Description

This video is about the Hip Joint.
In this video, we break down the anatomy of the hip joint, how it moves, what supports it, and what happens when it gets damaged. We go layer by layer, starting with the bones and landmarks of the acetabulum and femur, then look at the joint capsule, synovial membrane, ligaments, and finish off by exploring three common conditions that affect the hip joint: osteoarthritis, gout, and rheumatoid arthritis.
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Structures of the Hip Joint
Bony structures involved
• Head of femur (caput femoris): Articulates with the acetabulum to form the ball-and-socket joint.
• Acetabulum (acetabulum): Concave socket in the pelvis that receives the head of the femur.
Acetabular landmarks
• Acetabular margin (margo acetabuli): The rim surrounding the acetabulum.
• Acetabular notch (incisura acetabuli): A gap in the inferior rim of the acetabulum.
• Lunate surface (facies lunata): Smooth, crescent-shaped surface that contacts the femoral head.
• Acetabular fossa (fossa acetabuli): Central, non-articular depression in the acetabulum.

Intra-articular structures
• Acetabular labrum (labrum acetabulare): Fibrocartilaginous rim that deepens the socket and improves joint stability.
• Transverse acetabular ligament (ligamentum transversum acetabuli): Bridges the acetabular notch to complete the socket rim.
• Ligament of the head of femur (ligamentum capitis femoris): Connects the fovea of femoral head to the acetabular fossa and carries a small artery.
• Acetabular fat pad (pulvinar acetabuli): Fat within the acetabular fossa that cushions and supports the ligament.
Joint capsule
• Synovial membrane (membrana synovialis): Inner layer of capsule producing synovial fluid.
• Fibrous membrane (membrana fibrosa): Outer dense connective tissue layer providing mechanical stability.
Capsular ligaments
• Iliofemoral ligament (ligamentum iliofemorale): Y-shaped ligament from anterior inferior iliac spine to intertrochanteric line; resists hyperextension.
• Pubofemoral ligament (ligamentum pubofemorale): Extends from pubic part of acetabulum to lower femoral neck; resists abduction and extension.
• Ischiofemoral ligament (ligamentum ischiofemorale): Spirals from ischium to posterior femur; limits internal rotation.
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Hip Joint Movements
• Flexion (flexio): Thigh moves forward.
• Extension (extensio): Thigh moves backward.
• Abduction (abductio): Thigh moves laterally away from body.
• Adduction (adductio): Thigh moves medially toward body.
• Internal rotation (rotatio interna): Femur rotates inward.
• External rotation (rotatio externa): Femur rotates outward.
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Common Conditions Affecting the Hip Joint
Osteoarthritis (OA) Pathophysiology
• Degeneration of articular cartilage leads to joint space narrowing.
• Bone-on-bone friction causes inflammation and osteophyte (bone spur) formation.
• Risk factors: age, obesity, physical labor, joint trauma.
• Symptoms: groin pain, stiffness less than 30 mins in the morning, reduced range of motion, crepitus.
Gout Pathophysiology
• Deposition of monosodium urate crystals in synovial membrane.
• Causes acute inflammatory arthritis (synovitis).
• Risk factors: CKD, obesity, purine-rich diet, alcohol, thiazide diuretics.
• Symptoms: sudden pain, swelling, warmth, redness, extreme tenderness.
Rheumatoid Arthritis (RA) Pathophysiology
• Autoimmune disease targeting the synovial membrane.
• Leads to pannus formation and joint destruction.
• Risk factors: female sex, age 40–60, HLA-DR4, smoking.
• Symptoms: symmetrical joint pain, stiffness longer than 30 mins, fatigue, deformity.
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If you want a PDF version of this lecture, test your knowledge with a quiz, or explore a structured list of all anatomy videos, visit my website: taimtalksmed.com

Sources:
• Kozlowski, T. (2017). Memorix Anatomy, 2nd ed.
• Standring, S. (2020). Gray’s Anatomy, 42nd edition
• Tubbs RS, Shoja MM, Loukas M. (2016). Bergman’s Encyclopedia of Human Anatomic Variation
• White TD, Folkens PA. (2005). The Human Bone Manual
• Moore, K.L., Dalley, A.F., & Agur, A.M.R. (Clinically Oriented Anatomy)
• Kenhub.com
• Medscape

Programs used: Complete Anatomy (3D4Medical), PowerPoint, Canva, Camtasia

Summary written by ChatGPT

Transcript

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As we get older, one of the most common
problems we run into is that our joints

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start to wear down. And one that can
often get inflamed – is the hip joint.

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Some people feel stiffness in the morning,
others feel pain after a long walk.

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But to understand why, we need to go inside the
hip joint, look at how it’s built from inside out.

