I Thought It Was a Disc — It Was My Sacroiliac Joint
In clinical practice, it's a familiar scene: a patient points to a spot just below the beltline, one or two finger-widths off the crease of the buttock, and says that exact point stabs with pain. The pain is almost always one-sided, and it flares hardest at predictable moments — standing up after sitting too long, shifting weight onto one leg, rolling over in bed at night. Because the pattern resembles a pinched nerve, many people assume it's a lumbar disc problem and spend months cycling through lower-back stretches and traction therapy, watching the calendar move without the pain moving with it.
A pooled review by Cohen SP and colleagues, published in Anesthesia and Analgesia in 2005, estimated that roughly 15 to 30 percent of chronic low back pain cases actually originate at the sacroiliac joint. That range is a pooled estimate built from several different diagnostic criteria, so individual studies vary, and the authors were careful to flag a real limitation: in day-to-day practice, SI joint pain frequently overlaps with disc, hip, and myofascial problems, which means no single test can confirm the diagnosis on its own.
Plenty of patients are told nothing is wrong simply because imaging came back clean. That's misleading. SI joint dysfunction isn't a matter of a bone or a disc pressing on something — it's a problem with the joint's own micro-movement going slightly out of alignment, and that kind of dysfunction rarely shows up on an MRI or an X-ray. This is exactly why the diagnosis has to be built from a combination of where the pain sits, which movements provoke it, and how the area responds to direct pressure, rather than from a scan alone.
One office worker in her thirties had combined manual therapy and Pilates for more than six months and still felt the same sharp twinge in one hip every time she stood up from sitting. Asked in detail about her routine, it turned out she trained almost entirely on the pain-free side, avoiding the sore hip out of fear that using it would aggravate things. Protecting the painful side that consistently only locks the left-right imbalance in place more firmly, and the actual root cause — the joint's alignment problem — never gets addressed.
Why the Sacroiliac Joint Starts Slipping in the First Place
The sacroiliac joint sits at the back of the pelvis, linking the sacrum to the two wing-shaped iliac bones on either side. Its actual range of motion is tiny — a few millimeters at most — but it sits directly on the pathway that distributes the weight of the upper body down through both legs, so even a slight shift in its alignment ripples into every act of walking and sitting. The joint is wrapped in some of the thickest ligaments in the entire body, and dysfunction can develop in either direction: those ligaments becoming too loose, or becoming abnormally stiff.
Hypermobility (Instability) Type
This is when the ligaments loosen and the joint moves more than it should. It's common in late pregnancy and right after delivery, because the hormone relaxin loosens pelvic ligaments to prepare the body for birth, and the sacroiliac joint loosens right along with them. Most of the women who say, even six months after giving birth, that they still can't walk any real distance without a pelvic support belt fall into this category.
Hypomobility (Stiffness) Type
The opposite pattern is a joint that stiffens up and loses its normal range of motion. This shows up often in people who habitually shift their weight onto one leg while standing, in anyone who twisted a hip missing a step on the stairs and never fully recovered normal movement afterward, and in runners or soccer players whose sport repeatedly loads rotational force through one side of the body. Even a small difference in leg length can push chronically greater load onto the shorter side's hip, which tends to tip that joint toward the stiff, hypomobile pattern over time.
Both patterns share the same downstream effect: abnormal tension builds up in the ligaments and muscles around the joint, and that tension drives local inflammation and sensitizes the pain-signaling nerves in the area. That's precisely why, before deciding on a care direction, it's worth figuring out whether your pain is coming from a joint that moves too much or one that barely moves at all — treating the two the wrong way tends to make things worse rather than better.
