Hip and SI Joint: What’s the Difference?

The hip is a ball and socket joint used to rotate the body and extend the leg while standing. In contrast, the SI joint (sacroiliac joint) allows for changes in posture by connecting the pelvis to the spine. The difference between these two joints lies within their range of motion and their internal structures and functions. The hip joint is more mobile and moves more, whereas the SI joint is less mobile.

Despite being a ball and socket joint, the hip joint has a greater range of motion (ROM). It has almost 180 degrees of rotation in one direction and then 180 degrees in the other direction. The sacroiliac joint also rotates, but only about 30-60 degrees depending on which side of it is used. This is why the hip can be used to extend the leg while standing while the SI can only change posture.

Functional Differences

Range of Motion

The difference in function between the hip and SI joints goes along with their differences in the range of motion. Since the hip joint is more mobile, it rotates the body and extends the leg. The SI joint does not have that range of motion, which adapts to a different function. The sacroiliac joint is the connection between Sacrum and Ilium and is part of the foundation of the spinal alignment. Proper SI joint movement and alignment help with posture and allow for balance when standing upright or walking. While the hip is meant to be very mobile the SI joint is meant to be stable as is the lumbar spine.

Purpose of Movement

The structure of each joint can also explain why they are used for different purposes in everyday life. The ball portion of the hip is made up of two bones called the femoral head and the acetabulum.

A common complaint is an aching or persistent hip and SI pain. Hip pain can not only affect the lower back and pelvis areas but also the hip itself. Hip pain is extremely common and occurs most frequently in people over the age of 50. Also, Hip pain is much more likely to occur in women between 50 and 70. Usually, the pain is caused by tight muscles limiting their normal motion and leading to uneven wear and tear to the joint. This leads to osteoarthritic changes.  

SI pain on the other hand occurs when the SI joints become over-stretched or inflamed. SI pain is also a common source of lower back pain. This is also prevalent among young children and older adults.

Hip & SI Pain Relief with Chiropractic Care

Regular strength training exercises and proper mobility drills are beneficial at any age and stage. However, as chiropractors, we create custom recommendations as each person’s pain and the situation can be different. Whether the pain is sports-injury related or chronic pain that is unresolved, chiropractic treatments will be geared toward solving the root of your hip pain.

If you want more information on this, reach out to our SF chiropractors today, and learn more about how chiropractic can benefit you. 


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