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Hip Anatomy

Hip Joint

The hip joint is the largest weight-bearing joint in the human body. It is also referred to as a ball and socket joint and is surrounded by muscles, ligaments, and tendons. The thigh bone or femur and the pelvis join to form the hip joint.

Any injury or disease of the hip will adversely affect the joint's range of motion and ability to bear weight.

The hip joint is made up of the following:

  • Bones and joints
  • Ligaments of the joint capsule
  • Muscles and tendons
  • Nerves and blood vessels that supply the bones and muscles of the hip

Bones and Joints

The hip joint is the junction where the hip joins the leg to the trunk of the body. It is comprised of two bones: the thigh bone or femur and the pelvis which is made up of three bones called ilium, ischium, and pubis. The ball of the hip joint is made by the femoral head while the socket is formed by the acetabulum. The Acetabulum is a deep, circular socket formed on the outer edge of the pelvis by the union of three bones: ilium, ischium, and pubis. The lower part of the ilium is attached by the pubis while the ischium is considerably behind the pubis. The stability of the hip is provided by the joint capsule or acetabulum and the muscles and ligaments which surround and support the hip joint.

The head of the femur rotates and glides within the acetabulum. A fibrocartilagenous lining called the labrum is attached to the acetabulum and further increases the depth of the socket.

The femur or thigh bone is one of the longest bones in the human body. The upper part of the thigh bone consists of the femoral head, femoral neck, and greater and lesser trochanters. The head of the femur joins the pelvis (acetabulum) to form the hip joint. Next, to the femoral neck, there are two protrusions known as greater and lesser trochanters which serve as sites of muscle attachment.

Articular cartilage is the thin, tough, flexible, and slippery surface lubricated by synovial fluid that covers the weight-bearing bones of the body. It enables smooth movements of the bones and reduces friction.

Ligaments

Ligaments are fibrous structures that connect bones to other bones. The hip joint is encircled with ligaments to provide stability to the hip by forming a dense and fibrous structure around the joint capsule. The ligaments adjoining the hip joint include:

  • Iliofemoral ligament:This is a Y-shaped ligament that connects the pelvis to the femoral head at the front of the joint. It helps in limiting the over-extension of the hip.
  • Pubofemoral ligament:This is a triangular shaped ligament that extends between the upper portion of the pubis and the iliofemoral ligament. It attaches the pubis to the femoral head.
  • Ischiofemoral ligament: This is a group of strong fibers that arise from the ischium behind the acetabulum and merge with the fibers of the joint capsule.
  • Ligamentum teres:This is a small ligament that extends from the tip of the femoral head to the acetabulum. Although it has no role in hip movement, it does have a small artery within that supplies blood to a part of the femoral head.
  • Acetabular labrum:The labrum is a fibrous cartilage ring which lines the acetabular socket. It deepens the cavity, increasing the stability and strength of the hip joint.

Muscles and Tendons

A long tendon called the iliotibial band runs along the femur from the hip to the knee and serves as an attachment site for several hip muscles including the following:

  • Gluteals:These are the muscles that form the buttocks. There are three muscles (gluteus minimus, gluteus maximus, and gluteus medius) that attach to the back of the pelvis and insert into the greater trochanter of the femur.
  • Adductors:These muscles are located in the thigh which helps in adduction, the action of pulling the leg back towards the midline.
  • Iliopsoas: This muscle is located in front of the hip joint and provides flexion. It is a deep muscle that originates from the lower back and pelvis and extends up to the inside surface of the upper part of the femur.
  • Rectus femoris:This is the largest band of muscles located in front of the thigh. They also are hip flexors.
  • Hamstring muscles: These begin at the bottom of the pelvis and run down the back of the thigh. Because they cross the back of the hip joint, they help in extension of the hip by pulling it backward.

Nerves and Arteries

Nerves of the hip transfer signals from the brain to the muscles to aid in hip movement. They also carry the sensory signals such as touch, pain, and temperature back to the brain.

  • The main nerves in the hip region include the femoral nerve in the front of the femur and the sciatic nerve at the back. The hip is also supplied by a smaller nerve known as the obturator nerve.
  • In addition to these nerves, there are blood vessels that supply blood to the lower limbs. The femoral artery, one of the largest arteries in the body, arises deep in the pelvis and can be felt in front of the upper thigh.

Hip Movements

All of the anatomical parts of the hip work together to enable various hip movements. Hip movements include flexion, extension, abduction, adduction, circumduction, and hip rotation.

Hip Conditions

  • Hip Pain logo Hip Pain

    Hip pain, one of the common complaints, may not always be felt precisely over the hip joint rather in and around the hip joint. The cause for pain is multifactorial and the exact position of your hip pain suggests the probable cause or underlying condition causing it.

  • Femoroacetabular Impingement (FAI) logo Femoroacetabular Impingement (FAI)

    Femoro acetabular impingement (FAI) is a condition where there is too much friction in the hip joint from bony irregularities causing pain and decreased range of hip motion. The femoral head and acetabulum rub against each other creating damage and pain to the hip joint.

