SI Flashcards
What is the sacroiliac (SI) joint?
The sacroiliac joint is the articulation between the auricular surfaces of the sacrum and ilium. It is a synovial joint with one surface covered by hyaline cartilage and the other by fibrocartilage.
How do the ridges on the articular surfaces and the shape of the sacrum contribute to SI joint stability?
The ridges on the articular surfaces and the ‘keystone’ shape of the sacrum (wide superiorly and narrow distally) enhance stability in the SI joint.
What are some evolutionary adaptations of the pelvis for bipedal movement and lumbopelvic stability?
• Flaring of the ilia into the sagittal plane for more lateral attachment of the gluteus medius (primary pelvic stabilizer).
• Larger attachment site for gluteus maximus (originating from sacrum and sacrotuberous ligament), aiding forward propulsion in gait.
What role do ligaments play in stabilizing the sacroiliac joint?
Thickened ligaments stabilize the sacroiliac joint both anteriorly and posteriorly, especially on the dorsal side of the sacrum.
What is the main function of the posterior sacroiliac ligament?
It acts as the primary posterior stabilizer of the SI joint, attaching the sacrum to the ilium, and is located deep to the sacrotuberous ligament.
What is the attachment and function of the sacrospinous ligament?
The sacrospinous ligament attaches from the ischial spine to the sacrum/coccyx.
Where does the sacrotuberous ligament attach?
It attaches from the ischial tuberosity to the posterior superior iliac spine (PSIS), sacrum, and coccyx.
What is the function and attachment of the interosseous sacroiliac ligament?
This ligament provides stabilization by attaching the sacrum to the ilium.
What is the iliolumbar ligament and where does it attach?
The iliolumbar ligament attaches from L4-L5 to the iliac crest, providing additional stability.
What is the primary anterior stabilizer of the SI joint?
The anterior sacroiliac ligament, which attaches the sacrum to the ilium.
What joints articulate in the sacroiliac joint?
The auricular surfaces of the sacrum and ilium.
What type of joint is the sacroiliac joint, and what are its surface coverings?
It’s a synovial joint with one surface covered in hyaline cartilage and the other in fibrocartilage.
How do the articular surface ridges and keystone shape of the sacrum contribute to the sacroiliac joint?
They provide stability to the joint, with the sacrum’s wide superior base and narrower distal end enhancing joint stability.
How has human evolution affected the pelvis for bipedal movement?
The ilia flare into the sagittal plane, allowing lateral attachment for gluteus medius and a larger attachment for gluteus maximus, aiding in lumbopelvic stability and forward propulsion.
What role do the sacroiliac ligaments play in joint stability?
Thickened ligaments stabilize the sacroiliac joint anteriorly and posteriorly, especially on the dorsal side of the sacrum.
Name the primary posterior stabilizer of the sacroiliac joint.
The posterior sacroiliac (dorsal) ligament, attaching the sacrum to the ilium.
What is the attachment and function of the sacrospinous ligament?
It attaches the ischial spine to the sacrum/coccyx, contributing to sacroiliac joint stability.
Where does the sacrotuberous ligament attach, and what does it stabilize?
It attaches the ischial tuberosity to the PSIS, sacrum, and coccyx, stabilizing the posterior sacroiliac joint.
Which ligament is the primary anterior stabilizer of the sacroiliac joint?
The anterior sacroiliac (ventral) ligament, connecting the sacrum to the ilium.
What are the attachments for the iliolumbar ligament?
It attaches from L4-L5 to the iliac crest, providing additional support to the lumbopelvic region.
Which nerves provide innervation to the sacroiliac joint?
Branches of the sacral plexus, dorsal rami of S1 and S2, superior gluteal nerve branches, and obturator nerves.
How can irritation of the sacroiliac joint affect nearby nerves?
It can irritate the L4-L5 spinal nerves, potentially causing dermatomal pain referral characteristic of L4-L5.
What are the primary biomechanical functions of the sacroiliac (SI) joint?
The SI joint absorbs and distributes ascending forces from the ground and descending gravitational forces, acting as a stress reliever by absorbing shock and shear from movement involving the spine and both lower extremities.
