Chapter 27 The Sacroiliac Joint. Overview The sacroiliac joint (SIJ), which serves as the point of...

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Transcript of Chapter 27 The Sacroiliac Joint. Overview The sacroiliac joint (SIJ), which serves as the point of...

  • Slide 1
  • Chapter 27 The Sacroiliac Joint
  • Slide 2
  • Overview The sacroiliac joint (SIJ), which serves as the point of intersection between the spinal and the lower extremity joints is the least understood and, therefore, one of the most controversial and interesting areas of the spine The sacroiliac joint (SIJ), which serves as the point of intersection between the spinal and the lower extremity joints is the least understood and, therefore, one of the most controversial and interesting areas of the spine
  • Slide 3
  • Anatomy The ilium, ischium, and pubic bone fuse at the acetabulum to form each innominate The ilium, ischium, and pubic bone fuse at the acetabulum to form each innominate Each of the two innominates articulate with the sacrum, forming the sacroiliac joint, and with each other at the symphysis pubis Each of the two innominates articulate with the sacrum, forming the sacroiliac joint, and with each other at the symphysis pubis
  • Slide 4
  • Anatomy The sacrum is a strong and triangular bone located between the two innominates The sacrum is a strong and triangular bone located between the two innominates Provides stability to this area and transmits the weight of the body from the mobile vertebral column to the pelvic region Provides stability to this area and transmits the weight of the body from the mobile vertebral column to the pelvic region
  • Slide 5
  • Anatomy The articulating surfaces of the sacroiliac joint differ The articulating surfaces of the sacroiliac joint differ The iliac joint surfaces are formed from fibrocartilage The sacral surfaces are formed from hyaline cartilage. The hyaline cartilage is 3-5 times thicker than the fibrocartilage, so that between the sacral and iliac auricular surfaces, the sacroiliac joint is deemed a synovial articulation, or diarthrosis
  • Slide 6
  • Anatomy The configuration of the sacroiliac joints is extremely variable from person to person, and between genders in terms of morphology and mobility The configuration of the sacroiliac joints is extremely variable from person to person, and between genders in terms of morphology and mobility These differences are not pathological, but are normal adaptations These differences are not pathological, but are normal adaptations
  • Slide 7
  • Anatomy Like other synovial joints, the sacroiliac joint is reinforced by ligaments, but the ligaments of the sacroiliac joint are some of the strongest and toughest ligaments of the body Like other synovial joints, the sacroiliac joint is reinforced by ligaments, but the ligaments of the sacroiliac joint are some of the strongest and toughest ligaments of the body
  • Slide 8
  • Anatomy The anterior sacral ligament (ASL) is an anterior-inferior thickening of the fibrous capsule The anterior sacral ligament (ASL) is an anterior-inferior thickening of the fibrous capsule Relatively weak and thin compared to the rest of the sacroiliac ligaments Relatively weak and thin compared to the rest of the sacroiliac ligaments Extends between the anterior and inferior borders of the iliac auricular surface, and the anterior border of the sacral auricular surface Extends between the anterior and inferior borders of the iliac auricular surface, and the anterior border of the sacral auricular surface
  • Slide 9
  • Anatomy The interosseous ligament is a short ligament located deep to the dorsal sacroiliac ligament The interosseous ligament is a short ligament located deep to the dorsal sacroiliac ligament Forms the major connection between the sacrum and the innominate, filling the irregular space posterior-superior to the joint between the lateral sacral crest, and the iliac tuberosity Forms the major connection between the sacrum and the innominate, filling the irregular space posterior-superior to the joint between the lateral sacral crest, and the iliac tuberosity
  • Slide 10
  • Anatomy The dorsal sacroiliac ligament (long ligament) connects the PSIS (and a small part of the iliac crest) with the lateral crest of the third and fourth segment of the sacrum The dorsal sacroiliac ligament (long ligament) connects the PSIS (and a small part of the iliac crest) with the lateral crest of the third and fourth segment of the sacrum This is a very tough and strong ligament This is a very tough and strong ligament Sacral nutation (anterior motion) of the sacrum appears to slacken this ligament whereas counternutation (posterior motion) tautens the ligament Sacral nutation (anterior motion) of the sacrum appears to slacken this ligament whereas counternutation (posterior motion) tautens the ligament
