About SI Joint Pain

The sacroiliac joints are where the sacrum joins the hip bones

The joints are connected by strong ligaments designed for support & intended to remain stable

During pregnancy, the hormone relaxin loosens these ligaments

Sacroiliac Joint Anatomy 101

A joint is where two bones come together. The sacroiliac joint is where the sacrum bone and the ilium bone join one another.

The sacrum is located at the base of your spine. It is composed of five vertebrae that have fused together during development to form a single bone roughly the size of your hand. When you view the sacrum from the front, it looks like a triangle with its point facing down. When you view it from the side, you see that it curves, concave in front, convex behind, and that it tilts, so its top end is well forward of its bottom end. Protruding from the bottom end of the sacrum is the tailbone (coccyx).

Each half of the pelvis is composed of three bones, the ilium, the ischium and the pubic bone, that have fused together during development. The topmost bone (the one that forms the pelvic rim) is the ilium. The sacrum is wedged between the left and right ilium bones. On the upper part of the sacrum, on each side, there is a rough, rather flat surface that abuts a corresponding rough, flat surface on the ilium. These surfaces are called auricular surfaces. The places where the auricular surfaces of the sacrum and ilium come together are the sacroiliac joints.

The sacrum bears the weight of the spine. The SI joints distribute this weight so that half goes to each hip and, from there, to each leg. As gravity wedges the triangular sacrum firmly down between the inclined auricular surfaces of the ilium bones, it tends to force the ilium bones apart, but strong ligaments prevent them from moving. This wedging action and the resistance of the ligaments combine to form a stable joint.

Some of the ligaments that stabilize the SI joints cross directly over the line where the sacrum and ilium meet. Those on the front are called the ventral sacroiliac ligaments, and those on the back are the dorsal sacroiliac ligaments. Other strong ligaments (the interosseous ligaments) fill the space just above the SI joints, holding the ilium bones firmly against the sides of the upper sacrum. The normal, tilted position of the sacrum places its top end forward of the SI joints and its bottom end behind them. This setup means the weight of the spine tends to rotate the sacrum around the axis formed by the SI joints, pushing the top end down and lifting the bottom end up. The sacrotuberous and sacrospinous ligaments are ideally located to oppose this rotation by anchoring the lower end of the sacrum to the lower part of the pelvis (the ischium bones).

The auricular surfaces of the sacrum and ilium are lined by cartilage. The joint space is completely surrounded by connective tissue and is filled with a lubricating fluid called synovial fluid. Like other synovial joints, the SI joints can move; however, their range of motion is very limited. For example, trained chiropractors, physical therapists and other professionals learn to feel the PSIS tilting back slightly relative to the sacrum when a standing person lifts one knee toward the chest as if marching. This rocking action is thought to aid in walking. However, according to one anatomy text,

The sacroiliac synovial joint rather regularly shows pathologic changes in adults, and in many males more than 30 years of age, and in most males after the age of 50, the joint becomes ankylosed (fused, with the disappearance of the joint cavity); this occurs less frequently in females.¹

In other words, with age, the sacrum and the two ilium bones often merge into a single bone. This might explain why some orthopedic surgeons do not believe in SI joint injury. Perhaps they have operated on adults, seen with their own eyes that the sacrum is completely fused to the two ilium bones, and concluded that even the slightest dislocation of this joint is impossible. This may well be true in people whose joints have fused, but that leaves out the rest of us, more women than men, who, through heredity or lifestyle (including yoga), have retained mobility in our SI joints.

Symptoms

Stinging pain on one side of back pelvis when moving after sitting

"An ache on or around the posterior superior iliac spine (PSIS), on one side of the body only. The PSIS is the rear-most point of bone on the pelvis. Palpate it by pressing fingers into back of pelvis above buttock, about 2 or 3 inches to side of center line of upper sacrum.You will feel a distinct, bony prominence. If that spot, or the depression just to the inside of it, is achy or tender, while corresponding spot on other side of body is not tender, she probably has classic SI problem associated with yoga." (Roger Cole)

Differentiate symptoms from those of sciatica

Potential Causes of SI-Related Pain

Postural imbalance causing stress on joint

Loose ligaments allowing joint hypermobility

Cautions

Twists done forcibly can lead to SI joint instability

Notes

"In yoga, the most common SI problem occurs when the top of the sacrum tilts too far forward on one side of the body relative to the ilium. This may happen, for example, in asymmetrical forward bends like Janu Sirsasana." (Roger Cole)

Some Approaches*

Balance & stabilize hips & SI joints

Roger Cole gives detailed advice on approaches if an SI joint is currently out of place in Practice Tips for the SI Joints

Keep pelvis level by placing or imagining a block between the knees

If doing twists & forward bends, they should be felt in deep buttock or hip joint area, not in dimple above buttocks

Move with care in seated forward bends, twists, & wide-legged poses by moving the sacrum & ilium bones as a unit

In poses that move thighs away from each other, contract pelvic floor muscles, pull sit bones & pubic bones toward one another.

In wide-leg poses, narrow the waist, keeping pubic bones together. (Roger Cole)

Correct imbalances in other aspects of posture that might be root cause, such as weak arch in one foot (Doug Keller)

Stretch hamstrings, glutes & low back

Tone abdominals

Strengthen muscles supporting pelvis

Poses to Avoid

Utthita Trikonasna (Extended Triangle)

Janu Sirsasana (Head to Knee)

Poses that combine abduction with forward bending such as Baddha Konasana (Bound Angle), Upavistha Konasana (Seated Wide Angle), Prasarita Padottanasana (Wide Leg Forward Bend) (per Roger Cole)

Fire Hydrant

Lifting Leg Back

Figure 8s

Poses to Consider

Supta Padangusthasana (Reclined Leg Stretch)

Setu Bandhasana (Bridge) without arching – to strengthen abdominals

Salabasana (Locust) – to strengthen erector spinae & glutes

 

Pose Modifications

Adho Mukha Svanasana (Down Dog)

Turn heels out

Pelvic Tilt & Thrust

Avoid overarching low back

Setu Bandhasana (Bridge)

Focus on abdominal engagment – not backbend – by rolling up slowly & keeping hips in straight line from shoulders to knees (not arching) (Doug Keller)

Squeeze block between legs

Supta Padangusthasana (Reclined Leg Stretch)

Focus on maintaining natural lumbar curve

Note that with one side, the back is more likely to flatten or hips to tip; counter this by using a prop, focusing on neutrality &/or bending opposite knee

Parsvakonasana (Side Angle)

Treat the 2 sides differently based on pelvic asymmetry (see Sacroiliac Support for instructions)