Hip dysplasia
Hip dysplasia is an abnormality of the hip joint where the socket portion does not fully cover the ball portion, resulting in an increased risk for joint dislocation.[1] Hip dysplasia may occur at birth or develop in early life.[1] Regardless, it does not typically produce symptoms in babies less than a year old.[3] Occasionally one leg may be shorter than the other.[1] The left hip is more often affected than the right.[3] Complications without treatment can include arthritis, limping, and low back pain.[3] Females are affected more often than males.[1] Risk factors for hip dysplasia include female sex, family history, certain swaddling practices, and breech presentation whether an infant is delivered vaginally or by cesarean section.[3] If one identical twin is affected, there is a 40% risk the other will also be affected.[3] Screening all babies for the condition by physical examination is recommended.[3] Ultrasonography may also be useful.[3]
This article is about the disease in humans. For the disease in dogs, see Canine hip dysplasia.
Many of those with mild instability resolve without specific treatment.[3] In more significant cases, if detected early, bracing may be all that is required.[3] In cases that are detected later, surgery and casting may be needed.[3] About 7.5% of hip replacements are done to treat problems which have arisen from hip dysplasia.[3]
About 1 in 1,000 babies have hip dysplasia.[3] Hip instability of meaningful importance occurs in one to two percent of babies born at term.[3] Females are affected more often than males.[1] Hip dysplasia was described at least as early as the 300s BC by Hippocrates.[4]
Hip dysplasia can range from barely detectable to severely malformed or dislocated.
The congenital form, teratologic or non-reducible dislocation occurs as part of more complex conditions.
The condition can be bilateral or unilateral:
If the joint is fully dislocated a false acetabulum often forms (often higher up on the pelvis) opposite the dislocated femoral head position.
In acetabular dysplasia, the acetabulum (socket) is too shallow or deformed. The center-edge angle is measured as described by Wiberg.[6] Two forms of femoral dysplasia are coxa vara, in which the femur head grows at too narrow an angle to the shaft, and coxa valga, in which the angle is too wide.
A rare type, the "Beukes familial hip dysplasia" is found among Afrikaners that are members of the Beukes family. The femur head is flat and irregular. People develop osteoarthritis at an early age.[7]
Baby wearing a Pavlik harness
Diagram of Pavlik harness
Diagram of Frejka pillow
Traction
Epidemiology[edit]
Determining the incidence can be difficult.[56][57] In addition there is a wide margin in diagnostic results. A German study comparing two methods resulted in twice the usual rate for one method. The condition is eight times more frequent in females than in males.[9]
Native Americans are more likely to have congenital hip dislocation than any of the other races. The risk for Native Americans is about 25–50 in 1000. The overall frequency of developmental dysplasia of the hip is approximately 1 case per 1000 individuals; however, Barlow believed that the incidence of hip instability in newborns can be as high as 1 case for every 60 newborns,[58] with the rate dropping to 1:240 at one week.[59]
History[edit]
The Frejka pillow splint was named after Dr. Bedrich Frejka (1890-1972), a Czech orthopedic surgeon. The Pavlik harness was named after Dr. Arnold Pavlik (1902-1962), also a Czech orthopedic surgeon.
Society and culture[edit]
In the television program ER, Kerry Weaver uses a crutch owing to congenital hip dysplasia. In season 12, she undergoes a hip replacement to cure her dysplasia when her previously untreated joint worsens.[60]
Research[edit]
One avenue of research is using stem cells. They are applied in grafting (bone grafting) or by seeding porous arthroplasty prosthesis with autologous fibroblasts or chondrocyte progenitor cells to assist in firmly anchoring the artificial material in the bone bed.