Sacroiliitis; Symptoms, Causes, Manangement & Treatment


Sacroiliitis is an inflammation of the sacroiliac Joint (SI), usually resulting in pain. The sacroiliac joint (SI) is one of the largest joints in the body and is a common source of the buttock and lower back pain. It connects the bones of the ilium to the sacrum.


Clinically Relevant Anatomy

The sacrum articulates with the ilium, which helps to distribute body weight to the pelvis.

The SI joint capsule is relatively thin and often develops defects that enable fluid, such as joint effusion or pus, to leak out onto the surrounding structures.

True diarthrodial joint, the articular surfaces are separated by a joint space containing synovial fluid and enveloped by a fibrous capsule.

Has unique characteristics not typically found in other diarthrodial joints.

Consists of fibrocartilage in addition to hyaline cartilage and is characterized by discontinuity of the posterior capsule, with ridges and depressions that minimize movement and enhance stability.

Well provided with nociceptor and proprioceptors. Receives its innervation from the ventral rami of L4 and L5, the superior gluteal nerve, and the dorsal rami of L5, S1 and S2 or that it is almost exclusively derived from the sacral dorsal rami.


Osteoarthritis can cause degeneration of the joint resulting in pathologic articulation and motion leading to this condition.

Spondyloarthropathies can cause significant inflammation of the joint itself eg Ankylosing spondylitis,eactive arthritis, psoriatic arthritis, arthritis of chronic inflammatory bowel disease

Pregnancy is another cause of the inflammation due to the hormone relaxin leading to the relaxation, stretching, and possible widening of the SI joint(s). The increased weight of pregnancy also causes extra mechanical stress on the joint, leading to further wear and tear.

Trauma can cause direct or indirect stress and damage to the SI joint.

Pyogenic sacroiliitis is the most frequently reported cause of acute sacroiliitis.

Pain can originate from the synovial joint but can also originate from the posterior sacral ligaments



Reports on the prevalence of sacroiliac pain vary widely.
Some studies report the prevalence as 10% to 25% of those with lower back pain.

In those with a confirmed diagnosis, the presentation of pain was ipsilateral buttock (94% cases) and midline lower lumbar area (74%).

Up to 50% of cases have radiation to the lower extremity: 6% to the upper lumbar area, 4% percent to the groin, and 2% percent to the lower abdomen

Symmetrical sacroiliitis is found in more than 90% of ankylosing spondylitis and 2/3 in reactive arthritis and psoriatic arthritis.

It is less severe and more likely to be unilateral and asymmetrical in reactive arthritis, psoriatic arthritis, arthritis of chronic inflammatory bowel disease and undifferentiated spondyloarthropathy.

Characteristics/Clinical Presentation

Sacroiliitis commonly presents as lower back pain.
  • Pain in one or both buttocks, hip pain, thigh pain, or even pain more distal.
  • Pain is worse after sitting for prolonged periods or with rotational movements.
  • Intolerance with lying or sitting and increasing pain while climbing stairs or hills.
  • Poor sleep habits and unilateral giving way or buckling.
  • Pain with position changes or transitional motions (i.e., sit to stand, supine to sit).
  • Pain (varies widely) and is commonly described as sharp and stabbing but can also be described as dull and achy.
Important to ascertain more than just the timing and descriptions of the pain. Ask about a history of inflammatory disorders.

Obtain a thorough review of systems to evaluate for systemic symptoms such as fevers, chills, night sweats, and weight loss.

These symptoms are indicative of a more serious process indicating likely systemic illness.Patients report low back pain (below L5), pain in the buttocks and/or pelvis and postero-lateral on the thigh, which may extend down to one or both legs.

Differential Diagnosis

  • Ankylosing spondylitis
  • Hip tendonitis/fracture
  • Piriformis syndrome
  • Sacroiliac joint infection
  • Trochanteric bursitis

Diagnostic Procedure

If an inflammatory condition is suspected, consider ordering complete blood cell count, erythrocyte sedimentation rate, C-reactive protein, antinuclear antibody, human leukocyte antigen (HLA-B27), and rheumatoid factor. Although cancer is a far less common cause of sacroiliitis, if a cancerous process is suspected, consider ordering labs to assess for malignancy.


Plain radiograph

Conventional radiography remains the first line of imaging despite its poor sensitivity and specificity in early disease. Specific sacroiliac joint views are helpful in the evaluation and comparing both sides of sacroiliac joints.

Radiograph findings include: sclerosis of the endplates particularly on the iliac side; irregular joint end plates; widening of joint spaces


CT examinations offer greater sensitivity, accuracy and detailed information compared to plain radiography. However, due to higher radiation exposure, it is not advisable to use CT for diagnosis or follow-up purposes.

Nuclear medicine

Bone scans demonstrate increased radioisotope activity of the joints and helpful in localising the source of the pain. It is also valuable in excluding stress fractures and other bone pathologies.


