Hip Anatomy, Function and Common Problems

The hip joint is a ball-and-socket type joint and is formed where the thigh bone (femur) meets the three bones that make up the pelvis: the ilium at the rear, the ischium at the lower front and the pubis above it. The thighbone has a ball-shaped knob on the end that fits into a socket formed in the hipbone.

A smooth cushion of shiny white articular cartilage about 1/4 inch thick covers the femoral head and the acetabulum. The articular cartilage is kept slippery by fluid made in the synovial membrane (joint lining). Since the cartilage is smooth and slippery, the bones move against each other easily and without pain. Large ligaments, tendons, and muscles around the hip joint (called the joint capsule) hold the bones (ball and socket) in place and keep it from dislocating.

Hip Anatomy, Function and Common Problems

Hip bones from the front

Front View of the Hip Joint Bones

The weight-bearing bones in our body are usually protected with articular cartilage, which is a thin, tough, flexible, slippery surface which is lubricated by synovial fluid. The synovial fluid is both viscous and sticky lubricant. Synovial fluid and articular cartilage are a very slippery combination—3 times more slippery than skating on ice, 4 to 10 times more slippery than a metal on plastic hip replacement, and more than 30 times as slippery as metal on metal using the best petroleum-based lubricant. Synovial fluid is what allows us to flex our joints under great pressure without wear.

The hip joint is one of the largest joints in the body and is a major weight-bearing joint. Weight bearing stresses on the hip during walking can be 5 times a person’s body weight. A healthy hip can support your weight and allow you to move without pain. Changes in the hip from disease or injury will significantly affect your gait and place abnormal stress on joints above and below the hip.

It takes great force to seriously damage the hip because of the strong, large muscles of the thighs that support and move the hip. Osteoarthritis affects many people, and the brittle bones from osteoporosis in the elderly can lead to life threatening fractures.

Anatomic Terms

Anatomical terms allow us to describe the body clearly and precisely using planes, areas and lines. Instead of your doctor saying “his knee hurts” she can say “his knee hurts in the anterolateral region” and another doctor will know exactly what is meant. Below are some anatomic terms surgeons use as these terms apply to the hip:

  • Anterior — the abdominal side (front) of the hip
  • Posterior — the back side of the hip
  • Medial — the side of the hip closest to the spine
  • Lateral — the side of the hip farthest from the spine
  • Abduction — move away from the body (raising the leg)
  • Adduction — move toward the body (lowering the leg)
  • Proximal — located nearest to the point of attachment or reference, or center of the body
  • Distal — located farthest from the point of attachment or reference, or center of the body
  • Inferior — located beneath, under or below; under surface

Anatomy of the Hip

Joint capsule of the hip

Joint capsule of the hip

Like the shoulder, the hip is a ball-and-socket joint, but is much more stable. The stability in the hip begins with a deep socket—the acetabulum. Additional stability is provided by the strong joint capsule and its surrounding muscles and ligaments. It’s the need for such a high degree of stabilization of the joint that limits movement. If you think of the hip joint in layers, the deepest layer is bone, then ligaments of the joint capsule and the tendons and muscles are on top. Nerves and vessels supply the muscles and bones of the hip.

The hip joint capsule is a dense, fibrous structure which includes the iliofemoral, pubofemoral, and ischiofemoral ligaments. These ligaments along with the ligamentum teres and the labrum help give stability of the hip.

Bony Structures of the Hip

The adult skeleton is mainly made of bone and a little cartilage in places. Bone and cartilage are both connective tissues, with specialized cells called chondrocytes embedded in a gel-like matrix of collagen and elastin fibers. Cartilage can be hyaline, fibrocartilage and elastic and differ based on the proportions of collagen and elastin. Cartilage is a stiff but flexible tissue that is good with weight bearing which is why it is found in our joints. Cartilage has almost no blood vessels and is very bad at repairing itself. Bone is full of blood vessels and is very good at self repair. It is the high water content that makes cartilage flexible.

The hip is formed where the thigh bone (femur) meets the three bones that make up the pelvis: the ilium, the pubis (pubic bone) and the ischium. You can feel the arching bones of the ilium by placing your hands on your waist. The pubis attaches to the lower part of the ilium and curves forward. The ischium is slightly behind the pubis. The three bones converge to form the acetabulum, a deep socket on the outer edge of the pelvis.

