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.
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.
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)
Leading risk factors for a sacroiliitis include:
Working at height (carpenters, electricians, builders, painters)
Aged between teen years and middle age
Chronic autoimmune diseases
Specific genetic group predisposed to arthritis
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
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)
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 transitory benefit and require additional treatments 1-2 years later.
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.
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:
Antiinflammatory therapy (NSAIDs)
Activity modifying regime
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)