Question
Dear Dr. Anzalone,
I recently had a CT-scan for microscopic hematuria which thankfully didn't reveal anything serious, but did show sclerosis of right iliac bone. My urologist said it was nothing to be concerned about, just thickening of the hip bone. I had a CT-scan 1 1/2 years ago for the same issues which revealed kidney stones, but not the bone thickening. Would this mean bone loss or arthritis? I do have chronic hip and lower back pain from herniated discs and the right has been giving me more trouble than usual over the past few months, but I just attributed it to aging as I am 55.

Answer
Karen,

Thank you for your question. Sclerosis of bone generally refers to an increase of bone material that is deposited in a particular region of the bone. Generally, sclerosis occurs as a response to stress on the bone. How much sclerosis occurs, where it occurs, and at the pattern in which it occurs helps to distinguish sclerosis from being a benign process or a feature of a degenerative or pathological process. So to answer the first part of your first question, sclerosis would not indicate bone loss. It would be the opposite: an increase of bone material.

In order to say whether or not the sclerotic bone is part of an arthritic process, the sclerosis would need to occur around a joint. To be more accurate, the term 'subchondral sclerosis' is generally applied to a joint that appears to thicken because the bone on each side of the joint accumulates more bone matrix (the stuff that makes up the material composition of the bone) AND there would have to be narrowing of the joint space. A joint that is sclerotic but not narrowed may be considered to demonstrate early degenerative changes that would characterize beginning stages of degenerative joint disease, often called osteoarthritis, that are seen on x-ray, MRI, or CT scanning. Long before any of these changes to the bone are evident on imaging, the affected joint is probably undergoing degenerative changes as a result of constant inflammation and excessive mechanical stress.

It's difficult for me to say which process is going on in your situation without viewing the CT images or the radiology report. Anatomically speaking, the hip is referred to as the femoro-acetabular joint. This is the joint on the side of your pelvis roughly in the area of your side pants pockets. Many people refer to the sacro-iliac joint of the pelvis (which roughly overlies the area of the back pocket of your pants) as the hip, but this is not anatomically correct. I'm not sure which area is your area of pain.

And it gets a bit more complicated when trying to identify the source of various pain patterns. The femoro-acetabular joint may refer pain into the lower back. The sacro-iliac joint may refer pain into the groin, the femoro-acetabular joint, or the back of the leg, but usually not below the knee. One of the main muscles of the lower back, the quadratus lumborum, may refer pain into the sacro-iliac joint, as does the soleus muscle, one of the muscles of the calf. Pain from joints of the lower back and herniated discs in the lower back may also cause pain in the regions of the femoroacetabular joint or the sacro-iliac joint. Muscles on the side of the femoro-acetabular joint (the tensor fascia latae) may cause pain in the hip. Irritated bursae (structures that resemble water balloons that overlay joints and prevent tendons from rubbing against each other) may also create pain when they become inflamed that may be confused with joint pain. So when people say, "My hip hurts", it becomes critical to determine which joint they are talking about and where the pain is coming from (which anatomical structures).

I hope that this helps to answer your question.