What Is the Hip Joint?

A hip joint is composed of a femoral head and an acetabulum, and is a ball and socket joint, which is a typical acetabular joint.

A hip joint is composed of a femoral head and an acetabulum, and is a ball and socket joint, which is a typical acetabular joint.

Chinese name

Human Tissues and Organs

Foreign name

hip joint

Constitute

Femoral head acetabulum

Types of

Pestle joint

Anatomy of the hip joint

The femoral articular surface occupies 2/3 of the head area and is embedded in the acetabulum. The lunar surface of the acetabulum surrounds the acetabular fossa, which is filled with fat; the acetabular labrum is attached to the acetabular margin to increase the depth of the acetabulum. The acetabular transverse ligament closes the acetabular notch, and the nerve vessels enter and exit the joint through the ligament. The gap between the acetabular depression and the articular surface of the femoral head is the hip joint gap, and the gap in normal adults is 4 to 5 mm wide. The upper half of the gap is narrower, showing the distance between the two bony articular surfaces. The lower half is wider, showing the distance between the femoral head and the acetabular fossa. On the orthophoto, although the lower edge of the femoral neck and the upper edge of the obturator are not connected in normal people, they form a more natural curved curve, which is called the stern neck curve (Shent-on curve). The articular capsule is generally thick and weak behind; the hip bone is attached to the periphery of the acetabulum and the transverse ligament; the femur is attached to the anterior intertrochanter line, the upper and lower are attached to the large and small trochanters, and the rear is attached to the rotator The middle ridge is about 1cm.

Hip joint capsule and its ligaments

Figure 1 Hip joint capsule and its ligaments (A, anterior view B, posterior view)

1. Patella 2, joint capsule 3, patellofemoral ligament 4, femur 5, sciatic capsule ligament

Hip joint structure

The joint capsule itself is strengthened by ligaments. The sacrofemoral ligament is the strongest ligament in the whole body. It is inclined obliquely downward from the anterior inferior spinal spine into two strands and is attached to the intertrochanteric line. The pubic femoral ligament slants downward from the vicinity of the superior branch of the pubic bone and migrates to the joint capsule. The femoral ligament moves obliquely backward from the posterior part of the acetabulum (sciatic body), and migrates to the joint capsule. But the back of the joint capsule is still a weak point. The orbicular zone is the thickening of the circular fibers on the inner surface of the fibrous capsule, which surrounds the femoral neck. The ligament of the femoral head is triangular, its tip is attached to the femoral head, and the bottom is fused with the transverse ligament of the acetabulum. Its function is still controversial.

The synovial layer of the articular capsule is characterized in that in addition to lining the fibrous capsule, the fibrous capsule is also folded around the femoral neck to form a support band to the periphery of the articular cartilage. There are blood vessels to the head and neck in the support band. Arteries to the joints are mainly the branches of the superior and inferior gluteal arteries, the medial and lateral femoral arteries, and the obturator artery. The femoral nerve, obturator nerve, and femoral muscle nerve all branch into the joint. The hip joint can be used for multi-axis movement, but because the femoral head is deeply embedded in the acetabulum, and there are various ligament limitations, its amplitude of motion is much lower than that of the shoulder joint. When the knee is in the extended position, the hip flexion is only 80 degrees; when the knee is flexed, it can reach more than 110 degrees. Extension, limited by the patellofemoral ligament, only about 30 degrees. The extension is restricted by the pubic femoral ligament, the patellofemoral ligament, and the greater trochanter; the adduction is restricted by the lateral division of the patellofemoral ligament; the range of extension and retraction is about 45 degrees. The vertical axis of the femoral rotation is the line connecting the femoral head and the acetabulum to the medial and lateral condyles (not the longitudinal axis of the femoral body). The total range of rotation when standing upright is 40-50 degrees.

Coronal section of hip joint

Figure 2 Coronal section of the hip joint

1, acetabulum 2, joint cavity 3, femoral head ligament 4, synovial fold 5, large trochanter 6, joint capsule

The hip joint of children is far from being developed. It is characterized by the acetabular Y-shaped cartilage that has not healed or the distance between the three bones is large. Only a small mass-like ossification center appears in the femoral head. The size ratio of the acetabulum to the femoral head is small. There is a big difference, the distance between the two is wide, etc. Congenital hip dislocation is more common in young children, but its structure has not yet been developed.

Hip joint related diseases and treatment

Artificial hip arthroplasty is one of the most important and effective procedures for treating end-stage disease of femoral head necrosis, hip dysplasia, degenerative hip osteoarthritis, rheumatoid arthritis and other diseases.

Artificial femoral head replacement has less trauma, shorter operation time, less bleeding, less risk of anesthesia, and great clinical value. For patients with advanced age, low mobility before fracture, multiple diseases, and poor general condition, artificial femoral head replacement is better. The bipolar artificial femoral head adds a friction interface on the basis of the unipolar artificial femoral head, which can provide better functions and range of motion, help reduce acetabular articular surface wear, make postoperative pain, loosening of the prosthesis, and lower Decrease rate. For patients with poor physical conditions, bipolar artificial femoral head replacement was performed. During the follow-up, some patients suffered from sore hips, but they did not affect joint activities and could meet the daily needs of the elderly. With the improvement of total hip arthroplasty, the operation time is significantly shortened, the trauma is reduced, and the anesthesia technology can deal with the surgical complications in time, and the operation risk is significantly reduced.

And the acetabular prosthesis and femoral prosthesis are fully matched, providing a more stable and painless joint. However, the prosthesis is unstable and dislocated. Each of the two prosthetic replacement methods has its own advantages and disadvantages, which must be combined with the patient's pre-operative health status, especially his daily walking ability, comorbidities, and economic affordability. Treatment methods that minimize the risk of surgery, fast hip joint function recovery, long-term joint painlessness, and low risk of revision should be pursued. For pre-operative activities with large walking ability and good physical condition, total hip replacement should be used, and biological treatment should be used as much as possible. Fixed prosthesis.