9.6 Sacroiliac Joint & Pelvic Girdle Rehabilitation

9.6 Sacroiliac Joint & Pelvic Girdle Rehabilitation

Core Clinical Mandate: Disorder-specific Rehabilitation (14%) is the single largest content area on the NBCE Physiotherapy Test Plan, and its first named sub-topic is "spine and pelvis." The sacroiliac joint transmits every newton of load between the trunk and the lower limbs, and it is the region most often mislabelled as lumbar radiculopathy.

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Functional Anatomy

The sacroiliac joint (SIJ) is a paired, true synovial joint between the auricular surfaces of the sacrum and ilium, with a fibrous posterior component.

• Surfaces: the sacral side is hyaline cartilage; the iliac side is thinner fibrocartilage. The surfaces are irregular and become progressively more ridged with age, increasing friction and stability.
• Available motion: small — on the order of 2 to 4 degrees of rotation and 1 to 2 millimetres of translation. The joint is built for load transfer, not for movement, and "correcting a fixation" is better understood as restoring symmetric load transfer than as repositioning bone.
• Nutation is anterior sacral base rotation relative to the ilium (sacral promontory moves anteroinferiorly). Counternutation is the reverse. Nutation is the close-packed, more stable position and is recruited under load.
• Ligaments: the interosseous and short and long posterior sacroiliac ligaments resist nutation; the sacrotuberous and sacrospinous ligaments resist sacral nutation and control the pelvic outlet. The long dorsal ligament is a frequent source of localized posterior pain and is tensioned by counternutation.
• Innervation is variable and multi-segmental, commonly described from L4 through S3 — the anatomical reason SIJ referral is diffuse and mimics radicular pain.

Form Closure and Force Closure

Stability of the pelvic ring is conventionally modelled as two complementary contributions:

The myofascial slings that generate force closure:

• Posterior oblique sling: latissimus dorsi → thoracolumbar fascia → contralateral gluteus maximus. This is the principal gait sling; it tensions the fascia across the sacrum at heel strike.
• Anterior oblique sling: external oblique → abdominal fascia → contralateral internal oblique and adductors.
• Longitudinal sling: erector spinae → thoracolumbar fascia → sacrotuberous ligament → biceps femoris. This explains why chronic hamstring tension frequently accompanies SIJ dysfunction: the sacrotuberous ligament and biceps femoris are mechanically continuous.
• Lateral sling: gluteus medius and minimus → contralateral quadratus lumborum — the frontal-plane control system exposed by single-leg stance.

The Clinical Consequence: A pelvis that fails under load is almost never a bone out of place. It is a force-closure problem — most often a delayed or weak gluteus maximus and transversus abdominis with a compensating, overactive hamstring and erector spinae. That is what the examination and the exercise prescription must target.

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Clinical Presentation

• Pain location: most characteristically below the L5 spinous process and lateral to the midline, centred over the posterior superior iliac spine (PSIS). Patients frequently point to the PSIS with one finger — the Fortin finger test.
• Referral: buttock, posterior or lateral thigh, groin, and occasionally below the knee. Referral below the knee does not exclude the SIJ, which is why it is so often misdiagnosed as radiculopathy.
• Aggravating activities: transitional movements — rising from sitting, rolling in bed, stair climbing, single-leg stance, prolonged standing, and getting in and out of a car.
• History: often a fall onto the buttock, a missed step, a motor vehicle collision with a braced leg on the pedal, pregnancy and delivery, or repetitive asymmetrical loading.

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Examination: The Provocation Cluster

Palpatory and motion-based tests of the SIJ (positional symmetry, the standing or seated flexion test, the Gillet test) have consistently shown poor inter-examiner reliability. The reliable approach is a cluster of pain-provocation tests.

Interpretation rule: the cluster becomes clinically meaningful when three or more of the standard provocation tests are positive, and is far less informative when only one is. A cluster in which all tests are negative argues strongly against the SIJ as the pain source.