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So in this video, we’re going to break down the
anatomy of the hip joint, its bony structures,

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the ligaments that stabilize it, how
it moves, and some of the most common

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issues that can damage the hip joint.
What’s up everyone, my name is Taim. I’m

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a medical doctor, and I make animated medical
lectures to make different topics in medicine

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visually easier to understand. If you’d like a PDF
version or a quiz of this presentation, you can

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find it on my website, along with organized
video lectures to help with your studies.

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Alright, let’s get started.
You know I have this way to

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really understand something I need to remove all
structures and build it up layer by layer. So

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that is what I’m going to do here. So after
removing the ligament and capsules, what we

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can see now is a clean articulation between
the head of the femur and the acetabulum of

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the pelvis. We call this a ball-and-socket joint.
So if you now stand up, to add some muscle memory,

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kick your hip forward, that is called flexion.
Backwards is hip extension. The hip can also

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move outwards in abduction, and if you kick back
in towards the body, that is called hip adduction.

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Your hip can also rotate, it can do internal
rotation, so hip rotates inwards as leg kicks

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outward. The other way is called hip external
rotation. So that’s how the hip joint moves.

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Ok, this is how you never forget the
hip joint. First we move the femur away,

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and we focus on the acetabulum for a moment.
Each one of these landmarks has a function so the

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acetabulum has an acetabular margin, acetabular
notch, lunate surface and an acetabular fossa.

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Now what I’m going to do, is add some structures
on top of those landmarks. First we can see the

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acetabular labrum. This is a fibrocartilaginous
rim that is attached to the margin, and what it

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does is that it improves stability by making
the socket deeper. Then there’s a transverse

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acetabular ligament, which bridges across the
acetabular notch, stabilizing the joint from

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beneath. And we can see a central ligament here
called the ligament of the head of the femur.

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It connects from the fovea on the femoral
head into the acetabular fossa and helps

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carry a small artery into the joint.
Now let’s look at this in context. So

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here is the femur within the acetabulum, and
I’ve faded the hip bone completely to be able

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to see the structures within. So here we see the
acetabular labrum outlining the margin, and here

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you can clearly see how the ligament of the head
of the femur is anchored into the femoral head.

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And down here, the transverse acetabular ligament.
Now remember earlier when I mentioned the lunate

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surface? This is where it’s located, right here
is where the head of the femur articulates with

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this surface. It’s covered in articular cartilage,
a smooth layer that reduces friction and absorbs

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shock during movement. And it’s only this
lunate surface that’s in direct contact with

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the femoral head, not the whole acetabulum, and
that begs the question, what about this area in

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the middle then? Is it not covered by cartilage?
This is actually where we find the acetabular fat

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pad, also called the pulvinar acetabuli. It sits
within the acetabular fossa and acts as a space

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filler, cushioning and supporting
the ligament of the head of femur.

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Alright, I hope it makes sense so far. Let’s
keep building on this joint. The joint is

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directly covered by the synovial membrane of
the articular capsule. This layer is a thin,

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delicate membrane that lines the internal
surface of the capsule. And what it does

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is that it produces synovial fluid, which
lubricates the joint to reduce friction,

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and provides nutrients to the cartilage, since
the cartilage doesn’t have its own blood supply.

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Right on top of this synovial membrane, we find
the fibrous layer of the articular capsule. This

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layer is thicker, made of dense irregular
connective tissue, and it’s continuous with

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the periosteum of the femur and acetabulum.
This one plays a mechanical role, stabilizing

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the joint and resisting excessive movement.
Now, we’re not done. This joint has some extra

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layers of ligaments that reinforce this capsule.
The first one is the pubofemoral ligament, which

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runs from the pubic part of the acetabulum to the
lower part of the neck of the femur. It primarily

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prevents excessive abduction and extension.
The other ligament here is called the

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iliofemoral ligament. This has a Y-shape
and it runs from the anterior inferior

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iliac spine to the intertrochanteric
line of the femur. It’s often described

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as one the strongest ligaments in the body and
resists hyperextension when you stand upright.

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If we now rotate around to the back, we
can see the ischiofemoral ligament. This

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ligament originates from the ischial part of
the acetabulum and spirals upward to attach to

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the femoral neck. It’s more posterior and
supports the joint in internal rotation.

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And that’s it. That was the
anatomy of the hip joint. Very

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straightforward once you layer it logically.
But the thing about joints, especially the hip,

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is that they’re not invincible. Over time,
they can get inflamed and irritated. That’s

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when we start using a term you’ve definitely
heard before: arthritis, which literally

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means inflammation within the joint.
There are many causes of arthritis,

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but I want to just show you a few of the most
common ones that affect the hip joint. Not

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everything, just enough to give you a good
sense of what can actually go wrong in here.

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So let’s circle back for a moment.
Remember how I showed you cartilage

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on the surface of the femoral head and also
lining the lunate surface of the acetabulum.

