Anatomy

Your pelvis is made up of a ring formed by 2 pelvic bones and an upside down triangular shaped sacrum at the base of your spine. There are 2 SI joints, one on either side of the sacrum. This ring functions to transmit forces from the lower extremities to the trunk and from the trunk to the lower extremities. The SI joints are generally stable due to a restraint of fibrocartilage and interlocking surfaces with only very small movements (1-5mm) that occur with normal pelvic mechanics. Small deviations may persist and affect habitual standing posture/movement or vice versa. Motion generally decreases with age due to natural fibrosis/calcification of joint.

Pathology

Pain is typically on one side near the tailbone. Sufferers do not usually have neurologic symptoms such as numbness, tingling or weakness. Pain can increase with lifting a leg while lying on your back, walking, stair climbing, and asymmetrical movement with flexion and rotation. The problem can be due to joint hyper-mobility (too loose) or hypo-mobility (too tight). Causes of hyper-mobiity include an over stretched or strained joint, a pelvic rotation at same side SI joint, hypomobility or torsion on opposite SI joint or direct trauma. Causes of hypomobility include shortened tissue resulting from stabilizing a joint after a trauma or a torsion of the SI joint. It is important to remember that because one joint affects the other, it is possible that the problem may be on the non-painful side. When one side is hypermobile, the other side may be hypomobile.

Possible causes

• Falling on one hip/buttock
• Unexpected step off a curb
• Dancing, golfing, skiing, playing tennis… sports/activities involving asymmetrical flexion with rotation/twisting
• Pregnancy (laxity as a result of production of hormone relaxin or stiffened joint post-partum)
• Hip and/or core weakness
• Muscle imbalance surrounding the pelvis

How Physical Therapy Can Help

A physical therapist is able to assess any hypermobility or hypomobility you may have as well as if a pelvic rotation exists. They can do mobilizations to help correct any asymmetries,release tight muscles and fascia, recommend what muscles are important to stretch or not to over-stretch, and can work on any muscle imbalances surrounding the pelvis that could be contributing. Once you are back in alignment, they can teach you core and hip stability to maintain symmetry. There are also self-mobilization techniques they will teach you to do at home.

Preventative Measures

• Aim for symmetry of movement during postures
• Avoid skipping steps on stairs, jumping on one leg, long steps, leaning or twisting to one side while standing, crossing legs, carrying heavy objects on one side (baby, groceries, etc.)
• Sit with knees hip width apart, both feet flat on the floor and good posture
• Sleep either on back with a pillow under your knees or on your side with a pillow between knees
• Do not sleep in figure four position (one knee up and one leg straight)- this recreates the hyper/hypo mobility pattern

The author of this article is Laura Daniels, PT, DPT at Athletico – East Bank Club/River North.