Hip Dysplasia in the Child, Adolescent and Adult

The hip joint is a simple ball-in-socket structure. The ball-shaped femoral head rotates inside a cup-shaped socket called the acetabulum. Usually this joint works smoothly, with little friction  or wear.

The well-fitting surfaces of the femoral head and acetabulum which face each other are each lined with a layer of articular cartilage and lubricated by a thin film of synovial fluid which reduces friction inside the normal hip to less than 1/10 that of an ice cube gliding on ice. The labrum is a rim of fibrous cartilage, which lines the outer edge of the acetabulum. It serves to stabilize and cushion the hip joint.

In some people, the hip becomes symptomatic – painful, stiff, weak, unstable, or maybe even a combination of these symptoms.

“Arthritis” is often suggested as the cause of these hip symptoms, just as it is for aches and pains in the knee, shoulder, ankle, or finger joints.

Arthritis is a non-specific term used to describe inflammation of a joint.

There are 2 types of arthritis:

1. Inflammatory; such as rheumatoid.
2. Mechanical; such as osteoarthritis (OA).

To prevent progressive destruction of the joint from inflammatory arthritis, medication can be used to treat the inflammation. With osteoarthritis (OA) surgical procedures are often the best way to correct the underlying mechanical problems.

Hip Dysplasia

Hip Dysplasia, sometimes referred to as DDH  (Developmental Dysplasia of the Hip), is a relatively common abnormality in the shape of the hip joint. This abnormality originates at birth or in early childhood.

DDH is the most common developmental hip deformity causing symptoms in adults. In its most frequent form, hip dysplasia consists of a shallow acetabulum (hip socket). The shallowness of the acetabulum causes the head of the femur to exert excessive pressure on the rim of the acetabulum. If left untreated, this excess rim pressure can lead to pain and injury to the cartilage and/or bone, which may result in osteoarthritis.

The severity of DDH varies widely. In the mildest types of dysplasia, the hip is normal in outside appearance, is very close to normal on x-ray, and may not cause any symptoms until the patient is 30 years of age or older.

In the most severe form of dysplasia, termed “developmental dislocation”, the femoral head of the infant or child actually lies outside the acetabulum but under the muscles of the buttock and thigh.

Risk factors for developmental dislocation of the hip and hip instability include anything that involves stretching the hip ligaments.

Specific risk factors for DDH include the following:

1. Female (girls tend to have looser ligaments than boys)
2. First-born child
3. Large birth weight
4. Breech position
5. Family history of DDH
6. Injury or infection can also cause mechanical or structural damage to the hip that results in OA.

• Treatments for Hip Dysplasia
• Hip Dysplasia - Infant and Paediatric

Osteoarthritis

“Arthritis” is actually a very general term for a number of conditions that involve deterioration of a joint.

The most common type of arthritis is osteoarthritis, (OA), a local condition usually caused by abnormal mechanics between the femur and acetabulum.

Osteoarthritis involves cartilage degeneration due to mechanical factors. Most OA in the hip, at least 80%, occurs because of a developmental abnormality such as DDH. DDH is the most common developmental hip deformity causing osteoarthritis.

Some other causes of OA in the hip include Perthes disease, vascular necrosis, slipped capital femoral epiphysis (SCFE), and other impingement patterns. Often, these potentially damaging deformities do not cause symptoms. If they remain undiagnosed and untreated over the course of years, this may lead to OA that otherwise could have been prevented.

OA can often be prevented if the deformities leading to it are corrected before irreversible cartilage damage has been done.