Sacroiliac joint inflamation - Sacroiliitis
Anatomical location of the sacro-iliac joints


Sacroiliitis refers to the inflammation of the sacro-iliac joint, which connects the iliac bone on each side of the pelvis to the sacral spine.

Area of the pelvis where the pathology sacroiliitis occurs


Sacroiliitis is an inflammatory condition of the sacro-iliac joint that can arise after a traumatic event, infection or overuse. Chronic sacroiliitis causes fibrosis and calcification of the joint and in the long-term stiffness (ankylosis). 

This pathology is distinguished from sacroiliac joint dysfunction, which presents similar symptoms but is the consequence of abnormal motion at the sacro-iliac joint, which over time becomes inflamed. 

Occasionally, it occurs in the context of other diseases such as ankylosing spondylitis or Reiter’s syndrome. 

In patients with systemic chronic autoimmune spondylo-arthropathy of the spine, ongoing inflammation leads to bone loss and ossification of soft tissue also involving the sacro-iliac joint. Sacroiliitis is frequent in adolescent to middle aged individuals and is more common in men than women but can arise during pregnancy.

Arm abduction is restricted by the inflamed bursa and tendons, reducing the joint space
Cross section of the shoulder depicting the compression of the bursa (red) above the rotator cuff (white) and below the deltoid muscle


There are various classification systems for a shoulder impingement syndrome.

Stages of subacromial impingement in athletes - Jobe’s Classification

Pure impingement with no instability

Primary instability, with capsular and labral injury with secondary impingement, which can be internal or subacromial impingement

Primary instability due to intrinsic ligament laxity with secondary impingement

Pure instability with no impingement.

Grading of impingement changes - Milgrom’s Ultrasound Classification:

Stage 1 Bursal thickness from 1.5 to 2.0 mm

Stage 2 Bursal thickness over 2.0 mm

Stage 3 Partial or full thickness tear of the rotator cuff.

Impingement lesions - Copeland Levy Classification:

This is based on the location of the impingement, either on the acromial or the bursal side.

Acromial side

A0 normal - smooth surface

A1 minor deterioration, haemorrhage or local inflammation

A2 marked scuffing/damage of the undersurface of the acromion and coraco-acromial ligament

A3 exposed bone areas.

Bursal side

B0 normal - smooth surface

B1 minor deterioration, haemorrhage, inflammation

B2 major deterioration of the cuff, partial thickness tear

B3 full thickness tear of the rotator cuff

B4 massive cuff tear.

Two-part proximal humerus fracture

According to the Habermeyer Classification the fractures to the proximal humerus are divided into:

Type 0 one fractured part without dislocation

Type A two-part fracture of the great tuberosity and lesser tuberosity avulsion

Type B involves the humerus “surgical” neck below the femoral head as two-part, three-part and four-part with one or both tuberosities

Type C involves the humerus anatomical neck (between the head and greater tuberosity) as two-part, three-part and four-part with one or both the greater and lesser tuberosities.

These are defined further as:

One-part fractures are non-displaced fractures or fractures with minimal displacement

Two-part fractures only involve a single segment

Three-part fractures involve two segments

Four-part fractures occur when all humeral segments are involved (see image in pathology section)

The injury severity is proportional to the increasing number of fractures.

Three-part proximal humerus fractures

Difference in leg length can lead to sacroiliitis


There are various causes leading to sacroiliitis but in some cases the origin of the disease is unknown. These are:

Trauma (e.g. car accident with strong impact while pressing the break pedal)


Prolonged sacro-iliac joint dysfunction

Infection (bacteria migrating and depositing in the sacro-iliac joint)

Leg length discrepancy

Chronic arthritic conditions (rheumatoid/psoriatic arthritis, Reiter’s syndrome, autoimmune spondylo-arthropathy)


Bilateral sacro-iliac arthritis in predisposed individuals can manifest as sacroiliitis

Risk factors

Leading risk factors for a sacroiliitis include:

Frequent driving

Working at height (carpenters, electricians, builders, painters)