One detail worth understanding is why the pain radiates the way it does. The nerves supplying the sacroiliac joint capsule share root levels with branches that run into the gluteal muscles and the back of the thigh, so when the joint capsule is irritated, the brain doesn't always localize the signal cleanly to the joint itself — some of that irritation is felt as an ache spreading into the buttock or upper hamstring, even though nothing is actually wrong in the muscle tissue there. This is also part of why the condition is almost always one-sided rather than symmetrical: everyday movement patterns like carrying a bag on one shoulder, standing with weight shifted onto one hip, or driving with one foot resting near the pedal load one side of the pelvis more than the other for years at a time, so the ligament and capsule irritation accumulates unevenly long before any single incident makes it obvious.
Why This Is Hard to Diagnose
The sacroiliac joint sits in crowded anatomical company — the lumbar spine, the hip joint, and the sacral nerve plexus are all packed in close by — which makes pinpointing the true source of pain genuinely difficult. Pain clinics sometimes use a diagnostic block: injecting a local anesthetic directly into the joint and checking whether the pain temporarily disappears. Understanding that imaging alone often can't settle the question lets you have a much more specific conversation with your physician about which tests actually make sense before you start managing anything on your own.
Periods of rapid weight gain or loss, the first days after switching to a new pair of shoes after wearing the old ones for years, and the opening weeks of a new exercise routine can all produce a temporary creaking sensation as the joint adapts to a new loading pattern. In most cases the body settles into the new pattern within two to three weeks and the sensation resolves on its own. If discomfort is still there after that window, though, it's worth considering that this has moved past a simple adaptation response and into an actual joint dysfunction.
Self-Check: Telling It Apart From a Herniated Disc
A review by Laslett M, published in the Journal of Manual and Manipulative Therapy in 2008, reported that a cluster of provocation tests — combining compression, distraction, and Gaenslen's test, among others — identifies sacroiliac joint dysfunction more accurately than any single test on its own. These tests only mean anything when a trained clinician applies precise direction and force, so they aren't something you can faithfully reproduce alone at home. Still, the comparison in the table below gives you a rough sense of what you're dealing with before you ever set foot in a clinic.
| Feature | Sacroiliac Joint Dysfunction | Lumbar Disc Herniation |
|---|---|---|
| Pain location | One precise spot below the beltline, beside the buttock crease | Center of the low back or a wide area on either side |
| Referred pain | Buttock to back of thigh; rarely below the knee | Often extends down into the calf and foot with numbness |
| Aggravating movement | Standing on one leg, stairs, rolling over in bed | Bending forward, coughing or sneezing, sitting for long periods |
| How patients point | One finger, one exact spot | Open palm over a broad area |
| Pain with coughing | Little to no change | Often worsens as abdominal pressure rises |
Self-Check Checklist
If three or more of the following apply to you, it's worth keeping sacroiliac joint dysfunction in mind and scheduling a visit to an orthopedic or rehabilitation medicine specialist.
- You can point to the exact spot with one finger, not an open palm
- Pain gets worse when you stand on one leg to put on a sock or pull on pants
- Sitting for a long stretch on a soft couch hurts more than sitting on a firm chair
- One side hurts noticeably more going up stairs than down, or vice versa
- Bending forward or coughing doesn't change the pain much either way
- You've given birth, or recently took an impact to the pelvis from a fall or a misstep
If fewer than three items match, if the pain alternates between sides, or if numbness reaches all the way to your toes, it's worth considering that this isn't a sacroiliac issue on its own but is overlapping with a lumbar or hip problem. In that situation, going straight to an orthopedic clinic for a physical exam and imaging if needed will actually save more time than working through a self-care program first.
The 4-Week Step-by-Step Care Protocol
Sacroiliac joint dysfunction isn't something that clears up in a day or two, so instead of pushing intensity up out of impatience, checking your response week by week before advancing a stage does more to keep the problem from coming back. Below is a 4-week flow you can use as a reference when combining NIR care with self-management at home.
