Hip
What is the Anatomy of the 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 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.
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. Although osteoarthritis may affect various joints including the hips, knees, hands, and spine, the hip joint is most commonly affected. Rarely, the disease may affect the shoulders, wrists, and feet.
A hip fracture is a break that occurs near the hip in the upper part of the femur or thighbone. The thighbone has two bony processes on the upper part - the greater and lesser trochanters. The lesser trochanter projects from the base of the femoral neck on the back of the thighbone. Hip fractures can occur either due to a break in the femoral neck, in the area between the greater and lesser trochanter or below the lesser trochanter.
A pelvic fracture is a condition that occurs due to the breakage of the pelvic bone. It may cause damage to the internal organs, nerves and blood vessels associated with the pelvic region. The pelvic bone is a circular arrangement of bones connected with the help of strong ligaments to the lowermost region of the spine called the sacrum.
A hip labral tear is an injury to the labrum, the cartilage that surrounds the outside rim of your hip joint socket.
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.
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.
Hip arthroscopy, also referred to as keyhole or minimally invasive surgery, is a surgical procedure in which an arthroscope is inserted into your hip joint to check for any damage and repair it simultaneously.
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.
Hip surgery is a surgical procedure for the treatment of a hip injury or hip condition. The procedure involves repairing diseased or damaged structures of the hip joint in order to eliminate pain and restore normal hip function.
Hip resurfacing is an alternative to total hip replacement surgery where both the ball and socket of the hip joint are completely removed and replaced with plastic, metal, or ceramic prosthetics.
Hip labral repair is a surgical procedure to treat hip labral tears. A hip labral tear is a partial or complete rupture of the hip labrum, a ring of fibrous cartilaginous tissue that surrounds the socket of the hip joint. These tears are most commonly seen in athletes involved in high-impact sports such as ice hockey, soccer, and football and can also occur due to traumatic injury or degenerative conditions.
The hip joint is one of the most important and flexible joints in the human body which allows us to walk, run, bend and perform physical activities. It is a ball (femoral head) and socket joint formed between the hip bone and femur (thigh bone). The hip joint is surrounded by strong muscles and tough ligaments that prevent dislocation of the hip.
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.
Surgical correction of a hip fracture is known as hip fracture surgery. Hip fractures involve a break that occurs near the hip in the upper part of the femur or thigh bone. The thigh bone has two bony processes on the upper part - the greater and lesser trochanters. The lesser trochanter projects from the base of the femoral neck on the back of the thigh bone.
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.
Revision hip replacement is a complex surgical procedure in which all or part of a previously implanted hip joint is replaced with a new artificial hip joint. Total hip replacement surgery is an option to relieve severe arthritis pain that limits your daily activities.
