The SI joint is one of the most commonly missed sources of low back and buttock pain, and treatment aimed at the lumbar spine will not help it. When the diagnosis is confirmed and nonsurgical care has failed, minimally invasive fusion stabilizes the joint through a small incision at the side of the buttock.
Sacroiliac Joint Fusion. Licensed patient-education animation, ViewMedica.
The sacroiliac joint transmits the entire load of the spinal column into the pelvis. When it becomes painful, the pattern is distinctive: pain below the belt line, over the buttock, sometimes spreading into the groin or down the back of the thigh. It is often mistaken for a lumbar disc or a hip problem.
It is a common cause: published studies attribute roughly 15 to 30 percent of chronic low back pain to the SI joint. It also becomes more likely after a lumbar fusion, because load that used to spread across the lower spine is transferred into the pelvis.
Because a lumbar MRI will usually show something degenerative, patients often accumulate a long history of treatment aimed at the wrong structure. Diagnosing it depends on specific examination findings and injection testing.
Fusing an SI joint that is not the source of pain will not help, so the joint has to be confirmed as the source first.
Pain centered below L5 over the joint itself, often pointed to with one finger just medial to the posterior superior iliac spine. Pain above the belt line points elsewhere.
A set of physical maneuvers that stress the joint: distraction, thigh thrust, compression, Gaenslen's test and sacral thrust. Multiple positive tests substantially raise the likelihood the SI joint is responsible.
SI joint pain rarely shows up on a scan. X-rays and MRI are used here mainly to rule out the lumbar spine and the hip as the source.
An image-guided anesthetic injection into the joint. Meaningful, temporary relief is the confirmatory step, and most insurers require it before authorizing fusion.
Physical therapy targeting the pelvic stabilisers, activity modification, bracing, and therapeutic injections come first. Fusion is considered when those have been given a fair trial and have not worked.
Sacroiliac joint injection. Licensed patient-education animation, ViewMedica.
The patient is positioned prone. Intraoperative imaging and CT-guided navigation establish the trajectory across the joint before anything is placed.
A small incision over the side of the buttock. The approach passes through soft tissue without detaching muscle from the pelvis, which is why this is usually a same-day operation.
Guide pins are advanced across the joint under navigation, from the ilium through the SI joint and into the sacral body. Typically three implants are placed in a triangular configuration to resist rotation as well as shear.
Final imaging confirms position and that no implant has breached into the neural foramen or the pelvis. Closure is a few sutures.
Implants hold the sacrum and the pelvis still against each other, and bone grows across the joint over the following months. As a fusion, it stops the joint moving.
Above all, it is not for anyone whose diagnostic injection did not help. It is also not used for pain coming from the hip, or for inflammatory disease of the joint, which is treated medically by a rheumatologist.
Intraoperative CT with live instrument tracking. The sacrum has narrow safe paths and the nerve roots sit close by, so navigation is used to check each path as it is made.
Where used, a robotic arm holds the planned path steady so the guide pin does not drift along the dense outer bone of the pelvis.
A press-fit triangular profile resists rotation, and the porous surface is designed for bone to grow into it over the months following surgery.
See navigation and robotics for how these systems are used across procedures.
Figures are general ranges from the published literature and cannot be guaranteed for any one person. Weight-bearing in particular varies with the implant, bone quality and whether one or both joints were treated, so always follow the instructions you are given. Randomized trials of minimally invasive SI joint fusion have reported greater improvement in pain and function than continued non-surgical management in patients with a confirmed diagnosis. That is an average result and cannot predict any individual case.
SI joint fusion works well when patients are carefully selected. The biggest factor in a good result is whether the SI joint was the source of the pain, which is why the diagnostic steps above matter and why the answer is sometimes no.
Dr. Zaidi is an excellent surgeon. My back was an absolute mess. This is the best I have felt in 2 years. I can finally walk without any pain.Peggy C. · Google review
I saw Dr Zaidi to get options for treating my back pain. I have tried many different treatments but nothing worked. He explained what he might be able to do for me in great detail, and gave me reading material on my condition.Debi L. · Google review
Very personable. Very matter of fact. Not aggressive with treatment plan; starts slow in order to try all options to avoid surgery.Kaye M. · Google review
Verbatim from public Google reviews, shown with first name and last initial. These are general reviews of Dr. Zaidi's care, not accounts of SI joint fusion specifically. More patient reviews →