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Unit 3 > EEI 10/29a Hip Biomechanics I > Flashcards

EEI 10/29a Hip Biomechanics I Flashcards

1
Q

Innominate Union

A

Ilium
Pubis
Ischium

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2
Q

Central Point of Fusion of hip

A

acetabulum

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3
Q

how many innominates exist?

A

2
left and right
connect on anterior aspect of pubic symphysis

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4
Q

what encompasses the pelvis

A

Sacrum + 2 Innominates

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5
Q

ASIS

A
  • Most prominent aspect of the hip
  • When you feel your hip at the most superior point
  • Sartorius attaches there
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6
Q

Pubic Crest/Tubercules

A

Adductor muscles attach to these

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7
Q

what are the important posterior aspects of the hip?

A

-PSIS
-Ischial Tuberosity
(HS attach here)

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8
Q

Does palpating the posterior structures of the hip as a patient moves their trunk forward tell you a lot about their function or asymmetry?

A

no, you can’t tell the amount that their hip is moving…it is an unrealistic practice

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9
Q

important structures of the posterior femur

A

Head
Neck
Shaft

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10
Q

what is the importance of the femoral shaft?

A

-Courses medially
-Anterior convexity
-Importance of medial direction with respect to the 6 determinants of gait theory?
»When femur goes medially during walking, it allows for more efficient frontal plane movement

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11
Q

what is the importance of the medial direction of the femoral shaft?

A

When femur goes medially during walking, it allows for more efficient frontal plane movement

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12
Q

what aspects of the femur should be able to be palpated?

A

Greater Trochanter

  • attachment for glute med
  • piriformis attaches here
  • bursae sit under
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13
Q

how do you differentiate the piriformis?

A

sciatic nerve runs through it and superior/inferior gemellae sit under

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14
Q

different alignment angles of the femoral head in the acetabulum

A

angle of inclination

torsion angle

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15
Q

Angle of inclination

A

Hip alignment in the frontal plane
Normal: 125 (100-144)
Coxa Vara < 125
Coxa Valga > 125

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16
Q

Torsion angle

A

Hip alignment relative to rotation between shaft and neck of the femur

  1. Normal: 10-15 degrees antiversion from midline
  2. Excessive antiversion: >15 OR 35 degrees antiversion from midline
  3. Retroversion: <8 OR 5 degrees from midline
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17
Q

what is the significance of excessive antiversion?

A
  • it is more common to get excessive antiversion than retroversion
  • associated with dislocation
  • Femoral head sits more towards anterior aspect of the acetabulum (thus it can slip off from the front and dislocate)
  • increases articular cartilage wear
  • Yields toe in posture
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18
Q

What torsional angle causes toe in?

A

excessive antiversion

  • this happens because people internally rotate at their hips to provide more stability so that their femoral heads don’t pop out
  • overtime, they even stary to compensate with external tibial rotation
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19
Q

with _____version torsional angles, there is a ____ in ____ rotation and increase in ____ rotation of the hip so that it doesn’t _____

A 
antiversion
decrease
external rotation
internal rotation
sublux and dislocate
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20
Q

what occurs to the femoral head with different loading mechanisms?

A
  • coxa vara: loading more on superior femoral head (moves higher up)
  • coxa valga: loading more on inferior aspect of the femoral head (moves lower down)
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21
Q

what are different mechanisms for varying loads on the femoral neck?

A
  • coxa vara: rotational shearing through the neck (associated with SCFE)
  • coxa valga: compressive forces through the neck
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22
Q

what happens to the length of the limb with coxa vara?

A

shortens

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23
Q

what happens to the length of the limb with voxa valga?

A

lengthens

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24
Q

what happens to the torque production of the abductor muscles with coxa vara

A

the internal moment arm increases, thus the muscle can generate a greater torque with a smaller force

-requires less force to move

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25
Q

what happens to the torque production of the abductor muscles with coxa valga?

A

the internal moment arm of the muscle is shorter, thus to generate the same torque, it requires a lot more force to move
-more common with kids who have CP

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26
Q

what hip position generates a larger joint contact force?