Differential Diagnosis

Inflammatory Red Flags — Do Not Miss Axial Spondyloarthritis: Suspect inflammatory rather than mechanical sacroiliitis when the patient has insidious onset before age 45, morning stiffness lasting more than 30 minutes, pain that wakes them in the second half of the night, improvement with exercise but not with rest, alternating buttock pain, a good response to non-steroidal anti-inflammatory drugs, or associated uveitis, psoriasis, or inflammatory bowel disease. This pattern requires laboratory and imaging referral, not a course of stabilization exercise alone.

Other red flags in the pelvic region: a history of malignancy with new unremitting bone pain, fever with night sweats, a fall in an osteoporotic patient raising suspicion of a sacral insufficiency fracture, and any new bowel, bladder, or saddle sensory change, which demands immediate evaluation for cauda equina syndrome.

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Pubic Symphysis and Pregnancy-Related Pelvic Girdle Pain

• The pubic symphysis is a fibrocartilaginous joint completing the anterior pelvic ring. Because the ring is closed, pubic symphysis and sacroiliac dysfunction commonly coexist — a force applied at one end is transmitted to the other.
• Osteitis pubis / pubic-related groin pain presents with anterior pubic tenderness, pain on resisted adduction, and pain with cutting, kicking, and sit-ups. It responds to relative rest from provocative loading with progressive adductor and abdominal loading, including isometric adductor squeezes early.
• Pregnancy-related pelvic girdle pain is driven by relaxin-mediated ligamentous laxity combined with a rapidly shifting centre of mass and stretched abdominal wall — a pure form-closure failure requiring force-closure compensation.
  • Pelvic belt: worn low, directly over the greater trochanters, not around the waist. A belt placed too high does not compress the pelvic ring and will not help.
  • Exercise: transversus abdominis and pelvic floor co-activation, gluteal strengthening, avoidance of sustained single-leg loading and wide-legged positions, and symmetrical movement strategies for rolling and rising.
  • Symptoms typically improve substantially in the months after delivery as relaxin levels fall, but persistent pain is common and responds to the same force-closure approach.

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Rehabilitation Progression

1. Settle the irritable joint. Relative rest from the provocative pattern, activity modification for transitional movements (rolling with knees together, rising with symmetrical loading), and short-term modality use for pain control. A sacroiliac belt worn over the greater trochanters can provide immediate symptomatic relief and functions as a diagnostic test of force-closure benefit.
2. Restore the local stabilizers. Low-load, precisely cued transversus abdominis and pelvic floor co-activation, and lumbar multifidus activation at the involved segment, verified by palpation without global bracing.
3. Restore the gluteus maximus. The posterior oblique sling is the primary SIJ force-closure mechanism, and the gluteus maximus is the muscle most reliably inhibited in this population. Progress prone hip extension with a neutral spine → bridging → single-leg bridging → hip thrust → loaded hip hinge. Watch for hamstring and erector spinae substitution, which is the signature compensation.
4. Restore the lateral sling. Gluteus medius work in side-lying, then weight-bearing: step-downs, single-leg stance, and lateral band walks, judged by pelvic level rather than by repetitions completed.
5. Integrate the slings under load. Contralateral patterns that couple latissimus to opposite gluteus maximus — bird dog, chops and lifts, split-stance cable pulls, and loaded carries, particularly single-arm (suitcase) carries, which load the lateral and posterior slings directly.
6. Address the whole kinetic chain. Correct hip flexor and hamstring restriction, restore hip internal rotation, address a true leg-length discrepancy with a graded heel lift, and screen foot mechanics, since excessive pronation alters pelvic load transfer through the chain.
7. Return to load and sport with asymmetrical and rotational demands restored last: lunging, cutting, kicking, and lifting patterns performed with maintained pelvic control.

What Not To Do: Do not build a pelvic program out of passive modalities and end-range stretching of the hamstrings. The hamstring is usually tight because it is compensating through the longitudinal sling for an inhibited gluteus maximus. Stretch the compensator without restoring the stabilizer and the pain reliably returns.