Hip/Pelvis Kinematics

Question 1

Define Open and Closed kinematic chains

Answer 1

Open-Distal end is not fixed and only one joint has to move.

Closed-The distal end is anchored and more than one joint is forced to move.

Question 2

Name the bones and articular surfaces making up the hip joint and describe the direction and orientation of each. Describe the shape of the articular surfaces.

Answer 2

Femur…
Femoral Head–spherical convex articular surface of femur on acetabulum. Medial, slightly anterior, slightly superior.
Acetabulum–articular surface on innominate. Deep and articular surface is horseshoe shaped pg 472. (blue area shows weight bearing.) Inferior, lateral, slightly anterior. Susceptible to anterior dislocation.
Ilium, Ischium, Pubis, become Innominate–nameless. 1/2 of the pelvic girdle.

Question 3

Define–Angle of Inclination name the plane in which the angulation occurs, and give normal values over the life span.

Answer 3

The angle between the neck and the shaft of the femur in the frontal plane. 125 degrees is normal. Coxa (hip) Valga > 125 degrees. This is the angle of the bone, not the joint. (The angle pointed in is valgus?) As the head of the femur moves up, the valgal angle increases. Pg. 470 fig 12-7 (Vertical femur) Coxa vara, where the angle becomes more acute.

Lifespan. angle of inclination. baby 140 degrees. weight bearing moves the head down to 125 degree angle. Old age, the angle may begin to drop down. Density of bone allows for potential of the bone to drop down.

Question 4

Define–Femoral Torsion (Torsion Angle), name the plane in which the angulation occurs. and give normal values over the life span.

Answer 4

The anterior twist of the head an neck relative to the shaft and posterior aspect of the condyles. Transverse plane. 15 degrees anterior is normal. (Those who walk with toes facing in may have anteversion. pg 471 fig 12-8 & 9.

Anterverted is anterior to normal 15 degrees. Retroversion is anything below 15 degrees (even to zero).

Question 5

Define/Describe close-packed position of the hip. What is so “interesting” about the close-packed position for the hip?

Answer 5

Full extension, slight abduction, and internal rotation. Maximal congruency and joint capsule is taught. Ligaments get taught and not fully congruent. (Congruency occurs at 90 degrees, closer to loose-packed position.)

Question 6

List and name the plane the osteokinematic motions and state the number of degrees of freedom at the hip.

Answer 6

3 Degrees of Freedom
Sagittal plane–Flexion/Extension
Frontal plane–Abduction/Adduction
Transverse Place–Internal/External Rotation

Question 7

Describe the direction and location of the axes for each motion

Answer 7

Axis is on the convex side…the femoral head. Axis is dead center of the head for ant/post, med/lat, and vertical. Pg 47. Fg 12-19.

Question 8

Name the 3 additional motions of the pelvis moving on the femurs and describe each.

Answer 8

Anterior pelvic tilt. (sticking butt out) Pelvis moves anterior on femur. (Flexion)
Posterior pelvic tilt. (tucking butt in) Pelvis moves posterior on femur. Both in sagittal plane. (Extension)
Forward Pelvic rotation. (tied to internal rotation) the pelvis rotates anteriorly.
Backward Pelvic rotation. (tied to external rotation) pelvis rotates posteriorly. Must specify left or right. Left forward pelvic rotation occurs on the right hip joint.
Hip hike or pelvic hike. Left pelvic hike is about the weight bearing hip joint. (Left hip abduction…Position of hip would be abducted.)
Hip drop. (Adduction)

Question 9

Name the plane in which each of these motions take place.

Answer 9

Pelvic tilt–sagittal plane.
Hip hike and drop–frontal plane.
Pelvic rotation–rotational plane.

Question 10

What are the relative hip joint positions produced by these three pelvic motions during open and closed kinematic chains? (By the way, at this point you might also consider what is happening or what position results at the lumbar spine with these three pelvic motion, again depending on open v closed kinematic chain.)

Answer 10

FlexED position from FleXION. (Thigh at 90 degrees)
ABductED position from ABductION. (Thigh at lateral angle)
Internally RotatED position from Internal RotatION. (Thigh internally rotated)

Question 11

What are the arthrokinematics of the hip joint? Can you apply the convex-concave rule for both open and closed kinematic chain motion?

Answer 11

Most of the time, we talk about a spot on top of the femoral head in relation to a spot on top of the acetabulum because that’s where weight bearing takes place.
Hip flexion–posterior glide*
Abduction–medial/inferior slide*
Internal Rotation–Spin (looking at spot on top of the acetabulum)
Everywhere else is a slide.
Number 1 *arthrokinematic is slide. Roll in the joint will be symptomatic of joint problems.