Why does the SI joint primarily need to be stable?
It serves as a convergence point of high loads with a small range of motion, necessary to absorb shock during gait and to aid in childbirth.
How does lumbar movement influence the sacrum?
The sacrum directly articulates with L5 via the intervertebral disc, so lumbar movement directly impacts the sacrum.
What are the two primary movements of the sacrum relative to the ilia?
Nutation (sacral flexion) and counternutation (sacral extension).
Describe nutation and its significance.
Nutation is sacral base movement anteriorly with the apex moving posteriorly; it’s a closed-packed position for weight-bearing activities, providing posterior stability to the SI joint.
Describe counternutation and when it typically occurs.
Counternutation is sacral base movement posteriorly with the apex moving anteriorly, typically occurring in a non-weight-bearing position, such as lying supine.
What is the range of motion (ROM) for the combined movements of nutation and counternutation?
2-4 degrees of rotation.
Define form closure.
Form closure is the stability a joint receives from its bony articulation, theoretically achieving 100% stability without external forces, although this would eliminate joint mobility.
What is force closure, and why is it important?
Force closure is joint compression from myofascial and ligamentous tension providing lateral force, essential for bearing vertical loads, especially during unilateral lower extremity loading like in gait.
How does nutation contribute to force closure?
Nutation tightens the dorsal ligaments, increasing SI joint compression to prepare for weight-bearing stability.
Why is force closure critical during unilateral loading of the lower extremity?
Unilateral loading (e.g., during gait) increases shear forces at the SI joint, requiring additional stabilization from force closure to prevent joint strain.
What deep core muscles are crucial for stabilizing the lumbar spine and pelvis?
Multifidi, Transverse Abdominis, Respiratory diaphragm, and Pelvic diaphragm (pelvic floor).
How do the deep core muscles contribute to lumbopelvic stabilization?
They must be neurologically facilitated and fire in synergy to stabilize the lumbopelvic region before extremity movement.
List common reasons for dysfunction in core musculature.
Prolonged posture and imbalance, back pain, pelvic pain, surgery/injury, nerve impingement (intercostal, iliohypogastric, ilioinguinal), pregnancy/childbirth, obesity, disuse, and rib/thoracic spine immobility.
What factors affect SI joint stability?
Lumbopelvic instability, foot and ankle mechanics, thoracic spine immobility, hip immobility, pregnancy, leg length discrepancy, and scoliosis.
Why is the gluteus medius important for pelvic stability?
It helps maintain pelvic stability during gait, reducing shear stress on the SI joints.
What happens if the core and glutes lack lumbopelvic control?
Iliacus and psoas may compensate, leading to anterior pelvic tilt, hyperlordosis, nutation, SI joint hypomobility, and abnormal sacrum-ilium movement.
How do abnormal foot and ankle mechanics impact SI joint stability?
Overpronation or oversupination fails to absorb forces efficiently, passing excessive stress to the SI joints through the kinetic chain.
What thoracic spine movements are important for overall joint health?
Extension, rotation, and lateral flexion.
How does thoracic spine rigidity affect lumbar and SI joint stability?
It may cause compensatory lumbar movement, adding shear stress to SI joints and altering diaphragm and core mechanics.
Why is hip mobility essential for SI joint stability?
Restricted hip movement may cause compensatory lumbar mobility, leading to lumbar spine instability and increased shear stress on SI joints.
What postural dysfunction in the hips may affect SI joint stability?
Lower cross syndrome can lead to lumbar compensation and weakness in muscular slings needed for SI joint force closure and stability.
What are the effects of pregnancy on the sacroiliac (SI) joints?
Postural changes, muscular imbalance, hormonal changes causing joint laxity, nerve stretching/damage, and damage to core and pelvic floor muscles.
How does pregnancy-related center of gravity change affect the SI joints?
It leads to excessive lordosis, anterior pelvic tilt, and sacral nutation, initially enhancing force closure but eventually causing degeneration, inflammation, and ligament laxity due to prolonged stress.
