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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.

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.

Hip Labral Tear

Hip Labral Tear

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.

Hip Abductor Tears

Hip Abductor Tears

The tear or rupture of the hip abductor is commonly seen in runners and athletes involved in high-impact sports such as soccer or basketball. It can occur due to sudden bursts of activity or poor flexibility of the abductor muscle. Any traumatic or overuse injury or degenerative changes may also lead to a partial or complete tear of the gluteus muscle.

Hip Bursitis

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.

Hamstring Injuries

Hamstring Injuries

The hamstring is a group of three muscles that run along the back of the thigh from the hip to the knee. Hamstring injuries occur when these muscles are strained or pulled. They are common in dancers and athletes of all sorts including runners and those who play football, soccer, basketball, tennis, etc.

Hip Instability

Hip Instability

Hip instability can be traumatic or atraumatic. Traumatic instability can be caused by injuries from sports or motor vehicle accidents. These injuries can damage the bony structures, labrum, and cartilage of the hip joint and form loose bodies. It can range from severe dislocation to a simple subluxation (partial displacement) of the hip joint.

Hip Pointers

Hip Pointers

The hip joint consists of the femur (thighbone) and pelvic bone, which is made up of the fusion of three bones – the ischium, pubis, and ilium. The femur has two boney prominences close to the hip joint – the greater and lesser trochanters.

Hip Tendonitis

Hip Tendonitis

Tendons are strong connective tissue structures that connect muscle to bone. Hip tendonitis is a condition associated with degeneration of the hip tendons. This condition is mainly caused due to strain on the tendons which may occur due to overuse or biomechanical problems.

Piriformis Syndrome

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.

Hip Fracture

Hip Fracture

The hip joint is a “ball and socket” joint. The “ball” is the head of the femur or thighbone, and the “socket” is the cup-shaped acetabulum. The joint surface is covered by a smooth articular surface that allows pain-free movement in the joint.

Groin Injuries in Athletes

Groin Injuries in Athletes

Groin injuries are injuries sustained by athletes during sports activity. Groin injuries comprise about 2 to 5 percent of all sports injuries. The most common kind of groin injury is a groin strain or a pulled groin muscle. Typical groin injuries vary based on athlete’s gender, age, and sports, with most common groin injuries occurring in certain sports such as football with a prevalence rate as high as 12-16%.

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.

Snapping Hip Syndrome

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.

Gluteus Medius Tear

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.

Hip Arthroscopy

Hip Arthroscopy

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

Hip Labral Repair

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.

Arthroscopic Gluteus Medius Tendon Repair

Arthroscopic Gluteus Medius Tendon Repair

Arthroscopic gluteus medius tendon repair is a minimally invasive surgical procedure employed for the treatment of a gluteus medius tendon tear, when the tear does not respond to conservative treatment.

Hip Preservation Surgery

Hip Preservation Surgery

The hip is a ball and socket joint comprising of the femur (thigh bone) and the pelvic bone. The head of the femur (ball) articulates with a cavity (socket) called the acetabulum in the pelvic bone. To facilitate the smooth and frictionless movement of the hip joint, the articulating surfaces of the femur head and acetabulum are covered by spongy articular cartilage.