The sacroiliac (SI) joint connects the sacrum at the base of the spine with the large iliac bones of the pelvis. There are two joints, one on each side, which transfer the weight of the upper body to the lower limbs. Although the SI joint has minimal movement, inflammation or dysfunction in this region is a common source of chronic lower back pain. When conservative treatments fail, an SI joint injection is often used to reduce localized inflammation and pain.
Expected Duration of Standard SI Joint Injections
A standard SI joint injection consists of a local anesthetic, typically lidocaine, combined with a corticosteroid medication. This combination provides both immediate and longer-lasting relief in two distinct phases. The numbing agent acts quickly, often reducing pain within hours of the procedure. This initial, short-lived relief generally wears off within six to twenty-four hours.
The sustained effect comes from the corticosteroid, which is an anti-inflammatory medication. The steroid reduces inflammation within the joint, typically taking effect over 24 to 72 hours, or sometimes up to a full week. For most patients, the steroid provides pain relief that lasts anywhere from six weeks to six months.
This treatment is palliative, meaning it manages symptoms but does not fix the underlying structural issue. The goal is to create a window of opportunity for the patient to engage in physical therapy and rehabilitation without pain. Strengthening the surrounding muscles is key to long-term improvement. The injection may be repeated up to three or four times per year to maintain pain control.
Key Factors Determining Individual Relief Length
The duration of pain relief from a standard SI joint injection can vary significantly due to several patient-specific and technical factors. The severity of the underlying joint dysfunction is a major variable. Patients with advanced degenerative changes or chronic inflammation may find the relief wears off faster, as structural damage influences how much the corticosteroid can reduce pain signals.
Adherence to post-injection physical therapy and rehabilitation is a powerful determinant of sustained relief. The injection offers a temporary reprieve from pain, but long-term improvement depends on strengthening the muscles that stabilize the SI joint. Patients who utilize this pain-free period for prescribed exercises are more likely to experience a longer-lasting benefit.
Lifestyle and activity level also play a role in how long the effects persist. Excessive stress on the newly injected joint, such as repetitive straining or heavy lifting, can negate the steroid’s anti-inflammatory effects. Furthermore, technical precision is important; imaging guidance, like fluoroscopy, ensures the medication is delivered accurately into the joint space.
Advanced Treatments Offering Longer Term Relief
When standard corticosteroid injections provide only short-term relief, alternative procedures may be considered. One option is Radiofrequency Ablation (RFA), a minimally invasive technique that uses heat generated by radio waves to interrupt the pain signals transmitted by the nerves innervating the SI joint. The objective of RFA is to “turn off” the pain signal, rather than just reducing inflammation.
RFA often provides significantly longer relief compared to a steroid injection, with many patients reporting pain reduction lasting between nine and eighteen months. This extended duration is due to the mechanism of action, which involves creating a heat lesion on the targeted sensory nerves, preventing them from sending pain messages to the brain.
Another category involves regenerative medicine, such as Platelet-Rich Plasma (PRP) or stem cell injections. Unlike corticosteroids, which are anti-inflammatory, these biologics aim to promote tissue healing and repair, addressing the instability that often causes chronic SI joint pain. PRP involves injecting a concentrated dose of the patient’s own platelets, which contain growth factors that stimulate the body’s natural healing cascade. These procedures are intended to provide a more durable solution by potentially tightening damaged ligaments.