The Sacro Iliac joint is complex for sure. Besides having to axis of motion and a weird shaped joint surface, there are two of them, all the muscles that cross it have more than one joint that they control, the symmetry or lack of symmetry between the joints add a degree of complexity as well, and the entire weight of the upper body is transfered through the SI joints to the lower extremities.
This is an x-ray of the SI joints looking down on the middle of the joints from the top:
I will say this: We see many more problems with women than men with respect to the SI joint. The reasons for this are first, the wide pelvis and the shallower SI joint angles, second, the impact of hormones on ligament laxity, and third, the consequence of pregnancy (change in weight bearing loads and angles combined with ligament laxity). We usually see SI joint problems in people who were not recently pregnant after trauma of some sort. For example, runners who land in a hole or shallow spot unexpectedly, or people involved in a sudden breaking event or head on impact in a car for example.
My point is that absent pregnancy it is rare to see a true SI joint instability. On the other hand, we do see restrictions of SI joint mobility that do have consequences at the hips and lower back for example. How do you know if your SI joint is irritated? Well, if there is a true hypermobile SI joint that is symptomatic, you will most likely have unilateral pain in your buttock. In the event that the joints are simply hypomobile, then it is harder to determine on your own, and a good evaluation will reveal the restriction. Unfortunately, the symptoms that the irritated SI joint usually cause are also symptoms of other typical issues like lower back pain of discogenic origin, and a good physical evaluation is key to sorting out your symptoms.
The real challenge in treating the SI joint is not so much the hypomobile structure, because it is relatively easy to get a stuck joint moving again, but rather, the challenge is to stabilize the hypermobile joint. The reason for this, I alluded to earlier, and that is that every muscle that crosses the SI joint also crosses or controls another joint. For example, the Piriformis muscle is the major muscle that crosses the joint close to the joint line. But while the Piriformis muscle inserts on the inside of the Sacrum, it also inserts on the femur crossing the hip once it exits the pelvis crossing the SI joint.
You can see how intimately the Piriformis muscle relates to both the SI joint and the hip and the adjacent hip muscles as well as the Sciatic Nerve. So what do you need to do if you think you have an SI joint problem? First of all, use ice over the gluteal muscles. It seems to make a big difference. Second, get a good evaluation because the maneuvers that you need to make to figure this out need someone specialized to test and observe. Third, (and this depends on the evaluation) you will either need stabilizing exercises or mobilizing exercises. Finally, footwear might play a roll (Excessive pronation or supination will lead to stress across the SI Joint.) If you need stabilization though, an SI joint belt might be of service. This is often hit or miss though, but definitely worth a try.
My best advice is to get a good mechanical evaluation by a physiatrist, a physical therapist or a chiropractor, because that will determine the specific treatment strategy you need.
Posts
