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Hi, it is Tom here from Running Physio. Today I want to talk to you about hip dysplasia. You might have caught our recent video when we discussed some of the key sort of signs and symptoms of hip dysplasia, and today I want to focus on three types of hip dysplasia and how they present so that you can identify them in clinic.

So let's have a quick recap first of some of the key features of hip dysplasia before we start to look at some of the types and how you might identify them.

Hip dysplasia is often missed. It can take an average of five years to diagnose, and people often see three clinicians before someone suspects this diagnosis. So the key signs and symptoms of hip dysplasia, it's typically a young female patient that describes an insidious onset. Often with groin and or lateral hip pain. It's usually aggravated by walking, running and impact. In most patients with hip dysplasia, you would expect a positive FADIRs test. So flexion abduction, internal rotation. We think around about 80% will have mechanical symptoms like catching, clicking, locking, or popping, or symptoms of subluxation.

There may actually be increased range of movement or hypermobility and a family history of hip pain. These are the kind of standard key features to look out for that should wave a bit of a flag to say that there may be some hip dysplasia here. The question is then why is it important? Why does it matter that we identify hip dysplasia?

Well, there's a number of reasons. It can have a profound effect on function, influencing things like walking and ability to walk, sports tolerance, as well as lots of everyday activities.

Hip dysplasia is also associated with increased stress on the acetabular rim and labrum, and with an increased risk of arthritis in the hip. So it is something we want to identify early. There are commonly muscle or tendon pathologies that are associated with it, such as hip flexor pain or gluteal pain, so abductor pain. It actually is a condition which affects multiple areas around the hip and its health. The stability, the function, the pain, the hip joint, the labrum and the surrounding muscles and tendons can all be affected by hip dysplasia.

Plus, we know some patients may actually require surgery if they have prolonged instability, particularly if it hasn't responded well to conservative care. So It is something we want to be aware of and hopefully, the more we talk about it, the more people will identify and help people get the right treatment.

Throughout this video is a key reference here which is Wilkin et al. (2017). Now, if you want to learn more about hip dysplasia and the types of hip dysplasia, I'd really recommend having a look at this paper. We are summarising a lot of their findings here, so if you want to find out more, please do have a look into it.

Let's think about what hip dysplasia is then. It is a condition where we have a lack of coverage of the femoral head from the acetabulum. It's associated with instability, and that reduced coverage from the acetabulum can lead then to an increased pressure on the existing acetabulum. Because we are reducing the surface area through which we're able to place pressure. In terms of investigations, hip X-ray is actually quite a good starting point and can identify some of the key factors, but it's only a two-dimensional image of what is actually a complex three-dimensional problem.

Wilkin et al say really a CT is considered gold standard to really evaluate the boney anatomy and assess the hip in three dimensions because as you see, as we go through the types, dysplasia is actually really complex and there are lots of variabilities in play. There's lots of measures that are looked at here, but one that I thought was worth sharing with you is the LCEA. This is one of, as I said, multiple different measures that you see particularly from X-rays. This is the lateral center edge angle.

We've got some images here from Wong et al, which illustrate this. So in the top left, you have this LCEA. This lateral center edge angle of 18 degrees. Below about 20 degrees is considered to be diagnostic of dysplasia. You can see this small angle in the top left hand picture. This is a hip with dysplasia there, and you can see the lack of coverage of that femoral head.

Next to it, the top right hand side, here we have an LCEA of 24 degrees. This is one that's more considered borderline. There are these kind of gray areas where perhaps between 20 and 25 degrees, it isn't quite so clear whether we are looking at a truly dysplastic hip.

In the bottom left, the LCEA is 33 degrees, this is a normal hip in terms of dysplasia certainly from this finding. And then the bottom right, we have an increased LCEA, increased lateral center-edge angle. So we've got over coverage of the femoral head. So this would be more consistent with femoral acetabular impingement. I chose these images to share because they show you a little bit of the continuum here in terms of, coverage of the femoral head and dysplasia.

Going on from there then, let's talk about these three types that have been identified and how they may present. Wilkin et al describe these in detail, as I've said, but the three main types they talk about in terms of acetabular dysplasia are anterior, posterior and lateral or global dysplasia. Let's have a look into what the details are for each of these and how they might present.

With anterior instability, we are going to expect people to present with anterior hip pain, which is often aggravated by hip extension, particularly if we add in external rotation and any movements that are going to cause an anterior femoral head translation because there's a lack of acetabular coverage anteriorly, which allows there to be more movement and instability. This might be things like pain in the late stance phase of walking as we're going into hip extension, and patients may compensate by shortening their stride length.You may see a slower walking gait, reduced stride length in walking and running potentially. You may have positive prone instability tests. These commonly will combine things like hip extension with external rotation or abduction to take people into those positions where they're going to have less stability.

