Sacroiliitis

Lower Limb

Overview

Sacroiliitis is inflammation of the sacroiliac joint(s), characterized by pain in the lower back, buttocks, and/or lower limbs. It can result from mechanical dysfunction, inflammatory arthropathies (such as ankylosing spondylitis), infection, or trauma. Early identification and appropriate management are essential to prevent chronic pain and functional limitations.

Pathophysiology

The sacroiliac joint is a diarthrodial joint with limited mobility, primarily functioning to transfer load between the spine and lower limbs. Sacroiliitis develops through inflammatory cascades triggered by mechanical irritation, degenerative changes, or autoimmune conditions such as seronegative spondyloarthropathies. Inflammation leads to synovitis, cartilage degradation, and potential ligamentous involvement. Secondary muscle guarding and myofascial restrictions develop as protective mechanisms, further restricting joint mobility and perpetuating the inflammatory cycle.

Patient Education

Sacroiliitis responds well to movement, stability exercises, and activity modification; prolonged rest typically worsens outcomes, so gradually returning to functional activity with proper pelvic stabilization is essential for recovery.

Typical Presentation

Site

Unilateral or bilateral sacroiliac joint region, lower lumbar spine, buttocks, posterior and lateral thigh, occasionally radiating to groin or anterior thigh

Quality

Deep, aching, sometimes sharp or stabbing quality; patients may describe a 'catching' or 'grinding' sensation

Intensity

Mild to severe, often 4-8/10; variable throughout the day and with activity

Aggravating

Prolonged sitting or standing, unilateral weight-bearing, stair climbing, running or jumping, forward bending with rotation, crossing legs, getting in/out of vehicles, sleeping on affected side

Relieving

Movement and activity, lying down, compression (such as wearing an SIJ belt), heat, gentle mobilization

Associated

Pelvic instability, gluteal weakness, hip internal rotation restriction, leg length discrepancy, altered gait pattern, lower back stiffness, referred pain to knee or ankle

Orthopaedic Tests

Test descriptions are written with AI assistance from standard clinical texts. Where a test lists Sources, its description has been checked against them; those sources are independent and do not endorse OsteoKit. Accuracy figures and grades (A–D) appear only when checked against the published study; tests without one are marked “No accuracy study”.

Further reading: full test procedures are described in standard clinical examination texts, e.g. Magee & Manske, Orthopedic Physical Assessment (7th ed.), and Cook & Hegedus, Orthopedic Physical Examination Tests: An Evidence-Based Approach (2nd ed.).

No accuracy study

FABER Test (Flexion-Abduction-External Rotation)

Procedure

Patient supine. Place the ankle of the tested leg just above the opposite knee (figure-4 position). Stabilise the opposite side of the pelvis and apply gentle downward pressure to the bent knee.

Positive Finding

Pain over the sacroiliac joint or buttock on the tested side. Groin pain points to the hip instead.

Interpretation

Stresses both the sacroiliac joint and the hip. A positive result supports a painful sacroiliac joint but does not show inflammation. Sacroiliitis in axial spondyloarthritis is diagnosed from the clinical picture (inflammatory back pain, age under 45 at onset), blood tests and imaging such as MRI.

Sources

No accuracy study

FADIR Test (Flexion-Adduction-Internal Rotation)

Procedure

Patient supine. Flex the hip to 90°, then bring the knee across the body and rotate the hip inwards.

Positive Finding

Reproduction of the familiar pain in the groin or front of the hip.

Interpretation

A hip test, used here to tell hip pain from sacroiliac pain. A positive result points to the hip joint rather than the sacroiliac joint. FADIR is a hip test. The figure stored here was for hip joint problems, not sacroiliitis, so no figure is shown.

Sources

No accuracy study

Sacroiliac Joint Distraction Test

Procedure

Patient supine. Cross your forearms and place the heels of your hands on both anterior superior iliac spines. Apply a steady pressure downwards and outwards (backwards and laterally), holding for up to 30 seconds.

Positive Finding

Reproduction of the familiar pain over one sacroiliac joint or buttock. Local discomfort under the hands does not count.

Interpretation

One of the standard sacroiliac provocation tests. A positive result supports a painful sacroiliac joint but does not show inflammation. This entry previously described pain relief as the positive finding, which is incorrect.

Sources

No accuracy study

Sacroiliac Joint Compression Test

Procedure

Patient side-lying with the painful side up, hips and knees bent. Place both hands over the upper iliac crest and press straight down towards the floor, holding for up to 30 seconds.

Positive Finding

Reproduction of the familiar pain over the sacroiliac joint or buttock.

Interpretation

One of the standard sacroiliac provocation tests. The result is more useful as part of a set of provocation tests than alone. It does not show inflammation; imaging and blood tests are needed when inflammatory sacroiliitis is suspected.

