What is Sacroiliac (SI) Joint Fusion?

The sacrum is the wide, triangular bone at the bottom of the spine. It connects to the pelvis on each side in an L-shaped area called the sacroiliac (or SI) joint. Although it is called a joint, this connection does not really move; instead, it transfers weight from the spine to the legs and helps cushion the spinal column. In some cases, surgery is performed to fuse the joint in place and stabilize it. This surgery is called sacroiliac joint fusion.

Occasionally, the SI joint can become irritated, painful, or arthritic. Problems with the sacroiliac joint can be caused by trauma, infection, or other issues. The main symptom of SI joint damage is pain in the lower back, hips, and thighs. This pain may become worse when rising from a sitting position. When non-surgical treatments such as medications and physical therapy are not effective at relieving pain, surgery may be considered as an option.

During SI joint fusion, a small incision is made on the side of the buttock near the hip. The surgeon removes the cartilage, a firm, smooth substance between the bones. Then the joint is fused by the placement of rods, screws, or plates that hold the sacrum and the pelvis together. This reinforces the joint, stabilizing the pelvis and helping to support the upper body. You may be able to stand and walk the very next day after surgery but will need crutches to get around for the first few weeks. Full recovery and return to normal activities takes up to a year as the tissue around the joint grows and heals.

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