MOB TCD

Pubic Symphysis and Sacroiliac Joint

Professor Emeritus Moira O’Brien

FRCPI, FFSEM, FFSEM (UK), FTCD

Trinity College

Dublin

Pubic Symphysis

• Secondary cartilagenous joint

• Articular surface of medial aspect of body of pubis

• Covered with hyaline articular cartilage

• Disc of fibrocartilage in between

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• A cavity may develop in the disc, but it is not lined with synovial membrane

• The arcuate or inferior ligament is stronger than the superior pubic ligament

Pubic Symphysis MOB TCD

Secondary Changes in Symphysis

• There is normally very little movement at the pubic symphysis, except during the latter months of pregnancy

• Infection, e.g. Reiter’s syndrome

• Loss of hip mobility, especially internal rotation

Fricker, 1997

MOB TCD

Sacroiliac Joint

• Modified synovial plane joint • The auricular articular surfaces

of the sacrum and the Ilium • The hyaline cartilage on the

articular surfaces is rough• The capsule is attached just

beyond the articular margin• The interosseous sacroiliac

ligament is one of the strongest ligaments in the body and is posterior to the joint

• This articulation is almost immobile

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Sacroiliac Joint Accessory Ligaments

• Sacrotuberous ligaments• Sacrospinous ligaments• Iliolumbar ligaments• Posterior superior iliac spine is

middle of the joint posteriorly, it is superficial

• During gait, the amount of accessory movement at the sacroiliac joint helps to protect the lumbar intervertebral discs

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• Decreasing the torsional stresses associated with pelvic rotation

• Movement at the sacroiliac joint also helps to decrease forward shearing at the L5/S1 junction during the hip extension phase of gait

• More movement during pregnancy

Tigney & Lindsay et al., quoted in DeMann, 1997

Sacroiliac Joint MOB TCD

• Secondary changes may arise in the joint due to anatomical malalignments and biomechanical factors

• Leg length discrepancies• Poor running technique • The arms swing across the front of

the body, causing stress at the joint

Sacroiliac Joint MOB TCD

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