Introduction

The sacroiliac joint (SIJ) is the largest true synovial joint in the body. It is one of the most common sources of chronic low back pain, accounting for 15% to 30% of patients presenting with chronic low back pain. The presentation is variable, physical examination is unreliable, and currently diagnostic injection is the only accepted way to diagnose SIJ pain. The economic burden of chronic SIJ pain is unknown and underappreciated. The quality of life of patients with SIJ pain is worse than that of patients with chronic obstructive pulmonary disease or mild heart failure and is equivalent to that of patients with hip and knee osteoarthritis. Ackerman et al. estimated that pain from degenerative SIJ costs Medicare $18,527 per patient over 5 years. There is no definite treatment or established cure for chronic pain from SIJ. This is because chronic SIJ pain is a syndrome and not one disease. Many structures in and around the SIJ cause or contribute to SIJ pain. History and physical examination are helpful to rule out non-SIJ causes, but current clinical practice relies on a diagnostic SIJ block to properly diagnose SIJ as the pain generator. This chapter discusses the perioperative management of SIJ steroid injections performed under ultrasound and fluoroscopic guidance.

History of sacroiliac joint disorder

From Hippocrates (460–377 BC) to Vaesalius (1514–1564) and until Pare (Vaesalius, 1543; Pare, 1634; Lynch, 1920), the SIJ was considered relevant only during delivery, with no real movement during life, and getting fused or ankylosed with advanced age. It became a focus of interest in the early 20th century, but the landmark study of Mixter and Barr correlating disk rupture with back pain took the focus away from SIJ. The joint injection was described for the first time in 1938, but fluoroscopic guidance was used for the first time in 1979. Better understanding of the joint innervation has led to the innovation of radioablative neurotomy in the 2000s.

The SIJ is a diarthrodial synovial joint between two variably undulating surfaces of the sacrum and ilium, with a capsule strengthened by ligaments. The joint is formed between the S1 to S3 part of the sacrum and the ilium. The articular surfaces are covered with a layer of hyaline cartilage and a superficial layer of fibrocartilage. The combined thickness of the two layers is greater on the sacral side (3 mm) compared with the ilium (0.5 mm). The joint has an auricular or C-shaped, L-shaped configuration with a short cranial and a longer caudal limb. The sacral part is generally concave often with an intraarticular bony tubercle present in the middle aspect of the auricular surface of the sacrum. The iliac part is reciprocally convex. The caudal limb of this C- or L-shaped joint is the synovial aspect of the joint, and the upper part of the cranial limb is the fibrous joint.

The joint has very limited movement. In bipedal gait, the joint is a relay station of forces from the upper body down the legs and vice versa. It moves in all three axes. The mobility depends on positioning and the distribution of load but is usually limited to 2 degrees. The joint can rotate and glide up and down, as well as back and forth, but rotation of the sacrum (nutation and counternutation) around its transverse axis at S2 is considered to be the main movement.

The joint is well innervated, but details are not well known. Innervation from the ventral lumbosacral rami is reported but not verified, but innervations from the dorsal rami are well accepted. Contributions from L5 to S3 are reported, which include branches from the superior gluteal nerve, dorsal and ventral rami, and obturator nerve. Grob et al. argued that the SIJ is chiefly innervated by the dorsal sacral rami, based on their finding that all the nerve fibers identified by fetal dissection came from the dorsal mesenchyme.

Indications

Patients suspected of having SIJ pain are selected for joint injection. Even though the predictive value of clinical features (history and physical examination) is limited, it is a good starting point. Pain is mechanical in nature, with pain felt in the buttock or back of the thigh. Classically, SIJ pain is often reported as pain below L5. There are a number of clinical examination maneuvers, such as the FABER (flexion, abduction and external rotation) test, the Gaenslen test, the Gillet test, Yoeman’s test, the distraction test, and various compression tests, that can elicit pain stemming from SIJ dysfunction. They are provocation tests designed to elicit pain by stressing the joint. If at least three of these provocative maneuvers elicit pain, the patient is clinically suspected to have pain originating from the SIJ. This can be confirmed with a diagnostic SIJ block. Imaging of the spine, pelvis, or both is done to exclude other causes. Magnetic resonance imaging (MRI) is more useful than computed tomography in excluding inflammatory and neoplastic causes. MRI of the pelvis with a focus on the sacrum is also useful in diagnosing stress fractures of the sacrum, an important uncommon but underappreciated cause of chronic low back pain that mimics SIJ pain. Current literature states a subjective reported score greater than 75% acute relief of pain after injection is diagnostic of an SIJ source of pain.

Patient selection

Patients are selected for injection therapy (diagnostic or therapeutic) if

• 1.
  

  Clinical features are suggestive of SIJ pain.

