Podcast
Questions and Answers
What is the average center edge angle in the general adult population?
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?
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?
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?
During which phase of walking can hip forces exceed 300% of body weight?
What primarily contributes to protecting the hip joint during movement?
What primarily contributes to protecting the hip joint during movement?
What is the primary role of the hip joint in the body?
What is the primary role of the hip joint in the body?
What is the consequence of an intact acetabular labrum?
What is the consequence of an intact acetabular labrum?
Which branches of mechanics are involved in the study of biomechanics at the hip joint?
Which branches of mechanics are involved in the study of biomechanics at the hip joint?
What defines the angle of inclination in the proximal femur?
What defines the angle of inclination in the proximal femur?
What does a center edge angle of less than 25 degrees indicate?
What does a center edge angle of less than 25 degrees indicate?
What structure forms the socket for the femur at the hip joint?
What structure forms the socket for the femur at the hip joint?
At what average angle does the angle of inclination measure at birth?
At what average angle does the angle of inclination measure at birth?
Which part of the hip joint is primarily responsible for the mechanical seal around the hip?
Which part of the hip joint is primarily responsible for the mechanical seal around the hip?
Which condition is described by abnormal growth resulting in a misshaped proximal femur?
Which condition is described by abnormal growth resulting in a misshaped proximal femur?
What causes the angle of inclination to decrease after birth?
What causes the angle of inclination to decrease after birth?
What type of biomechanics focuses on the forces acting on the body rather than the motion itself?
What type of biomechanics focuses on the forces acting on the body rather than the motion itself?
What is a result of a malformed, dysplastic acetabulum?
What is a result of a malformed, dysplastic acetabulum?
Which of the following is NOT a region studied in regional biomechanics?
Which of the following is NOT a region studied in regional biomechanics?
Which of the following bones contributes the largest percentage to the acetabulum formation?
Which of the following bones contributes the largest percentage to the acetabulum formation?
What is the normal adult value of the angle of inclination?
What is the normal adult value of the angle of inclination?
What type of movement is referred to in the study of kinematics?
What type of movement is referred to in the study of kinematics?
Which components make up the innominate bone?
Which components make up the innominate bone?
What does the center-edge angle measure?
What does the center-edge angle measure?
What may excessive anteversion lead to in walking mechanics?
What may excessive anteversion lead to in walking mechanics?
What is a consequence of the acetabular labrum being poorly vascularized?
What is a consequence of the acetabular labrum being poorly vascularized?
In which position is the hip joint considered to be in a close-packed position?
In which position is the hip joint considered to be in a close-packed position?
What is the typical intracapsular pressure within a healthy hip joint?
What is the typical intracapsular pressure within a healthy hip joint?
What is the primary difference between femoral-on-pelvic and pelvic-on-femoral osteokinematics?
What is the primary difference between femoral-on-pelvic and pelvic-on-femoral osteokinematics?
Why might a person with capsulitis find comfort in holding the hip in partial flexion?
Why might a person with capsulitis find comfort in holding the hip in partial flexion?
Which type of lumbopelvic rhythm involves both pelvis and lumbar spine moving in the same direction?
Which type of lumbopelvic rhythm involves both pelvis and lumbar spine moving in the same direction?
During hip motion, what maintains the femoral head seated within the acetabulum?
During hip motion, what maintains the femoral head seated within the acetabulum?
What best describes the condition of ligaments and capsule during the open-packed position of the hip?
What best describes the condition of ligaments and capsule during the open-packed position of the hip?
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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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