Aged between teen years and middle age

Male gender

Chronic autoimmune diseases

Specific genetic group predisposed to arthritis



‍The glutei muscles of the buttocks are subject to symptomatic consequences to sacroiliitis

The most frequent symptoms of sacroiliitis include:

Pain to the low back radiating to the buttocks, front thigh and hip (unilateral or bilateral)

Pain increasing after prolonged standing and siting or when rolling over in bed, walking stairs

Stiffness of the hips and low back in the morning wake

Weakness of hip muscles

Muscle spasms buttocks

Difficulty in walking with long steps


External rotation of the hip is one of the procedures used for the diagnosis of sacroiliitis


Clinical examination begins with medical history to review potential preexisting diseases and past injuries that may contribute to sacroiliitis. 

The Faber test is employed to monitor functional changes and pain level during hip flexion, abduction and external rotation. 

In addition, the examiner will assess the presence of spinal deformities especially in the thoracic and lumbar tracts.

X-ray imaging is not considered to be specific but may indicate degenerative changes of the bones forming the sacro-iliac joint and spine. 

Improved imaging is obtained with MRI using contrast agent (gadolinium) to visualise the accumulation of fluid and ongoing inflammatory processes (abscess).

Other laboratory tests include:

White blood cell count

C-reactive protein levels in blood (inflammation parameter)

Blood cultures if bacterial infection is suspected

Genetic testing for predisposition to autoimmune arthritis (HLA-B27).


Electrical stimulation

Nonoperative treatment

When an infection is confirmed the patient is treated initially with intravenous antibiotics followed by oral antibiotics. 

If sacroiliitis manifests in association with spondylopathy, the patient is given a strong antiinflammatory therapy, local injection of steroids, oral NSADs or other specific drugs such as TNF inhibitors. 

Other topical therapy includes muscle relaxants and anaesthetics. 

Improvement of joint lubrication and pain is achieved with local injection of hyaluronic acid.

In pregnancy this condition is usually transitory and improves after birth. If pain does not resolve the sensory nerves around the sacro-iliac joint are destroyed using a special technique named radiofrequency ablation or with the implantation of an electrical stimulator in the sacrum. This method however may only provide a transitory benefit and requires additional treatments 1-2 years later.

Two examples of sacro-iliac fusion although performed after a pelvic fracture and not in sacroiliitis

Surgical treatment

Surgery is only indicated in case of trauma, severe infection with large abscess formation and significant degenerative changes of the sacro-iliac joint. 

When conservative treatment does not improve and pain is sustained, a joint fusion may be the only option. The surgery consists firstly, in the removal of the cartilage on either side of the bones forming the joint followed by the fusion of the sacrum and iliac bones with plates and screws. 

By blocking completely the movement at the sacro-iliac joint the pain should resolve but may persist in some cases.

Bridge pose is useful to strengthen the buttocks muscles and protect the sacro-iliac joints


In patients with reduced mobility of the sacro-iliac joint, physiotherapy focuses on restoring flexibility with gentle exercise to improve strength of the trunk, buttocks and thighs and abdominal muscles.

In case of excessive mobility the therapist will recommend the use of a belt to help stabilising the sacro-iliac joint. 

Following surgery a period of 6 weeks of rest is necessary prior to commence a rehabilitation program.

Physiotherapy treatment includes:


Ice/heat treatment


Joint mobilisation



Antiinflammatory therapy (NSAIDs)

Activity modifying regime.

In case of leg length discrepancy the use of shoe orthotics helps realign the pelvis and spine to prevent sacroiliitis


The incidence of sacroiliitis can be prevented by following the rules below:

Maintenance of muscular strength of the lower back, core pelvic muscles and buttocks

Improve flexibility to the lower spine

Ergonomic advice during physical activity, sitting and sleeping

Use of lumbar support with prolonged sitting

Wearing of orthotics to reduce leg length discrepancy or incorrect walking

Modify daily habits to prevent falls (laced shoes, illuminate house at night, install railings, non-skid tiles in bathroom)

Adherence to occupational health and safety procedures and use of road traffic safety equipment (seatbelt, harness, balustrades)

Pharmacological treatment and monitoring of predisposing chronic conditions (arthritis group).