Hip biomechanics

Question 0

What is Coxa valga?

Answer 0

> 135 degrees

Increased compression force on the femoral head.

Question 1

What is Coxa Vara?

Answer 1

<120 degrees

Increased tension force on the femoral neck

Question 2

What is the angle of inclination at birth?

Answer 2

150 degrees and normally decreases to 125 degrees at adulthood.

Question 3

Angle of Torsion

1. Normal Antetorsion
2. Excessive Angle (Anteversion)
3. Retroversion

Answer 3

1. Normal Antetorsion= 8-12degrees
2. Excessive Angle= >12degrees
3. Retroversion= <8degrees

Question 4

What are the characteristics of Excessive Anteversion?

Answer 4

• In-toeing
• Increased angle
• Increased anterior exposure
• Increased chance of dislocation
• Increased chance of labral lesions
• Chances increase even more when combined with excessive femoral anteversion
• Tight internal rotators

Question 5

What are the characteristics of Retroversion?

Answer 5

• Toes pointed out
• Decreased angle
• Tight external rotators
• Associated with low back pain

Question 6

Acetabular Labrum

Answer 6

• Surrounds the head of the femur
• Fibrocartilage
• Increases the articular surface of the acetabulum by 10%

Question 7

Iliofememoral ligament

Answer 7

• Also called ligament of Bigelow or Y ligament
• From the AIIS to the inter trochanteric line
• Strongest ligament
• Prevents hyperextension and ER

Question 8

Pubofemoral ligament

Answer 8

• From the pubis to the intertrochanteric line

* Limits abduction and ER

Question 9

Ischiofemoral Ligament

Answer 9

• Attaches from the posterior acetabulum to the trochanteric fossa
• Limits IR
• Weakest intrinsic ligament of the hip

Question 10

Ligamentum Teres

Answer 10

• Intracapsular ligament
• From the acetabular notch to the fovea
• Can be injured by trauma to the hip
• Little or no mechanical support to the hip
• Mainly for nutrition

Question 11

Joint Arthrokinematics for FEMUR ON PELVIS;

Flexion & Extension

Answer 11

Flexion: Posterior/Inferior spin & glide

Extension: Anterior spin & glide

Question 12

Joint Arthrokinematics for FEMUR ON PELVIS;

Abduction & Adduction

Answer 12

Abduction: Superior roll / Inferior glide

Adduction: Inferior roll / Superior glide

Question 13

Joint Arthrokinematics for PELVIS ON FEMUR;

Flexion & Extension

Answer 13

Flexion: Anterior pelvic tilt

Extension: Posterior pelvic tilt

Question 14

Joint Arthrokinematics for FEMUR ON PELVIS;

ER & IR

Answer 14

IR: Anterior roll/posterior glide ER: Posterior roll/anterior glide

Question 15

Joint Arthrokinematics for PELVIS ON FEMUR;

Abduction & Adduction

Answer 15

Abduction: Ipsilateral tilt

Adduction: Contralateral tilt

Question 16

Joint Arthrokinematics for PELVIS ON FEMUR;

ER & IR

Answer 16

ER: Anterior ipsilateral pelvic motion is accompanied with posterior contralateral movement

IR: Posterior ipsilateral pelvic motion is accompanied with anterior contralateral movement

Question 17

Hip closed pack position is?

Answer 17

Full hip extension, slight internal rotation, slight abduction.

Question 18

Hip open pack position is?

Answer 18

30degrees hip flexion, 30degrees hip abduction, slight ER

Question 19

What is the hip capsular pattern?

Answer 19

Flexion, abduction, and IR > Extention

Question 20

What are the primary hip flexors?

Answer 20

Iliopsoas, sartorius, rectus femoris, TFL, pectineus

Question 21

What are the primary hip extensors?

Answer 21

Gluteus maximus, hamstrings, posterior gluteus medius, piriformis

Question 22

What are the pelvic force couples for anterior tilt?

Answer 22

Hip flexors: psoas major, iliacus, sartorius all provide an inferior force or pull from the ASIS

Erector spinae, pulls from the PSIS or sacrum

Question 23

What are the force couples for posterior pelvic tilt?

Answer 23

Trunk flexors: rectus abdominis and external obliques attach from the ASIS/pubic synthesis region and posteriorly tilt the anterior portion.

Hip Extensors: gluteus maximus and hamstring group inferiorly pull from ischial tuberosity and PSIS to initiate the posterior tilt from the posterior side of the pelvis.

