Chapter 2 Flashcards
Are the biomechanics of the pelvis a confirmed and highly agreed upon?
no, it is a controversial area
Debate on amount of SI motion
For years it was thought that there was no motion.
What is the motion classification of the SI joint?
Diarthrodial
Upper 1/3 is an amphiarthrosis
What is the Importance in SI joint in relation to low back pain
Much so-called “low back pain” is caused by sacroiliac problems.
b) Often undiagnosed or incorrectly diagnosed.
Major mechanical functions of pelvis
a) Attaches the spine to the lower extremities and transfers weight to them
b) Shock absorption
c) Gyroscopic action during gait
d) In females, important in the birth process
what makes up the pelvis joints?
Pelvis consists of a three joint complex
a) 2 SI joints
b) Pubic symphysis
What kind of joint is the SI joint and what kind of surfaces does it have?
Synovial joint with atypical surfaces
What kind of joint is the pubic symphysis?
Pubic symphysis classified as a fibrocartilaginous joint
a) Amphiarthrosis
What 3 surfaces make up the SI joint?
Auricular surface
Iliac surface
Sacral surface
What is the appearance of the auricular surface?
(1) Ear (auricular) shaped or boot shaped
(2) Cephalad portion
(a) Referred to as the “upper joint”
(3) Caudad portion
(a) Referred to as the “lower joint”
What plane is the auricular surface in?
Predominantly in the sagittal plane (10° to sagittal plane)
What are the characteristics of the iliac surface?
(1) Fibrocartilage
(2) Central convex ridge
(3) Large rough bony surface posterior and superior to joint for ligamentous attachment
(4) Iliac tuberosity behind the joint
(a) Roughened area behind jt.
What are the characterics of the sacral surface?
(1) Hyaline cartilage
(2) Three times thicker than iliac surface
(3) Central groove (concavity)
(4) Wedge shaped superior to inferior (viewed P-A, A-P)
(5) S-shape anterior to posterior (viewed from side)
What is the pubic joint characteristic?
a) Articulation in median plane
b) Amphiarthrosis
c) Contains interpubic fibrocartilaginous disc
What are the intrinsic ligaments of the pelvis?
- bind sacrum to the ilium
Anterior ligament
(a) Anterior superior
(b) Anterior inferior
Posterior SI ligament
(a) Dorsal ligaments
(b) Interosseous SI ligament
What are the extrinsic ligaments of the pelvis?
(1) Sacrotuberous ligament
(2) Sacrospinous ligament
(3) Iliolumbar ligaments
What muscle crosses the SI joint?
None, no muscle crosses the SI joint
What muscles influence SI motion?
(1) Multifidus, erector spinae (SI ligament)
(2) Hamstrings, gluteus max., and piriformis have fibrous attachment to sacrotuberous ligament
(3) Psoas (anterior joint capsule)
(4) Quadratus lumborum (iliolumbar ligaments)
What is the innervation of the pelvis?
Exact innervation is debated1, but neural elements have been identified in the joint capsule and adjoining ligaments suggesting innervation for both pain and proprioception
What is the joint architecture of the SI joint?
(1) Synovial diarthrodial joint
(2) Auricular (ear) shape
(3) Corresponding groove/ridge
(4) Locking sacral wedge shape, plus interlocking sacral S configuration
Which gender has a greater “S” shape in their SI joint and what does this lead to?
Males have an increased “S” and it associates with decreased mobility
How does the SI joint appear at birth?
a) Joints undeveloped, smooth and flat, glide in any direction; stability provided by ligaments
b) Begin to develop during walking
How does the SI joint appear in the teens?
a) Roughening of surfaces, development of grooves and ridges
(1) Male more pronounced than female
b) Track bound movement develops
What occurs in the SI joint in the 3rd to 4th decade?
a) Articular changes in surface anatomy are well established.
b) Joint surfaces become more irregular.
c) enlargement of iliac tuberosity
d) beginning of joint surface erosions
e) possible osteoarthrosis (DJD) on iliac surface (more in males)
What occurs in the SI joint in the 5th and 6th decade?
a) Joint surfaces become more irregular.
b) Each individual joint is unique in its topography to varying degrees (more pronounced in males).
c) possible osteoarthrosis (DJD) developing on sacral surface and continuing on iliac surface (more in males)
d) possible development of joint adhesions, osteophytes, and fusion
What occurs in the SI joint in the 7th decade and beyond?
a) interarticular adhesions
b) high prevalence of bony ankylosis (fusion)
(c) Fusion occurs mainly in the superior part of the joint.
What are the two weight bearing arches of the pelvis?
Anterior and posterior arch
What is the function of the posterior arch?
Posterior arch
(a) Major weight bearer
(b) First three sacral segments
(c) Two pillars of bone running through
the SI and acetabular fossa
What resists the gravitational forces acting on the posterior arch in terms of weight bearing in the pelvis?
It is a down and posterior force which is resisted by:
(a) wedge shaped sacrum
(ii) Down and anterior; resisted by: (a) “S” shaped joint (b) posterior ligaments (c) interosseous ligaments (d) sacrotuberous ligaments
What is the anterior arch of the pelvis?
(a) Pubic rami
(b) Connects posterior arches and acts as a compression strut
What part of the SI joint promotes stability through form closure?
