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Hip Anatomy

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

  • Osteoarthritis of the Hip Osteoarthritis of the Hip

    Osteoarthritis, also called degenerative joint disease, is the most common form of arthritis. It occurs most often in the elderly. This disease affects the tissue covering the ends of bones in a joint called cartilage. In osteoarthritis, the cartilage becomes damaged and worn out, causing pain, swelling, stiffness and restricted movement in the affected joint.

  • Greater Trochanteric Pain Syndrome 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.

    The trochanter is a bony prominence (projection or protuberance) of the thighbone (femur) near its joint with the hip bone. It serves as a site for muscle attachment.

  • Femoroacetabular Impingement Femoroacetabular Impingement

    Femoroacetabular impingement (FAI) is a condition characterized by excessive friction in the hip joint from the presence of bony irregularities. These cause pain and decreased range of hip motion.

    The femoral head and acetabulum rub against each other, causing damage and pain to the hip joint.

  • Avascular Necrosis Avascular Necrosis

    Avascular necrosis, also called osteonecrosis, is a condition in which bone death occurs because of inadequate blood supply to it. Lack of blood flow may occur when there is a fracture in the bone or a joint dislocation that may damage nearby blood vessels. Hip joint is most commonly affected; however, the knee and shoulder may also be involved.

  • Developmental Dysplasia Developmental Dysplasia

    Developmental dysplasia of the hip (DDH) or hip dysplasia is a condition that is seen in infants and young children because of developmental problems in the hip joint. The femur (thighbone) partially or completely slips out of the hip socket leading to dislocation at the hip joint. It is most common in the first-born baby with a family history of the disorder.

  • Legg-Calve-Perthes-Disease Legg-Calve-Perthes-Disease

    Legg-Calve-Perthes disease (LCPD) or Perthes disease is a disorder of the hip that affects children, usually between the ages of 4 and 10. It usually involves one hip, although it can occur on both sides in some children. It occurs more commonly in boys than girls.

  • Periprosthetic Hip Fractures Periprosthetic Hip Fractures

    Hip replacement is a surgical procedure in which the damaged cartilage and bone are removed from the hip joint and replaced with artificial components. Any resulting fractures or breaks in the bone around the implant are called periprosthetic hip fractures. They usually occur around the stem of the implant and sometimes to the socket (acetabulum).

  • Periprosthetic Hip Infections Periprosthetic Hip Infections

    A very small percentage of patients (less than 1%) who undergo hip replacement may develop an infection around the hip joint following surgery. This infection is called a periprosthetic hip infection.

    Your immune system is usually able to protect your body from bacteria or other infectious organisms by attacking it through the lymph system or blood stream.

Hip Procedures

  • Total Hip Replacement Total Hip Replacement

    Total hip replacement is a surgical procedure in which the damaged cartilage and bone are removed from the hip joint and replaced with artificial components. The main indication for total hip replacement is arthritis.

    Arthritis is the inflammation of joints, which results in pain, swelling, stiffness and limited movement. Hip arthritis is a common cause of chronic hip pain and disability.

  • Revision Hip Replacement Revision Hip Replacement

    During total hip replacement, the damaged cartilage and bone are removed from the hip joint and replaced with artificial components. At times, hip replacement implants can wear out for various reasons and may need to be replaced with the help of a surgical procedure known as revision hip replacement surgery.

  • Anterior Hip Replacement Anterior Hip Replacement

    Direct anterior hip replacement is a minimally invasive hip surgery to replace the hip joint without cutting through any muscles or tendons as against traditional hip replacement that involves cutting major muscles to access the hip joint.

  • Minimally Invasive Total Hip Replacement Minimally Invasive Total Hip Replacement

    Minimally invasive total hip replacement is a surgical procedure performed through one or two small incisions rather than the single long incision of 10–12-inches as in the traditional approach.

    The hip joint is one of the body's largest weight-bearing joints and is the point where the thighbone (femur) and pelvis (acetabulum) join.

  • Outpatient Anterior Approach Hip Replacement Outpatient Anterior Approach Hip Replacement

    Outpatient anterior approach hip replacement refers to surgery accessed from in front of the hip in an outpatient setting. It is a minimally invasive procedure that has been developed to cause less muscle damage, faster recovery, and less disruption in a patient’s life.

  • Outpatient Hip Replacement Outpatient Hip Replacement

    Hip replacement surgery is one of the most common orthopedic surgeries performed. It involves the replacement of the damaged hip bone (ball shaped upper end of the femur) with a ceramic ball attached to a metal stem that is fixed into the femur and placing a new cup with a special liner in the pelvis.

  • Hip Hemiarthroplasty Hip Hemiarthroplasty

    Hip hemiarthroplasty is a surgical technique employed to treat hip fractures. In this procedure, only one half (ball section) of the hip joint is substituted by a metal prosthesis.

    The hip joint is one of the body's largest weight-bearing joints and is the point where the thigh bone (femur) and the pelvis (acetabulum) unite.

  • Correction of a Painful Hip Replacement Correction of a Painful Hip Replacement

    A hip replacement is a surgical procedure where an injured or damaged hip joint is replaced with an artificial hip joint known as a prosthesis.

    Reoperation of a total hip replacement to resolve a painful hip condition arising out of a damaged or worn out prosthesis (artificial hip joint) is known as correction of a painful hip replacement.

  • Correction of a Loose Hip Replacement Correction of a Loose Hip Replacement

    A hip replacement is a surgical procedure where an injured or damaged hip joint is replaced with an artificial hip joint known as a prosthesis.

    Reoperation of a total hip replacement to resolve a painful hip condition and loss of motion due to a loosened prosthesis (artificial hip joint) is known as correction of a loose hip replacement.

  • Hip Resurfacing Hip Resurfacing

    The hip joint is also known as a ball and socket joint, where the ball (femoral head) of the thigh bone fits into the socket (acetabulum) of the pelvic bone.

    Damage to the hip bones can be treated by hip resurfacing, which is a surgical procedure in which the damaged parts of the femoral head are trimmed, and the socket is removed and replaced with metal caps.

  • Robotic Total Hip Replacement Robotic Total Hip Replacement

    Total hip replacement is a surgical technique where the severely damaged cartilage and bone of the hip joint are removed and substituted with an artificial prosthesis which is bio-compatible and functions like a normal hip. It is one of the most common joint replacement procedures, subsequent to knee replacements.

  • American Academy of Orthopaedic Surgeons
  • New England Orthopedic Society
  • aahks
  • Massachusetts General Hospital
  • tufts school of medicine