TCH6210: PELVIS Lecture Notes

The sacroiliac (SI) joints are among the most misunderstood and controversial joints in the spine.
They are classified as mobile diarthrodial joints (synovial joints).
Sacroiliac joint syndrome is a controversial topic but is increasingly recognized.

True Synovial Joints: Sacroiliac joints (SI) are true synovial joints consisting of:
Sacral facet: Mostly hyaline cartilage.
Ilium facet: Mostly fibrocartilage.
Joint surfaces cover S1-S3 and have about a 30° medial to lateral orientation.
The joint surface shape can be C-shaped, L-shaped, or boot-shaped, allowing for movement between upper and lower joint surfaces.
Upper Joint: Influenced by loads from above (spine).
Lower Joint: Influenced by loads from below (lower extremities).

SI joints consist of a 5-joint complex that includes:
2 SI joints.
2 posterior facet joints.
1 intervertebral disc (IVD).
This complex serves as a kinematic link between the lower extremities and the spine, allowing movement during gait and postural changes.
SI joints absorb compressive forces, facilitating load transfer from the axial skeleton to the lower extremities.

The sacrum acts as a “keystone” in an arch, providing additional support during weight-bearing activities due to a "locked in" phenomenon.
SI joint motion is primarily secondary (passive); there are no major primary muscle movers for this joint.
Total motion at the sacroiliac joint is small. Key movements include:
Anterior Rotation of the ilium relative to the sacrum = Extension.
Posterior Rotation of the ilium relative to the sacrum = Flexion.
SI motion correlates with femoro-acetabular flexion and extension:
Hip extension leads to ilium anterior rotation.
Hip flexion leads to ilium posterior rotation.

Assessing small amounts of SI joint motion can be challenging; various methods used include:
Motion palpation.
Static palpation.
Postural analysis.
Symptoms and physical indicators.
Mistakes in analysis may lead to maladjustment of the joints.
Typically, the painful side is swollen and traumatized, while the opposite side may be restricted.
Common causes of SI joint misalignment can include:
Tight Piriformis- sacral tilt
Tight muscles: e.g., hamstrings can lead to PI (posterior inferior) ilium.
Weak gluteal muscles may lead to AS (anterior superior) ilium.
Chronic postures: e.g., one leg forward may lead to PI ilium.

In the context of Activator Methods, a short leg is often associated with a PI ilium.
Conversely, a long leg may correlate with an AS ilium.

PI Ilium: Posterior inferior malposition, related to flexion restriction, extension misalignment. Tight Hamstrings
AS Ilium: Anterior superior malposition, related to extension restriction, flexion malposition. Tight Rectus femoris/ weak glut max
Flexion Restriction: Stuck or fixed in extension.
Extension Restriction: Stuck or fixed in flexion.

Specific contact points are critical for testing and creating motion:
Contacting the left sacral apex may create different rotations around the oblique axis.
Identifying decreased lumbar lordosis relates to sacral positioning, such as nutation and counter-nutation.
Understanding these positions aids in correct adjustments and patient care.

Always consider the functional impact of pelvic and sacral positions on overall body mechanics and assessment. Proper identification of joint malpositions is crucial to effective intervention.