| Week | Goal | NIR Setting | Supporting Care |
|---|---|---|---|
| Week 1 | Calm the acute flare | 660 nm primary, 4–6 J/cm², 10 minutes, once daily | Avoid pain-triggering positions (standing on one leg, lying on one side for long periods) |
| Week 2 | Restore range of motion | 850 nm primary, 8–10 J/cm², 12–15 minutes, 1–2 times daily | Lie in a neutral pelvic position; begin gentle pelvic tilts |
| Week 3 | Begin building supporting muscle strength | 660+850 nm combined, 8–12 J/cm², 15 minutes, 4–5 times per week | Add low-intensity stabilization work: single-leg bridge, side plank |
| Week 4 | Return to daily activity and prevent recurrence | 660+850 nm combined, 6–10 J/cm², 10–15 minutes, 3–4 times per week | Resume normal activity while watching for any return of pain and adjusting intensity accordingly |
Keep the device 0 to 3 cm from the skin, and before moving to the next stage, it's safer to watch for at least three days to confirm the current intensity isn't making pain worse. If single-leg-stance pain is still there once you reach week 3, don't force your way into week 4 — dropping back to the week 2 intensity is the better call.
A few concrete markers make the week-to-week decision easier than just going by feel. To move from week 1 into week 2, the resting pain score should be at least two points lower than where it started, and you should be able to roll over in bed without waking from the pain. To move into week 3, single-leg standing — putting on a sock, stepping into pants — should be manageable without a sharp catch, even if some dull ache remains. To move into week 4, the stabilization exercises added in week 3 should be completable at the prescribed sets without the pain score rising afterward. Any week where the score climbs rather than falls, or a new symptom appears, is a signal to hold at the current stage for a few extra days rather than advancing on schedule.
Building the Habit of Tracking Progress
Scoring your pain from 0 to 10 at the same time every day and writing it down lets you look back objectively at exactly which stage progress stalled at, and which movement made the pain spike again. Logging the score right before and right after each NIR session also helps you zero in on the wavelength and duration that actually work for you. Hydration and sleep quality both affect how fast tissue recovers, so during the four weeks of the protocol it's worth also keeping water intake above 1.5 liters a day and holding to a consistent bedtime.
The same spot often feels different first thing in the morning versus at the end of a full day of activity, so timing your NIR session for whichever part of the day the pain is most noticeable tends to make the effect feel more pronounced.
Common Mistakes and How to Correct Them
Looking at cases where the exact same protocol produces unusually slow progress, a handful of patterns show up again and again.
Stretching Only the Painful Side
Stretching only the painful hip every single day can actually worsen ligament laxity on that side, pushing the problem from a hypomobility pattern toward a hypermobility one instead. Strength and balance on the pain-free side of the pelvis need attention too.
Rolling With a Foam Roller Without Any Core Work
Pressing the area with a foam roller or a massage ball only produces temporary release. Without core and gluteal strength to stabilize the pelvis side to side, the same spot tightens right back up within a few days. As covered in our guide to Carpal Tunnel Syndrome NIR LED Care, local release and strength work always need to happen together.
Jumping Straight Back to Full Intensity Once Pain Eases
Once pain has dropped by roughly half, going straight back to your previous hiking or running intensity often triggers a relapse in week 3 or 4. Rather than jumping intensity all at once, holding at 70 to 80 percent of your previous activity level for one more week before scaling up gradually is the safer path.
Ignoring Uneven Shoe Wear or a Leg-Length Difference
If one heel wears down noticeably faster than the other, that's a sign your gait itself is asymmetrical. Leave that unaddressed while repeating NIR care and stretching, and the actual cause stays in place — you'll keep cycling through improvement and relapse.
Watching Only the Pain Score and Ignoring Posture
A lower pain score after NIR care doesn't mean the underlying cause has been resolved. Habits like standing with weight shifted onto one hip or always carrying a heavy bag on the same shoulder created the left-right imbalance in the first place, and leaving them unchanged means the pain quiets down only to resurface once you've repeated that same posture for long enough again.
Put simply: whatever method you use, if you don't correct the left-right imbalance and repetitive habits that created the pain — and focus only on the sore spot itself — improvement and relapse will keep repeating in a loop.
