Sacroiliitis: Inflammation of SI Joint

Sacroiliitis is inflammation of one or both surfaces of sacroiliac (SI) joint. Sacroiliac joint lies between sacrum (last triangular part of the spine) and ilium (pelvic bone). One or both SI joints can be affected.

Symptoms:

Patients usually present with typical symptoms of low back pain. Pain can be more on the side of the joint affected. Pain can radiate down to buttocks or upwards in paraspinal area. Occasionally, patients have symptoms similar to slip disc with pain radiating down the leg with numbness. Pain usually worsens with activities.

Causes of Sacroiliitis:

Trauma: Any injury in the hip area can affect SI joint. A fracture involving sacrum or ilium bone going through SI joint will cause pain in the area. A mal-united fracture will lead to arthritis in SI joint.

Arthritis: Age related chronic wear and tear will cause degenerative arthritis. Various inflammatory arthritis caused by rheumatological diseases (Ankylosing Spondylitis, Reiter’s Disease, Lupus, Psoriasis) affect SI joint commonly.

Pregnancy and Childbirth: Various hormones generated during pregnancy will lead to relaxation of joints to assist in child-birth. This may stress SI joints and can leads to sacroiliitis. During vaginal childbirth, widening of pelvis may disrupt SI joint leading to sacroiliitis.

Infection: Bacterial or tubercular infections can affect Si joints.

Lumbo-sacral fusion surgeries: A fusion surgery in the lumbo-sacral area will lead to excessive stress on SI joints during weight transmission. It is not uncommon to have sacroiliitis in these patients.

Diagnosis:

A high index of suspicion is required to diagnose sacroiliitis as symptoms mimic that of lumbar spine pathologies. A local tenderness directly over sacroiliac joint will elicit pain. Certain specific physical tests to stress Si joint will cause pain on the affected side.

X-ray/ MRI/ CT Scan: X-ray will show joint arthritis and hardening of bone around SI joint. In infection, joint will be destroyed. MRI will show inflammation and infection in detail. CT scan will show roughened joint surfaces.

Blood Tests: ESR and CRP will be elevated in inflammatory and infectious arthritis. Positive HLA B-27 will help in diagnosing Ankylosing Spondylitis.

Anesthetic Injection: A local anesthetic injection given inside the joint should relieve pain coming from SI joint. It is either done under fluoroscopy guidance in operation theater or under CT guidance.

Treatment:

Primary treatment of sacroiliitis is same as that of any patient with back pain. Local application of heat/ cold, pain medicines and physiotherapy provides relief in majority of the patients. Some amount of activity restriction and activity modification is required to prevent aggravation of symptoms.

Local Steroid Injection: For degenerative and inflammatory sacroiliitis, a mixture of local anesthetic with small dose of steroid can be injected under fluoroscopy or CT guidance. This will reduce inflammation in the joint and will provide long lasting relief from pain.

Biopsy: In suspected infective sacroiliitis, a biopsy (fluoroscopy or CT guided) if required to find the nature of infection and effective antibiotic treatment.

Radiofrequency (RF) Ablation: RF ablation is a pain management procedure in which tiny nerves supplying the Si joints are ablated by radiofrequency, so pain from inflamed Si joint is not perceived.

Surgery: Surgery is kept as a last resort in following situations:

• Severe pain not responding to medical line of treatment and injections
• Fracture involving sacroiliac joint
• Infective sacroiliitis: To take biopsy (if fluoro/ CT guided biopsy was negative) and to debride the joint (if not responding to antibiotics).

Usually a sacroiliac joint fusion surgery is performed, in which the joint is debrided and bone grafted. Various internal fixation devices are available which helps achieve the fusion.