Hip Biomechanics

Question 1

What are the biomechanic functions of the hip joint?

Answer 1

i) support weight of torso

ii) transfer forces up through pelvis and trunk

Question 2

What is the hip joint type? (all categories)

Answer 2

i) synovial
ii) simple
iii) ball & socket
iv) unmodified ovoid
v) stability > mobility

Question 3

What is the pain pattern for osteoarthritis of the hip?

Answer 3

i) proximal inner thigh
ii) anterior thigh
iii) ischial tuberosity

Question 4

What is the pain pattern for a labral tear at the hip?

Answer 4

i) lateral peritrochanteric area

ii) central groin

Question 5

What movements does the ilifemoral ligament resist?

Answer 5

Extension (with external rotation).

Question 6

Which hip ligament(s) blend with the joint capsule?

Answer 6

i) ischiofemoral

ii) pubofemoral

Question 7

In what position is the ischiofemoral ligament taut?

Answer 7

Extension with full internal rotation. Superior fibres are more taut with adduction, inferior fibres are more taut with hip flexion.

Question 8

Which movements does the pubofemoral ligament resist?

Answer 8

Extension and abduction.

Question 9

What is the resting position of the hip joint?

Answer 9

30’ flexion
30’ abduction
slight external rotation

Question 10

What is the close packed position of the hip joint?

Answer 10

Full extension
Full abduction
Full internal rotation

Question 11

What is the capsular pattern of the hip joint?

Answer 11

flex > ABD > IR (FABIR)

Question 12

Describe normal hip joint end feels.

Answer 12

Flexion is soft tissue approximation. All other movements are tissue stretch or capsular.

Question 13

Describe the biomechanic contributions to hip joint stability in normal standing (ligaments, intra-articular etc.).

Answer 13

In near full hip extension, the COM is posterior to the axis of the hip joint creating an extensor torque. The extracapsular ligamentous complex (especially ilifemoral) passively prevents further extension therefore stabilizing the joint via passive flexor torque. The femoral head is aligned with the thickest part of the articular cartilage therefore protecting the subchondral bone.

Question 14

Which region of the acetabulum has the thickest articular cartilage?

Answer 14

Anterosuperior region.

Question 15

Describe the biomechanic consequences of a hip flexed posture in standing.

Answer 15

In flexion, the COM is anterior to the axis of the hip joint therefore creating a flexor torque. The glutes and hamstrings need to prevent further flexion by generating an extensor torque. This increases energy demands and therefore need for rests as well as increases joint forces. There is also increased stress secondary to misalignment of cartilage.

Question 16

What are three possible ways to address a hip flexed standing posture?

Answer 16

i) hip extension ROM
ii) APT/PPT pelvic stability
iii) Ab strengthening to improve relative PPT.

Question 17

Which region of the hip experiences arthritic changes first and why?

Answer 17

The anterior aspect of the joint. This is because it is the region of stance phase loading.

Question 18

What pattern of ROM restrictions would you expect in early osteoarthritis of the hip?

Answer 18

i) decreased extension

ii) decreased internal rotation

Question 19

How might a patient with early hip osteoarthritis prefer to position their hip (2 options) ?

Answer 19

i) flexed and adducted. AND/OR

ii) extended and abducted

Question 20

What pattern of ROM restrictions would you expect in late osteoarthritis of the hip?

Answer 20

flex > ABD > IR. May be paired with restricted extension and ER.

Question 21

What causes ROM restrictions in early osteoarthritis of the hip?

Answer 21

Compensations for pain relief. Ex. reduced stride length and stance time causes reduced extension and internal rotation.

Question 22

What is the relationship or AROM and PROM in late osteoarthritis of the hip?

Answer 22

The difference between AROM and PROM is much greater in the presence of severe OA.

Question 23

In what ways does gait change in the presence of hip osteoarthritis?

Answer 23

i) slower (reduced cadence and stride length)
ii) +ve Trendelenberg (or reverse)
iii) Increased APT and frontal plane rotation (compensate for reduced hip extension)

Question 24

Why might a reverse Trendelenberg be present in hip osteoarthritis?

Answer 24

i) Weak hip abductors.
ii) Loading COM in a position where hip ABDs are at an inefficient length (not being used) reduces mechanical load on the hip and is less painful.

Question 25

What are the osteokinematic movements at the hip joint and the normative ROM values?

Answer 25

i) flexion (110’-120’)
ii) extension (10’-15’)
iii) abduction (30’-50’)
iv) adduction (30’)
v) internal rotation (30’-40’)
vi) external rotation (40’-60’)

Question 26

Describe planar and axial movement of hip flexion/extension.

Answer 26

i) sagittal plane

ii) coronal axis

Question 27

Describe planar and axial movement of hip ABD/ADD.

Answer 27

i) coronal plane

ii) sagittal axis

Question 28

Describe planar and axial movement of hip rotation.

Answer 28

i) transverse plane

ii) longitudinal/vertical axis

Question 29

What is a cardinal swing?

Answer 29

A swing or glide that is not paired with a spin.

Question 30

Which movements at the hip have cardinal swings?

Answer 30

i) ABD/ADD

ii) IR/ER

Question 31

Describe the arthrokinematics of hip flexion. How would you treat restriction?

Answer 31

Spin. Traction and distraction.

Question 32

Describe the arthrokinematics of hip extension. How would you treat restriction?

Answer 32

Spin. Traction and distraction.

Question 33

Which manual therapy technique is indicated in a capsular pattern of restriction about the hip?

Answer 33

Distraction.

Question 34

Describe the arthrokinematics of hip abduction.

Answer 34

Superior roll, inferior glide.

Question 35

Describe the arthrokinematics of hip adduction.

Answer 35

Inferior roll, superior glide.

Question 36

Describe the arthrokinematics of hip internal rotation.

Answer 36

Anterior roll, posterior glide.

Question 37

Describe the arthrokinematics of hip external rotation.

Answer 37

Posterior roll, anterior glide.

Question 38

What is the normative value for the angle between the femoral neck and medial shaft?

Answer 38

125’

Question 39

Describe coxa vara and valga.

Answer 39

i) Coxa vara is when the angle between the femoral neck and medial shaft is <125’
ii) Coxa valga is when the angle is >125’

Question 40

Describe femoral retroversion and excessive anteversion.

Answer 40

Femoral torsion of >15’ is excessive anteversion and <15’ is retroversion.

Question 41

What is normal femoral torsion in adults?

Answer 41

The femoral neck projects 15’ anteriorly from the M/L axis of the femoral condyles.

Question 42

What is normal femoral torsion in children?

Answer 42

Children are normally femorally anteverted approx. 40’.

Question 43

What can result from abnormal femoral torsion?

Answer 43

i) articular wear
ii) increased dislocation risk
iii) articular incongruency

Question 44

Describe the compensatory gait pattern of excessive femoral anteversion. What is a common resultant impairment?

Answer 44

The femur now rests in external rotation. To improve acetabular alignment, patients will walk with in-toeing to compensate. This increases the moment arm of hip ABDs and they no longer work efficiently.

Question 45

Describe the bottom-up effects of overpronation in the lower kinetic chain. Name one treatment from this approach.

Answer 45

i) pronation (ankle valgus)
ii) tibial IR
iii) knee valgus
iv) femoral IR and ADD
- Tx w/ orthotics

Question 46

Describe the top-down causes of overpronation. Name one treatment with this approach.

Answer 46

i) Femur IR and ADD
ii) knee valgus
iii) tibial IR
iv) pronation
- Strengthen hip ABDs and ERs.