A

Coxa valga

since it requires a larger muscle force to generate movement, the contact force also increases

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27
Q

how does hip stability change with coxa vara?**

A

with vara, there is more stability because there is a greater percentage of femoral head in contact with the acetabulum
»ADDUCTION shifts head down and creates more stability

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28
Q

how does hip stability change with coxa valga?***

A

if valga goes into ADDUCTION, it becomes UNSTABLE

ABduction generates more stability

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29
Q

what is SCFE?

A

Slipped capital femoral epiphysis

  • more common in overweight male children
  • fractured growth plate
  • femoral head comes off of femoral neck
  • there are different levels of SCFE
  • Increase RISK with coxa VARA
30
Q

red flags and treatment for SCFE?

A

pt complains of knee pain and pain down the thigh, you see them turn foot in

can lead to avascular necrosis of the femoral head

–> treatment is stabilization with a pin

31
Q

what is the articulation of the hip joint?

A

acetabulum of pelvis

femoral head

32
Q

palpation of the ____ gives you a sense of where the ____ of the hip joint is

A

inguinal ligament

middle

33
Q

femoral head details

A

located inferior and middle to 1/3 of inguinal ligament
-2/3 is a perfect sphere
-covered with articular cartilage EXCEPT the fovea
>Fovea has ligamentum teres

34
Q

where is the cartilage thickest on the femoral head?

A

anterior to the fovea

and takes the most force especially because it gets continuously loaded and increases with Wolf’s law

35
Q

what is the significance of the ligamentum teres?

A
  • similar to the ACL, intracapsular BUT extrasynovial
  • stretched during flexion and ADDuction
  • no major role in stability

Acts like windshield wiper to move around synovial fluid

36
Q

what is the purpose of the acetabulum?

A

-not a complete circle
horse shoe shaped and connects notch at transverse acetabular ligament that makes it more spherical
-covered with articular cartilage except for acetabular fossa where ligamentum teres attaches
-Cartilage is thickest anterior and superior

37
Q

Gait pattern

A
  1. initial contact
  2. early stance
  3. mid stance
  4. toe off
38
Q

how does the hip joint force change with gait

A
  1. at initial contact, not a lot of joint force
  2. as we accept weight, joint force peaks
  3. force stays high from early to mid stance
    »Based on larger contact area
    »acetabular notch widens to distribute the forces throughout the entire acetabulum and femoral head
39
Q

what does the acetabular labrum do?

A
  • it’s a fibrocartilage ring
  • adds stability
  • distributes forces more evenly throughout the joint
40
Q

what is the role of stability for the acetabulum?

A

-Deepen the joint acetabulum) by 30%
-Gripping the femoral head
-Adds Stability
- Increase Surface Area so Decrease Contact Area
Spreading out the force

41
Q

Alignment of acetabulum

A
  • If angle is shorter, less coverage area of femoral head by acetabulum
  • If angle is larger, more coverage area (femoral acetabular impingement - FAI)

–>both impact osteokinematics

42
Q

can you have excessive anteversion of the acetabulum?

A

Yes - angle between posterior and anterior aspect of acetabulum changes and alters contact forces and potential stability of the hip joint

43
Q

CAM hip deformity

A

deformity of femoral head
-get excessive bone growth on the anterior aspect of the femoral head
-more common in males
»jams the femoral head and neck into the acetabulum
-increases impingement during flexion and internal rotation of the hip

44
Q

overtime, what does CAM deformity cause?

A

– VALGUS: Hip internal rotation and ADDuction

Bad for ACL

45
Q

what is the pincer hip deformity?

A

bony growth of anterior aspect of acetabulum

  • adds more stability
  • increases impingement during flexion and internal rotation of the hip
  • more common in females
46
Q

if you reproduce symptoms with ADduction and internal rotation, what does that mean?***

A

if the patient feels pain, then you know that they have an impingement

47
Q

what movements are bad for CAM and PINCER hip deformities?

A

they both cause hip internal rotation and ADDuction

THUS, they have repetitive valgus and it’s bad for ACL and PFJ

48
Q

risk factors from bony growths caused by CAM and Pincer deformities?

A

changes arthrokinematics and joint contact forces, thus increases risk of OA

49
Q

what other injuries are associated with FAI?

A

acetabular labrum injuries

50
Q

treatment for FAI?

A
  1. Conservative – Intraarticular injections (not a good thing!) – PT: Strengthen hip/core, correct movement patterns, flexibility
  2. Surgical – Debride/repair labrum – Osteoplastic procedures
    – Overtreating with surgery unfortunately
51
Q

what encompasses the hip capsule?

