biomechanics and pathology Flashcards
- What are the internal forces acting on the hip?
a. active and passive forces arising from muscular and ligamentous pressures
- Describe the external forces acting on the hip?
a. ground reaction forces
- What type of forces must the hip manage with walking, stair, running?
a. walking- four times body weight
b. single leg stance 2.5x body weight
- What characteristic of the articular surfaces of the hip allow it to manage ground reaction forces?
a. the entire articular surface of the acetabulum is compressed when managing ground reaction forces
b. 70-80% of the femoral head is in contact with the acetabulum
- What part of the hip joint is most susceptible to OA?
a. the areas that bear the greatest weight which is primarily the anterior superior surface
- What is the femoral neck shaft angle?
a. angle between the femoral shaft and neck typically about 125 degrees
- How does body type effect femoral neck shaft angle?
a. tall slim people tend to have longer columns and greater column angles
b. short stocky people tend of have smaller column and smaller angles
- What is the femoral retrotorsion?
a. the head and neck of the femur position posteriorly to the transverse axis through the femoral condyles
- What is femoral anteversion angle?
a. the angle of the retrotorsion of the femur
b. measured by the difference in the transverse axis of the acetabulum and the long axis of the neck of the femur
- How does the anteversion angle change as we develop?
a. it decreases with age until full ossification
- What is the mechanical axis of the hip?
a. the line perindicular to the acetabular rim
- What is the transverse axis of the acetabulum?
a. line the runs in the transverse plane through the center of the femoral head
- What is the acetabular angle?
a. the angle between the mechanical axis and the transverse axis
b. 30-40 degrees anteriorly facing
- What is the open pack position of the hip?
a. 30 flexion
b. 30 adduction
c. 20 ER
- What is the closed pack positions of the hip?
a. maximum extension from zero
b. internal rotation
c. abduction
- Does RA effect men or women more?
a. women 3:1
- How do OA and RA compare
a. pathology
i. OA- reactive changes in the margins of the joint and subchondral bone
ii. RA- inflammatory process proliferation of synovial tissue and granulation of articular surface membrane
b. etiology
i. OA age, obesity, repetitive stress, genetics
ii. RA unknown, with possible genetic contributions
c. clinical manifestations
i. OA localized, slow onset of joint pain, stiffness (short duration)
ii. RA remission/exacerbation, long duration pain swelling fever, malaise, more common in women
d. common sites
i. OA- weight bearing joints
ii. RA- hands, wrist, knee, foot shoudler, hip, elbow, aankle, TMJ, SC, cervical spine
e. systemic manifestations
i. OA- none
ii. RA- pleuritis of heart and lungs, Sicca (dry mucous membranes)
- What is Coxa valga?
a. femoral neck shaft angle greater than 125 degrees
- How does coxa valga effect hip strength?
a. Decreases hip strength do to a smaller lever arm
- What is coxa vara?
a. femoral neck/shaft angle less than 115 degrees
- How does coxa vara impact the biomechanical chain?
a. decreased hip abduction due to early impact of the greater trochanter into the ilium
- What is femoral anteversion?
a. angle of retrotorsion greater than 20 degrees
- How does femoral anteversion impact the biomechanical chain?
a. toe-in gait
b. increased Q-angle
c. increased lordosis
- What is femoral retroversion?
a. angle of retrotorsion less than 12 degrees
- How does femoral retroversion impact the biomechanical chain?
a. femoral ER
b. supinated foot
c. decreased Q angle
- How many pathologies does the OGI ciriculum list as potential causes of hip AVN?
a. 31 with direct trauma and vascular impairments off various sorts toping the list
- What is Legg-Calve-Perth disease?
a. coxa plana or a flatening of the femoral head due to AVN
- Why is the hip susceptible to avascular necrosis?
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- What is the typical patient population for Legg-Calve- Perth disease
a. children 3-12 with boys > girls
- What is slipped capital femoral epiphysis?
a. During adolescence the femoral head slips inferiorly at the epiphyseal plate
- What is the typical patient population for slipped capital femoral epiphysis?
a. 10-15 years boys twice as more than girls
- How does congenital hip dislocations occur?
a. hormonal
b. genetic laxity with shallow acetabulum
c. breechdelivery
d. envirnemental
e. often anteverted
- Do men or women have priformis syndrome and hip dysplasia more?
a. Women 6:1 piriformis and 5:1 dysplasia
- What causes trochanteric bursitis?
a. repetitive adduction or leg length discrepancy with muscular imbalance
b. increased Q-angle
- What are the bursa of the greater trochanter?
a. glut max and tendon of glut med (largest)
b. glut med and greater trochanter
c. glut minimus and greater trochanter
- What are the typical causes snapping hip syndrome?
a. thickening of the posterior border of the iliotibial band
b. slipping of the psoas tendon over the iliopectinal eminence on the pubis
c. osteochondromatosis, subluxation of hip or loose bodies
- Describe ishiogluteal bursitis?
a. found between iscial tuberosity and glut max
b. close to the sciatic nerve and posterior femoral cutaneous
- Describe iliopectineal bursitis
a. Similar to snapping hip because the bursa lies on the front of the hip separating the psoas tendon from the joint