Acetabulum in the pelvisThe shape of the acetabulum is a half of a sphere; the femoral head is about two-thirds of a sphere. Without weight bearing, the ball-and-socket are not completely congruent. As the joint bears more weight, the contact of the surface areas increases as does joint stability. The articular cartilage is thicker on the back part of the socket where most of the force is placed on the joint with walking, running and jumping. When standing, the body’s center of gravity passes through the center of the acetabula. Obviously, injury to the acetabulum can affect its ability to distribute weight bearing.

Bones of the Hip Joint

Bones of the Hip Joint

The hip joins the leg to the trunk of the body at the hip joint. The hip joint is made up of the ball of the femoral head that fits into the cup-shaped acetabulum. The large round head of the femur rotates and glides within the acetabulum. The depth of the acetabulum is further increased by a fibrocartilagenous labrum attached to the acetabulum. The socket of the hip is much deeper than the socket in the shoulder and encompasses a greater area of the ball.

The femur is the longest bone in the body. The neck of the femur connects the femoral head with the shaft of the femur. The capsular ligament of the hip joint attaches to the posterior part of the femoral neck. The neck ends at the greater and lesser trochanter prominences. The greater trochanter serves as the site of attachment for the abductor muscles. The lesser trochanter is the site of the iliopsosas tendon.

The greater trochanter is a very prominent bump on the femur and easy to feel on the outside of your thigh. It is the widest part of the lower legs and is where the tendons of several muscles attach including the gluteus, obturator, gemelli and piriformis muscles. The lesser trochanter serves as the attachment for the iliopsoas and iliacus muscle tendons.

Hip Ligaments

The liofemoral ligament in the hip

The liofemoral ligament in the hip

The stability of the hip is increased by the strong ligaments that encircle the hip (the iliofemoral, pubofemoral, and ischiofemoral ligaments). These ligaments completely encompass the hip joint and form the joint capsule. The iliofemoral ligament is the strongest ligament in the body. Damage to the ligamentum teres can result in avascular necrosis because of injury to the small artery within the ligament that supplies most of the blood to the head of the femur. Death of the bone in the femoral head is one cause for hip replacement.





The ischiofemoral ligament of the hip

The ischiofemoral ligament of the hip

Muscles of the Hip

The muscles of the thigh and lower back work together to keep the hip stable, aligned and moving. It is the muscles of the hip that allow the 4 basic movements of the hip:

  • flexion – bend
  • extension – straighten
  • abduction – take the leg away from the body
  • adduction – bring the leg back toward the body

The hip muscles are divided up into three basic groups based on their location: anterior muscles (front), posterior (back), and medial (outside). The muscles of the anterior thigh make up the quadriceps group (vastus medialis, intermedius, lateralis and rectus femoris muscles). The quads make up about 70% of the thigh’s muscle mass. The purpose of the quads is flexion (bending) of the hip and extension (straightening) of the knee.

The gluteal, hamstring and piriformis muscles are located in the buttocks. The gluteus maximum is the main hip extensor and helps keep up the normal tone of the iliotibial band. The gluteus maximus also keeps the head of the femur from sliding forward in the hip socket; if it can’t do this, pain results form the femoral head pressing against the soft tissues in the front of the hip joint. The gluteal and sartorius muscles also help abduct the hip—that is, move the leg away from the midline of the body (using the spine as a midline reference point). It is abduction that allows us to walk sideways. When the glutes are weak, it is the hamstrings that pick up the slack. Hamstrings can be constantly strained injuries can take awhile to heal when the glutes (gluteus maximus and gluteus medius) are weak.

Adduction—bringing the leg back towards the midline—is performed by the hip adductor muscle group (gracilis muscle, pectineus muscle).

The hip also has the ability to rotate internally (medially)—turning the foot in (pigeon-toed) and externally (laterally)—turning the foot out. Medial rotation is needed for squatting. The piriformis muscle assist in lateral rotation of the hip. Lateral rotation is needed for crossing the legs.

The hip muscles do not attach right at the hip joint, thereby giving the hip more stability. The gluteus medius muscle connects to the greater trochanter, a bony prominence on the neck of the femur. The gluteus medius helps keep the pelvis level when you walk.

The facia lata, which is not a muscle but the deep fascia of the thigh, is known as the iliotibial band. The function of this band is to prevent dislocation of the hip. If this band is too tight, it can cause hip and knee problems.

