Joint Biomechanics - Hip Flashcards
Hip Joint
Diarthroses: powerful weight bearing ball and socket joint between acetabulum(concave) and femoral head (convex).
Flexion/extension - Sagittal plane, transversal axis.
Abduction/adduction - Frontal plane, antero-posterior axis.
Internal/external rotation - Transverse plane, longitudinal axis.
Good functionality in endurance and explosive movements.
Acetabulum - Lunate Surface
Lunate surface of the acetabulum is covered with hyaline cartilage and articulates with the head.
Inferior margin of lunate is interrupted by acetabular notch, spanned by the transverse acetabular ligament that connects the two ends.
Acetabulum - Labrum
Edge of the acetabulum.
Prevents bone to bone contact.
Increases surface area.
Protects femoral head in extreme movement.
Center Edge Angle/Angle of Wiberg
Represents the amount of inferior tilt of the acetabulum. Measures the amount of coverage over the femoral head.
Using a line connecting the lateral rim of the acetabulum and the center of the femoral head, and the vertical line through the center of the femoral head.
Around 38° in men.
Around 35° in women.
What is the orientation of the acetabulum on the hip bone?
Inferiorly, laterally and anteriorly
Angle of Acetabular Anteversion
Magnitude of anterior orientation of the acetabulum on the hip bone.
Around 18,5° in men.
Around 21,5° in women.
Head of Femur
2/3 of a sphere, flat on the top. Stability is increased by it.
Fovea not covered with articular cartilage, where ligament of the head of the femur (ligamentum teres) is attached.
Femoral head attached to it, angulated so that the head faces medially, superiorly and anteriorly.
Degree of Center Edge Angle
18° - Developmental dysplasia of the hip
24° - Borderline
33° - Normal
48° - Femoro-acetabular impingement (bone to bone)
Angle of Inclination (neck to shaft angle)
2 angulations made by the head and the neck in relation to the shaft.
Occurs in the frontal plane.
Ranging from 115° to 140° in normal adults.
Greater in infancy and declines in elderly.
Coxa Vara
Pathologic decrease in the angle of inclination of the femur. Significantly less than 115°.
Coxa Valga
Pathologic increase in the angle of inclination of the femur. More than 140°.
Angle of Torsion
Can be viewed by looking down the length of the femur.
One axis is through the femoral head and neck and the other axis is through the femoral condyles.
Average angle 15°-20° in adults without impairments.
Axis of the head and neck is positioned anteriorly compared to the axis of condyles.
Antiversion
Pathologic increase in the angle of torsion (more than 20°).
Easy internal rotation, difficult external rotation.
Retroversion
Pathologic decrease in the angle of torsion (less than 15°).
Easy external rotation, difficult internal rotation.
Normal Hip Range of Motion
Flexion: 140° Extension: 15° Abduction: 40-50° Adduction: 20-30° External Rotation: 45-50° Internal Rotation: 35-40°
Hip Flexion Range of Motion
With a flexed knee, without help: 120°
With a flexed knee, passively (with help): 145°
With a extended knee: 90° (because of hamstring tension)
Extracapsular Ligaments - Iliofemoral Ligament
Y-shaped with two parts: superior, inferior. Strongest of the three ligaments. Origin: AIIS, acetabular limbus Insertion: Intertrochanteric line Anterior-superior.
Extracapsular Ligaments - Ischiofemoral Ligament
Origin: Ischium
Insertion: Greater trochanter
Posterior.
Extracapsular Ligaments - Pubofemoral Ligament
Origin: Superior ramus of the pubis
Insertion: Intertrochanteric line
Anterior
Role of the Ligaments During Extension
All ligaments in tension, iliofemoral under greatest tension (prevents excessive posterior tilt of pelvis).
Role of the Ligaments During Upright Standing
All ligaments are under moderate tension.
Role of the Ligaments During Hip Flexion
All ligaments are relaxed.
Role of the Ligaments During Adduction
Iliofemoral ligament is taut while pubofemoral and ischiofemoral slacken.
Role of the Ligaments During Abduction
Pubofemoral and ischiofemoral ligaments are taut and iliofemoral ligament is slack.
