Back Pain Doctor in Frontenac, MO

FRONTENAC, MISSOURI

Back pain across the belt line that is worse getting out of a car, worse standing on one leg, and reproducible by pressing one spot beside the tailbone is a joint problem. It is among the most treatable causes of low back pain and among the most frequently missed.

Getting here from Frontenac

Frontenac is roughly 12.4 miles from the Natural Bridge Road office, about 19 minutes via I‑270 south and Clayton Road. Patients from here often come after an epidural aimed at the lumbar spine did nothing, which is a common ending when the actual source is a few inches lower and to the side.

The sacroiliac joint is a real pain generator

The sacroiliac joints connect the base of the spine to the pelvis. They move very little, which is part of why they were dismissed as a pain source for decades. Studies using controlled diagnostic blocks put them behind a meaningful fraction of chronic low back pain — commonly cited in the range of fifteen to thirty percent in patients referred to pain clinics.

That is not a marginal number. It means that in a room of people with persistent low back pain and unremarkable lumbar imaging, a substantial minority have a joint problem that no lumbar MRI will ever show.

Sacroiliac joint pain covers the anatomy and the presentation.

How it presents

The pattern is reasonably distinctive once you know to look:

Pain centered below the belt line and to one side, often pointed to with a single finger just medial to the posterior superior iliac spine
Referred pain into the buttock and sometimes the posterior thigh, usually stopping above the knee
Worse rising from sitting, getting out of a car, rolling over in bed and standing on the affected leg
Often unilateral, and often clearly worse on one side than the other
Frequently traced back to a fall onto the buttock, a pregnancy, a leg length difference, or a fusion above it

The one‑finger test is genuinely useful. Patients with sacroiliac pain point; patients with discogenic pain sweep a hand across the low back.

Confirming it

No imaging study confirms sacroiliac pain. Degenerative change in the joint is common and correlates poorly with symptoms, exactly as it does everywhere else in the spine.

The examination uses provocation maneuvers — distraction, thigh thrust, compression, the sacral thrust and Gaenslen maneuver. Individually each is unreliable. When three or more reproduce the patient’s familiar pain, the probability of a sacroiliac source rises substantially, and that is the threshold most clinicians use.

Definitive confirmation is an image‑guided anesthetic block into the joint. If the pain goes away for the duration of the anesthetic, the joint is the source. Sacroiliac joint injection describes the procedure and what a positive result licenses.

Why it gets missed

Several reasons compound. Lumbar imaging is ordered first and finds something, because it always finds something in an adult, and the search stops there. The provocation examination is not routinely performed outside of pain and physical medicine practice. And the referral pattern into the buttock and thigh reads as sciatica to anyone not examining the joint.

The most common route to this diagnosis in our practice is a patient who has had one or two lumbar epidurals with no effect. That failure is a clue rather than a failure — a correctly placed epidural that changes nothing argues against the lumbar spine.

Sciatica or referred pain covers the separation from true radicular pain.

Treatment once it is confirmed

A confirmed sacroiliac source responds to a combination of targeted injection and specific rehabilitation. The injection reduces inflammation in the joint and, more importantly, makes it possible to do the gluteal and core work that stabilizes it. Without that work the relief tends not to last.

For patients whose pain returns predictably after each injection, radiofrequency treatment of the lateral branch nerves supplying the joint is an option with a reasonable evidence base, working on the same principle as radiofrequency ablation in the facet joints.

Where the joint is genuinely unstable rather than simply painful, that is a different problem and a surgical conversation. It is uncommon, and it should not be the first thing offered.

What Frontenac patients ask

Can an MRI show sacroiliac joint pain?

It can show inflammation in the joint, which matters for inflammatory arthritis, and it can show degenerative change, which usually does not mean much. It cannot establish that the joint is the source of your pain. That takes an examination and, when needed, a diagnostic block.

Why does it hurt more on one side?

The joints are loaded asymmetrically by almost everything — a leg length difference, a habit of standing on one leg, an old ankle injury, a pregnancy. Unilateral pain is the rule rather than the exception here, and it is one of the features that distinguishes it from discogenic pain.

I had a lumbar fusion and now this started. Is that related?

Frequently, yes. A fusion transfers load to the segments and joints adjacent to it, and the sacroiliac joints are directly below the most common fusion levels. The onset of new sacroiliac pain after a lumbar fusion is a recognized pattern. Failed back surgery covers the broader picture.

Will one injection be enough?

Sometimes, particularly when it is paired with the rehabilitation that addresses why the joint was overloaded. When relief is real but short, that is useful information and points toward a longer‑acting option rather than toward repeating the same injection indefinitely.