Hip dysplasia of humans

Table of contents
I. Basic facts about hip dysplasia
II. Two major types of hip dysplasia
1. Congenital hip dysplasia
2. Developmental hip dysplasia
III. Methods of detecting CHD and DHD

The main goal of this paper is to give a clear explanation and define such medical term as “hip dysplasia”, speak about its diagnosis and prognosis and ways of detecting. Though this disease affects not only humans but also animals (especially dogs), only human hip dysplasia will be discussed in this paper. This term is often used to describe health problems of human beings connected with wrong formation of the hip joint. Hip dysplasia, also known as hip dislocation, has several types, such as Congenital hip dislocation, Congenital dislocatable hip and Developmental dysplasia of hip. More often hip dysplasia can be found in newborn babies or very young children. However, there are some cases when the disease is not detected in time. Because there are several types of hip dysplasia this work will also discuss peculiarities of each type and differences between them.

I. Basic facts about hip dysplasia.
The first point of hip dysplasia that is necessary to discussis the definition of this term and short history of it. According to Webster’s dictionary dysplasia is defined as abnormal growth or development, that’s why hip dysplasia is an abnormal development of hip, which causes instability of hip joint and dislocation of the thigh bone from the socket in the pelvis [1]. Usually this disease is innate, though recent researches have shown that it develops during the first weeks - months and sometimes year of life. That’s why it has been called developmental hip dysplasia. According to historical evidences hip dysplasia was known as early as the time of Hippocrates. Nowadays there are two types of hip dysplasia known in medicine congenital dysplasia and developmental dysplasia. So, what is hip dysplasia? According to medical researches displasia is a result of abnormal development of the hip when the relationship between the thigh bone, called femur, and shallow socket, called acetabulum is disrupted. Acetabulum is the large cup-shaped cavity at the junction of pelvis and femur [1]. Because of this disruption neither femur nor acetabulum develops in a proper way. Before a baby is born its hip must be developed in a way in which femur is located right in the center of acetabulum, in its turn acetabulum must cover the head of femur. In cases of hip dysplasia wrong development of the acetabulum makes femoral head ride in an upward direction out of the joint socket. This is especially noticed when a certain weight is put on the hip [3]. In the event when a baby was born healthy and had no hip displasia there’s a possibility of getting developmental hip displasia during the next six weeks of baby’s life, which are considered to be a critical period for hip joint formation. That’s why it’s very important to hold a proper examination in order to identify the disease or a possibility of getting it in future. If proper examination wasn’t done or a mistaken diagnosis was established there’s a high chance of future morbidity that might cause more serious health problems, such as the development of osteoarthritis [2].
According to scientific researches and statistics hip dypslasia more often can be found in females than in males, it’s more frequently detected in infants with breech presentation and very rarely in Afro-American people [5]. Though hip dysplasia has been a subject of study for many years still doctors hesitate on the matter what causes hip dislocation. It’s been noticed that hip dysplasia runs in families, and usually girls are under risk of getting the disease. That’s why it’s possible to assume that among factors causing hip dysplasia is certain genetic information. Also factors of the environment make cause hip dysplasia due to the different rate of the disease in different countries. In order to find out whether a baby has hip dysplasia pediatricians usually do the Barlow or the Ortolani tests. In cases when hip dysplasia is not detected right away, by the age of one a child might be lame [4].