“Fortin finger sign”- reproduction of pain after applying a deep palpation with the four-hand fingers posteriorly at the patient's SI joint(s).

FABER test- reproduction of pain after flexing the hip while also abducting and externally rotating the hip.

Sacroiliac distraction test- reproduction of pain after applying pressure to the anterior superior iliac spine.

SacroIliac compression test- reproduction of pain after applying pressure downward on the superior aspect of the iliac crest.

Gaenslen test- reproduction of pain after having the patient flex the hip on the unaffected side and then dangle the affected leg off the examining table. Pressure is then directed downward on the leg to extend further the hip, which causes stress on the SI joint.

Thigh thrust test- reproduction of pain after flexing the hip and applying a posterior shearing force to the SI joint.

Sacral thrust test- reproduction of pain with the patient prone and then applying an anterior pressure through the sacrum.

Medical Management

Can be very helpful if the pain is due to hypermobility. Therapy can help to stabilize and strengthen lumbopelvic musculature. If the pain is due to immobility, then physical therapy can help increase mobilization of the SI joint.

The patient must be referred to a physiotherapist. Suggest 3 to 4 days bed rest for severe acute cases. For persistent cases (2 to 4 weeks) with severe pain, a sacroiliac joint injection may be recommended to confirm the sacroiliac joint as the source of the pain and to introduce the anti-inflammatory medication directly into the joint.

Advise 3 to 4 days of bed rest after the injection. Next it is recommended to continue with the restrictions and begin with flexion strengthening exercises after the pain and inflammation have been controlled. These exercises include side-bends, knee chest pulls and pelvic rocks.

NSAIDs and muscle relaxants can be prescribed during the acute phase of presentations. These are less effective as cases become more chronic.

Real-time image-guided intra-articular anesthetic/steroid injections can be performed for diagnostic and therapeutic effect. If the condition persists (6 to 8 weeks) with no improvement of at least 50 percent, repeat corticosteroid injections. Subsequently begin strengthening exercises including sit-ups and weighted side bends. Start with general conditioning of the back and increase slowly to low-impact walking or swimming. Take up normal activities with proper care of the back.

If the previous treatments do not provide adequate relief, then some providers will consider radiofrequency ablation.

Usually, surgery is reserved as a last resort for patients with chronic pain. In such cases, one can consider SI joint fusion with SI screws

Physical Therapy Management

Reducing inflammation in the SI-joint and increasing the flexibility of the lumbosacral spine and SI areas are the main goals of treatment. Give advice on proper lifting techniques involving the knees. The patient should also avoid movements such as tilting, twisting and extremes of bending. Maintaining correct posture is necessary, therefore a lumbar support for the office chair and vehicle is advised.

In the early treatment stages heat, cold or alternating cold with heat are effective in reducing pain.

In the early stage, we can also use a pelvic belt or girdle during exercise and activities of daily living. These SI belts provide compression and reduce SI mobility in hypermobile patients.

The belt should be positioned posteriorly across the sacral base and anteriorly below the superior anterior iliac spines. This belt may also be used when this condition becomes chronic (10-12 weeks).

Once the acute symptoms are under control, the patient can start with flexibility exercises and specific stabilizing exercises. To maintain SI and lower back flexibility, stretching exercises are principal.

These exercises include side-bends, knee chest pulls, and pelvic-rocks with the aim of stretching the paraspinal muscles, the gluteus muscles and the SI joint.

After hyperacute symptoms have resolved these kinds of exercises should be started. Each stretch is performed in sets of 20. These exercises should never surpass the patient’s level of mild discomfort.

Specific pelvic stabilizing exercises, postural education and training muscles of the trunk and lower extremities, can be useful in patients with sacroiliac joint dysfunctions.

The transversus abdominis, lumbar multifidi muscles and pelvic floor are the muscles that will need most training. Training of transversus abdominis independently of other abdominal muscles is effective to provide more stabilization of the sacroiliac joints and prevent laxity, which can cause low back pain.

Therefore it is necessary to teach the patient how to contract the transversus abdominis and multifidus. During this learning process it is necessary to give the patient feedback. Also the specific co-contraction of the transversus abdominus and the multifidus should be included in the revalidation program.

The best position to teach the patient to co-contract these muscles is in four point kneeling. When the patient can properly perform this exercise, it is time to increase the intensity by changing the starting position.

Other examples of exercises may include: modified sit-ups, weighted side-bends and gentle extension exercises.

Strengthening of the pelvic floor muscles is also important because they oppose lateral movements of the coxal bones, which stabilizes the position of the sacrum. Activation of the transversus abdominis and pelvic floor muscles will reduce the vertical sacroiliac joint shear forces and increase the stability of the sacroiliac joint.

After rehabilitation, low-impact aerobic exercises such as light jogging and water aerobics are designated to prevent recurrence.

If the patient has a leg length discrepancy or an altered gait mechanism, the most reliable treatment would be to correct the underlying defect. Sacroiliitis is also a feature of spondyloarthropathies. In this case, this condition should also be treated.

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