Question 24

Hip Abductors

Answer 24

* Stabilize the pelvis and hips while walking * Weak hip abductors associated with back and knee problems. Make sure you assess the whole kinetic chain. * Trendelenberg

Question 25

Hip Adductors

Answer 25

* Create motion in all 3 planes * Assist the primary hip flexors and extensors to provide a more forceful stride in running/cycling. * Active in all degrees of movement

Question 26

Hip Internal Rotators

Answer 26

*Rotate the pelvis over the femur during the stance phase, cause the opposite leg to move anterior

Question 27

Hip external rotators

Answer 27

* Most active during changes of direction activities | ex: plant leg to change directions... externally rotate at hip to change directions

Question 28

What is the most powerful External rotator?

Answer 28

Gluteus Maximus

Question 29

Hip external rotators are commonly weak in LE injuries; | examples?

Answer 29

patellafemoral syndrome IT band syndrome

Question 30

Straight leg raise stabilization with hip movement | -Normal Activation

Answer 30

Rectus abdominis stabilizes pelvic position Maintains normal lumbar curve

Question 31

Straight leg stabilization with hip movement | -Decreased Activation

Answer 31

Rectus abdominis fails to stabilize pelvic position which allows hip flexors to increase lumbar curve Anterior pelvic tilt

Question 32

Normal Hip extension

Answer 32

Pelvic position in standing maintained by iliofemoral ligament tension.

Question 33

Decreased hip extension

Answer 33

Hip extensor muscles required to actively contract to maintain pelvic position in neutral Not obtainable secondary to very tight iliofemoral ligament and tight iliopsoas Increase compression between acetabulum and head of femur

Question 34

What is the obturator internus sling?

Answer 34

Obturator internus forms a functional sling via lessor sciatic notch. Active contraction caused ER and increased joint compression between acetabulum and femoral head to provide stability during movement. Use of the lesser sciatic notch as a pulley system maximizes the mechanical advantage of the obturator internus

Question 35

Dynamic forces acting on the hip joint?

Answer 35

Occur during walking or running Generated from increased muscle activity & Ground reaction force during walking/running

Question 36

Static forces acting on the hip joint?

Answer 36

Force on the hip is more than just body weight

Question 37

Static forces; | What is the percentage of weight does each hip carries during 2 legged standing?

Answer 37

33% | heads/arms/trunk = 66%

Question 38

Static forces; | During 1 legged standing the force on the hip is about...

Answer 38

2.5 times the body weight | 100% from BW, 150% from abductors

Question 39

What side is a cane held on?

Answer 39

The opposite side to the weakened/injured extremity and it is moved with the weakened injured limb.

Question 40

What is the reasoning for what side the cane is held on?

Answer 40

1. Wider base of support and stability 2. Improved balance 3. Off load weight bearing of injured extremity 4. Should follow normal rhythm of gait

Question 41

Hip Osteoarthritis occurs in what percentage of the aging population?

Answer 41

10-20%

Question 42

What are the two types of femoral acetabular impingement?

Answer 42

1. Cam | 2. Pincer

Question 44

What is Cam?

Answer 44

A shear force on the acetabular rib. Jamming of the femoral head against the acetabulum.

Question 45

What is slipped capital femoral epiphysis?

Answer 45

Important pediactric and adolescent hip disorder that is common in adolescents, obese. Associated with retroversion of the hip and coxa vara due to increased forces on hip. Results from a Alter-Harris fracture

Question 46

What is the angle of inclination?

Answer 46

120-125degrees Frontal plane angle occurs between a line bisecting the neck of the femur and a line bisecting the shaft. Keeps lower leg parallel in standing

Question 47

When is bursitis common?

Answer 47

Mostly sedentary women age between 40-60

Question 48

What is lumbopelvic rhythm when looking at the pelvis moving on the femur?

Answer 48

Ipsidirectional Hip & spine moving in the same direction Ex: bending over

Question 49

What is the contradirectrional movement when talking about the pelvis moving on the femur?

Answer 49

Hip & spine moving in opposite directions Allows for decoupling of upper and lower areas of the body Ex: standing up straight, sitting, walking

Question 50

What is Pincer?

Answer 50

Impingement between the acetabulum and femoral head-neck junction. Seen with acetabular retroversion.

Question 51

American college of rheumatology diagnostic criteria for OA

Answer 51

Hip pain Less than 115 degrees hip flexion Less than 15 degrees internal rotation