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.
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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.
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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.
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Postless Hip Arthroscopy
Postless hip arthroscopy is a minimally-invasive surgical technique that does not involve the use of perineal posts. Surgery is performed by arthroscopy. An arthroscope is a small, fiber-optic instrument consisting of a lens, light source, and video camera.
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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.
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Periacetabular Osteotomy
Periacetabular osteotomy is a surgical procedure to treat a congenital hip condition called hip dysplasia. Hip dysplasia is either present from birth or develops in the first few months of life. Patients suffering from this condition have a shallow socket (acetabulum) of the hip joint.
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Femoral Derotational Osteotomy
Femoral derotational osteotomy (FDO) is a surgical procedure employed for the treatment of femoral torsion and a damaged/dislocated hip joint due to spasticity in children and adults.
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Hip Microfracture
Hip Microfracture is a marrow-stimulating technique that creates a network of small holes in the bone below the hip cartilage (subchondral bone). The goal of the procedure is to increase the blood supply to stimulate cartilage growth.
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Proximal Hamstring Repair
Proximal hamstring injuries can usually be treated with non-surgical options such as the RICE protocol, immobilization, and physical therapy.
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Open Gluteus Medius Repair
Open gluteus medius repair is a surgical procedure employed for the treatment of gluteus medius tears.
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Hip Labral Tear
A hip labral tear is an injury to the labrum, the cartilage that surrounds the outside rim of your hip joint socket.
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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.
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Hip Instability
Injury or damage to these structures can lead to a condition called hip instability when the joint becomes unstable.
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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.
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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.
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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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Iliopsoas Tendonitis
Iliopsoas tendonitis also referred to as snapping hip syndrome, is an inflammation of the iliopsoas tendon or the surrounding area. The iliopsoas is the hip flexor tendon located over the front of the hip socket.
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Hip Osteonecrosis
Hip osteonecrosis occurs due to disruption of the blood supply to the highest part of the thigh bone (femoral head). Due to lack of nourishment, the bone tissue of the femoral head dies and gradually collapses, which may further lead to degeneration of the underlying cartilage.
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Athletic Pubalgia
Athletic pubalgia, also known as sports-hernia and Gilmore’s groin, is a condition characterized by chronic pain due to damage or strain to the soft tissues in the groin and pelvic region.
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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.
