The sacrum is the triangle area below the lumbar spine. There are two iliac bones that connects to both sides of the sacrum. Sometimes people refer to the Sacroiliac as the hip but the hip joints actually comprises of the femur or your thigh bone and your Illia or iliac bone. On an X-ray the illia or iliac bones look like the elephant ears in a pelvic x-ray.
The sacroiliac joint (SI joint) is a large and weigh-bearing joint. All the weight of the body and upper extremities are supported by the SI joint and it has the distinct problem of having almost all of it’s supportive ligaments running parallel to the joint itseslt
As people age, that joint starts to fuse and some people get arthritis in that joint. SI pain usually feels like low back and buttock type pain. Usually the pain doesn’t radiate below the knee, but in rare occasions it can.
Something that is very common is pain on the side of the legs, which is called bursitis. Whenever a person has pain the body moves just a little bit differently than if they didn’t have pain which is usually the cause of bursitis. This pain can be very severe and radiate from the front or back of the hips and legs.