Accuracy and diagnostic readings of HIP MRI

Ross A. Hauser, MD; Danielle R. Steilen-Matias, MMS, PA-C

You went and had an MRI of your hip. Your MRI came back and showed a lot of degenerative problems. You may have been told you have “bone on bone” and that nothing can be done for this sort of hip replacement. You went in for hip surgery. After months of rehabilitation, you still have the same hip pain. Upon further review and another MRI, it is determined that your pain is actually coming from your SI joint and/or your lower back. You may be finding yourself on this page because you are now researching alternatives to SI joint and low back surgery, or here Hip-spine syndrome before and after failed hip replacement and lumbar spinal fusion complication.

Something we hear, perhaps more often than one would think is, “How was my hip MRI so wrong?”

A Review of Research on the Value of Hip Scans

A person with long-term hip pain management will typically tell us about all the tests, images, scans, CDs, and other digital images they have of their problem hip. They then will ask how can they get these films to us. These patients are very anxious to avoid either a hip arthroscopic surgery or a hip replacement surgery. They sometimes think that the quicker we can review their images, the quicker they can avoid the surgery.

We tell many of these people, “Come in for an examination. Let us look at how you walk and what type of range of motion you have in your hip. Then if we need to confirm or dismiss something in your hip, we will take a look at your films.” In our thinking, the quicker we can do a physical examination, the quicker we can assess whether or not we can help them avoid hip surgery.

For some people, telling them that we do not want to see all these imaging studies first, is hard to understand.

For these people, their entire problematic hip medical history has been guided by imaging. Some people are so confused by this that they mistake what we are telling them and ask, “Do I need to get a new MRI?” The answer is almost always NO. In our experience, people who have already had a hip replacement on one side, even a successful one, and do not want to “go through all that again,” understand the limitations of film best.

Pictures of the hip, are they worth it?

Ross Hauser, MD discusses some very common MRI findings in asymptomatic patients and why MRI can lead to surgery even when that may not be the true pain-producing structure. 

What are the types of imaging a person can be ordered when they have chronic pain? Are these tests accurate in helping him or her in treatment? Are these tests accurate?

A look at the imaging studies

Usually, a person with chronic hip pain will come into our office and they will have one, two, three, or all four of the following performed over a period of time.

  • Hip X-ray
  • Hip CT (computed tomography)
  • Hip MRI (Magnetic resonance imaging), and
  • Hip Ultrasound

What’s the difference between these imaging techniques?

Perhaps the question is not what is the difference in the techniques, but rather what is the difference in how helpful these images can be.

The x-ray shows:

For the most part, the initial imaging examination will be an X-ray. An X-ray will be most effective in showing degenerative bony abnormalities and loss of joint space, signifying cartilage loss. In degenerative hip disease, it is usually the X-ray that convinces someone with hip pain that they have advancing hip osteoarthritis, bone death or avascular necrosis, bone spurs, and loss of cartilage.

The CT scan shows:

CT or CAT scans are looking for soft tissue damage that the X-rays do not see. This would be muscle, ligaments, and tendons. Because of the complexity of the hip, this imaging test is usually not favored for hip pain patients as images are poorly defined.

The MRI shows:

For some people, the end-all of all end-alls is the MRI image. It is extraordinarily difficult for people to believe that their MRI is not telling the correct story of their hip pain. The research questioning MRI accuracy will be shown below.

An MRI is looking for things the X-ray and the CT scan cannot show. This would be soft tissue damage, fluid buildup, or hidden swelling. The MRI may also reveal bone deformities that the X-ray did not show.

  • When you are offered a hip MRI, you may hear terms such as Direct or Indirect Hip MRI Arthrography. The terms signify a difference in the use of contrast material to make the image clear. Indirect is where contrast material is injected into the bloodstream and circulates through the body, or Direct, where contrast material is injected directly into the hip.

Ultrasound

Ultrasound allows visualization of pathology during motion. In our clinic, we use this tool on selected patients to see directly and immediately into the joint. We can then treat the visualized musculoskeletal condition with Prolotherapy. We also will use this tool in patients seeking treatment for pain following joint replacement.

It is hard to figure out what is causing the patient’s hip pain. It can be any one of a number of things, the MRI seems to be the tool most doctors like to use, but is accurate enough?

