Biomechanics of the Hip Joint
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Questions and Answers

What is the average center edge angle in the general adult population?

  • 35–45 degrees
  • 25–35 degrees (correct)
  • 30–40 degrees
  • 15–25 degrees
  • What does excessive acetabular anteversion indicate?

  • Vulnerability to anterior subluxation or dislocation (correct)
  • Increased stability of the hip
  • Normal acetabular development
  • Vulnerability to posterior subluxation
  • Which structure helps maintain a negative intra-articular pressure in the hip joint?

  • Capsule
  • Acetabular fossa
  • Articular cartilage
  • Acetabular labrum (correct)
  • During which phase of walking can hip forces exceed 300% of body weight?

    <p>Stance phase</p> Signup and view all the answers

    What primarily contributes to protecting the hip joint during movement?

    <p>Eccentric muscle action</p> Signup and view all the answers

    What is the primary role of the hip joint in the body?

    <p>It serves as a base joint for the lower extremities.</p> Signup and view all the answers

    What is the consequence of an intact acetabular labrum?

    <p>Decreased peak pressure</p> Signup and view all the answers

    Which branches of mechanics are involved in the study of biomechanics at the hip joint?

    <p>Kinematics and Kinetics</p> Signup and view all the answers

    What defines the angle of inclination in the proximal femur?

    <p>The angle in the frontal plane between the femoral neck and shaft</p> Signup and view all the answers

    What does a center edge angle of less than 25 degrees indicate?

    <p>Acetabular retroversion</p> Signup and view all the answers

    What structure forms the socket for the femur at the hip joint?

    <p>Acetabulum</p> Signup and view all the answers

    At what average angle does the angle of inclination measure at birth?

    <p>165-170 degrees</p> Signup and view all the answers

    Which part of the hip joint is primarily responsible for the mechanical seal around the hip?

    <p>Acetabular labrum</p> Signup and view all the answers

    Which condition is described by abnormal growth resulting in a misshaped proximal femur?

    <p>Femoral dysplasia</p> Signup and view all the answers

    What causes the angle of inclination to decrease after birth?

    <p>Increased physical activity and muscle loading</p> Signup and view all the answers

    What type of biomechanics focuses on the forces acting on the body rather than the motion itself?

    <p>Kinetics</p> Signup and view all the answers

    What is a result of a malformed, dysplastic acetabulum?

    <p>Chronic dislocation and increased stress</p> Signup and view all the answers

    Which of the following is NOT a region studied in regional biomechanics?

    <p>Spine joint</p> Signup and view all the answers

    Which of the following bones contributes the largest percentage to the acetabulum formation?

    <p>Ilium</p> Signup and view all the answers

    What is the normal adult value of the angle of inclination?

    <p>125 degrees</p> Signup and view all the answers

    What type of movement is referred to in the study of kinematics?

    <p>The physiological range of joint motion</p> Signup and view all the answers

    Which components make up the innominate bone?

    <p>Ilium, Acetabulum, Pubis, Ischium</p> Signup and view all the answers

    What does the center-edge angle measure?

    <p>The extent of femoral head coverage by the acetabulum</p> Signup and view all the answers

    What may excessive anteversion lead to in walking mechanics?

    <p>Inward toeing</p> Signup and view all the answers

    What is a consequence of the acetabular labrum being poorly vascularized?

    <p>It has a limited ability to heal on its own.</p> Signup and view all the answers

    In which position is the hip joint considered to be in a close-packed position?

    <p>Full extension with slight internal rotation and abduction.</p> Signup and view all the answers

    What is the typical intracapsular pressure within a healthy hip joint?

    <p>Less than atmospheric pressure.</p> Signup and view all the answers

    What is the primary difference between femoral-on-pelvic and pelvic-on-femoral osteokinematics?

    <p>The fixity of the pelvis and femurs during movement.</p> Signup and view all the answers

    Why might a person with capsulitis find comfort in holding the hip in partial flexion?

    <p>It reduces intracapsular pressure.</p> Signup and view all the answers

    Which type of lumbopelvic rhythm involves both pelvis and lumbar spine moving in the same direction?

    <p>Ipsidirectional lumbopelvic rhythm.</p> Signup and view all the answers

    During hip motion, what maintains the femoral head seated within the acetabulum?

    <p>Intracapsular pressure.</p> Signup and view all the answers

    What best describes the condition of ligaments and capsule during the open-packed position of the hip?