Blood Vessels and Nerves of the Hip

Sciatic nerve

The sciatic nerve is located where it could get injured from a backwards dislocation of the femoral head.

The nerves in the hip supply the various muscles in the hip. These nerves include the femoral nerve, lateral femoral cutaneous nerve, and obturator nerve . The obturator nerve is also responsible for sensation over the thigh. The sciatic nerve is the most commonly recognized nerve in the hip and thigh. The sciatic nerve is large—as big around as your thumb—and travels beneath the gluteus maximus down the back of the leg and then branches on down to the foot. Hip dislocation can cause injury to the sciatic nerve. Nerves carry signals from the brainto the muscles to move the hip and carries signals from the muscles back to the brain about pain, pressure and temperature.

The blood supply to the hip is primarily from the internal and external iliac, femoral, obturator, and superior and inferior gluteal arteries. The femoral artery is well-known because of its use in cardiac cath; it travels from deep within the hip down the leg to the knee. The main blood supply for the femoral head comes from vessels that branch off the femoral artery.


Bursae are fluid filled sacs lined with a synovial membrane which produce synovial fluid. The synovial fluid is similar in consistency to raw egg white. Bursae are often found near joints. Their function is to lessen the friction between tendon and bone, ligament and bone, tendons and ligaments and between muscles. There are as many as 20 bursae around the hip. Inflammation or infection of the bursa called bursitis.

The greater trochanteric bursa is located between the greater trochanter (the bony prominence on the femur) and the muscles and tendons that cross over the greater trochanter. This bursa can get irritated if the iliotibial band is too tight. Two other bursa that can get inflamed are the iliopsoas bursa, located under the iliopsoas muscle and the bursa located over the ischial tuberosity (the bone you sit on).

Common Problems of the Hip

Simple dislocation from upward pressure

Simple dislocation from upward pressure


Surgery of the Hip

The hip joint is largely responsible for mobility. So any injury, trauma, or disease that affects its function can significantly reduce a person’s independence. If you suspect that you might be having troubles with your hips, don’t hesitate to visit a trusted doctor to find out what you can do to mitigate and resolve the symptoms you might be experiencing. Note that the information in this article is purely informative and should never be used in place of the advice of professionals.



  1. Laurel Fry says:

    I had a double knee replace meant on Nov. 5th. 2017. The therapist told me I am going to have trouble with my right hip and she was right.She asked me if any one was putting a roll under my hip I told her not my left one only the right. NOW, My Left hip has hurt so much, I can not describe it. The pain is awful. And I don’t know how she knew or why she told me that but she did. As many times as I go back to my Doctor he keeps telling me he can’t see anything wrong. But I know there is something wrong . I go to walk and it’s like I am going to fall down . I have to grab something. Other times it feels like it just snapped. Can you please suggest what I need to do.

  2. Hammad Aziz says:


  3. OLIVER D. T. says:

    can fracture to the acetabelum cause paralysis…is it necessary to have surgery or it can heal by itself?

  4. I am called Jake I am 15 and have a disease called perthese which is basically the ball joint that fits into the hip has eroded and their is no longer a ball anymore. I was told that I would need hip replacement around the age of 14 but haven’t had one yet. I believe that I would not need one anymore as I have had no problems or pains only in the winter.

  5. Cindy Schmidler says:

    The best advice we can give is for you to consult with your primary care doctor. They will help you to decide the best option for you. Best wishes!

  6. millie delost says:

    I am 86 yrs. old and told I have nodules in both lungs and copd. I feel good , no pain and no breathing problems and feel good except a bad hip. Is it safe to have hip surgery?

  7. Hello,you can call me Linda,I am sixty six years old and I just under went a complete hip replacement on my right hip.I am only four feet ten inches tall,I am small but I have gang wait the last free years since becoming a diabetic witch i am insulin dependent.when I a woke from my surgery i had a bad pain i my groan,it has been three months an I still have it,my doctor told me that I have extra small bones and that they don’t make extra small joints so he put a small hip replacement in but it was to big so he had to stretch the socket,I am having a hard time,I for see my doctor for another three months,my lower back is still hurting an so is my groan,what should I do