What muscle imbalances are common during pregnancy due to postural changes?
Shortened hip flexors and lengthened abdominals and hip extensors, which can weaken over time and reduce force closure and lumbopelvic stability.
How do hormonal changes during pregnancy impact the SI joints?
They cause ligament laxity, increasing movement and the risk of degradation and inflammation in the SI joints to facilitate childbirth.
What impact does childbirth have on the pelvic floor muscles and pudendal nerve?
The pelvic floor muscles stretch and often tear, weakening them and possibly inhibiting their function, which affects overall core stability.
List some other conditions that can cause SI joint dysfunction.
Connective tissue disorders, osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, and trauma.
What is the treatment focus for SI joint dysfunction from conditions like arthritis or connective tissue disorders?
Addressing tissue impairments, optimizing biomechanics, reducing joint stress, and strengthening surrounding musculature for increased stability.
What are common signs and symptoms of SI joint dysfunction?
Pain over SI joints (inferomedial to PSIS), tenderness on palpation, low back pain, radiating leg pain (L4-L5 dermatomal pattern), pain when turning in bed, and pain with load transfer (e.g., sit-to-stand, standing on one leg).
Which dermatomal patterns are associated with referral to the lower extremity in SI joint dysfunction?
L4-L5 dermatomal patterns.
What are common compensation patterns seen in SI joint dysfunction?
Compensation patterns often involve the piriformis, iliopsoas, adductors, pelvic floor muscles, and fibrosing of the joint.
Why do SI joint dysfunction tests have poor specificity and sensitivity?
The minimal movement at the SI joint makes specific tests for dysfunction unreliable, with poor interrater reliability; three or more positive tests are often needed for diagnosis.
What is the gold standard for diagnosing SI joint pain?
An intra-articular injection of anesthetic under radiological imaging guidance.
What does a positive Stork test indicate?
Absence of proper pelvic mechanics or lack of posterior rotation of the non-stance leg innominate during single-leg stance.
How is the Forward Bend test performed, and what indicates a positive result?
With hands on the iliac crests and thumbs under PSIS, observe PSIS movement during forward bending. Unequal cranial movement of PSISs indicates restriction.
Describe the Femoral Shear Test (Thigh Thrust) and its positive sign.
Flex the hip to 90 degrees, stabilize the sacrum, apply vertical pressure to the femur; reproduction of SI joint pain is positive.
How is the Fortin Finger Test conducted, and what does a positive result indicate?
The patient points to pain located inferomedial to the PSIS, indicating possible SI joint involvement.
Describe the FABER’s test and what a positive result indicates.
Patient’s hip is placed in figure-4 position; point-specific pain at the SI joint suggests dysfunction.
How is Gaenslen’s Test performed, and what does a positive result indicate?
Patient flexes one hip maximally while the other extends off the table; SI joint pain in the extended hip suggests dysfunction.
What is the purpose of the Active Straight Leg Raise test?
To assess SI joint pain reproduction with leg raise; if core activation reduces pain, stabilization exercises may be beneficial.
What does a positive SI Joint Compression Test indicate?
Point-specific SI joint pain during downward pressure on the iliac crest, testing posterior SI ligaments.
Describe the SI Joint Distraction Test and a positive result.
Apply downward and outward pressure on the medial ASIS to distract the anterior SI joint; SI joint pain indicates dysfunction.
What does a positive Prone Straight Leg Raise test indicate for SI joint dysfunction?
Pain during the leg raise that decreases with SI joint stabilization suggests benefit from stabilization exercises.
Why might functional movement tests be useful in diagnosing SI joint pain?
Movements like squats, lunges, or step-downs may reproduce SI joint pain, aiding in diagnosis.
What is the general treatment approach for SI joint pain?
Address postural alignment, muscle length and strength, treat tissue impairments, optimize biomechanics, and provide exercise and mobility interventions.
What additional treatments may be recommended for SI joint dysfunction?
Joint mobilization, muscle energy techniques, exercise prescriptions, physiotherapy referral, orthotics for foot alignment, and lumbopelvic braces if needed.
