The types of diagnostic imaging for hip pain | Are they accurate in showing doctors what is causing your pain?
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 a hip surgery.
For some people, telling them that we would not want to see all these imaging studies first, is hard to understand. For these people, his or her 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 into asking, “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.
A Review of Research on the Value of Hip Scans
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? For an overview of these general question please see my article: Patients ask: Is my MRI accurate? If you are looking for more information specific to your MRI, CTs and Ultrasound stay here.
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 tendon. 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 more 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 allows visualization of pathology during motion. In our clinics, 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.
The research into accuracy
July 2017: 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 includes conditions such as osteoarthritis, fracture, and avascular necrosis, synovitis, loose bodies, labral tears, articular pathology and, femoro-acetabular 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) 113 patients who had MRI arthrogram and who underwent hip arthroscopy was included in the study.
- The MRI arthrogram findings were compared to that found on arthroscopy.
What is happening here is that these patients got an MRI. They went to arthroscopic surgery. The arthroscopic surgery is considered the gold standard of 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 84% and specificity 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 84% and specificity 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, overall accuracy 80%.
You may have hip delamination. This is where the cartilage separates from the bone.
- Researchers found delamination on MRI 7% on the time, but were pretty positive it was delamination (specificity 98%) when they did find it. The overall accuracy of MRI for delamination accuracy 39%.
AN MRI to determine articular cartilage defects
The articular cartilage is the cartilage that wraps the bones of the ball and socket of the hip. Chondral changes is a term to describe damage to this cartilage. The study results on the accuracy of this MRI test is 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 most diagnosis that sends more people to hip replacement than any other. Accuracy 58%. Let that sink in.
AN MRI to 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 creates 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 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 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 conclusion of this study from the research team?
“Our study conclusions are MRI arthrogram is a useful investigation tool in detecting labral tears, it is also helpful in the diagnosis of femoro-acetabular impingement. However, when it comes to the diagnosis of chondral changes, defects and cartilage delamination, the sensitivity and accuracy are low.”
Not the only study
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.
“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 MRI. 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 look 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.
In the video below, we start with a hip examination of a middle age woman, then a middle age man. Here I will show you the type of examination to determine if these two people, who were recommended to hip replacement surgery are Prolotherapy injection candidates. In other words, candidates that we can help avoid the hip replacement.
If you have questions about hip pain, Get help and information from our Caring Medical Staff
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]
2 Annabell L, Master V, Rhodes A, Moreira B, Coetzee C, Tran P. Hip pathology: the diagnostic accuracy of magnetic resonance imaging. J Orthop Surg Res. 2018;13(1):127. Published 2018 May 29. doi:10.1186/s13018-018-0832-z [Google Scholar]