  • Slide 11
  • Anatomy The sacrotuberous ligament is comprised of three large fibrous bands, broadly attached by its base to the posterior inferior iliac spine, the lateral sacrum, and partly blended with the dorsal sacroiliac ligament The sacrotuberous ligament is comprised of three large fibrous bands, broadly attached by its base to the posterior inferior iliac spine, the lateral sacrum, and partly blended with the dorsal sacroiliac ligament Stabilizes against nutation (forward rotation) of the sacrum Stabilizes against nutation (forward rotation) of the sacrum Counteracts against the dorsal and cranial migration of the sacral apex during weight bearing Counteracts against the dorsal and cranial migration of the sacral apex during weight bearing
  • Slide 12
  • Anatomy The sacrotuberous ligament extends from the ischial spine to the lateral margins of the sacrum and coccyx, and laterally to the spine of the ischium The sacrotuberous ligament extends from the ischial spine to the lateral margins of the sacrum and coccyx, and laterally to the spine of the ischium Counteracts against nutation of the sacrum Counteracts against nutation of the sacrum
  • Slide 13
  • Anatomy The pubic symphysis is classified as a symphysis as it has no synovial tissue or fluid, and contains a fibrocartilaginous disc The pubic symphysis is classified as a symphysis as it has no synovial tissue or fluid, and contains a fibrocartilaginous disc The bone surfaces of this joint are covered with hyaline cartilage, but are kept apart by the presence of the disc The bone surfaces of this joint are covered with hyaline cartilage, but are kept apart by the presence of the disc
  • Slide 14
  • Anatomy Thirty-five muscles attach directly to the sacrum and/or innominate Thirty-five muscles attach directly to the sacrum and/or innominate These muscles primarily function to stabilize the sacroiliac joint rather than to move it These muscles primarily function to stabilize the sacroiliac joint rather than to move it
  • Slide 15
  • Anatomy The piriformis muscle The piriformis muscle Primarily functions to produces external rotation and abduction of the femur Primarily functions to produces external rotation and abduction of the femur Also thought to function as an internal rotator and abductor of the hip if the hip joint is flexed beyond 90 Also thought to function as an internal rotator and abductor of the hip if the hip joint is flexed beyond 90 Capable of restricting sacroiliac joint motion Capable of restricting sacroiliac joint motion
  • Slide 16
  • Anatomy The term pelvic floor muscles primarily refers to the levator ani, a muscle group composed of the pubococcygeus, puborectalis and iliococcygeus The term pelvic floor muscles primarily refers to the levator ani, a muscle group composed of the pubococcygeus, puborectalis and iliococcygeus The levator ani muscles join the coccygeus muscles to complete the pelvic floor The levator ani muscles join the coccygeus muscles to complete the pelvic floor The pelvic floor muscles work in a coordinated manner to increase intra-abdominal pressure, provide rectal support during defecation, inhibit bladder activity, help to support the pelvic organs, and assist in lumbopelvic stability The pelvic floor muscles work in a coordinated manner to increase intra-abdominal pressure, provide rectal support during defecation, inhibit bladder activity, help to support the pelvic organs, and assist in lumbopelvic stability
  • Slide 17
  • Anatomy Neurology Neurology It remains unclear precisely how the anterior and posterior aspects of the sacroiliac joint are innervated, although the anterior portion of the joint likely receives innervation from the posterior rami of the L2 S2 roots Contribution from these root levels is highly variable and may differ among the joints of given individuals It is the joints highly variable and complex innervation that produces a very diffuse pattern of pain referral from this area
  • Slide 18
  • Biomechanics The pelvic area must function to absorb the majority of the lower extremity rotation, while still permitting motion to occur The pelvic area must function to absorb the majority of the lower extremity rotation, while still permitting motion to occur It is likely, that the movement of the pelvis is in the nature of deformations and slight gliding motions around a number of undefined axes, with the joints of the pelvic ring deforming in response to body weight and ground reaction forces It is likely, that the movement of the pelvis is in the nature of deformations and slight gliding motions around a number of undefined axes, with the joints of the pelvic ring deforming in response to body weight and ground reaction forces
  • Slide 19
  • Biomechanics There is very little agreement, either among disciplines, or even within discipli