Sacroiliac Jt. Flashcards
Anterior Tilt
ASIS move inferiorly and PSIS move superiorly (ASIS move anteriorly)
Creates relative flexion of hip
Increases lumbar lordosis
Posterior Tilt
PSIS move inferiorly and ASIS move superiorly (ASIS move posteriorly)
Creates relative extension of hip
Flattens lumbar lordosis
Nutation: Sacral Flexion
(Sacral Locking)
Relative anterior tilt of the base of sacrum relative to ilium
base of sacrum moves anteriorly, coccyx moves posteriorly SACRUM
posterior pelvic tilt PELVIS
Ilia move closer together
Ishial tuberosities move farther apart
Counternutation: Sacral Extension
Sacral unlocking
Relative posterior tilt of the base of the sacrum relative to the ilium
Base of sacrum moves posteriorly, coccyx moves anteriorly SACRUM
anterior pelvic tilt PELVIS
Ilia move farther apart
Ischial tuberosities move closer together
What does the Iliolumbar ligament do?
Stabilizes lumbosacral jt
Reinforces anterior aspect of jt
Basically connects everything together anteriorly
What does the Interossesous ligament do?
STRONGEST SI JT LIGAMENT
Rigidly binds sacrum and ilium
(Runs straight across/transversely to connect the sacrum and ilium)
What does the Anterior sacroiliac ligament do?
Thinner compared to other SI ligaments
Thickening of anterior jt capsule
Limits nutation
-> base of sacrum moving anteriorly
Runs from top of base of Sacrum to ilium (curves)
What does the Long posterior sacroiliac ligament do?
Limits anterior pelvic tilt (rotation) OR sacral counternutation
Runs from ilium to coccyx (prevents coccyx from going anterior)
What does the short sacroiliac ligament do?
Limits all pelvic and sacral movement
What does the Sacrotuberous and Sacrospinous ligament do?
Limit nutation and posterior innominate tilt
Provide vertical stability (resist superior translation of sacrum)
Runs from coccyx to ischial tuberosity
Walking
Reciprocal flexion and extension of LEs
- Each side of pelvis rotates out of phase with other
- Most pronounced in SAGITTAL PLANE, but also occurs in TRANSVERSE PLANE
- Intrapelvic torsions are greater with increased walking speed
What happens in Lumbar Flexion?
Innominate and Sacrum
Innominate: Anterior tilt
Sacrum: Counternutation
What happens in Lumbar Extension
Innominate and Sacrum
Innominate: Posterior tilt
Sacrum: Nutation
What happens in Lumbar Rotation
Innominate and Sacrum
Innominate
Ipsilateral side: posterior tilt
Contralateral side: anterior tilt
Sacrum
Ipsilateral side: nutation
Contralateral side: counternutation
What happens in Lumbar Side Bend
Innominate and Sacrum
Innominate
Ipsilateral side: anterior tilt
Contralateral side: posterior tilt
Sacrum
Ipsilateral side: counternutation
Contralateral side: nutation
What happens with Restricted hip flexion?
Greater flexion in lower thoracic and lumbar regions is needed to compensate
(Tight hamstrings)
What happens with Restricted lumbar mobility?
Greater hip flexion is required to compensate
(Back pain)
Phases of Extending to Upright from Flexed Position
- Initial Trunk Extension
- Hip extension, via activation of hip extensors (glut max and hamstrings) - Middle phase
- Trunk extension occurs via shared activation of hip and lumbar extensors - Muscle activity is largely decreased once LOG shifts posterior to hips
Center Edge Angles
Definite dysplasia: less than 16 degrees; prone to dislocation
Possible dysplasia: 16-25 degrees
Normal: 25-40 degrees
Excessive acetabular coverage greater than 40 degrees
What is Coxa Valga?
GREATER angle of inclination (greater than 125 degrees)
Femoral articular surface contact area w/ acetabulum DECREASES -> which DECREASES joint stability (increase jt. degeneration, instability and joint reaction force)
Vertical WBing line shifts closer to shaft of femur
-> Decreased distance between femoral head and greater trochanter DECREASES MA of hip ABDUCTORS
-> Increased force demand to counterbalance adduction during single leg stance
-> Abductors could be weakened
What is Coxa Vara?
Angle of inclination DECREASES (less than 125 degrees)
Femoral head rests deeper in acetabulum -> which improves congruence
MA of hip abductor muscles will be INCREASED
-> decreased force needed by abductors in SLS and decreased joint reaction force
Disadvantage: INCREASED bending moment along femoral head and neck
-> increased density due to increased tensile stresses
-> increase shear force along femoral neck will INCREASE FRACTURE RISK
Excessive Anteversion (Angle of Torsion)
Pathological INCREASE in angle
Angle greater than 15-20 degrees
Increased IR ROM and decreased ER ROM
Reduces hip joint stability
“In-toe” in standing or during gait to improve alignment of articular surfaces
Retroversion (Angle of Torsion)
Pathological DECREASE in angle of torsion
Angle less than 15-20 degrees
Associated with increased ER ROM and decreased IR ROM
“Out-toe” in standing to improve articular alignment
What does the Iliofemoral ligament (Y ligament) do?
Limits…
- Hyperextension
- Superior portion limits adduction
- Lateral portion limits some ER
- Posterior Pelvic Tilt
What does the Pubofemoral ligament do?
