Lecture 11: Hip Joint

How does the acetabular labrum enhance hip stability?

- Deepen the socket by ~30% - "Seal" hip joint and maintain a negative intra-articular pressure, which creates a suction resisting distraction of joint surfaces

What are the osteokinematics of the hip joint during closed kinematic chain movements?

Pelvic-on-femoral Weight bearing movement Lumbopelvic rhythm

Describe the open chain (NWB) osteokinematics of the Hip Joint during IR

IR: 35 ° - ischiofemoral ligament

Describe the compensatory movements in the Lumbopelvic Rhythm during trunk flexion with limited lumbar flexion.

Increased or excessive hip flexion

Describe the compensatory movements in the Lumbopelvic Rhythm during trunk flexion with limited hip flexion.

Increased or excessive lumbar and thoracic flexion

What is a CAM Impingement (FAI)?

Related to increased Alpha angle (> 60 degrees) Excessive bony protrusion of the femoral head

What is a Pincer Impingement (FAI)?

Related to increased Center Edge Angle (> 40 degrees) Excessive bony coverage of the femoral head

Femoroacetabular Impingement (FAI)

Two types: 1. Pincer 2. Cam - acetabulum is the primary tissue that is injured

What are the normal angles for lumbar and hip flexion?

40° lumbar flexion 70° hip flexion

Describe the Lumbopelvic Rhythm during trunk extension

Extension 1. Lumbar spine extends 2. Pelvis rotates posteriorly

Describe the open chain (NWB) osteokinematics of the Hip Joint during Extension

Extension: 20° - iliofemoral and pubofemoral are taut

What are the osteokinematics of the hip joint during open kinematic chain movements?

Femoral-on-pelvic Non-weight bearing movement

Describe the Lumbopelvic Rhythm during trunk flexion

Flexion 1. Lumbar spine flexes 2. Pelvis rotates anteriorly

Describe the open chain (NWB) osteokinematics of the Hip Joint during Flexion

Flexion: 120° - ischiofemoral ligament is taut

Describe the open chain (NWB) osteokinematics of the Hip Joint during Abduction

Abduction: 40 ° - pubofemoral ligament

Describe the open chain (NWB) osteokinematics of the Hip Joint during Adduction

Adduction: 25 ° - ischiofemoral ligament (superior fibers)

What are the axes of rotation for movements at the hip joint?

All 3 axes of rotation pass through femoral head -Flexion-extension Mediolateral -Abduction-adduction Anterior-posterior -Internal-external rotation Superior-inferior

Describe the open chain (NWB) osteokinematics of the Hip Joint during ER

ER: 45 ° - iliofemoral and pubofemoral ligaments

Describe the closed chain (WB) osteokinematics during hip IR

Lumbar Spine: Contralateral rotation Pelvis: Ipsilateral rotation Purpose of lumbar movement: to maintain the trunk upright and forward direction

Describe the closed chain (WB) osteokinematics during hip abduction

Lumbar Spine: Contralateral sidebend Pelvis: Contralateral hike Purpose of lumbar movement: to maintain the trunk upright and forward direction

Describe the closed chain (WB) osteokinematics during hip flexion (seated)

Lumbar Spine: Extension Pelvis: Anterior Tilt Purpose of lumbar movement: to maintain the trunk upright and forward direction

Describe the closed chain (WB) osteokinematics during hip extension (seated)

Lumbar Spine: Flexion Pelvis: Posterior Tilt Purpose of lumbar movement: to maintain the trunk upright and forward direction

Describe the closed chain (WB) osteokinematics during hip ER

Lumbar Spine: Ipsilateral rotation Pelvis: Contralateral rotation Purpose of lumbar movement: to maintain the trunk upright and forward direction

Describe the closed chain (WB) osteokinematics during hip adduction

Lumbar Spine: ipsilateral sidebend Pelvis: contralateral drop Purpose of lumbar movement: to maintain the trunk upright and forward direction

What is the "Ipsidirectional" lumbopelvic rhythm?

Movement of joints in Flexion & Extension • Pelvis and lumbar spine rotate in the same direction • Maximizes the angular displacement of the entire trunk • Increase reach of the upper extremity

What is the "Contradirectional" lumbopelvic rhythm?

Movement of joints while walking -Pelvis and lumbar spine rotate in opposite direction -The supralumbar trunk can remain upright as the pelvis rotate over the femur

What is the Alpha angle?

The angle is obtained by: 1. circle circumference of the femoral head 2. line in the center of the femoral neck along its longitudinal axis 3. second line along the osseous femoral head