David Metcalfe, PhD, MRCP, MRCS, MRCEM, discusses the clinical examination for hip osteoarthritis.
David Metcalfe, PhD, MRCP, MRCS, MRCEM, discusses the clinical examination for hip osteoarthritis.
>> [Background music] Hello, and welcome to JAMA Evidence, our monthly podcast, focused on core issues and evidence-based medicine. I'm David Simel, the Editor of the Rational Clinical Examination Series, and Professor of Medicine at the Durham Veterans' Affairs Medical Center and Duke University. Today, we are discussing the clinical evaluation for hip osteoarthritis. Joining me to talk about this topic is Dr. David Metcalf, who is a physician and clinical lecturer at the Nutfield Department of Orthopedics, Rheumatology, and Musculoskeletal Sciences, which is based at the University of Oxford, in Oxford, United Kingdom.
David, I'm looking forward to our discussion today, because I went for a job last weekend, and now my hip hurts. Or should I say, I think it's my hip? And that is where I want to start our conversation. Patients may think they have hip pain, but their physician, like me, may have long forgotten any surface anatomy that we were taught in medical school, and to make it more difficult, we've got our patient on the phone in this age of a pandemic, so I'm that patient. Walk me through the patterns of hip pain location, and maybe guide me where to put my hand to describe the location of pain to you?
>> Yes, and thank you very much for inviting me today. So, the pain caused by hip osteoarthritis is often quite poly-localized. Patients can complain of pain over quite a large area. So, if you were going to demonstrate this area with your hands, you might place them over the front and outer aspects of the thighs, into the groins, around to the buttocks, and finally down into the back of the upper thighs. But patients with chronic hip pain can develop central sensitization, which can lead to some surprising distributions of pain some distance from the hip itself.
Some studies have even reported hip joint pain that is experienced below the knee. So, as always in clinical medicine, things aren't always necessarily as straightforward as in the textbooks. >> Well, that distribution does help me understand where patients perceive hip discomfort, and a little bit about why it was difficult for me to figure out if it was my hip or not. But of course, what I immediately worried about was, "Oh, my gosh, I've got hip osteoarthritis." So, how common is hip osteoarthritis?
>> So, of course the prevalence of hip osteoarthritis depends on the population that we're talking about. So, the evidence from large cohort studies suggests that symptomatic hip osteoarthritis affects around 6 percent of people aged over 60. But we are probably more interested in the prevalence of hip osteoarthritis amongst people seeking help for pain around the hip. And the best studies we have suggest that around a third of patients seen by a primary care practitioner for pain around the hip will have radiographic evidence of hip osteoarthritis.
>> Okay, great. I didn't get a hip x-ray, and I didn't go see my primary care doctor because I knew I'd have you on this call. So we've addressed the location of hip pain, and the prevalence of hip osteoarthritis. Talk to me a little bit about hip motion, and can you describe the planes of motion, so I can figure out why certain activities may affect the discomfort, while others don't? >> So your listeners will recall that the hip is a ball and socket joint, and so it can move through multiple planes, and we usually talk about range of motion in terms of degrees, with the joint at zero degrees when it's in the anatomical position, and joint ranges of motion can be estimated or measured formally using a goniometer.
It's conventional to examine hip movements with the patient let down, and I can certainly talk through the hip movements, although listeners will likely find this easier to appreciate from a good diagram. So, hip extension can be measured with the patient laid prone, and with the patient in this position, the hip can be extended simply by lifting the leg off the couch into the air when the hip doesn't extend very far, and usually only from around 0 to 20 degrees. Flexion is examined with the patient supine, and in this position, the patient's knee is lifted up and moved toward their abdomen and the normal range of hip flexion is something in the region of 0 to 140 degrees.
And when the hip is flexed in this position, the foot can be held still, and then the knee moved across the midline, and I will internally rotate the hip. And the normal range of internal rotation is 0 to 30 degrees. The hip can then be moved away from the midline, which will externally rotate the hip, usually between 0 and 40 degrees. Adduction and abduction are measured by placing the patient's feet back together. The hip is then adducted, that's A-D ducted by moving the patient's foot across the midline.
Normal adduction is 0 to 30 degrees. And finally, the hip can be abducted, that's A-B ducted, by moving the patient's foot away from the midline. Normal abduction is 0 to 40 degrees. I'm conscious that this all sounds onerous, but it actually doesn't take very long in clinical practice. >> David, you mention use of a goniometer. Most primary care doctors don't carry a goniometer with them, so how do you recommend that they actually quantify the amount of movement?
>> So, I think goniometers probably aren't used very commonly, and I think that's okay, because if a patient has markedly reduced joint range of motion, then that should be obvious, and we shouldn't really be talking about really subtle differences. I think it's important that clinicians compare one side to the other side, the painful side to the unaffected side, although of course that can be problematic because osteoarthritis is often bilateral. I think the other thing that clinicians can do is just get used to examining hips that don't have reduced range of motion, and when they do find a hip that is stiff, that should be obvious.