Limits…
- Hip extension
- Abduction
- ER
What does the Ishiofemoral Ligament do?
Limits…
- Hip extension
- IR
- Hyperflexion
- Superior fibers limit extreme adduction (esp. when hip is flexed)
What does the Ligamentum Teres do?
Primary function
- Serves as channel for branch of obturator artery
- Supplies blood to femoral head
Secondary function
- Resists extremes of combined ADD, flexion and ER or combined ADD, extension, and IR
Open and Close Packed Position
Open packed position
10-30 degrees flexion, 10-30 degrees abduction, and slight ER
Close packed position
Full extension, with slight abduction and IR
-> with extension, ligaments twist around femoral head and neck, pulling femoral head into acetabulum
Close packed position of hip is NOT position of optimal articular contact of hip
What is the position of optimal articular contact?
~90 degrees flexion, abducted, and ER (frog leg position)
What are the Structural Adaptations to Weight Bearing?
2 major trabecular
- medial compressive
- lateral tensile
The greatest resistance to forces is where trabeculae intersect
Zone of weakness: area in femoral neck where trabeculae are thin and dont cross each other
-> less reinforcement and MORE potential for fracture
Combined forces (ground reaction force & HAT) create a bending moment
-> tensile force on superior aspect
-> compressive forces on inferior aspect
What plane are the weight bearing forces along?
Frontal Plane: compressive forces medially and tensile forces laterally
Sagittal Plane: compressive forces posteriorly and tensile forces anteriorly
What are the Normal ROM Values for the motions at the hip ?
Flexion: 125 degrees
Extension: 10-30 degrees
Abduction: 45 degrees
Adduction: 30 degrees
IR: 45 degrees
ER: 45 degrees
What are the pelvic motions happening in the sagittal plane?
front and back
Anterior tilting
- Produces relative flexion of the hip
- Increases lumbar lordosis
Posterior tilting
- Produces relative extension of the hip
- Flattens lumbar lordosis
What are the pelvic motions happening in the frontal plane?
Lateral pelvic tilt: motion occurring on NWBing side
(Standing on one leg: leg that is up has a lateral pelvic tilt cuz it is elevated)
Hip hiking -> elevation of pelvis (leg that is raised)
Pelvic drop -> drop of pelvis (side that is WBing)
ABD vs. ADD
Right pelvic hike (standing on left leg, right leg raised): hip hiking right leg will create LEFT hip ABD
Right pelvic drop (standing on left leg, right leg raised): pelvic drop on right leg will create LEFT hip ADD
Lateral shift: used in bilateral stance
Right lateral shift
- standing on 2 feet, leaning to the right, my RIGHT leg is ADD, left leg is ABD
- if i want to go back to neutral, my LEFT ADDUCTORS and my RIGHT ABDUCTORS work together to bring me to neutral
Left lateral shift
- leaning on my left side, LEFT side is ADD, RIGHT is ABD
- if i want to go to neutral, my RIGHT ADDUCTORS and LEFT ABDUCTORS work together to bring me to neutral
What are the pelvic motions happening in the transverse plane?
IR and ER
Standing on left side
- Forward rotation from my right side results in IR of LEFT hip jt
- Backward rotation from right side results in ER of LEFT hip jt
Arthrokinematics of Femur Moving on Acetabulum: Flexion and Extension
Flexion
- Head of femur primarily SPINS in place with a small posterior slide
Extension
- Head of femur primarily SPINS in place with a small anterior slide
Arthrokinematics of Femur Moving on Acetabulum: Abduction
Head of femur rolls superiorly and slides inferiorly
VCO
Arthrokinematics of Femur Moving on Acetabulum: IR and ER
IR
- Head of femur rolls anteriorly slides posteriorly
ER
- Head of femur rolls posteriorly slides anteriorly
VCO
What force couple anteriorly tilts the pelvis?
Hip flexors (iliopsoas and Sartorius pull down) and erector spinae (pull up) anteriorly tilt the pelvis
What force couple posteriorly tilts the pelvis?
Hip extensors (hamstrings and glute max pull down) and abdominal muscles (Rectus abdominus and external obliques pull up) to posteriorly tilt the pelvis
What is the normal Angle of Torsion?
Normal= 10-20 degrees
What is different about the SI jt when we are younger?
-more movement
- surface is smoother
- Angle of inclination is larger (150 degrees)
-> decreases as we age
- Angle of torsion is larger
-> decreases as we age
Adductor Muscles assist…
- Assist with hip flexion when it starts from neutral or extended position
- Acts as hip extensors when it starts from flexed position
Internal Rotators are capable of…
Capable of greater torque production as hip flexion angle increases
External rotators…
- Torque production decreases as hip flexion angle increases
- Piriformis positioned for ER at 0 degrees of hip flexion, but IR beyond 90 degrees of hip flexion
What is passive insufficiency of the hamstrings?
Limits hip flexion if knee is extended
What is passive insufficiency of Rectus femoris
Will limit hip extension if knee is flexed
What is active insufficiency of the hamstrings
If i extend my hip i cannot fully flex my knee
Muscle doing two actions at once
What is active insufficiency of Rectus femoris
If my hip is fully flexed, i cannot extend my knee.