Warning Signs That Mean See a Doctor
Most sacroiliac joint dysfunction improves with self-care, but if any of the following signs are present, stop self-managing and see an orthopedic or rehabilitation medicine specialist first.
- Noticeable weakness in the leg or difficulty lifting your foot at the ankle — this needs to rule out nerve compression, not just a joint problem
- Numbness or loss of control involving bladder or bowel function — this is a sign to go to the emergency room immediately
- Severe pain right after trauma (a fall, a car accident) with a complete inability to bear weight — imaging is needed to rule out a fracture
- Fever along with heat and swelling at the painful site — this needs to be checked for infectious arthritis and similar conditions
- Pelvic pain during pregnancy accompanied by abdominal tightening or regular contractions — this could signal preterm labor, so an OB-GYN check comes first
- Pain stays the same or gets worse despite faithfully following the 4-week protocol — another overlapping cause needs to be ruled out
NIR care and self-management remain wellness-level supporting tools; they are not a substitute for the medical diagnosis or treatment of a condition. If even one of the signs above applies to you, seeing a doctor comes before continuing NIR sessions.
For reference, a mild warm feeling right after an NIR session, or a day or two of residual stiffness, is a common and unremarkable response, distinct from the warning signs above. If it's hard to tell the difference, lower the intensity and watch for a day or two — if the pain trends worse rather than better even after that, that's the point to consider seeing a doctor.
When things feel ambiguous, rather than judging it yourself, a single visit to a nearby orthopedic or rehabilitation medicine clinic to confirm whether your current state is safe to manage at home makes the rest of the 4-week protocol something you can follow with far more confidence.
Applying This to Everyday Situations
Office Work, Sitting 8 Hours a Day
If pain is worse on a soft, couch-style office chair than on a firm one, adjust your cushion height so weight lands evenly on both hips and get up to walk once every 50 minutes. Crossing your legs while seated keeps twisting the pelvis toward one side, so it's worth avoiding as much as possible.
Frequent Long-Distance Driving
Reclining the seat too far back pushes the pelvis backward and easily creates asymmetric load on the SI joint. Keep the backrest around 100 to 110 degrees, set seat height so hip and knee are roughly level, and take a short walk at a rest stop every hour to loosen up pelvic movement. The underlying principle of managing repetitive load overlaps with what's covered in our guide to Tennis Elbow (Lateral Epicondylitis) LED Phototherapy Guide.
During Pregnancy and After Childbirth
A large share of late-pregnancy pelvic pain is the hypermobility type caused by relaxin. Physically supporting the joint with a pelvic belt comes first, and if NIR care is used, it should be applied briefly to the lower back and hip area while never irradiating the abdomen directly, with the decision always made alongside your OB-GYN provider.
Hiking, Running, and Other One-Sided Repetitive-Load Sports
If one side of the pelvis throbs specifically on downhill stretches, use trekking poles to distribute load, and check your shoe heel wear to see whether you're repeatedly leaning to one side. The hip-area care principles in our guide to Bursitis (Hip and Knee) NIR Care Guide are worth referencing here as well.
Sleep Position
Lying on your side with the painful hip on top and a pillow between your knees makes it easier to keep the pelvis neutral instead of twisted. Sleeping face-down, on the other hand, rotates the pelvis toward one side and can leave you feeling stiffer in the morning, so it's better avoided.
Doing Lower-Body Work at the Gym
In movements like squats or lunges that shift load between both legs, if one side wobbles noticeably more than the other, lower the weight and check in a mirror whether your stance width and foot angle are symmetrical. It's safer to hold off on single-sided exercises like lunges or step-ups until pelvic stability on the painful side has recovered to some degree.
Working in a Building With a Lot of Stairs
Lightly holding the handrail while going up or down stairs distributes some of your body weight off the joint, and skipping two steps at a time is worth avoiding since it puts a sudden burst of rotational force through the pelvis. Alternating between the elevator and the stairs, and gradually increasing your total daily stair use, helps prevent an acute flare-up.
