Dislocation of hip

Dislocation of the hip is a common injury to the hip joint. A dislocated hip, much more common in girls than in boys, is a condition that can either be congenital or acquired. Understanding the epidemiology, anatomy, difference between congenital and acquired, screening, treatments, and rehabilitation are all relevant to the topic.

Congenital

As of the year 2009 there are a total of 3,718 cases of congenital hip dislocation. The epidemiology is divided into five age groups which are newborns less than one year old, the next age group is people from the ages of 1-17, the third age group is 18-44 years old, the fourth age group is 45-64, and the final age group is 65-88 years old. The age group of <1 has 2,233 cases which accounts for 60.07% of all known cases. The age group of 1-17 has 686 cases which accounts for 18.44% of all cases of congenital hip dislocation. The next age group which is 18-44 has 249 cases which accounts for 6.70% of all cases and the age group of 45-64 has 332 cases which is about 8.93% of all cases. Finally, the age group of 65-84 has 158 cases which accounts for 4.25% of all cases of congenital hip dislocation.The epidemiology also shows that females are more prevalent to get congenital hip dislocation compared to their male counterparts. Females had 2,571 cases which is 69.15% of all cases while for men there are 1,136 cases which makes up 30.56% of all cases of congenital hip dislocation. The costs vary from age groups. The mean costs for the age group <1 is $7,803 while the median cost is $ 7,045. The costs for the age group of 1-17 are $13,573 for a mean and the median cost is $12,513. The mean cost for the age group of 18-44 is $16,656 and the median cost is $14,082. Finally, the age group of 45-64 has a mean cost of $14,388 and a median cost of $12,321. The amount of days of the hospital stay varies as well. In the age group 1-17 the length of stay is about 2.7 days, for the people ages 18-44 the average stay is 4.4 days, and the people ages 45-64 stay for about 3.4 days in the hospital setting.

Acquired

Hip dislocation cases in people in the age group from 1 through 17 years old is 434 which is 16.20%, the age group of 18-44 has 1,026 cases which accounts for 38.30% of hip dislocations, the age group of 45-64 has 563 cases which account for 21.00% of cases, and people from the ages of 65 through 84 years old have 210 cases which makes up 7.82% of cases of hip dislocation. Hip dislocation is more prevalent in males by 2% compared to females. Hip dislocation cases in males are 1,348 which accounts for 50.31% of cases and the number of hip dislocations in females are 1,312 which makes up of 48.96% of hip dislocations. Hip dislocation most likely occurs at the age group of people ages to 18-44.

X-ray showing a joint dislocation of the left hip.

Posterior vs. anterior

Nine out of ten hip dislocations are posterior. The affected limb will be shortened and internally rotated in this case.

In an anterior dislocation the limb will not be lengthened as noticeably and will be externally rotated.

Congenital vs. acquired

Congenital hip dislocation must be detected early when it can be easily treated by a few weeks of traction. If it is not detected, the child’s hip may develop incorrectly seen when the child begins to walk. If one hip is affected the child will have a limp and lurch and with bilateral dislocation there will be a waddling gait. On physical exam, with the baby in the supine position, the examiner flexes the hips and knees both to 90 degrees, and, holding the knees, pushes gently downward, which may induce a posterior dislocation or subluxation. Keeping the baby in this 90 degree flexed position, the examiner then externally rotates the thighs. A normal infant will demonstrate no evidence of dislocation. It can also be detected with the Galeazzi test. Congenital hip dislocation is much more common in girls than boys.

Acquired hip dislocations are extremely painful and commonly occur during car accidents. They may be treated by surgical realignment and traction.

Acquired Hip Injuries

Usually hip dislocation occurs when the head of the femur dislodges from its socket form the pelvis. In most patients, the femur shifts out of its socket in a posterior dislocation direction. The hip is now in a position where it is twisted in toward the middle of the body. The femur could also shift in an anterior direction which the hip will twist outward and away from the middle of the body. This dislocation is very painful and patients are unable to move when it occurs. Due to the dislocation, there could be some nerve damage resulting in loss of feeling in the foot or ankle.

To actually dislocate a hip, a great amount of force needs to be applied. Motor vehicle accidents are the most common ways that hip dislocations occur. Falls from high areas, such as a ladder, can also generate enough force to dislocate a hip. In older individuals, even a slight fall could cause this type of injury. This type of wear and tear that the body undergoes throughout the years leads to increased incidents of hip dislocation in the older population.

Hip injuries in sports are also quite common. In contact sports such as rugby and American football hip dislocation is a result of great amounts of force applied to the body during contact and collision. In other sports such as water skiing, skiing/snowboarding, gymnastics, and basketball these injuries are less common because there are fewer collisions in contact. However, when the amount of force to the hip joint is greater than the muscles of the hip can compensate for, hip injuries can still occur.

Several other injuries are also associated with hip dislocation. Fractures in the pelvis and legs, and minor back or head injuries can also occur along with a hip dislocation that is caused by a fall or athletic type of injury.

Congenital dislocation of the left hip. Closed arrow marks the acetabulum, open arrow the femoral head.

Congenital Hip Dislocation

Congenital hip dislocation also known as dysplasia of the hip is a condition in which a child is born with a hip problem. Congenital hip dislocation is when the formation of the hip joint is abnormal. The ball at the top of the thighbone which is known as the femoral head is not stable within the socket which is also known as the acetabulum. This abnormality may cause the ligaments of the hip to be loose or stretched. This condition is usually diagnosed once the baby is born; it mostly affects the left side of the hip in first-born children, girls, and babies born in a breech position. Girls are most prone to getting the hip dislocation compared to boys. The cause of this condition is still unknown; however, some factors of congenital hip dislocation are through heredity and racial background. It is also a known fact that it is more likely to occur in Native Americans than any of the other races. It also has a low prevalence risk in African Americans and southern Chinese. Native Americans are most likely to get congenital hip dislocation than any of the other races. The risk for Native Americans is about 25-50 cases for every 1000 people. 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.

The early sign of congenital hip dislocation is when a person is able to hear “clicking” sounds when the legs are moved apart from one another. This condition can be treated if detected early. If this condition goes undetected it can cause one leg to “look” shorter than its counterpart and the buttocks folds are also not symmetrical which causes more creases to be present on the affected side, and skin folds at the thigh are uneven. Another sign is that when a child begins to walk he or she may have a limp and favor the affected side when walking. When a child is walking they may be also walking on their toes or they may even “waddle” like a duck. If the condition goes undetected this may cause negative long term effects such as osteoarthritis as well affect the gait of the child when they first learn to walk. This condition may also cause the baby to start to learn how to walk much later than expected.

 

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