II. Two major types of hip dysplasia
As it has been mentioned above there are two major types of hip dysplasia known nowadays: congenital and developmental. Congenital hip dislocation also known as CHD is a malformation of hip joint that can be detected exactly after the birth. Congenital hip dysplasia has some basic features such as different length of legs and their asymmetry, uneven thigh fat folds and degraded mobility on the side which was affected.
It’s hard to identify what causes CHD, but clinical studies have shown that congenital hip dislocation runs in families, and affects more women than men. Also there’s a large chance for a baby to have CHD in cases of breech position births. First born children are more likely to have CHD than second and third ones. A great role in the development of CHD also plays hormonal swing of mother. Very often children having CHD don’t show any features of the disease, that’s why a thorough physical examination is strongly recommended on the second day of life of infant. There are two basic methods used in medicine for detection of congenital hip dysplasia. They are the Barlow test and the Ortolani test. The main principle used in both methods is moving infant’s hips in order to determine whether femoral head is able to move in and out of the hip joint. Other methods used to detect CHD are X-ray analysis and ultrasonographic detection, which will be discussed later in the work [6].
While examining an infant pediatrician may diagnose several types of CHD. The first one is congenital hip dislocation, which means that hip is already dislocated at birth. The second one is congenital dislocatable hip, which means that hip is in the correct place at birth, but it can dislocate completely under any kind of stress. The third diagnose is congenital subluxatable hip, which means that hip can dislocate only partially under stress. And the last one is acetabular dysplasia, which is a situation when acetabulum is shallow and causes hip instability [4].
Correct treatment of congenital hip dysplasia will help to avoid almost all health problems associated with it in future. If CHD is not properly treated shortly after birth the prognosis of the disease is the following. A child may grow with a limp or waddling gait. Unless surgery is done a child might have difficulties in walking and experience a lot of pain.
Second type of human hip dysplasia is Developmental hip dysplasia, also known as DHD, which is a modern medical term used for hip dysplasia showing that in some cases infants having normally developed hips develop hip dysplasia during the first months of life. Usually it happens not later than during the first year of life. In order to prevent the development of the disease it’s necessary to hold an examination of a newborn baby. In cases if no signs of the disease were found during the first examination, other examination when an infant is one, two, four, six, nine and 12 months old are also required. If during this examinations limited abduction is detected, it could be a trustworthy sign of DHD. The best method of detecting DHD is arthrography of the hip, however this type of examination is not advised to use in newborn babies. There are other methods used by pediatricians to evaluate state of health of a child, such as radiography and ultrasonography, though radiography is not effective when used in children younger than four months, because it cannot show the full picture yet. However, ultrasonography is rather effective in small infants, and is able to show different abnormal findings if they are present. Usually ultrasonography is used if physical examination detected some sort of abnormalities and in high-risk newborns. Speaking about factors that influence the development of DHD they are similar to those influencing CHD. They are family tendency, breech presentations and some orthopedic problems, such as clubfoot deformity and other congenital conditions and diseases. Among obvious symptoms of developmental hip dislocation are infant’s legs of different length, uneven thigh folds and wider space between legs in comparison with normal [7].
Developmental hip dislocation may result in even more complicated problems ending up in the development of osteoarthritis. Health problems caused by DHD are knee pain, back pain, abnormal gait and limping [8].

III. Methods of detecting CHD and DHD
Nowadays, clinical examination for hip dysplasia is established in many countries of the world. The primary method of detecting hip dysplasia is physical examination; however its accuracy is still under the question. As it has been mentioned above, there are two methods of detecting hip dysplasia known as Ortolani and Barlow tests. These tests have been common techniques for finding hip abnormalities in newborns. However, these tests cannot be performed in a baby who is constantly moving, because its muscle activity restrains movements of the affected hip. These methods are proved to be more effective when done in the newborn period [9].
Non-physical methods of detecting CHD and DHD in babies are ultrasound examination, radiographic assessment or x-ray examination, and computed tomography scan. Ultrasound examination was used to detect hip dysplasia in 1978 for the first time. The main principle of this method is based on classification of infants’ hips according to their shape and depth of acetabulum. According to this method there are four types of hips. The first type is considered to be normal; the second type is used to represent a hip with slightly shallow acetabular cup, and if a child is older than three months this is considered to be abnormal; the third type of hip is subluxated; the last is the fourth type, which is used to represent a dislocated hip. It is believed that results of ultrasonography very much depend on operator conducting the examination, on his/her professional skills; and that ultrasound examination provides best results when a baby is 4-6 weeks old.
Radiography or x-ray examination is usually held when a child is already 3-5 months old. The test is usually performed in a hospital radiology department by a qualified clinician. Sometimes there’s a need to take several pictures in order to get different views of joint. However, there’s a disadvantage of this method, because x-ray examination can be made at the age when hip dysplasia can be hardly treated without any surgery [9].
The next method of detecting hip dysplasia is computed tomography, which is diagnostic method using a combinations of x-rays and computer technology. This method is effective at examination of any part of body not only hips [7].

Having spoken about hip dysplasia of humans, its diagnosis, prognosis, and methods of detecting it’s necessary to make a conclusion. Although this disease is rather rare in occurrence: its incidence is 4 per 1000 live-births in the general population [4], it’s necessary to examine all newborns during their first days of life and continue regular examination until they start walking. This will prevent the development of hip dysplasia, because only detected in time it can be treated successfully. Otherwise, if it’s not noticed in time hip dysplasia can lead to the development of more serious health problems such as limping and osteoarthritis. Though it’s impossible to hold any prenatal examination to detect CHD, it’s necessary to pay more attention to infants born with breech presentation, because they have the highest risk of getting hip dysplasia.

1. http://www.healthofchildren.com/C/Congenital-Hip-Dysplasia.phpl
2. http://www.emedicine.com/radio/topic212.php
3. http://www.healthatoz.com/healthatoz/Atoz/ency/congenital_hip_dysplasia.jsp
4. http://www.orthoseek.com/articles/hipdys.phpl
5. http://www.learningradiology.com/notes/bonenotes/conghipdysplasiapage.php
6. http://www.arthritis-symptom.com/a-c/congenital-hip-dysplasia.php
7. http://www.lpch.org/DiseaseHealthInfo/HealthLibrary/orthopaedics/ddh.phpl
8. http://www.cs.nsw.gov.au/rpa/neonatal/html/newprot/ddh7.php
9. http://www.aafp.org/afp/990700ap/177.phpl

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