Hip

Cards (147)

  • "coxofemoral joint"

    Articulation of the acetabulum of the pelvis and the head of the femur
  • Hip joint
    • Diarthrodial ball-and-socket joint with three degrees of freedom: flexion/extension in the sagittal plane, abduction/adduction in the frontal plane, medial/lateral rotation in the transverse plane
    • Supports the weight of the head, arms, and trunk (HAT) both in static erect posture and in dynamic postures
  • "acetabulum"

    Lateral aspect of the pelvic bone (innominate or os coxa): ilium, ischium, pubis
  • Ischium forms 2/5, ilium forms 2/5, pubis forms 1/5 of the acetabulum
  • Acetabulum
    • Periphery (lunate surface) is covered with hyaline cartilage (horseshoe-shaped)
    • Inferior aspect of the lunate surface (the base of the horseshoe) is interrupted by a deep notch called the acetabular notch
    • The acetabular notch is spanned by the transverse acetabular ligament that connects the two ends of the horseshoe
    • Forms a fibro-osseous tunnel through which blood vessels pass into the deepest portion of the acetabulum called the acetabular fossa
    • Deepened by the fibrocartilaginous acetabular labrum, which surrounds the periphery of the acetabulum
  • Acetabulum position
    • Laterally inclined 50°; anteriorly rotated (anteversion) 20°; and anteriorly tilted 20°
    • Normal functioning of the hip requires optimal femoral head coverage by the acetabulum; femoral head coverage is largely determined by acetabular depth
  • Acetabular depth

    Can be measured as the center edge/angle of Wiberg formed by a line connecting the lateral rim of the acetabulum and the center of the femoral head and a vertical line from the center of the femoral head
  • Acetabular dysplasia
    • Abnormally shallow acetabulum that results in a lack of femoral head coverage
    • Normal->25°, definite dysplasia- <16°, possible dysplasia -16° to 25, may indicate excessive acetabular overcoverage->40°
  • Coxa profunda and acetabular protrusio
    • Conditions in which the acetabulum excessively covers the femoral head, leading to limited range of motion (ROM) and internal impingement between the femoral head-neck junction and acetabulum
  • Anteversion of the acetabulum
    Acetabulum is positioned too far anteriorly in the transverse plane
  • Anteversion of the acetabulum
    • Acetabulum that is positioned with less inclination
    • Can lead to instability
  • Retroversion of the acetabulum
    Acetabulum is positioned too far posteriorly in the transverse plane
  • Retroversion of the acetabulum
    • Acetabulum that is positioned with more inclination
    • Can lead to overcoverage and impingement between the acetabulum femoral-head neck junction
  • Acetabular Labrum

    A ring of wedge-shaped fibrocartilage that rims the entire periphery of the acetabulum
  • Functions of the acetabular labrum
    • Deepens the acetabulum
    • Acts as a seal to maintain negative intra-articular pressure
    • Decreases force transmitted to the articular cartilage
    • Provides proprioceptive feedback
  • Abnormally shallow acetabulum
    Increases stress on the surrounding capsule and labrum
  • Transverse acetabular ligament

    Considered to be part of the acetabular labrum
  • Femoral head
    Attached to the femoral neck; the femoral neck is attached to the shaft of the femur between the greater and lesser trochanters
  • Femoral head

    • Angulated so that the femoral head faces medially, superiorly, and anteriorly
    • Articular area of the femoral head forms approximately 2/3 of a sphere and is more circular than the acetabulum
  • Fovea or fovea capitis
    • Small, roughened pit inferior to the most medial point on the femoral head
    • Not covered with articular cartilage and is the point at which the ligament of the head of the femur (ligamentum tares) is attached
  • Angle of inclination
    Occurs in the frontal plane between an axis through the femoral head and neck and the longitudinal axis of the femoral shaft
  • Angle of torsion
    Occurs in the transverse plane between an axis through the femoral head and neck and an axis through the distal femoral condyles
  • Normal angle of inclination
    • Greater trochanter lies at the level of the center of the femoral head
    • Normal range 110° to 144° (approximates 125°)
  • Angle of inclination of the femur changes across the life span
  • It approximates 150° at birth and gradually declines to about 125° at skeletal maturity, then continue to decline again in the elderly
  • Coxa valga
    Pathological increase in the angulation between the neck and shaft
  • Coxa vara
    Pathological decrease in the angulation between the neck and shaft
  • Coxa Valga
    • Angle of inclination in the femur is greater than 125°
    • Brings the vertical weight-bearing line closer to the shaft of the femur, diminishing the shear, or bending, force across the femoral neck
    • Decreases the length of the moment arm of the hip abductor muscles
    • Abductor muscles will be unable to meet the increased demand and will be functionally weakened
    • Reduction in force is actually reflected in a reduction in density of the lateral trabecular system
    • Decreases the amount of femoral articular surface in contact with the dome of the acetabulum
    • Decreases the stability of the hip and predisposes the hip to dislocation
  • Coxa Vara
    • Gives the advantage of improved hip joint stability
    • Decreased angle between the neck and shaft of the femur will turn the femoral head deeper into the acetabulum
    • Increase the length of the moment arm of the hip abductor muscles by increasing the distance between the femoral head and the greater trochanter
    • Seen by the increased density of trabeculae laterally in the femur, caused by the increase in tensile stresses
    • The increased shear force along the femoral neck will increase the predisposition toward femoral neck fracture
  • Slipped capital femoral epiphysis/SCFE
    • Results when weight-bearing forces slide the femoral head inferiorly on the cartilaginous epiphysis of the head of the femur
    • The epiphyseal obliquity makes the plate more vulnerable to shear forces at a time when the plate is already weakened
    • Most common adolescent hip disorder occurring when the femoral head displaces posteriorly on the femoral neck at the level of the growth plate (physis)
  • Angle of Torsion of the Femur
    • Best be viewed by looking down the length of the femur superiorly
    • Axis through the femoral head and neck in the transverse plane will lie at an angle to an axis through the femoral condyles, with the head and neck torsioned anteriorly (laterally) with regard to an angle through the femoral condyles
    • Angle of anterior torsion decreases with age
    • In the newborn, 30° to 40°
    • This angle decreases of approximately 1.5° per year until skeletal maturity
    • In the adult, 10° to 20° (15° for males and 18" for females)
  • Femoral Anteversion
    • Angle of anterior torsion is greater than 15° to 20°
    • Associated with increased medial rotation ROM and concurrent decreased lateral rotation so that the total excursion of hip rotation motion remains the same
    • Femoral anteversion and coxa valga are commonly found together (but each may occur independently of the other)
    • Reduces hip joint stability because the femoral articular surface is more exposed anteriorly
    • Line of the hip abductors may fall more posterior to the joint, reducing the moment arm for abduction resulting need for additional abductor muscle force
  • Medial femoral torsion

    Abnormal position of the knee joint axis
  • Medial femoral torsion

    Same abnormal condition as femoral anteversion
  • Femoral anteversion
    Alters the mechanics at the hip joint
  • Medial femoral torsion
    Alters the mechanics at the knee joint
  • When femoral head is anteverted
    1. Anterior capsuloligamentous structures and musculature may push the femoral head back into the acetabulum
    2. Causes the entire femur to rotate medially with toe-in
  • Toe-in position of the foot

    May appear to diminish over time
  • Underlying hip problem

    Generally remains, even though foot placement looks better
  • Femoral retroversion

    Opposite of anteversion, creates problems opposite those of femoral anteversion