  8. Connie Elam says:

    I am 88 years old and have a good quality of life. I have had good doctors and surgeons to help me. I have a by-pass, pacemaker, artificial aortic valve and have type 2 diabetes, a fib, and sometimes anemia. All the above comes with prescriptions to the help for all my implants and etc. A new problem has come up and so far no one can locate the problem. It is a pain I wake with in the morning but goes away after about an hour of activity. I do not take any pain killers! The pain I have is in the left hip area and it is really bad. Can anyone help me identify where it is coming from and how to treat it. Some times pressure on my lower back helps relieve pain. Thanks Connie E

  9. Linda Haywood says:

    I have pain in my lower left pelvis and went to a specialist after a C.T.Scan. she said it is a tumor growing in my left posterior pelvis area and it is effecting my leg muscles as well as my hip, pelvis and groin. I can hardly walk and she wants me to try Radiation to shrink thr tumor. Is lazer an option?

  10. Richard Diaz says:

    February of 1999, I had a left hip replacement and all went well then on August of 2012, I had a left hip revision which my surgeon replaced the socket lining and the titanium ball. Since then I keep getting hip pains from time-to-time which really hurts. I consulted my surgeon in October 2013 and told him and he said, “I may have hip bursitis or tendonitis.” He told me to lean against a wall at an angle to stretch the left tendon which I have done many times and it seems to work but, not all the time and when the pain returns, it is brutal. Do I have any other options?

  11. LYNN MAYO says:

    On a recent MRI an ovoid region of enhancement measuring 1.5×0.7×0.9 cm was viewed posterior to the right femoral head immediately adjacent to the ischiofemoral ligament and at the level of the superior and inferior gemelli muscles. I have recently survived a 5cm malignant tumor in the rectum which is no longer visualized or found at the cellular level. Could this region be a hemangioma and/or osseous metastasis? I was diagnosed with an external skin hemangioma as a child which rectified itself by the age of 5.

  12. I went to Cozumel , Mexico on a cruise earlier this month. (November) And while I was walking around the shops in the port, my hip popped out and I nearly hit the ground, twice. And the pain was very bad. My left leg became very stiff, and I could hardly move my leg at all. However, as soon as I was able to sit down, it kind of reset my hip for a short time, but it continues to pop out. Anyone know why all of a sudden it is doing this? I am 52 years old, I used to go to the chiropractor several times a year, and he would adjust it a few times a year. But I havent gone to one in a few years now. Any help would be apprciated… Bill T.

  13. Chris Crossland says:

    i am a 53 year old male. I walk a plant floor repairing machinery, occasionally more than a mile a day. moving my legs forward to take a step causes extreme pain in my hip, both sides, causing me to stumble and ultimately can not move at all for a minute or so. It takes days to heal from this. What causes this ? , and what can I do to fix. Thank you, Chris

  14. In 1999, at the age of 57 yrs., I had a date-skiing accident. While turning from R to L, my slalom ski flipped out, a tearing and excruciating pain as I tore my L pelvic area. I’ve no idea how they got me out of the water. My husband drove us home n I went to the ER. Only an x-ray was taken – no MRI. I was told I had a L pelvic avulsion fracture n was sent home on crutches n told “it’ll heal”. Incredibly painful. Years went by as I complained of “butt pain” when I sat anywhere. It even took me several years with episodes of unrelenting hip pain to the extent that I realized that it was due to that accident. Doctors kept saying it was my back and I kept saying it was my hips. Finally I persuaded a doctor to order an MRI. You got it – both hamstrings n gluteal (minimus n medius)ligaments were avulsed completely. No doctor has wanted to take ownership of this serious problem. I am now 73 y.o. n recently (July 07, ’15) had a hip replacement with the intent to alleviate the persistent, debilitating pain. What I really needed was repair of my ligaments – and I still do. BUT my hip replacement is infected n AGAIN no doctor wants to take ownership. One surgeon, mid 2014, said I was not a candidate for surgery d/t my shoulders (2 replacements on L shoulder d/t 1st leaving me with a useless L shoulder n R shoulder with biceps tear n possibly another rotator cuff tear) as I’d have to be on crutches. I’m now on IV antibiotics but know I need to repair at least my R ligaments. However, n I do not really know why, I am weak (low hemoglobin) n do not feel strong enough to have surgery. On March 16, ’16, I have an appt. with an orthopedic surgeon @ USC n can only hope he will take on my case. Rather than crutches, I now have a scooter n could non-weight-bearing for the 6 weeks it would take to heal the repaired ligaments. With so many years of not being heard, it is mind boggling that, as a registered nurse, as in I was in the medical field, that no-one heard me. I have no idea as to what decision to make. My R side is much worse than my L.