A

the capsule attachment is over the entire acetabulum and the femoral neck

-Implications are femoral neck (intraarticular) fractures

52
Q

are we more concerned with intraarticular fractures or extraarticular fractions of the hip capsule?

A

intra - leads to more long term tissues like OA

53
Q

hip capsule is reinforced by:

A

LIGAMENTS - All limit EXTENSION of the hip

  1. Iliofemoral ligament (Y ligament)
  2. Pubofemoral ligament
  3. Ischiofemoral ligament
54
Q

What is the significance of the Y ligament?**

A

Iliofemoral ligament (Y ligament)- has strongest tensile forces in the body
- Limits extension and external rotation
- Strongest ligament in body
- Role with people who have weakness in glute max, muscular dystrophy or SCI
- Kids with CP - hanging on Y ligaments
»>They rely on passive restraints of Y ligament

55
Q

significance of the pubofemoral ligament?**

A
  • it is the anterior aspect of the capsule

- limits ABduction and extension in addition to some external rotation

56
Q

Significance of ischiofemoral ligament?***

A
  • Posterior aspect

- Limits extension and internal rotation

57
Q

what ligament do kids with CP have issues with?

A

they are hanging on Y ligaments
»>They rely on passive restraints of Y ligament

-GLUTEs are doing NOTHING

Adopt this position for stability

58
Q

close pack position of the hip**

A
  • Hips close pack position is NOT in position of maximal congruency between bones
  • Close Pack is in FULL hip EXTENSION - at about 20 degrees
  • This is because of the ligaments limit extension
  • There is also some slight Abduction and internal rotation
59
Q

open pack position of the hip

A
  • Maximal articular congruency
  • moderate ABducton and external rotation
  • 90 degrees hip flexion
60
Q

open chain movement of hip

A

femur moving on the pelvis

61
Q

sagittal plane, open chain flexion movement of the hip

A

-flexion
>normal hip flexion = 120 degrees (with knee bent)
>hip flexion with knee straight/extended = LESS because of hamstrings

62
Q

HS length tests for testing open chain flexion of the hip

A
  1. SLR test - measures proximal hamstring length/tightness (KNEE FLEXION)
    90/90 HS length test - Distal HS tightness hip at 90 degrees and move knee to see how far we can go into KNEE EXTENSION
63
Q

sagittal plane, open chain extension movement of the hip

A

-20 degrees
-limiting structures:
»ligaments (iliofemoral, pubofemoral, ischiefemoral)
»psoas major (strong hip flexor muscle) - tight psoas leads to limited/loss extension

64
Q

when knee is flexed in closed pack, can you get into hip extension easily?

A

No, this is because of the rectus femoris that crosses hip and leads to less ROM in hip extension

65
Q

if you want to measure true hip extension, what would the position of the knee be?

A

extended

66
Q

frontal plane movement of the hip?

A
  • ABduction: Limiting structures are pubofemoral lig, and adductor muscles; Normal is 40degrees
  • ADduction: Normal is 25 degrees; Limiting structures: Ischiofemoral lig, IT band, Abductor muscles
67
Q

over’s test

A

tests length of IT band
-side lying, drop hip in adduction and extension and see how far hip goes into adduction

–abductor muscles have a lot to do with how far someone goes (not just an IT band test)

68
Q

horizontal plane movement of the hip

A

internal/external rotation of the hip

  • internal = 35-45 degrees, limiting structures are ischiofemoral lig, external rotators (deep butt muscles - piriformis and gemellae)
  • external = 45 degrees, typically see more external than internal; limiting structures are iliofemoral lig, pubofemoral lig, internal rotators, adductors muscles
69
Q

different mechanisms to test hip rotation

A

-Sitting at 90 degrees of hip flexion (open pack)
-Prone = 0 degrees of hip flexion (close pack)
-Get different measurements because bringing in different structures
»>Will want to do one vs the other for patients based on their pathology

70
Q

what total arc of motion is normal for hip rotation

A

90 degrees for total arc of motion

71
Q

what happens when you have 80 degrees IR and 20 degrees ER? Is it too much motion or excessive anteversion

A

this is because of transverse plane femoral alignment (excessive anteversion)

Unit 3 (6 decks)

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