Anatomy and Biomechanics of SIJ Flashcards
SIJ functions
load transmission- downward from head, trunk and upper limbs and lower limbs
upward from ground reaction forces
shock absorption - protect impact forces from reaching lumbar spine
childbirth - temporary increase joint laxity/movement. lower sacrum rotates posteriorly
increase pelvic outlet
load transfer across pelvis
pelvic ring
sacrum = keystone
downward = direction of BW force from trunk to femurs
upward = direction of force from femurs to trunk
joint features of SIJ
Diarthrodial joint
Synovial fluid
Articular surfaces covered with hyaline cartilage – Sacral > iliac
Normally asymmetrical!
At birth – surfaces flat
Puberty – roughened & irregular (M>F)
Fibrous capsule – reinforced by ligaments
Innervation from L2 – S4
Ligaments of SIJ
Interosseous sacroiliac ligament
iliolumbar ligament
sacrospinal ligament
sacrotuberal ligament
anterior sacroiliac ligament
anterior sacrococcygeal ligament
anterior longitudinal ligament
list the primary stabilising ligaments
Anterior sacroiliac ligament
Interosseous ligament
Short & long dorsal ligaments
list the secondary stabilising ligaments
Sacrotuberous ligament
Sacrospinous ligament
list the structures that become activated and stretched during pelvic nutation
stretched ligaments - interosseous, sacrospinous, sacrotuberous
active muscle - rectus abdominis, multifidi and erector spinae, bicep femoris
form closure
a stable situation where joint surfaces are closely fitting and no extra forces are required to maintain stability.
Shape of articular surface
Friction coefficient of articular cartilage
Integrity of joint ligaments
purpose of assessing active SLR
testing lumbo-pelvic structures ability to transfer load
core muscle control
muscles responsible for muscle control during active SLR
Transversus Abd (Richardson et al 2002)
Multifidus
Biceps femoris: continuous with Sacrotuberous ligt
Oblique slings: load transference during rotational activities
Gluteus maximus: contraction Sacrotuberous ligt tension
Contralateral Latissimus dorsi
Sacrak nutation
anterior sacral-on-iliac rotation
OR
posterior ilium-on-sacrum rotation
OR
both
Trunk forward bending
sacral counternutation
posterior sacral-on-iliac rotation
OR
anterior ilium-on-sacrum rotation
OR
both
Trunk bending back
describe biomechanics of trunk flexion
Sacrum nutates - 60°
Interosseous ligts / Sacrotuberous ligt taut
Articular ridges resist
Occ counternutates EOR
Bilateral anterior innominate rotn (on femora)
describe biomechanics of trunk extension
Sacrum counternutates?
Long dorsal ligament taut
Pelvis relatively more unstable in counternutation
Bilateral posterior innominate rotn (on femora)
describe biomechanics of hip flexion
Posterior innominate rotn = sacral nutation
describe the biomechanics of hip extension
Anterior innominate rotn = sacrum counternutates
possible traumatic/degenerative causes of SIJ pain
Pelvic #
Arthrosis – often contralateral to hip OA
Osteitis condensans ilii
Ligamentous / Muscular sprain
possible inflammatory causes of SIJ pain
AS
Psoriatic arthritis
mechanical causes of SIJ pain/dysfunction
Hypermobility
Hypomobility
Combination of both
pelvic asymmetrical causes of SIJ pain/dysfunction
sacral torsion/rotation
innominate upslip/downslip
innominate rotation ant. or post.
metabolic causes of SIJ pain/dysfunction
Osteoporosis
Paget’s Disease
other causes of SIJ pain/dysfunction
Infections
Tumours
Deep Gluteal Syndrome (aka Piriformis Syndrome)
Referral from Lumbar Spine / Viscera
pregnancy
describe pelvic girdle pain
Pain experienced between the posterior iliac crest and the gluteal fold, particularly in the vicinity of the SIJ. The pain may radiate in the posterior thigh and can also occur in conjunction with/or separately in the symphysis
possible cause of pelvic girdle pain
Transient osteoporosis
Diastastis rectus abdominis (DRA)
PF dysfunction
Hip dysfunction
Femoral Head AVN
Lumbar dysfunction
subjective findings of pelvic girdle pain
Often unilateral pain
Usually younger person involved in sport e.g.
dance, running, tennis
OR
Pregnancy / childbirth related
Pain aggravated by loading:
Stairs: step up
Sit stand
Prolonged standing
Turning in bed
Getting in & out of bed
Gait (WB phase)
describe form closure
a stable situation where joint surfaces are closely fitting and no extra forces are required to maintain stability.
what contributes to form closure
Shape of articular surface
Friction coefficient of articular cartilage
Integrity of joint ligaments
risk factors of antepartum
Prior h/o pregnancy, MSK dysfunction
Higher BMI
Smoking
Work dissatisfaction
Lack of belief of improvement of PGP
aim of physical exam of SIJ/Pelvis
Is SIJ or PS the source of nociception?
PSIS / buttock is very common referral area for lumbar / hip problems
are SIJ moving normally
Is pelvis symmetrical
pelvic girdle pain assessment
ODI
Pelvic girdle questionnaire
Fear-Avoidance Beliefs Questionnaire
Pain Catastrophizing Scale
pain provocation ax
faber’s test
gaenslens test
functional load - SLS, STS, turning in bed
mobility ax
ASLR
Endurance test - trunk flex, ext
dynamometry - hip ADD, hip EXT
diastasis recti abdominis - > 2 fingers
what does active straight leg raise
Lumbo-pelvic structures ability to transfer load
Core muscle control
management strategy for antepartum pelvic girdle pain
Exercise – consider
Low risk & minimal adverse events
SIJ belt – consider it but conflicting evidence
MT – emerging but weak evidence
management strategy for postpartum pelvic girdle pain
Education – biomechanical & BPS, load pain minimisation
Eg. Turning in bed?
Exercise – ↑ ms performance, ↓ pain & disability
All types stabilisation (TrA, back extensors & PF force closure focus), strengthening incl. hip add/abd
Often with SIJ belt
Strong evidence MT in conjunction with cointerventions ST ↓ pain & disability
Strong evidence MT is no better than stabilization exs for LT improvement (>6/12)
diagnostic criteria for pelvic girdle pain
can be diagnosed by
pain provocation tests (P4 *, Faber *, Gaenslen’s test and modified Trendelenburg’s test * / march test) +
pain palpation tests (long dorsal ligament test * and palpation of the symphysis *)
functional test - ASLR
