SI Joint Pain vs. Lower Back Pain: How NYC Residents Can Tell the Difference

TLDR

Pain near your lower back or buttocks does not automatically mean a spine problem. Here is what to know right now:

SI joint pain is almost always one sided, near the lower back dimples, and rarely travels below the knee
Lower back pain from the spine often shoots down the leg, past the knee
A normal MRI does not rule out SI joint dysfunction, this is the most common reason it gets missed
Climbing subway stairs, sitting on hard plastic seats, and standing on a moving train are classic SI joint triggers
The most reliable way to confirm SI joint pain is a targeted diagnostic injection, not imaging
Up to 30% of chronic lower back pain cases are actually SI joint pain in disguise

If you have been told your MRI is normal but you are still in pain every time you climb subway stairs or sit through a long commute, you are not imagining it. SI joint dysfunction is one of the most commonly missed diagnoses in chronic lower back pain, and the physical demands of daily life in New York City make it even more likely to develop and go undetected.

Here is how to understand what is actually going on.

Why NYC Life Is Hard on the SI Joint

The sacroiliac joint sits where your spine meets your pelvis, one on each side, right at the dimples of your lower back. Its job is to absorb shock and transfer load between your upper body and legs every time you move.

Now think about what a typical NYC day looks like:

Standing on a swaying subway car, constantly engaging your core and pelvis to stay balanced
Sitting on hard plastic seats that push your pelvis into a poor position
Climbing stairs at subway stations, which can load lower extremity joints at 6 to 8 times your body weight
Walking miles on concrete that offers zero shock absorption

Each of these is a direct mechanical stressor on the SI joint. For roughly 15 to 30% of people with chronic lower back pain, the SI joint is the actual pain source, not the spine.

What SI Joint Pain Actually Feels Like

Patients often describe it as a deep, dull ache, almost like a toothache, located near one side of the lower back or buttock. Key characteristics:

Almost always one sided
Centered near the lower back dimples or the top of the buttock
Can refer into the groin or upper thigh
Rarely travels below the knee
Worsens when climbing stairs, sitting for long periods, rolling over in bed, or standing on one leg

That last point is a classic NYC tell. If your pain flares every time you stand on one foot to get dressed or step onto a crowded train, the SI joint is worth investigating.

What Lower Back Pain From the Spine Feels Like

Lumbar spine pain typically comes from discs, nerves, or vertebral joints. The pattern is different:

Often feels more central or spreads across both sides of the lower back
Shooting or burning pain that travels below the knee, sometimes to the calf or foot
Worsens with bending forward, lifting, or prolonged standing
Often accompanied by numbness, tingling, or weakness in the leg

Feature	SI Joint Pain	Lumbar Spine Pain
Location	One sided, near lower back dimples	Central or bilateral lower back
Leg pain	Buttock and upper thigh only	Below the knee, into calf or foot
Worst trigger	Stairs, sitting, rolling in bed	Bending, lifting, prolonged standing
MRI findings	Often normal	Usually shows disc or nerve changes
Side affected	Almost always one side	Can be one or both sides

Why SI Joint Pain Gets Missed So Often

This is the part that frustrates most patients. Standard MRI is excellent at showing disc problems and nerve compression but frequently misses SI joint dysfunction. Patients spend months or even years being treated for a lumbar spine problem that was never actually there.

The diagnostic process for SI joint pain relies on physical examination and hands on tests, not imaging alone. Doctors use specific maneuvers to stress the joint and recreate your familiar pain:

Thigh Thrust Test: Downward pressure through the thigh, the most sensitive test for SI joint dysfunction
Distraction Test: Outward pressure on the front of the pelvis, highly specific for SI joint irritation
Compression Test: Squeezing the pelvis in a side lying position
FABER Test: Moving the leg into a figure four position to stress the hip and SI joint
Gaenslen’s Test: Stressing the joint through rotational force

If three or more of these tests reproduce your familiar pain, SI joint involvement is very likely regardless of what your MRI shows.

The Gold Standard: Diagnostic Injection

The most reliable way to confirm SI joint pain is a sacroiliac joint steroid injection using a local anesthetic. If the injection significantly reduces your pain, it confirms the SI joint as the source. This single test does what no scan can: it tells you exactly where the pain is coming from.

For NYC patients navigating multiple specialists and conflicting opinions, this diagnostic clarity is often the turning point after years of uncertainty.

Who Is Most at Risk in NYC

SI joint dysfunction does not affect everyone equally. Higher risk groups include:

Women during or after pregnancy, hormonal changes loosen pelvic ligaments significantly
Patients who have had prior lumbar spine surgery, which shifts extra load onto the SI joint
Daily commuters who spend long periods standing on moving trains or sitting on hard surfaces
People who walk several miles daily on concrete without supportive footwear
Anyone with a leg length discrepancy, which creates uneven pelvic loading with every step

What to Do If This Sounds Like You

If your lower back or pelvic pain has lasted more than 6 weeks, is consistently one sided, and has not responded to treatment aimed at your spine, ask specifically about the SI joint.

A proper physical examination using targeted provocative tests, followed by a diagnostic injection if needed, can give you a clear answer quickly. You do not need to keep guessing.

The team at Maywell Health specialises in diagnosing and treating sacroiliac joint pain with a thorough, patient first approach that goes beyond what a standard MRI can show.