These can have a normal lateral center edge angle, and this is part of the reason why X-ray alone may not be ideal and where CT may be indicated in some cases. Because a lot of the time these cases of dysplasia get missed, they're often misdiagnosed. You can think of someone coming in with anterior hip pain that's irritated in extension and you might think, okay, this is a hip flexor tendinopathy.

And commonly then people are given lots of stretches. Those stretches will take them into those less stable positions, those hip extension positions. That's something to take away from this. Don't be sending people out with lots of stretches to do. That's type one, the anterior instability.

Type two, posterior instability. These really highlight some of the complexity of this condition. These can have both anterior and posterior hip pain. And this is because they may actually have some over coverage, some femoral acetabular impingement anteriorly with under coverage posteriorly, so lack of acetabulum posteriorly, which allows that femoral head to glide posteriorly.

These are typically aggravated by loading into flexion or into internal rotation, so perhaps going up and down stairs or slopes, going into deeper squat positions potentially. There may be a history of a low energy posterior hip dislocation. So if someone's dislocated their hip posteriorly with a fairly minor trauma, that can suggest some posterior instability.

And again, these may have a normal lateral center edge angle, so won't always be identified on X-ray. And once again, they can be misdiagnosed as SIJ pain or piriformis syndrome. They may have static nerve type symptoms and again, be given lots and lots of stretches and hopefully you can appreciate that stretches for a condition that's defined by instability are not really the best option in terms of treatment.

We know too, that with things like femoral acetabular impingement, trying to get people to work into pinchy uncomfortable positions, isn't that helpful either. So I'd be very, cautious about administering stretches for people with pain around the hip. Really reason through when it's indicated, because we also know they tend to aggravate tendinopathy. It's very common for people with dysplasia to also present with coexisting tendinopathy.

We've had anterior instability, posterior instability. Finally, type three is known as lateral or global instability. Now, this may be your more classic picture of dysplasia that we discussed right at the start.

We may have deficiency of the superior lateral aspect of the acetabulum, plus or minus some anterior or posterior deficiency, which will then influence the symptoms. And this is where it can be very complex, and why it's a good one to involve an orthopedic surgeon potentially rather than trying to manage it on your own.

Now this often results in diffuse activity-related pain. There may be these mechanical symptoms like subluxation, may also be abductor fatigue. So people describe with long periods of walking or perhaps with running that they get fatigue like symptoms in the gluteal muscles. Again, we can often misdiagnose these as gluteal tendinopathy.

There may be symptoms with static overload like prolonged standing. Maintaining one position for a period of time can be uncomfortable as well. Here we would expect the lateral center edge angle to be reduced typically less than 25 degrees in this case, but symptoms will vary depending on the acetabular coverage. Pelvic tilt can influence that as can hip, anteversion and retroversion, as well as involvement of the labral or muscle and tendons around the joint.

It's quite complex condition. And we can see quite a variety in presentations. As I said in the previous video on this, I'm not coming at this as from the position of someone who's an expert in hip dysplasia. I'm coming at this as someone who wants to learn more about this and share it with you. And what I'm learning is that hip dysplasia actually is really quite complex. It's more common than many of us would think. And it's easily missed.

What I'm hoping people would take away from this is an increase in suspicion when young patients, particularly young female patients are coming into your clinic with anterior and or lateral hip pain, it should be something that's on our radar potentially. And hopefully recognising some of these signs and symptoms might help us to change management.

For example, if you suspect it's an anterior stability, if they've got anterior pain, we've got pain and hip extension, not then going off and sending them off, doing loads of stretches into hip extension positions. And your management may center around taking people out of some of these unstable positions, at least initially when symptoms are irritable and building strength and control around the joint. And it may be about thinking about their chosen activities. Are they in yoga, for example, four or five times a week and repeatedly stretching an unstable hip and actually not really helping their condition in that sense.

So these are some of the types. I also want to find out more about how we manage hip dysplasia. I will be returning with more content on that. The more I learn, the more I'll, share with you and try and get some good expert input into that. I hope you found that useful to identify these three types of hip dysplasia, the anterior instability, posterior instability, and lateral or global instability, being the three main types. That key reference by Wilkin et al is really worth a read if you want to find out more about this.

Thanks again for listening. Bye for now.