Role of the Ligaments During External Rotation
Pubofemoral and iliofemoral are taut while ischiofemoral slackens.
Role of the Ligaments During Internal Rotation
Ischiofemoral ligament is taut while pubofemoral and iliofemoral slacken.
Arthrokinematics of the Hip
Convex femoral head gliding on concave acetabulum.
- Roll and slide in opposite directions.
Hip antero-posterior glide: Flexion, internal rotation
Hip postero-anterior glide: Extension, external rotation
Hip inferior glide: Abduction
Hip superior glide: Adduction
Line of Pull for Muscles of the Hip
Usually directed from insertion towards origin.
Hip joint is weight-bearing, transmitting the weight of the body above via the lower limbs to the ground.
- Capable of immediate controlled power when needed for sudden powerful activities.
- Retain the ability to maintain a set position for long periods of time.
Limitation of Hip Flexion
With flexed knee: contact of the thigh with the anterior abdominal wall.
With extended knee: tension in the hamstrings.
Agonist and Synergists of Hip Flexion
Agonist: Iliopsoas, sartorius, tensor fasciae latae, rectus femoris, adductor longus, pectineus.
Synergist: Adductor brevis, gracilis, gluteus medius (anterior).
Limitation of Hip Extension
Tension in the associated ligaments and by the shape of the articular surface.
Agonists and Synergists of Hip Extension
Agonist: gluteus maximus, biceps femoris (long), semitendinosus, semimembranosus and adductor magnus (posterior).
Synergist: Gluteus medius, adductor magnus (anterior).
Limitation of Hip Abduction
Tension in the adductor muscles, ischiofemoral and pubofemoral ligaments. Acetabulum.
Agonists and Synergists of Hip Abduction
Agonist: Gluteus medius, minimus and tensor fasciae latae.
Synergist: Piriformis, sartorius, rectus femoris gluteus maximus.
Limitation of Hip Adduction
Opposite limb, tension in the abductors and iliofemoral ligaments.
Agonists and Synergists of Hip Adduction
Agonist: Pectineus, adductor longus, gracilis, adductor brevis, adductor magnus.
Synergist: Biceps femoris (long), gluteus maximus, quadratus femoris, obturator externus.
Agonists and Synergists of Hip Internal Rotation
Agonist: Gluteus medius, minimus, tensor fasciae latae, adductor longus, adductor brevis, pectineus.
Synergist: Semimembranosus, semitendinosus.
Agonists and Synergists of Hip External Rotation
Agonist: Gluteus maximus, piriformis, obturator internus, gamellus inferior, superior and quadratus femoris.
Synergist: Gluteus medius, minimus, obturator externus, sartorius and biceps femoris (long).
Forward Rotation of the Pelvis on the Femur
Occurs in unilateral stance (on one leg) when the side of the pelvis, opposite to the supporting hip, moves anteriorly. It produces internal rotation of the supporting hip.
Backward Rotation of the Pelvis on the Femur
Occurs when the side of the pelvis, opposite to the supporting hip, moves posteriorly. It produces external rotation of the supporting hip joint.
Rotation of the Pelvis
Motion of the entire pelvic ring in the transverse plane around a vertical axis.
Anterior and Posterior Pelvic Tilt
Motions of the entire pelvic ring in the sagittal plane around a coronal axis.
Anterior Tilt of the Pelvis
Produces hip flexion on a fixed femur.
Moves ASIS anteriorly and inferiorly.
Sacrum moves further away from the femur.
Posterior Tilt of the Pelvis
Produces hip extension on a fixed femur.
Brings the pubis symphysis up and the sacrum closer to the femur.
Lateral Tilt of the Pelvis
Frontal plane, antero-posterior axis
Normally aligned pelvis has the two ASIS horizontal (same position).
During unilateral stance, one hip is pivot for motion of the opposite side of pelvis.
Elevate: pelvis hiking
Drop: pelvis drop
Lateral Pelvic Shift
Bilateral stance, hip and knee on one leg are flexed, making the opposite side weight bare and work like during unilateral stance.
