The winter is here and for many that means time for off-season rest, recovery and planning for next year. This e-report will introduce the sacro-iliac joint (SI joint) and its relevance to everyone who is active - whether they be on the bike, in the water, on the ice or on the run.

The SI joint is one of two joints in the pelvis. It is the articulation between the sacrum (tailbone) and the two pelvic bones. The sacrum is the base of the spinal column and thus mechanically links the thorax to the lower limbs.

The motion at the SI joint is very small - forward and back - 2-4 degrees, as there are very strong ligaments providing the support. This stability is also created by the unique shape of the joint surfaces - ridges and depressions that fit together specifically like a puzzle. What is important is that the joint does not move in isolation - it is a part of a kinetic chain; adapting to the motions from the lower limbs as well as the spinal column.

As a result of this, small changes in structure or mechanics at distant locations, muscle imbalances around the pelvis, being too flexible or not flexible enough and improper sport mechanics or equipment, will have a large effect at the SI joint and its associated structures.

Often, one of the most common causes of problems is direct traumatic injury- a fall on the buttocks, a motor vehicle accident or a lateral blow to the pelvis. The force applied to the pelvis and the direction of these forces can aggravate the ligaments supporting the joint as well as the joint surfaces (cartilage) between the bones. The resulting inflammation and/or increase in joint laxity leads to local joint pain and associated muscle dysfunction.

The SI joint is commonly aggravated during pregnancy. This is due to the changes in hormones, (specifically relaxin) which serve to loosen the ligaments of the pelvic girdle. This, coupled with the increase in body mass and the change in a woman's center of gravity often leads to SI joint problems in the later months of pregnancy.

It is important to be aware that since the SI joint is a part of a kinetic chain, many athletes report a recent history of foot, ankle, knee, hip or spine injury, before a diagnosis points to the SI joint.

SI joint problems have many symptoms, in part due to the numerous structures -muscular, nervous and ligamentous - that are associated with the region.

The following tend to be the most common:

• Back pain- especially low back
• Glute (Buttocks) pain
• Thigh pain
• "Sciatic Like pain" - pain in the lumbar region, radiating into the glutes and hamstrings
• Difficulty sitting for long periods

With any mechanical dysfunction, the efficiency of muscle contraction and the specific range of motion of that kinetic chain is severely hampered. In an acute case, walking is enough to aggravate anyone - lets not think about what training or competing will do to pain levels.

The off-season is a great time to tweak your mechanics or correct any pain patterns that may have been popping up during the year.

Some of the approaches in the treatment of the SI joint usually fall into a "mobilization approach" or a "stabilization approach".

Mobilization of the SI joint is focused on loosening a rigid joint - via specific manual techniques. Stabilization involves strengthening of specific pelvic and core muscles. If necessary, stabilization can be assisted via the use of a specific belt, known as a sacroiliac belt. In both cases, discussing the requirements of your activity with your therapist will assist in the specificity of the exercises that are perscribed.

Strengthening and stretching of the muscle groups associated with the pelvis (hamstrings, adductors, low back muscles, abdominals, glutes) all need to be addressed and can be discussed with your therapist.

Other forms of management may include injections at the irritated joint, anti-inflammatories and if needed, SI joint fusion - as directed by your MD.

For further explanation of the rehabilitation of the SI joint, visit the Team at Toronto SEMI.

References:

1. Kapandje, I.A., The Physiology of the Joints. Vol. 3.
2. Karageanes, S., Principles of Manual Sports Medicine.
3. Mitchell Jr., F., The Muscle Energy Manual, Vol 3.