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