And at that point, they'd be relying on estimates of range of motion, and I think that's probably what most clinicians would do, rather than reaching for their goniometer. >> Alright. Well, let's move on to a discussion of symptoms. What are the most reliable symptoms for identifying a patient who is going to have hip osteoarthritis on plain film radiographs? >> So, I think the first thing to say is that unfortunately, few symptoms in isolation are any good at identifying which patients will have radiographic hip osteoarthritis.
And when we reviewed the evidence, the clear winner by some margin was when the patient reports the worst pain they experience is being in the medial thigh and that's highly suggestive of hip osteoarthritis. But unfortunately, these symptoms are only reported by a very small number of patients. And so it's not going to clinch the diagnosis in most cases. The only other symptom that stood out as being particularly promising was pain on climbing stairs or walking down slopes. And when their symptoms are present, it effectively doubles the baseline obviously of their being radiographic hip osteoarthritis.
But beyond those two features, actually the symptoms as reported in the history, we didn't find were particularly useful. >> Okay, so pain on the medial thigh, and then pain that accelerates, I guess when you're not on the level, either up or down. >> Absolutely. >> Alright. Well let's talk about the maneuvers you do as a physician to help sort this out. You described two components to maneuvers, which was a range of motion and pain during the examination.
I imagine you're going to start out with my pain-free hip to compare sides. So, what maneuvers are easiest to perform for generalist physicians? >> So, thankfully, there seems to be a few more clues during the physical examination than from the history. And the clear winner inarguably was this posterior hip pain on squatting. This sign increased the odds of hip osteoarthritis by over six times. But I'm conscious that not all patients with hip pain will be enthusiastic about completing this maneuver.
Fortunately, simple, passive hip movements can also be extremely helpful. The painful hip, as we said earlier, will usually be compared to the unaffected side, but that assumes that the hip osteoarthritis isn't affecting both sides, which is often going to be an assumption too far. But the best predictors included groin pain when the hip was adducted or abducted, decreased hip adduction, decreased internal rotation. And in addition to that, the presence of normal hip adduction and normal hip abduction were the most useful signs in identifying patients who didn't have hip osteoarthritis as well.
So I think that if a patient has got hip stiffness, particularly affecting adduction, abduction, and internal rotation, those are highly suggestive of the patient having hip osteoarthritis. >> Well, let's put it all together now. In your review, you have a really nice conceptual approach for making the diagnosis. Tell us how to use the best symptoms and examination findings to come up with a rationally-based diagnosis of hip osteoarthritis.
>> So our review lists all the features that suggest of hip osteoarthritis, and those that point towards an alternative diagnosis. So, we use this list as part of an algorithm for identifying which patient should go for hip radiographs. So, where the history and examination point towards an alternative cause, this could be made clinically depending on what it is, or it might require cross-sectional imaging, such as MRI of the hip or lumbar spine. However, when the history and examination strongly suggest hip osteoarthritis, the diagnosis can be made clinically in patients with mild to moderate symptoms.
These patients can be given appropriate advice about exercise and analgesia. Patients with severe or unremitting symptoms should clearly undergo radiographic imaging. If the radiographs are normal, they should merit a further search for alternative causes. However, if the radiographs support a diagnosis of hip osteoarthritis, then these patients will probably at that stage require orthopedic referral to discuss treatment options. >> David, I've enjoyed talking with you today. Are there any particular things or pearls of wisdom about hip osteoarthritis that you'd like to share with our listeners?
>> I think some of your listeners might be thinking about after all of this, surely the easiest thing to do is just to organize hip radiographs; they're cheap, they're quite easy to organize, and the radiation risk isn't huge either. But one of the difficulties is that radiographic hip osteoarthritis is really common in the general population, and it's often asymptomatic. If fact, we know that only a fifth of patients with radiographic evidence of hip osteoarthritis actually experience pain. And, of course, there are many other causes of hip pain. So if a clinician doesn't carefully consider pre-test probability, they risk finding incidental hip osteoarthritis on plain radiographs, but they might convince themselves they found the diagnosis, and the risk, then, is that the patient ends up with the wrong treatment for their greater trochanteric pain syndrome, or lumbar radiculopathy, or whatever else is causing their pain.
And I suspect that's a greater risk to patients who've had imaging than the ionizing radiation. >> [Background Music] Well, thanks. This has been a great discussion. More information about this topic is available in The Rational Clinical Exam, and on our website, JAMAEvidence.com, where you can listen to our entire roster of podcasts. I'm David Simel, and I'll be back with you soon for another edition of JAMA Evidence.