(1) Wedge shape of the sacrum
(2) Interlocking groove (sacrum) and ridge (ilium)
(3) S-shaped joint surfaces
What part of the SI joint stabilizes the joint through force closure?
Tension in muscles, ligaments and thoracolumbar fascia aids in stabilizing the SI joints (force closure).
(1) Creates lateral to medial pressure from the ilia to the sacrum, compressing the SI joints
(2) Clutch-like bracing system
True or false, only either form or force closure is required to stabalize the hip joint?
Both form and force closure are
important in maintaining SI stability.
What are the research fingings of the range of SI joint average flexion and extension?
1 to 8 degrees of average total flexion and extension
What is sacral nutation?
(lumbosacral extension): sacral base moves anterior and inferior
(a) When the lumbosacral region extends, the
sacrum nutates
What is sacral counternutation?
sacral base moves posterior and superior
(a) When the lumbosacral region flexes, the sacrum counternutates.
During pregnancy, how much of an increase of pelvic joint occurs?
Increased pelvic joint mobility (i) 2.5 times increases mobility
What does the sacrum do during delivery?
Sacrum nutates and counternutates during delivery
What is the amount of increase in the symphysis pubis during pregnancy?
4-9mm increased symphysis width
What sacral movement occurs with inhalation?
Counternutation
What sacral movement occurs with expiration?
Sacrum nutates
What do all curves do during inspiration?
All curves decrease during inspiration
What do all curves do during expiration?
All curves decrease
What movement occurs when the ilium is in flexion?
PSIS moves posterior and inferior
(i) Static malposition where ilium is in flexion: PI ilium
What movement occurs when ilium is in extension?
PSIS moves anterior and superior
(i) Static malposition where ilium is in extension: AS ilium
What movement is the SI joint motion named in reference to?
The ilium movement in relation to the sacrum regardless of which bone is moving
What is flexion of the SI joint associated to?
(a) The ilium flexes relative to the sacrum.
(b) The sacrum nutates relative to the ilium.
What is extension of the SI joint associated to?
(a) The ilium extends relative to the sacrum.
(b) The sacrum counternutates relative to the ilium.
What structure is used as a reference point for SI rotation?
PSIS
What does the gonstead listing EX mean in regards to SI rotation?
PSIS moves away from midline
What does the gonstead listing IN mean in regards to SI rotation?
PSIS moves towards midline
What is internal (medial) rotation of ilium known as in gonstead listings?
EX (PSIS moves away from midline)
What is external (lateral) rotation of ilium known as in gonstead listings?
IN (PSIS moving towards the midline)
What is the sacral gyroscopic motion?
(a) Movement occurs during locomotion.
(b) Combination of rotation and translation
(c) Sacral motion is opposite of iliac motion (i) Flexion of ilium sacral nutation
(ii) Extension of ilium sacral counternutation
How do the sacral motions compare during walking?
Sacral motion on one side contrasts with opposite motion on other side during gait
(i) The right side nutates (anterior and inferior movement of the base), while the left side counternutates (posterior and superior movement of the base), and vice versa.
How are the pelvic motions during walking?
One ilium moves opposite to the other during gait
The right ilium flexes while the left ilium extends, and vice versa.
What is the thoracolumbar movement during gait?
(1) Trunk rotation is opposite pelvis rotation
(2) Increased lordosis with hip extension (i.e., toe-off)
(3) Slight momentary scoliosis toward swing side due to pelvic tilt
What is the stabilizer of the pelvis?
(1) Sacrum acts as the keystone in an arch
(a) Supports trunk
(b) Provides locking mechanism for static loads
What is a shock absorber in the pelvis?
(1) Lumbosacral angle influences lumbar curve
- (a) Spinal curves allow the spine to act like a spring.
- (b) Loss of lumbar lordosis increases stress to the spine and lower extremities with consequent functional and degenerative
adaptational changes.
(2) Transfers weight during locomotion
(3) Decreases rotational and lateral flexion stress to lumbar spine (Illi)
(a) In gait, sacrum moves opposite the ilium to reduce stress to the lumbars.
What is the importance of SI function from a chiropractic role?
a) Catch mechanical faults early and may prevent early degenerative changes
b) Pain is often the result of a pathomechanical process rather than a pathological process.
c) Use tools of palpation, observation, x-ray, etc., to identify problems in early stages
(1) approach unique to our profession
Areas to evaluate in posture?
a) Iliac crests
b) PSISs
c) Greater trochanters
d) Gluteal folds
e) Pelvic tilt
What is statically palpated in the pelvis?
Soft tissue
(a) Tenderness and texture of pelvis region muscles and ligaments
(i) Start superficially and work deeper
Bony
(a) Alignment symmetry, tenderness, etc. of bony landmarks
(i) Iliac crests (ii) PSISs (iii) Sacral base, borders and apex (iv) Coccyx
What test is used during standing motion palpation of pelvis?
Gillet’s test
During upper joint gillet’s test where are the Dr’s thumbs placed?
PSIS and sacral tubercle
During upper joint gillet’s test what should occur if the patient flexes the ipsilateral hip?
Flexion occurs
Dr.’s thumbs should approximate as ilium flexes on the sacrum and the PSIS moves posteriorly and inferiorly
During upper joint gillet’s test what should occur if the patient flexes the contralateral hip?
Extension occurs
Dr.’s thumbs should separate as the sacrum counternutates relative to the ilium and the sacral tubercle moves inferiorly