The Sacroiliac Joint

1
Chapter 27

• The Sacroiliac Joint

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

3
Anatomy

• 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

4
Anatomy

• 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

5
Anatomy

• 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

6
Anatomy

• 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

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

8
Anatomy

• 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
• Extends between the anterior and inferior borders
  of the iliac auricular surface, and the anterior
  border of the sacral auricular surface

9
Anatomy

• 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

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
• 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

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
• Stabilizes against nutation (forward rotation) of
  the sacrum
• Counteracts against the dorsal and cranial
  migration of the sacral apex during weight
  bearing

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
• Counteracts against nutation of the sacrum

13
Anatomy

• 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

14
Anatomy

• 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

15
Anatomy

• The piriformis muscle
• 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
• Capable of restricting sacroiliac joint motion

16
Anatomy

• 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 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

17
Anatomy

• 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

18
Biomechanics

• 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

19
Biomechanics

• There is very little agreement, either among
  disciplines, or even within disciplines about the
  biomechanics of the pelvic complex. The results
  from the numerous studies on mobility of the
  sacroiliac joint have led to a variety of
  different hypotheses and models of pelvic
  mechanics over the years

20
Biomechanics

• Osteopathic model
• The sacrum rotates around two oblique axes
• The innominates are capable of rotating
  anteriorly and posteriorly
• Distinction made between sacroiliac impairment
  and iliosacral impairment

21
Biomechanics

• Chiropractic model
• As one innominate flexes, the ipsilateral sacral
  base moves anterior and inferior, and as the
  other innominate extends, the sacral base on that
  side moves posterior and superior

22
Biomechanics

• Biomechanical model
• When the sacrum nutates, or flexes, relative to
  the innominate, a linear glide occurs between the
  two L-shaped articular surfaces of the sacroiliac
  joint.
• The shorter of the two lengths, level with S 1,
  lies in a vertical plane
• The longer length, spanning S 2-4, lies in an
  anterior-posterior plane

23
Biomechanics

• Snijders and Vleeming defined kinetics within the
  lumbar/pelvic/hip region by introducing the
  concepts of extrinsic and intrinsic stability
  of the pelvic girdle and the self-locking
  mechanism
• Their work instituted the terms form closure and
  force closure to describe the passive and active
  forces that help to stabilize the pelvis and the
  sacroiliac joint

24
Biomechanics

• Form closure
• Form closure refers to a state of stability
  within the pelvic mechanism, with the degree of
  stability dependent upon its anatomy, with no
  need for extra forces to maintain the stable
  state of the system
• Relies on incongruity of the articular surfaces,
  the friction coefficient of the articular
  cartilage and the shape of the articulating
  surfaces

25
Biomechanics

• Force closure
• Force closure requires intrinsic and extrinsic
  forces to keep the sacroiliac joint stable
• These dynamic forces involve the neurological and
  myofascial systems, and gravity. Together, these
  components produce a self-locking mechanism for
  the sacroiliac joint
• Critical to the self-locking mechanism is the
  ability of the sacrum to nutate

26
Examination

• Under the premise that a relationship between
  pelvic asymmetry and low back pain exists,
  orthopedic, osteopathic, and physical therapy
  texts promote the use of pain provocation
  (symptom-based) tests and biomechanical
  (mechanical-based) tests that include static
  (positional) and dynamic (motion or functional)
  tests

27
Examination

• Given the questionable reliability and validity
  of the tests for the sacroiliac joint, the
  clinician should guard against forming a
  diagnosis based on the results of a few tests
• Ideally, the diagnosis needs to be based on the
  results from a thorough biomechanical examination
  that includes pain provocation and static and
  dynamic tests

28
Examination

• As several recent studies have found improved
  inter-rater reliability in the diagnosis of low
  back pain when using a combination of physical
  examination procedures as opposed to a single
  model approach, it might be logical to assume
  that a similar approach would work with the SIJ

29
Examination

• History that indicates SIJ dysfunction
• A history of sharp pain awakening the patient
  from sleep upon turning in bed
• Pain with walking, ascending or descending
  stairs, standing from a sitting position, or with
  hopping or standing on the involved leg
• A positive straight leg raise at, or near, the
  end of range (occasionally early in the range
  when hyperacute), pain, and sometimes limitation,
  on extension and ipsilateral side bending of the
  trunk

30
Examination

• Systems Review
• Given the number of visceral organs in the
  vicinity of the sacroiliac joint, a thorough
  systems review is needed to rule out a visceral
  source for the symptoms

31
Examination

• Observation
• An examination of posture is performed to check
  for the presence of asymmetry
• However, as pelvic landmark asymmetry is probably
  the norm, positive findings are to be expected

32
Examination

• Hip Range of Motion
• The evidence to demonstrate whether hip rotation
  is limited in patients with signs of sacroiliac
  joint dysfunction is inconclusive

33
Examination

• Palpation of bony landmarks
• An altered positional relationship within the
  pelvic girdle should only be considered positive
  if a mobility restriction of the sacroiliac joint
  and/or pubic symphysis is also found

34
Examination

• Weight bearing and non-weight bearing kinetic
  tests
• These tests are designed to assess the
  osteokinematics occurring at the sacroiliac joint
  during patient generated movements
• The tests assess the mobility of the innominate,
  and the ability of the sacrum to nutate
  (ipsilateral test), and to side bend
  (contralateral test)

35
Examination

• The short and long-arm tests
• These tests are used to confirm or refute the
  findings from the kinetic tests

36
Examination

• Sacroiliac Joint Stress Tests
• Designed to assess the integrity of the joint and
  the surrounding ligaments
• Believed to be sensitive for severe arthritis or
  ventral ligament tears, although they have been
  shown to be poorly reproducible

37
Intervention

• Thus far, the success of interventions at this
  joint has been mixed, due in part to the poor
  reliability with many of the examinations used
• The success of any intervention depends on the
  quality and accuracy of the examination and the
  subsequent evaluation

38
Intervention

• It follows that if the examination gives an
  inaccurate diagnosis, the intervention may have a
  mixed result
• Given that the chosen intervention for the
  sacroiliac joint, like the spine, depends largely
  on the philosophy or background the clinician
  uses to establish the diagnosis, a variety of
  diagnoses for the same biomechanical dysfunction
  can arise

39
Intervention

• Acute phase goals
• Decrease pain, inflammation, and muscle spasm
• Increase weight bearing tolerance, where
  appropriate
• Promote healing of tissues through sufficient
  stabilization (may require belt)
• Increase pain-free range of sacroiliac joint
  motion
• Regain soft tissue extensibility around the
  pelvic region
• Regain neuromuscular control
• Allow progression to the functional stage

40
Intervention

• Functional phase goals
• To significantly reduce or to completely resolve
  the patients pain
• To restore full and pain-free sacroiliac joint
  range of motion
• To integrate the lower kinetic chains into the
  rehabilitation
• Complete restoration of gait, where appropriate
• The restoration of pelvic and lower quadrant
  strength and neuromuscular control