  15. I’ m having pain on my right side in my lower back and what appears to be in the ligaments and/ or muscles and into my right hip. What would cause such a pain. It has flared up before in the past. Generally with heat and rest the signs ant pain subsides over several days.

  16. Tracy Hennigar says:

    31 years ago I was involved in a car accident where I was positioned at the time of impact was between front bucket seats in a 1970 style Ford Maverick, which was totaled in the accident. No seat belts on, of course, and we were turning a left corner at an intersection when a vehicle attempted to pass us in that intersection. The impact was initially against the drivers door, then our car spun, hit a pole, spinning yet, hit a power pole thirdly, came to rest on four wheels, right side up. I was unconscious for a few moments, came to I was still right there, only wedged tightly in between seats. Hospital reports verified a torn left quad. non weight bearing for about a week, then crutches for a month and physical therapy, all seemed okay (18 years old). NOW, I have returning pain to that quad, constant, and what appears to be greater trochanter pain, BAD, when sitting, or laying on either side, right or left, my left femur bone does poke out slightly more where it meets the hip than right when palpated and left leg longer than my right. Could it be possible we misdiagnosed a femur fracture all those years ago? Their traveling speed was estimated at 55mph, ours, 10 mph, we were turning corner, they didn’t brake prior to or upon impact, in fact kept going down the road, then thought better and came back. I am now and have been an EMT for 25 years, so I understand MOI, mechanism of injury and the pain is unbearable at times, I just don’t know if this can crack eventually and cause me to go down completely.

  17. Richard Lenchus says:

    out of 38 “MIND GIANT” doctors who have now become business salesmen and women and no longer care for patients in their 15 minute round to feed hospitals and pharmaceutical companies I am pressed to believe that any actually went to medical school where “Do no harm” was part of their oath.
    How is it with all our modern equipment Doctors and their “Trained” staff cannot identify a NERVE pain even with contrast and give relief?
    How is it a pharmaceutical company can charge a senior who is needy of a drug $13.50 for a pill one day and $750.00 for the SAME PILL the next day? Check out the senator from Mass, who is fighting this. IS IT ALL ABOUT GREED AND NOT HUMAN PAIN AND SUFFERING? Is life so worthless?
    Will I get an answer to this from anyone?

  18. Richard Lenchus says:

    I am disappointed that we can land a robot on Mars and yet not find a nerve damage that is in the upper thigh to relieve the pain that is causing the leg to atrophy.

  19. Hello, I am 63. More than 20 years ago I shattered my calcaneous bone in my right foot due to falling vertically off a ladder. of course, the foot is a problem but I manage it. i also stupidly, lifted a heavy pot plant about 8 yrs ago and heard a loud crack.
    Now I find my right hip bone is giving me twinges when i turn too suddenly. The exact location is the right back top of the hip just below the waistline. Any movement where the hips are see-saw e.g. dancing, is impossible now. Sitting with one leg at an angle i.e. half cross legged results in limping until everything gets back into alignment. Question is; can this be managed by strengthening the muscles there or should i go for X rays? What supplements should i be taking – calcium etc?

  20. I am experiencing the pain on hip, gluteal area down to leg (outside) and even foot. Which exercise should I do?
    Thank you

  21. Enid Pennel says:

    I am 86, and physically and mentally fit! about two weeks ago, I experienced dicomfort and short, sharp pain in right groin….painful, when adduct right leg. When I get up from sitting position, I experience this dicomfort in the right groin. When I lift my rt. leg above knee heigjht, this dicomfort is experienced. I also experiene cramps in my leggs at night
    Thank you

  22. judith panzino says:

    about 15 yrs ago I broke my femur and now and the especially today ,I would be walking and thought my hip was going to pop out,would lose my balance, does it have anything to do my surgery from long time ago.

  23. Media Partners says:

    Thank you and glad you found our site helpful.

  24. This website really has all of the info I needed about this
    subject and didn’t know who to ask.

  25. Thanks for your helpful post. Here I learned How The stability of the hip is increased by the strong ligaments that encircle the hip (the iliofemoral?

  26. is hip balls are well jointed to ishile ?

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