What exactly is hip dysplasia?
As the name suggests, it’s a deformation or a misalignment of the hip joint. The cup-like-formed acetabulum of the pelvis (also called the hip socket) and the round femoral head facilitate the movement of the legs. Both are covered with cartilage and a layer of fluid, which ensure a frictionless movement of the joint. The formation of the joint begins in the third month of pregnancy, yet it will not fully develop until the end of the pregnancy.
By the time of birth, the newborn’s pelvis is almost entirely made out of cartilage. The ossification begins shortly after birth. The hip joint is reinforced by ligaments and the joint capsule. Muscles enable movement as well as supporting the hip joint.
The German term for hip dysplasia was first used in 1936 to refer to a delayed growth of the ossification of the hip socket. The generic term of “infantile dislocation of the hip joint” was created by Dr. Ewald Fettweis. It is one of the most common skeleton structure disorders, and girls are 7 times more likely to be affected. Hip dysplasia is diagnosed in Germany with a frequency rate of 2-4 % and a luxation of the hip with 0.4 – 0.7%.
What causes hip dysplasia?
This malformation or dysplasia occurs due to a disruption or delay of the ossification of the pelvis, i.e., the transformation of cartilage into bone. The dislocation of the hip joint is not complete by birth and can happen in a breech birth or due to a malformation of the general structure of the hip area. A newly born child has a cartilage-like pelvis, whose rate of ossification differs with each individual infant. In this context, this ossification is called “shape-stabilization of the bone.”
There are multiple reasons why this shape-stabilization of the bone may not develop correctly:
1) Genetically determined delay of maturing
2) An exogenous physical injury due to:
– The infant’s legs being forced upwards due to a breech position in the womb
– Lying on the stomach (especially in the first 3 months)
– Incorrect swaddling
– Lying on the side (inconvenient positioning of the infant’s legs prevents the natural spread-squatting-position)
– The use of a baby walker
– Unnecessary, incorrect infant gymnastics
– Taking the infant’s measurements by holding it by the feet, dangling it with its head down and its full weight on the hip joints. This can strain the baby’s hip socket, or possibly pull the femoral head out of the acetabulum.
– Incorrect or rough treatment of the infant and/or an unfortunate combination of different factors
The muscles themselves are another important aspect. According to Adolf Lorenz, the most appropriate position for the baby’s legs is the one the child naturally assumes in the uterus. In this position, the strong muscles used for sitting push the femoral head straight into the acetabulum, which leads to the cartilage diminishing, and being replaced with bone tissue. Orthopedists have discerned that the ideal position for an optimum growth of a child’s hip is an inflection at the hip joint of at least 90° (ideally 110°), while bending the knees and spreading them “at an angle of 35°-40°.” This is called the spread-squat-position, also referred to as the frog-position. Notice that when you pick up an infant, it naturally braces itself in this position, pulling its legs up into a spread-squatting-position, with the soles of the feet (almost) touching each other.
Prevention and Therapy
How is it treated?
For over 100 years now, orthopedists, especially in German-speaking countries, have been dedicating their research to the infantile dislocation of the hip joint, or hip dysplasia. Before that, a dislocation was regarded incurable and thus, doctor’s even discouraged treatment. At the time there were no methods available to make a proper diagnosis.
Towards the end of the nineteenth century, two pioneers made breakthrough discoveries, almost simultaneously. The Austrian orthopedist Adolf Lorenz published his work “About the mechanical treatment of innate dislocation of the hip joint” (1895), and Wilhelm Konrad Röntgen discovered X-ray technology that still bears his name in some languages including German: Röntgen. An exciting period in medicine commenced, full of new enlightenment and hope, but also of disappointment and harm. Many generations of medical scientists took part in its victories and failures, many of which we have lived to witness.
The Lorenz Cast and other failed treatments
In 1895, Adolf Lorenz introduced a method to treat hip luxation, the Lorenz-cast, which allowed an inflection and bracing of the legs at a 90-degree angle to the pelvis. Although signs of improvement were visible at first, the consequences were severe with long-term damage and complications. In dire need of a lasting solution, a multitude of methods – including special trousers, bandages and casts – and surgical procedures were attempted. Needless to say, these methods, although developed with the best intentions, were not successful.
Dr. Graf’s medical breakthrough: the ultrasound pelvic examination
As early as 1971, carefully documented preventative examinations of infants were introduced in Germany. Today, these obligatory examinations begin at birth and continue well into adolescence in order to spot any potential dangers and symptoms at their early stages. This allows immediate treatment to begin when indicated. An amazing medical breakthrough made it possible to diagnose a pelvic malformation at birth: the ultrasound examination of the pelvis, invented by Dr. Reinhard Graf in 1979.
Graf’s method is based on measuring different angles focusing on the acetabulum. He analyzes and divides pelvic joints into nine different categories, which helps to determine the right therapy. The therapy can consist of everything from check-ups on a regular basis to interventions like spreading the legs, and repositioning, or fixating them.
Before Graf’s screening, children were usually diagnosed only after nine months of age, which drastically limited the hope of successful treatment. Needless to say, the earlier a malformation is recognized, the more successful therapy one can hope for.
How can you recognize it?
What can parents do to preserve their children’s healthy hip joints and recognize a potential complication?
1) Insist on an ultrasound right after birth in the case of any conspicuous medical history in the family.
2) Look at the obligatory ultrasound which is made during the 3rd precautionary examination, and get your child treated immediately if there is anything of concern.
3) Let the child sleep on its back during the night with its knees bent, securing this physiological position by placing a rolled up towel under the child’s knees.
4) Avoid the potential dangers listed above, such as taking the infant’s measurements by holding it at its feet and hanging it with its head down.
5) Carry the child in a physiologically sound baby carrier or a sling, as two-thirds of the world’s population does. A trained midwife or a baby wearing consultant will be glad to assist you in finding the healthiest and ideal position for your child. After all, children want to be carried!
Bund deutscher Hebammen. 2004. Das Neugeborene in der Hebammenpraxis. Hippokrates. Association of German Midwives. 2004. The Infant/New-born at the Midwife’s practice. Hippokrates.
Dr. Fettweis, Ewald. 1992. Das kindliche Hüftluxationsleiden – Die Behandlung in Sitz-Hock-Stellung. Ecomed.
Dr. Fettweis, Ewald. 1992. Suffering (from) an infantile hip luxation – Treatment in the Spread-Sqatting-Position. Ecomed.
Dr. Fettweis, Ewald. 2004. Hüftdysplasie- Sinnvolle Hilfen für Babyhüften. Trias.
Dr. Fettweis, Ewald. 2004. Hip dysplasia – How to treat infantile hips. Trias.
Niethard, Pfeil. 2003 (4. Aufl.). Orthopädie. Thieme.
Niethard, Pfeil. 2003 (4. edition.). Orthopedics. Thieme.