These sacroiliac joints (arrowed) connect the base of the spine (the Sacrum,) to the Pelvis. They are large joints, but can occasionally get into trouble.

They are just under your dimples of Venus.

sacroiliac joint between spine and pelvis

They have a small amount of movement, during breathing and walking.

Sacroiliac joints do get stuck occasionally, and this can cause pain.

Pain can then be felt in (“referred to”) the buttock, groin, side of hip (gluteal region,) upper thigh and knee.

Tailbone (coccyx) pain sometimes comes from our sacroiliac joint.

I generally only examine this joint if nothing is obvious in the Lumbar spine, and a person is complaining of pain in the areas mentioned.

More commonly if symptoms are not completely resolved after treating any Lumbar lesions, examination may show one of these joints is stiff.

This is often on the opposite side to their pain.

Examination of these sacroiliac joints

Examination is difficult. It is much easier if the persons' weight is not jamming the sacrum down. I do this with a person suspended by their elbows, feet off the floor, using this adjustable apparatus.

The person lifts and lowers each leg in turn, while I see any movement between one thumb on their sacrum and one in the greater sciatic notch.

A stiff joint nearly always responds to manipulation, with immediate relief of some of the persons' pain.

apparatus for SIJ examination

Examination for unequal leg lengths and pelvic rotation.

This should be a routine part of every back examination I carry out. It isn't. My excuse is that I don't see new patients, But it still turns up every so often.

Leg length inequality can be just the way you grew up, or it can be apparent only, due to rotation of the pelvis.

To check your leg lengths, initially have someone squat behind you, as you stand with both knees fully straightened and and with equal weight on both legs.

They put a hand on top of each of your hip bones, digging their hands into your waist enough to feel the top of the bones.

With their eyes at the same level as their hands, are your hip bones at the same level? They should be.

Anterior superior iliac spines


If they're not, then the observer needs to come around to your front and find the pointed front ends of your hip bones. These are just behind the outer end of your groin crease on each side.

Once they locate these bony points, they press their thumbs in immediately under them and compare the vertical height of their two thumbs.

Moving right along, around the back...

Posterior superior iliac spines

pelvic bones back side view

These are the bony bumps at the back of the hip bones (the iliac crests.) They are under your dimples of Venus.

From behind, press on the top of the iliac crests, and move back along them as they curve down. This will point towards the PSIS.

This isn't easy, but there is another option...

The greater sciatic notch

This is level with the upper end of the crease between your buttocks, and about half way out across the buttock.

You need to relax your buttocks and they need to dig their thumbs in deeply, then angle up to push against the horizontal bone.

This is the upper margin of your greater sciatic notch, and is another suitable landmark.

Assess each of these, to reduce the risk of error.

1. the iliac crest - top of hip bone
2. the anterior superior iliac spine - pointed front end
3. the posterior superior iliac spine - bump at back end
4. the superior margin of the greater sciatic notch - bone deep under muscle in middle of buttock.

Interpretation of the findings on these examinations

True short leg - tilting of the pelvis

Each of the four landmarks will be lower on the same side.

The sacroiliac joints may not able to fully compensate for the pelvic tilt, so the spine above this develops an S bend to keep one's center of gravity between the feet and trunk erect.

Short leg is quite common, but is much more so in people with backache. It is sometimes worth building up the heel of someone's shoe to partially compensate for it.

Anterior iliac - rotation of the hemi-pelvis

Here the ASIS will be lower, and the PSIS will be higher, than the same points on the opposite side. The hemi-pelvis is rotated clockwise, looked at from the side.

I correct this if I find it in the context of back or leg pain. It is treated by manipulation of the sacroiliac joint, using the thigh as the lever to rotate it back.


Primary inflammation (sacroiliitis) is an early feature of Ankylosing spondylitis, with pain and stiffness often starting in the teens.

See knee notes for causes of joint (here sacroiliac) inflammation

Fibrositis and fibrositic nodules.

People sometimes point out tender lumps under the skin in their sacral/ posterior iliac crest region. These are usually 1cm (half an inch) across and not attached to the underlying bone nor muscle fascia.

Tender swelling sounds like inflammation, and so the name ending in "itis." It has been abandoned as a concept, however - sore but not inflamed.

I don't try to treat these lumps, and just look for joint and muscle problems in the area.


Your two pelvic bones are joined at the front by a plate of gristle called the pubic symphysis. Problems in this area are covered well on a site by an experienced chiropractor While you are on that site, be sure to look at the teddybears' picnic page.

Lateral hip pain

Greater trochanter pain syndrome (GTPS) is felt at the attachment of the gluteal muscles to the top of your thigh bone. This is the most prominent hard part at the side of your hips.

The glutei are the big muscles here, which pass down from your pelvic bones to the thigh. Like Goldilocks and the bears there are three of these - gluteus maximus, medius and minimus.

G.maximus lifts you up if you've bent right over to pick something off the floor. The others stop you falling over every time you lift a foot as you walk.

Between them and the bone are three bursae for lubrication. A bursa is like a balloon, with a very smooth inner surface and empty except for a little fluid.

Trochanteric bursitis is inflammation of the most constantly present of these, between Gluteus maximus and the other structures. This is often associated with damage and partial rupture of the muscle tendons, best demonstrated with MRI.

Most people have less severe trouble, readily helped by gluteal stretching as described on the knee pages.

Buttock pain

Buttock pain may be from local muscles, referred from our back, from the sacroiliac joint or from true sciatica...

Groin pain - hip joint or hernia?

I think most people refer to the side of the pelvis as their hip, but hip joint pain is felt mostly in front, in the groin.

An incipient hernia can cause groin pain before any lump can be seen.

Tailbone (Coccyx) pain, or Coccydynia

A very dangerous practical joke - removing someones chair just before they sat down - once earned me a well deserved whack from my father.

This can result in a bruised or broken tailbone or disruption of the sacro-coccygeal joint or subluxation of the sacroiliac joint.

Coccyx pain appearing without any history of injury, may be referred sacroiliac joint pain.

It may be due to the sacro-coccygeal joint being stiff and sore. This is treated simply, by holding the coccyx between ones thumb and index finger, and vigorously moving it back and forwards.

Ones (gloved) index finger is inside the anus to do this.

It is painful treatment, but lasts only about ten seconds and does relieve the coccyx pain.

Multiple injuries up along a "closed kinetic chain" can include the sacroiliac joint.

Landing on ones' feet isn't always a "soft landing."

One can sprain our ankle and sacroiliac joint at the same time, with the force transmitted up through locked knee and hip joints (hence the term closed kinetic chain.)

I frequently see people with ankle or knee injuries, where delayed recovery is because SIJ or spinal joint damage has been missed.

From sacroiliac page to sciatica page

back to home pain page


Is there something else you would like to read about?
This search button will bring up anywhere on this site your words are mentioned...


Custom Search


The contactpage.

If you are interested in a home study course on examination of the spine, please send me your e-mail address by the contact form.