    <p>They are in a slackened state.</p> Signup and view all the answers

    Study Notes

    Biomechanics of the Hip Joint

    • Biomechanics studies how forces interact within a living body.
    • Kinematics describes motion without considering the forces involved.
    • Kinetics describes the effect of forces on the body.

    Hip Joint Anatomy

    • The hip joint is formed by the articulation of the femoral head and the acetabulum of the pelvis.
    • It functions as the "base" for the lower limbs and the pelvis and trunk.
    • Hip injuries can significantly affect mobility and daily activities.

    Innominate Bone

    • The innominate bone is made up of the ilium, pubis, ischium, and acetabulum.

    Femur

    • Femoral dysplasia refers to abnormal growth and development leading to a misshaped proximal femur.
    • Angle of Inclination: The angle between the femoral neck and shaft in the frontal plane, typically decreasing from 165-170 degrees at birth to 125 degrees in adulthood.
      • Coxa vara: Decreased angle of inclination (<120°)
      • Coxa valga: Increased angle of inclination (>135°)
    • Femoral Torsion: The angle of rotation of the femoral head relative to the femoral condyles in the transverse plane.
      • Excessive anteversion: Increased angle of torsion, causing "in-toeing".
      • Retroversion: Decreased angle of torsion, causing "out-toeing”.

    Acetabulum

    • The acetabulum forms the socket of the hip joint, with contributions from the ilium, ischium, and pubis.
    • Acetabular dysplasia can lead to hip instability and pain.
    • Center-Edge Angle (CE Angle): Measures the acetabulum's coverage of the femoral head in the frontal plane. Normal range: 25-35 degrees.
      • Decreased angle ( <20°) can lead to hip instability.
    • Acetabular Anteversion Angle: Measures the acetabulum's coverage of the femoral head in the transverse plane. Normal range: approximately 20 degrees.
      • Excessive anteversion (>20 degrees) can lead to anterior hip instability.

    Hip Joint Arthrology

    • The hip joint is a classic ball-and-socket joint, stabilized by connective tissues and muscles.
    • Articular cartilage and cancellous bone in the proximal femur help absorb forces.
    • Joint stability is compromised by disease, malalignment, or trauma.

    Hip Joint Structure

    • Femoral Head:
      • Fovea: Small pit where ligamentum teres attaches.
      • Ligamentum teres: Intracapsular ligament providing minimal stability.
      • Articular cartilage: Covers the head for smooth movement.
    • Acetabulum:
      • Acetabular notch: Indentation at the inferior rim of the acetabulum.
      • Lunate surface: Articular surface of the acetabulum.
      • Acetabular fossa: Non-articular area at the bottom of the acetabulum.
      • Labrum: Fibrocartilaginous ring surrounding the rim of the acetabulum.
      • Transverse acetabular ligament: Bridges the acetabular notch.

    Hip Joint Forces and Pressure

    • Hip forces fluctuate from 13% of body weight during swing phase to over 300% during midstance phase.
    • Acetabular labrum helps maintain intra-articular pressure, creating a "suction seal" for stability and preventing synovial fluid leakage.
    • Tears in the labrum can hinder healing due to poor vascularization.

    Hip Joint Capsule and Ligaments

    • The hip joint capsule is a thick, fibrous sac that encloses the joint.
    • Ligaments within the capsule provide additional stability.

    Hip Joint Positions

    • Close-Packed Position: Full extension, slight internal rotation and abduction.
    • Open-Packed Position: 90 degrees of flexion, moderate abduction, and External rotation.

    Hip Joint Intracapsular Pressure

    • Healthy hip intracapsular pressure is normally less than atmospheric pressure.
    • This negative pressure contributes to hip stability.

    Hip Joint Osteokinematics

    • Femoral-on-Pelvic Osteokinematics: Movement of the femur relative to the pelvis.
    • Pelvic-on-Femoral Osteokinematics: Movement of the pelvis relative to the femur.

    Lumbopelvic Rhythm

    • Pelvic rotation over the femoral heads influences lumbar spinal alignment.
      • Ipsidirectional lumbopelvic rhythm: Pelvic and lumbar rotations in the same direction.
      • Contradirectional lumbopelvic rhythm: Pelvic and lumbar rotations in opposite directions.

    Arthrokinematics

    • During hip motion, the femoral head typically stays within the acetabulum.

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    Hip Joint, Lecture 1 PDF

    Description

    Explore the intricate biomechanics of the hip joint, including its anatomy and the forces that influence its movement. This quiz covers important topics like kinematics, kinetics, and the structure of the innominate bone and femur. Test your understanding of how these elements work together in human movement.

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