  • Hip Bursitis logo Hip Bursitis

    Hip bursitis is a painful condition caused by the inflammation of a bursa in the hip. Bursae are fluid-filled sacs present in the joints between bone and soft tissue to reduce friction and provide cushioning during movement.

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  • Hip Labral Tear logo Hip Labral Tear

    The hip joint is a ball and socket joint in which the head of the femur is the ball and the acetabulum forms the socket. The labrum helps to deepen the socket and provide stability to the joint. It also acts as a cushion and enables smooth movement of the joint.

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  • Gluteus Medius Tear logo Gluteus Medius Tear

    A gluteus medius tear is the partial or complete rupture of the gluteus medius muscle due to severe muscle strain. Gluteus medius tears often occur at the tendinous attachment to the greater trochanter of the femur bone.

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  • Hip Synovitis logo Hip Synovitis

    Hip synovitis, also called transient hip synovitis or toxic synovitis, is a condition characterized by inflammation of the synovial tissues that surround the hip joint. It is the most common cause for sudden hip pain that occurs in young children between the age of 2 and 9. It affects boys more commonly than girls and is most of the time limited to only one side of the hip.

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  • Hip Abductor Tears logo Hip Abductor Tears

    Hip abductors are a major group of muscles found in the buttocks. It includes the gluteus maximus, gluteus medius, gluteus minimus, and tensor fascia lata muscles.

  • Gluteus Tendon Tear logo Gluteus Tendon Tear

    The gluteal muscles (situated in the buttocks) are necessary for the stability and movement of the hip joints. The tendons of two gluteal muscles (gluteus medius and gluteal minimus) are attached at the outer hip region and are often called the “rotator cuff of the hip.” These tendons may be subject to injury or tearing due to various reasons.

  • Snapping Hip Syndrome logo Snapping Hip Syndrome

    Snapping hip syndrome is a condition in which you hear or feel a snapping sound in the hip when you swing your legs, run, walk or get up from a chair. The sound can be experienced in the back, front or side of the hip.

  • Greater Trochanteric Pain Syndrome logo Greater Trochanteric Pain Syndrome

    GTPS, also called trochanteric bursitis, is a localized painful condition affecting your outer thigh and hip area where the pain is typically confined to only the outer side of the femur at the edge of the hip.

  • Hip Flexor Strain logo Hip Flexor Strain

    A hip flexor strain is an overuse injury to the flexor muscles of your hip and can range from a minor stretch injury to a complete tear of the muscle fibers or tendons.

  • Piriformis Syndrome logo Piriformis Syndrome

    The sciatic nerve is a thick and long nerve that passes below or through the piriformis muscle and goes down the back of the leg and finally ends in the feet in the form of smaller nerves. Piriformis syndrome is a rare neuromuscular condition caused by the compression of the sciatic nerve by the piriformis muscle.

  • Groin Injuries in Athletes logo Groin Injuries in Athletes

    The sciatic nerve is a thick and long nerve that passes below or through the piriformis muscle and goes down the back of the leg and finally ends in the feet in the form of smaller nerves. Groin Injuries in Athletes is a rare neuromuscular condition caused by the compression of the sciatic nerve by the piriformis muscle.

Hip Procedures

  • Hip Arthroscopy Logo Hip Arthroscopy

    Hip arthroscopy, also referred to as keyhole or minimally invasive surgery, is a procedure in which an arthroscope is inserted into your hip joint to check for any damage and repair it simultaneously.

  • Hip Labral Repair Logo Hip Labral Repair

    Labrum is a ring of strong fibrocartilaginous tissue lining around the socket of the hip joint. Labrum serves many functions where it acts as a shock absorber, lubricates the joint, and distributes the pressure equally. It holds the head of the femur in place and prevents the lateral and vertical movement of the femur head within the joint. It also deepens the acetabular cavity and offers stability against femoral head translation.

  • Femoroacetabular Osteoplasty Logo Femoroacetabular Osteoplasty

    Femoroacetabular osteoplasty is the surgical reshaping of the protruding bony surface of the femur or acetabulum of the hip joint. FAO is performed arthroscopically as a minimally invasive procedure. An arthroscope is a small, fiber-optic instrument consisting of a lens, light source, and video camera.

  • Physical Therapy for Hip Logo Physical Therapy for Hip

    Physical therapy is an exercise program that helps you to improve movement, relieve pain, encourage blood flow for faster healing, and restore your physical function and fitness level. The main aim of physical therapy is to make your daily activities, such as walking, getting in and out of bed and climbing stairs, easier.

  • Cartilage Repair Logo Cartilage Repair

    Hip cartilage is a white, tough, flexible tissue covering the ball (femoral head) and socket (acetabulum) of your hip joint. It acts as a cushion or shock-absorber and allows the bones to slide over one another by providing a smooth surface in the joint.