Doctors at Queen Elizabeth Hospital in the United Kingdom and the University Medical Centre, Rotterdam, The Netherlands wrote in the European Journal of Orthopaedic Surgery and Traumatology: (1)

“The assessment of a patient with chronic hip pain can be challenging. The differential diagnosis of intra-articular pathology causing hip pain can be diverse. These include conditions such as osteoarthritis, fracture, and avascular necrosis, synovitis, loose bodies, labral tears, articular pathology and, femoroacetabular impingement. Magnetic resonance imaging (MRI) arthrography of the hip has been widely used now for diagnosis of articular pathology of the hip.”

In simpler terms, it is hard to figure out what is causing the patient’s hip pain. It can be any one of a number of things, the MRI seems to be the tool most doctors like to use, but is it any good?

Here are the research findings:

  • A retrospective analysis (looking back on) of 113 patients who had an MRI arthrogram and who underwent hip arthroscopy was included in the study.
  • The MRI arthrogram findings were compared to those found on arthroscopy.

What is happening here is that these patients got an MRI. They went for arthroscopic surgery. Arthroscopic surgery is considered the gold standard for determining what is going on in your hip because there is a camera inside your hip taking pictures. When the MRI is doubted this is the “look-and-see hip surgery,” you may be told to get. In this study, what was seen from the “outside” the MRI was compared to what was seen on the inside “the arthroscopic surgery.”

We are going to talk about two terms sensitivity and specificity in MRI readings. You may have heard your doctor discuss them and may not have been sure what he/she was really talking about. So let’s explain what these terms mean. It may give you a much deeper understanding of the accuracy of what your hip MRI report says:

Hip Labral Tears

  • In this research, the doctors found Labral tear sensitivity at 84% and specificity of 64% against the arthroscopic findings.

Let’s say you went and had an MRI for a hip labral tear. The radiologist tells you, based on this research, that the test has a sensitivity of 84% and a specificity of 64%. What does this mean?

  • The MRI will identify something (sensitivity) as a labral tear 84% of the time. But it is really only a labral tear (specificity) 64% of the time, an overall accuracy of 80%.

Hip delamination

You may have hip delamination. This is where the cartilage separates from the bone.

  • Researchers found delamination on MRI 7% of the time but were pretty positive it was delamination (specificity 98%) when they did find it. The overall accuracy of MRI for delamination accuracy is 39%.

AN MRI to determine articular cartilage defects

The articular cartilage is the cartilage that wraps the bones of the ball and the socket of the hip. Chondral change is a term to describe damage to this cartilage. The study results on the accuracy of this MRI test are going to be somewhat surprising.

  • Chondral changes-sensitivity 25%, specificity 83%, accuracy 58%.

This is one of the determinates of “bone on bone,” the probable single diagnosis that sends more people to hip replacement than any other. Accuracy 58%. Let that sink in.

AN MRI of Femoro-acetabular impingement (CAM deformity)

Femoroacetabular Impingement (FAI) or sometimes diagnosed simply as Hip Impingement is a condition where abnormal contact and rubbing of the ball and socket portion of the hip bones create joint-damaging friction. This “bone-on-bone” situation subsequently develops into degenerative osteoarthritis in addition to causing injuries to the labral area. Please see my article for more on this subject Femoroacetabular Impingement and Prolotherapy

  • The MRI diagnosed Femoro-acetabular impingement (CAM deformity)-sensitivity 34% of the time. When it was diagnosed, it was diagnosed correctly 83% of the time. Overall accuracy is 66%.

It is interesting to note bone-on-bone diagnosis accuracy of 58% – 66%

We see many patients, who after our examination are told that our treatments can help them say to us, “But I have bone on bone, my only option is a hip replacement.” Remember what we said above. For some people, the end-all of end-alls is the MRI image.  It is extraordinarily difficult for people to believe that their MRI is not telling the correct story of their hip pain.

The conclusion of this study from the research team is?

“Our study conclusions are MRI arthrogram is a useful investigation tool in detecting labral tears, it is also helpful in the diagnosis of femoroacetabular impingement. However, when it comes to the diagnosis of chondral changes, defects, and cartilage delamination, the sensitivity and accuracy are low.”

When the hip damage is not so obvious on MRI and the person has hip pain

This was not the only study to document the problems of hip MRI. In May 2018, doctors in Australia published these findings in the Journal of Orthopaedic Surgery and Research. (2)

“Conventional non-arthrographic (no contrast dye) MRI offers an accurate non-invasive (non-surgical) method to screen patients with symptoms referable to the hip by revealing the presence of labral tears, chondral defects, and ligamentum teres tears/synovitis. This study demonstrates that tears and synovitis of the ligamentum teres as potential sources of hip pain can be accurately identified on conventional non-arthrographic MRIs. However, MRI has poor specificity and negative predictive value, and thus, a negative MRI result may warrant further investigation.”