  
  
• 2.
  

  Other causes of pain have been excluded.

  
  
• 3.
  

  Pain is chronic (at least 3 months).

  
  
• 4.
  

  Pain is intense (>5/10) or affecting quality of life.

  
  
• 5.
  

  The patient has failed conservative therapy (e.g., physical therapy, nonsteroidal antiinflammatory drugs).

  
  
• 6.
  

  There are no contraindications to injection therapy.

Contraindications

Absolute contraindications include:

• 1.
  

  Inability or refusal to give consent

Relative contraindications include:

• 1.
  

  Patient-reported or documented history of allergic reaction to cortisone injections

  
  
• 2.
  

  Local malignancy

  
  
• 3.
  

  Coagulopathy or current or recent use of blood-thinning agents

  
  
• 4.
  

  Pregnancy

  
  
• 5.
  

  Systemic infection, septic joint, or osteomyelitis

  
  
• 6.
  

  Type 2 diabetes with a history of poor glycemic control

Preprocedure considerations

Preprocedure considerations for SIJ injections are similar to those for most outpatient pain procedures. The procedure itself is low risk and not very painful. The medication and the needle used in the procedure pose no major risk to the patient. The joint has no vital structure around it that can pose a major risk. The main risk of the injection is patient dependent. The patient’s habitus and the underlying medical conditions may make the injection challenging. Important preprocedure considerations are

• 1.
  

  Evaluate major comorbidities. The procedure is elective. The patient should be in optimal medical condition if possible. Optimal metabolic (e.g., blood sugar) and cardiovascular management is desirable.

  
  
• 2.
  

  Review medications, especially anticoagulants, and whether they need to be discontinued or not. In general, most medications can be continued. The American Society of Regional Anesthesia app is very helpful.

  
  
• 3.
  

  Have appropriate laboratory testing performed if needed.

  
  
• 4.
  

  If sedation is planned for the procedure, then appropriate instruction should be given regarding NPO (nothing by mouth) status, a ride home, and so on.

  
  
• 5.
  

  Have a pregnancy test performed if fluoroscopy is used and if the test is indicated.

  
  
• 6.
  

  Review drug allergies carefully, especially to radiocontrast dye.

  
  
• 7.
  

  Provide intravenous access if needed for anxiolysis or potential drug reaction.

  
  
• 8.
  

  Evaluate the patient’s ability to lie in a prone position. It is a short procedure, but many patients may not be able to stay still for 10 to 15 minutes because of their body habitus or other painful parts of the body. This is especially an issue when trainees are doing the procedure under supervision because of the extended time needed.

  
  
• 9.
  

  Document lower extremity strength because there is a potential for lower extremity weakness from the injectate.

Attention to the multitude of factors involved in caring for these patients is essential to decrease morbidity from this procedure.

Equipment and supplies

• 1.
  

  C-arm and table

  
  
• 2.
  

  Procedure tray

  
  
• 3.
  

  Sterile drape

  
  
• 4.
  

  Antiseptic scrub (alcohol, povidone-iodine, and chlorhexidine)

  
  
• 5.
  

  Quincke spinal needle: 22 or 25 gauge × 3.5 inches

  
  
• 6.
  

  25-gauge, 1-inch needle for skin infiltration

  
  
• 7.
  

  Syringes

  
  
  
  
  • a.
    

    Two 3-mL syringes

    
    
  • b.
    

    One 5-mL syringe

  
  
  
  
• 8.
  

  J-loop or short extension tubing

  
  
• 9.
  

  Sterile gauze

  
  
• 10.
  

  Adhesive bandages

  
  
• 11.
  

  Local anesthetic

  
  
  
  
  • a.
    

    1% to 2% lidocaine for the skin wheal

    
    
  • b.
    

    Bupivacaine 0.25% to 0.5% for the joint

    
    
  • c.
    

    Steroids (any of the following)

    
    
    
    
    • (1)
      

      Triamcinolone acetate

      
      
    • (2)
      

      Betamethasone

      
      
    • (3)
      

      Dexamethasone

    
    

  
  
  
  
• 12.
  

  Injectate

  
  
  
  
  • a.
    

    Diagnostic injection: bupivacaine

    
    
  • b.
    

    Therapeutic injection: bupivacaine and steroid

  
  

The volume of the injectate is kept at 2 mL or less because the joint volume in anatomic studies has shown that the mean joint volume is 1.08 mL (range, 1–2.5 mL).

Step-by-step image-guided technique

Although SIJ injections can be performed without imaging guidance, according to various studies, there is only a 12% to 22% chance of the needle reaching the SIJ with a landmark technique. This portion of the text explains the step-by-step guide of SIJ injections with fluoroscopic guidance. The technique was described by Dr. Dussault originally in 2000.