Lower limb

Sacroiliac joint articular cartilage (Sacrum & Ilium)

Cartilago articularis articulationis sacroiliacae

Origin

Thick hyaline cartilage on sacral auricular surface (2–3 mm)

Insertion

Thinner fibrocartilage on iliac auricular surface (1 mm)

Function

Provides interlocking friction-optimized joint surface absorbing tremendous axial torso loads

Innervation

Avascular and aneural (capsule and subchondral bone innervated via L4–S3)

Movement & chain

Minimal micro-gliding and shock attenuation during gait stance phase

Palpation

Not palpated directly

Clinical

Sacroiliitis in ankylosing spondylitis (erosions and joint space narrowing progressing to ankylosis); SI joint arthrosis.

Segmental innervation

L4–S3

In clinical practice

Fluoroscopy-guided SI joint intra-articular injection and core pelvic rehabilitation

Region in the model

Lower limb