Sources

No accuracy study

Thigh Thrust Test (Pelvic Shear Test)

Procedure

Patient supine. Flex the hip on the tested side to 90° with the knee bent. Place one hand under the sacrum and apply a gentle, gradually increasing force down the length of the femur, towards the plinth.

Positive Finding

Reproduction of the familiar pain over the sacroiliac joint or buttock on the tested side.

Interpretation

One of the standard sacroiliac provocation tests. A positive result supports a painful sacroiliac joint but does not show inflammation. Use it within a set of provocation tests.

Sources

No accuracy study

Gaenslen Test

Procedure

Patient supine, close to the edge of the plinth. The patient hugs the near knee to the chest while you lower the other leg over the edge into hip extension, applying gentle overpressure. Repeat on the other side.

Positive Finding

Reproduction of the familiar pain over the sacroiliac joint or buttock.

Interpretation

One of the sacroiliac provocation tests, but it also stretches the hip flexors and extends the lumbar spine, so pain may come from several structures. Use it within a set of provocation tests. It does not show inflammation.

Sources

⚠ Red Flags

  • •Systemic signs: fever, chills, night sweats, unintentional weight loss (suggesting infection or malignancy)
  • •History of intravenous drug use, immunosuppression, or recent infection (osteomyelitis/discitis risk)
  • •Bilateral SIJ pain with morning stiffness >30 minutes and elevated inflammatory markers (HLA-B27 positive, CRP/ESR elevation) suggesting ankylosing spondylitis
  • •Progressive neurological deficit, bowel/bladder dysfunction, or saddle anesthesia (cauda equina syndrome)
  • •Severe night pain unrelieved by position changes or medication
  • •History of cancer with unexplained SIJ pain
  • •Sudden onset following significant trauma with severe pain and inability to weight-bear

⚡ Yellow Flags

  • •High pain catastrophization or fear-avoidance beliefs regarding movement
  • •Prolonged disability claims or workers' compensation involvement
  • •Psychosocial stressors including depression, anxiety, or job dissatisfaction
  • •Inconsistent clinical presentations or non-anatomical pain patterns
  • •Poor compliance with rehabilitation or repeated failed treatment attempts
  • •Secondary gain behaviors or illness conviction disproportionate to clinical findings

Osteopathic Techniques

Refer first

This condition needs medical assessment and management first. Do not use manual techniques on the affected area of the lower back or pelvis. Any osteopathic care is supportive, away from the affected area, and only once the treating team has cleared it. Inflammatory (spondyloarthropathy) and infective causes must be ruled out first, with blood tests and imaging as needed.

Rehabilitation Exercises

Pelvic Tilts

Range of MotionBeginner

Piriformis Stretch (Supine Figure-Four)

StretchingBeginner

Quadratus Lumborum Stretch (Side-Lying)

StretchingBeginner

Gluteus Medius Activation (Clamshells)

StrengtheningBeginner

Bridge Hold with Pelvic Stability

StrengtheningIntermediate

Side-Lying Hip Abduction

StrengtheningIntermediate

Single-Leg Stance with Core Engagement

StrengtheningIntermediate

Tandem Stance (Heel-to-Toe Standing)

BalanceIntermediate

Quadruped Rocking with Neutral Spine

PosturalBeginner

Monster Walks (Lateral Band Walking)

StrengtheningIntermediate

Stationary Cycling with Proper Pelvic Alignment

CardiovascularIntermediate

Clam-to-Leg Lift Progression

StrengtheningAdvanced

Referral Criteria

  • •Persistent sacroiliitis unresponsive to conservative management after 6-8 weeks of appropriate osteopathic and physiotherapy intervention
  • •Suspected inflammatory arthropathy (ankylosing spondylitis, reactive arthritis) indicated by bilateral SIJ involvement, elevated inflammatory markers, and positive HLA-B27; refer to rheumatology
  • •Signs or symptoms of infection (fever, systemic malaise, elevated WBC) or osteomyelitis/discitis; urgent referral to medical doctor and orthopedic surgery
  • •Progressive neurological deficit or evidence of nerve root compression; refer to neurosurgeon or orthopedic spine specialist
  • •Significant structural abnormality on imaging (severe degenerative changes, instability, anatomical variant affecting function) requiring surgical consultation
  • •Cauda equina syndrome presentation (bilateral SIJ symptoms with saddle anesthesia, bowel/bladder dysfunction); emergency referral to hospital
  • •Severe, unremitting pain despite optimal management suggesting need for advanced imaging (CT, MRI) or injection-based interventions; refer to sports medicine or interventional radiology
  • •Psychological distress, depression, or significant psychosocial barriers to recovery; refer to clinical psychologist or mental health professional for integrated care
  • •Chronic pain behavior or complex pain presentation requiring multidisciplinary pain management team input