Hip Arthritis Getting Worse? New Research Says It Could Be the Bone

POSTED ON 5/3/2016 IN Hip BY Christopher Centeno

Is your hip arthritis getting worse? In addition to cartilage breakdown, your bone could also be deteriorating. A bright spot (or dark spot depending on the imaging sequence used) on the bone on MRI is called a bone marrow lesion (BML, also called a BME which means bone marrow edema). It's an area in the bone that has sustained microscopic fractures, and these bone lesions are more reliably associated with pain and lead to the big cysts we see often in hip arthritis. .

Is Your Hip Arthritis Getting Worse Due to a BML?

We used to believe that the degree of arthritis, or cartilage degeneration, was associated with pain (i.e., more arthritis equals more pain), but research has dispelled this urban myth. One of the few MRI findings that has withstood the test of time and many different research studies as being related to pain is a BML. A bone marrow lesion, is an area in the bone that's swollen. Basically, it's the bone's reaction to bad cartilage or the excessive forces due to instability, and as mentioned above, BMLs are also associated with microscopic fractures in the bone. For lack of a better term, BMLs are “pissed off bone.” Many patients will get these as their cartilage first goes bad, but then the bone and the remaining tissues react and get thicker and stronger, so they go away (as does the pain). Chronic bone marrow lesions are a bad sign, as it means the bone's ability to compensate for the bad cartilage is substandard. BMLs aren't just found in the bones of the hip. Bone marrow lesions can be found in the knee, ankle, and other bones. We classify BMLs by the imaging sequence on which they're found-so there's are T1 and a T2 types.

What are T1 and T2 BMLs?

The terms T1 and T2 in radiology signify the type of imaging sequence used. T1 weighted images show water as dark, while T2 images show water as bright. Bone, due to it's fat content also appears different on these images as it's shows up as dark on T1 and white on T2. In my video above, you'll see that we call a BML that's bright on a T2 sequence a T2 BML. A BML that's dark on a T1 sequence is called a T1 BML. While the first type denotes swollen bone (water in the BML is bright against the normally dark bone), the latter type represents dying bone (dark on a T1 image against the white appearing bone).

Studies Show T2 BMLs Associated with Hip Pain

A recent study shows that bigger T2 BMLs at the start of the study (also called BMEs), were associated with hip arthritis getting worse (i.e. more hip pain) and poorer quality of life as the study progressed. This is consistent with other studies correlating T2 BMLs with hip pain. For example, this study published in Clinical Rheumatology stated, “Cross-sectionally, the presence of large femoral, acetabular, or any hip BMLs was associated with higher odds of hip pain…High cartilage signal was strongly associated with hip BMLs, but not with pain.” Again, you can clearly see yet another study showing that cartilage loss and pain aren't really correlated all that well. Cartilage loss without a BML is not a painful condition. However, on the other hand, cartilage loss with a BML is a painful condition. It's a bit like smoke and fire. Where's there's smoke there's fire, but you can have fire without smoke.

What This Means for Hip Arthritis Stem Cell or PRP Treatments

Our registry data shows that, on average, patients with severe hip osteoarthritis (OA) don't respond as well to a same-day stem cell procedure as those with severe knee OA. This doesn't mean that patients with severe hip OA don't respond at all—we have seen some patients surprise us. On the other hand, patients with mild and moderate hip arthritis, however, tend to respond better to a same-day stem cell injection. Interestingly, hips have fewer native stem cells than knees (i.e., hips lack the same self-repair mechanism as knees, and research shows hip and knee arthritis are different diseases). Hips can also have much more rapid bone changes on MRI than knees. In fact, a hip can deteriorate within a year, while knees can smolder for many years. These two things-hip BMLs and the rapid onset of hip arthritis, suggest to me that hip arthritis is much more of a bone disease than it's cousin knee arthritis. This also tells me that we should likely be treating not only the joint with stem cells but also the bone. We first began treating hip T2 BMLs way back in 2008, following the work of Philippe Hernigou who had published excellent results by using a same day stem cell procedure to treat hip avascular (AVN) or osteonecrosis (ON). Since then we've treated >100 AVN/ON hips with promising results. In fact, when you insert stem cells into these lesions under x-ray guidance, as long as the disease isn't too far advanced, you can reliably heal the bone as seen on post-op hip MRIs showing normal bone signal that corresponds to patient relief. This past few years, we've been treating hip BMLs in select hip arthritis patients without known AVN/ON in a similar fashion. Based on this new research, we're starting to get the sense that the research is catching up to where our heads were at a few years ago. Meaning that the new research is suggesting that we all may want to get a little more aggressive with these bone lesions and inject the bone in hip arthritis patients with as much intensity as we inject the joint.

The upshot? If hip arthritis getting worse and becoming more painful is something you're dealing with, the culprit is less likely your cartilage and more likely the resulting bone marrow lesions. A bright or dark spot on your hip MRI will confirm this, and stem cell treatments for both the hip joint and the bone may be a reasonable nonsurgical solution.  


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