for normal ambulation? (MTP joints are biaxial)

Minimum of 65 degrees at Metatarsal phalangeal joints for normal ambulation

What muscle (group) contributes 80% of plantarflexion torque?

Triceps surae (gatrocnemius and soleus)

What muscle is the primary dorsiflexor of the ankle?

Tibialis anterior

What is the function of the foot intrinsics?

-Move collectively as a group

-Provide stability or balance of foot

What is Pes Planus?

“flat feet,” increases stress of muscles that control pronation- no arches on medial side

What is Pes Cavus?

higher than normal arch of the foot, forces are not absorbed transmitted proximally

What is hallux valgus?

Lateral deviation of big toe

The big toe sticks out laterally

In gait is the adult conscious or subconscious?

Subconscious level

Define gait?

Achieving upright locomotion on foot (walking, running, or jogging)

Define ambulation?

Type of Locomotion

Usually clinically-with or without an assistive device

What is “upright posture” supported by?

Supported by “antigravity” muscles

What is postural sway?

-Body is not stationary, even standing in place

-Small motions during this=postural sway

What is the ankle recovery strategy?

-Postural control initiated at the ankle

-Preferred strategy when challenge is small

What is the hip recovery strategy?

-Control of posture from hip, pelvis, and trunk

-Preferred strategy when challenge is large and fast

What is the stepping recovery strategy

-Used for very large and rapid changes in center of mass

(COM)

-Essentially one needs to take a step to regain balance

and prevent falling

The gait cycle is divided in to two phases: what are they?

“Stance” and “Swing”

Define “double limb support"?”

When both feet are in stance

(both feet in contact with the ground)

What are the functional tasks of gait?

-Weight Acceptance

-Single limb support

-Limb Advancement

Define Step length?

  Distance between initial contact (heel strike) of one foot to the initial contact of the other

Define Stride length?

Distance between initial contact of foot and initial contact of SAME foot

Define Step width?

Horizontal distance between two feet

Define Angle of Progression?

7 degrees of out toeing compared to the straight line of progression

What is the “Center of Pressure” and how does it change through the gait cycle?

Location within foot where GRFs( Ground Reaction Forces) are applied

-At IC, CoP is just lateral to heel

-As body weight moves over foot, CoP continues forward

-Near center of foot at midstance

-Moves medial between first and second metatarsal heads

during terminal stance and pre-swing

What LE muscles are working at initial contact?

tibialis anterior, gastrocnemius and soleus, quad turns on

What LE muscles are working at loading response?

anterior tibialis, quad bends, gluteus maximus and medius

What LE muscles are working at Midstance?

the Gluteus medius is working at midstance

What LE muscles are working at terminal stance?

gastrocnemius and soleus working at terminal stance

What LE muscles are working at swing?

Hamstrings (turn on to slow down swing to the appropriate speed)

What are the kinetics of the Upper extremity while ambulating?

Arm swing—posterior motion at shoulder occurs largely through a posterior deltoid contraction; no major muscle bursts occur with anterior shoulder motion

What are the kinetics of the Trunk while ambulating?

-Trunk extensor activity is evident at IC to counterbalance flexion torque of spine

What are the characteristics of immature walking?

-Short steps; increased cadence

-Exaggerated periods of double limb support

-Upper extremities used for balance

- Lack of pelvic mobility

What are the characteristics of mature walking?

-Stability in stance

-Sufficient foot clearance in swing

-Prepositioning of foot during swing for IC

- Adequate step length

-Efficient energy expenditure

What is the effect of an assistive device on gait?

-Upper extremities must hold onto device; no reciprocal arm swing

-Generally, more energy is required

-Cognitive demands are greater

Explain how running is different than walking?

-The swing is longer than the stance

-two period of limb support occur- it’s a double float

-more speed and cadence

-greater force pushed onto the ground

What is “double float”?

When both the knee drives come from the hips and glutes, the legs then hang relaxed

What does person with CP’s gait look like?

-Increased hip flexion/adduction/medial rotation

-Weak hip extensors/abductors/quadriceps and leg muscles

-Increased energy cost of ambulation

What happens to gait with CVA?

-Increased energy expenditure to cover same distance

as an unimpaired individual (because it takes longer)

-Flexor muscles active during swing

-Extensor muscles active during stance

-Premature and continued stance muscle activity

What happens to gait with Parkinson’s?

Increased speed with shortening stride length

-Difficulty stopping and changing direction

-Diminished trunk and pelvic motions

What happens to gait with ataxia?

-Uneven step length

-Irregular step width

-Absent rhythm

What happens to gait with quad weakness?

-Knee placed in full extension because quadriceps may not be strong enough to control knee flexion

-Knee may have tendency to hyperextend (locks)

What happens to gait with knee motion restriction?

-Stride length is shortened

-Knee does not reach full extension at midstance; center of mass (COM) remains lower throughout gait cycle

What happens to gait with ankle motion restriction?

-Early heel rise during stance

-During swing, may need to increase hip flexion/knee flexion to prevent “tripping”

What happens to gait with glut med weakness?

-Trendelenburg gait

-Compensation occurs by leaning toward affected side

-Assistive device (cane) is recommended on unaffected side