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The thing is, as you move your hip in all
directions, extension, flexion, adduction,

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abduction—the cartilage that covers the femoral
head and the lunate surface starts taking on a lot

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of stress. And over time, it can start wearing
out. Now, when the cartilage begins to thin,

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we start to lose that nice smooth gliding surface,
and what that leads to is narrowing of the joint

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space. The bones come closer together, and that
friction between them triggers inflammation

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inside the joint. And when the body tries to fix
this, it sometimes does way more than it should,

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and you starts forming little bony growths at the
margin of the joint. These are called osteophytes,

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or bone spurs. They’re basically the body’s
way of trying to stabilize the joint,

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but they can actually limit movement further. So
instead of this nice clean arc, the joint margin

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now becomes uneven and irregular.
This process – of wear and tear,

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cartilage breakdown, and bone spur
formation—is what we call osteoarthritis.

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So who gets this? The typical person that comes
to mind is someone elderly, right? That’s the most

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common group—adults over 60, just from natural
use of the joint over time. But it’s not just

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age. Obesity increases the load on the hip joint,
making the cartilage wear down faster. People with

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heavy physical jobs, like warehouse workers, or
people who’ve had repeated trauma to the joint,

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like athletes or construction workers—they’re also
at risk. Even someone who had a hip dislocation

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or fracture when they were younger, or
congenital problems like hip dysplasia,

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that can set them up for osteoarthritis later on.
Now what does osteoarthritis actually feel like?

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It usually starts with a slow, gradual pain in
the groin or front of the thigh. Patients often

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say it’s a deep ache. Sometimes there’s crepitus—a
clicking or grinding when they move. The hip feels

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stiff in the morning, but it tends to loosen up
in under 30 minutes. Over time, it gets harder

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to rotate the hip internally or to abduct it. And
walking gets difficult—climbing stairs, bending

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over, even putting on shoes can be a problem.
Now another issue that can affect this joint

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is something called gout. Gout is actually
a metabolic condition. What happens is that

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uric acid, which is normally dissolved in the
blood, starts to build up. And when it reaches a

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certain concentration, it forms sharp, needle-like
crystals that deposit in joints. The immune system

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sees these crystals and basically freaks out. It
sends in neutrophils and triggers this intense

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inflammatory response called synovitis—meaning
inflammation of the synovial membrane.

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That inflammation causes the joint to swell up,
turn red and warm, and become incredibly painful.

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It’s usually sudden, like it flares up at
night, and it becomes so sensitive that

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even touching the skin can hurt. Over time, if
untreated, the inflammation starts to erode the

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cartilage and damage the underlying bone.
Now who gets gout? It’s often people with

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chronic kidney disease, because their kidneys
can’t get rid of uric acid properly. It’s also

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linked to hypertension, especially if they’re on
medications like thiazide diuretics. It tends to

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hit men between 30 and 50 years old. Obesity makes
it worse, and so does a high-purine diet—think

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red meat, seafood, beer. Even low-dose aspirin
can raise uric acid levels and trigger a flare.

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In the hip, gout isn’t super common, but when it
happens, it can be brutal. Sudden pain, intense

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swelling, the joint feels hot, and movement
becomes almost impossible during the attack.

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Alright, one more condition to mention—Rheumatoid
Arthritis. RA is in a different category entirely.

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This one is autoimmune. Your own immune
system targets the synovial membrane and

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causes it to thicken and swell. This inflamed
tissue—called pannus—starts invading and

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destroying the cartilage and bone underneath.
So the joint becomes unstable, deformed,

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and gradually loses its function.
And what’s wild is that it’s often

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symmetrical—so both hips might get affected
over time. The damage can happen even when

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the joint is at rest, because it’s driven
by the immune system, not wear and tear.

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So who’s at risk? RA affects women more often than
men, especially between ages 40 and 60. There’s

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often a genetic component—HLA-DR4, HLA-DR1—so if
someone has a family history, they’re more likely

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to get it. Obesity increases the risk, and smoking
is a major trigger. Some research even links it to

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periodontal disease or certain environmental
exposures like silica dust or asbestos.

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Symptoms-wise, RA in the hip shows up as deep
groin pain or outer thigh pain. It gets worse with

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inactivity—so people often wake up feeling stiff.
The stiffness can last more than 30 minutes,

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sometimes hours. And as the inflammation eats
away at the joint, range of motion decreases,

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and walking becomes difficult. You’ll often
see weakness in the surrounding muscles,

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and in later stages, night pain becomes a big
issue—especially when lying on the affected side.

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So that’s the hip joint. From its deepest
structures, layer by layer, all the way

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to the most common problems that affect it.
Hope this all made sense and that this video

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helped. In the next part of the skeletal
series, we’re going to look at the femur.

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So if you’re ready to keep building your
anatomy knowledge from the ground up,

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click the next video, and I’ll see you there.
If you want a handmade PDF version of this

0:10:40.160,0:10:44.000
lecture, take a quiz to test your knowledge,
or access an organized list of all my videos,

0:10:44.000,0:10:47.200
you can find everything on my website.
Thanks for watching! See you in the next one.