What does this mean? 

It means that when the MRI looks at your hip it is pretty confident when the labral tears, chondral defects, and ligamentum teres tears/synovitis (the big ligament of the hip) are obvious. But, when this damage is not so obvious and the person has hip pain, we should listen to the patient and not rely on the MRI to contradict them. “A negative MRI result may warrant further investigation.” In our office, this further investigation is a physical examination.

So how could my hip MRI be wrong?

In March 2019, in the surgeon’s journal Clinics in Orthopedic Surgery, (3) researchers shared these findings with the international medical community.

We are going to go back to talking about sensitivity (the test’s ability to identify something that may be causing your pain) and specificity (the MRIs ability to determine that what it thinks is causing your pain is in fact actually causing your pain).

In this research, the doctors and radiologists investigated the sensitivity, specificity, and accuracy of magnetic resonance imaging (MRI) and computed tomography arthrography (CTA), on the basis of arthroscopic findings, to diagnose acetabular labral tears and chondral lesions.

  • They reviewed the results of MRI and subsequent CTA in 36 hips that underwent arthroscopic surgery (33 patients; 17 males [17 hips] and 16 females [19 hips]; average age, 35 years)
  •  All patients had positive impingement test results and groin pain.

The sensitivity, specificity, and accuracy of computed tomography arthrography for the detection of acetabular labral tears by two observers were 60%, 80%, and 64%, respectively, and 65%, 70%, and 69%, respectively.

  • In other words, 64% of the time or 69% of the time, the computed tomography arthrography and its interpretation correctly identified acetabular labral tears. How was this verified? By observation during arthroscopic surgery.
  • So it is possible that 31-36% of people had arthroscopic surgery to DISPROVE what the computed tomography arthrography suggested.

If you think that is bad. Here is the comparison to MRIs

  • The MRI offered little help to the radiologists in determining the accuracy of reading in acetabular labral tears. The MRI could only think it found the problem according to one observer, 36% of the time, and 46% of the time to the other observer.

What could the researchers conclude other than:

  • This study demonstrated that the accuracy of MRI to detect an acetabular labral tear and a chondral lesion of the hip joint was not sufficient. CTA was reliable in the diagnosis of acetabular labral tears. However, both CTA and MRI were also of limited value to detect chondral lesions.”

This was followed up in January 2020 paper from the Feinberg School of Medicine, Northwestern University in the Journal of orthopaedics (4) which suggests “a poor correlation in labral measurements between magnetic resonance arthrogram imaging and intraoperative measurements, suggesting that this imaging modality may be insufficient in providing accurate measurements of labral size.”

In March 2023, research led by the University of Munich and the University of California at San Francisco (5) evaluate the accuracy of morphological signs of cartilage acetabular delamination (cartilage damage and defects) in non-arthrographic (simpler and more general) magnetic resonance imaging (MRI) using (and comparing) intra-articular arthroscopic findings in patients undergoing FAI surgery. While the non-arthrographic MRI showed good results in seeing acetabular chondral delamination, inter-observer reproducibility among different radiologists was only moderate. (Different radiologists saw different things).

This was also suggested in a July 2022 paper in the Archives of Orthopedic and Trauma Surgery (6) which stated: “The accuracy of direct magnetic resonance arthrography (dMRA) on detecting labral pathologies or acetabular chondral lesions depends on the examiner and its level of experience in hip arthroscopy. The highest values are found for the hip-arthroscopy-trained orthopaedic surgeons.”

Summary and contact us. Can we help you?

We hope you found this article informative and that it helped answer many of the questions you may have surrounding your hip problems and hip instability.  If you would like to get more information specific to your challenges please email us: Get help and information from our Caring Medical staff

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Similar articles:

Rapid destructive hip osteoarthritis: When MRI and X-Rays show nothing and suddenly you need a hip replacement

What causes long-term hip pain after hip replacement?

References

1 Rajeev A, Tuinebreijer W, Mohamed A, Newby M. The validity and accuracy of MRI arthrogram in the assessment of painful articular disorders of the hip. European Journal of Orthopaedic Surgery & Traumatology. 2017:1-7. [Google Scholar]
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