November 02, 2011
One of the salient features of a well-designed baby carrier is that it keeps the carried baby in a correct ergonomic position. The obvious question which follows from such a statement is what constitutes a correct ergonomic carrying position for a newborn baby?
A minimum requirement for an ergonomically correct position is that it should ideally promote a healthy development of the baby’s hips and spine.
One of the conditions which pediatricians will normally investigate in a newborn child and in subsequent well-baby check-ups is that of developmental dysplasia of the hips (DDH).
Hip Dysplasia definition and occurrence
DDH is a disorder related to what is commonly known as the hip joint. The hip joint is where the head of the thigh bone (the femur) meets with the hip socket (the acetabulum). Hip dysplasia is diagnosed when there is either a complete or partial dislocation of the head of the thigh bone, so it no longer fits snugly and firmly into the hip socket; or instability, as when the head of the thigh bone comes in and out of the socket.
Doctors tend to stress the term developmental dysplasia of the hip, as the above conditions may not be present at birth. The earlier a dislocated hip is detected, the simpler and more effective is the treatment. Despite newborn screening programs, dislocated hips continue to be diagnosed later in infancy and childhood, in some instances delaying appropriate therapy with resultant quite significant encumbrances to the affected child and parents.
Hip Dysplasia at birth is not a very common condition, around 1.4% is affected, and approximately 1% of all infants are evaluated or treated for the condition. Estimates of the incidence tend to vary quite significantly, depending on when and which type of examination is performed. Universal ultrasound screening has determined that as many as 7-10% of all newborn infants have hip instability shortly after birth. Curiously, it is most prevalent amongst first born girls, about 8 times more common than amongst boys. Some of the known risk factors for hip dysplasia include being born into a family with a history of hip dysplasia, and being born in the breech position (being born entering the birth canal with feet or buttocks first). In breech babies, the frequency of hip dysplasia varies from 5-25% and approaches the lower number when C-section is the method of delivery. This means that mechanical forces during birth may increase the risk of hip dislocation or hip dysplasia.
Interestingly, swaddling – with the baby’s legs are stretched out and kept together – has also been established as a risk factor for DDH. This is a greater risk factor than family history or breech birth. This position tends to pull the thigh bone head out of the hip socket. So if one adopts the practice of swaddling, one should make sure that the legs are spread apart.
DDH certainly is no trivial condition. If not caught and treated correctly, there is a very real possibility of a limp, constant and/or debilitating pain, complicated treatment and impaired mobility later in life. Undetected hip dysplasia causes approximately 10% of all total hip surgeries performed in the USA and it is the most common cause of hip arthritis in young women.
Babies in the breech position are more likely to have hip instability than babies in a normal womb position.
What may cause hip dysplasia?
The etiology – that is, the cause of DDH – was previously understood to be primarily a congenital condition, whereby the thigh bone head for mysterious reasons was not able to latch on to the hip socket. Currently, DDH is thought to arise in part because of a premature “unfolding” of the baby. During the baby’s time in the uterus, the legs will naturally be completely bent at the hip and also be spread apart. At the time of birth, the thigh bone head consists largely of cartilage, which gradually turns into bone.
However, the degree to which the cartilage has turned into bone at the time of birth can vary quite substantially, resulting in different levels of susceptibility to DDH. To ensure a proper forming and continuous placement of the thigh head bone in the hip socket during the ossification (bone formation) process, the legs should not be stretched out for too long a period of time. They should instead be kept bent in an adapted position which maintains some similarities to that of the position while in the uterus.
The medical treatment of DDH in the first year will normally include placing the child in a “Pavlik harness.” The position in which the harness keeps the baby is also more commonly known as the frog position.
Do baby carriers cause hip dysplasia?
When your baby sits inside his ergonomic baby carrier in a supported and spread leg M position with his knees bent and higher than his bottom, he is sitting in a healthy position that won’t cause hip and leg problems, like hip dysplasia.
Some prominent orthopedists, such as the German orthopedist Dr. Fettweis advocate baby carrying in a good ergonomic carrier as a way of preventing DDH. The best baby carrier for hip dysplasia is a carrier that supports the baby’s legs in such a way that the baby is sitting in the frog position, with his legs apart and his knees pulled up a little higher than the hip joints.
One of the advantages stressed by orthopedists is the movement that the carrying adult will confer upon the baby and especially the baby’s legs and hip joints. The baby will respond with contractions of the relevant thigh muscles, hence providing exercise to the muscles while at the same time having the thigh bone head constantly pushed correctly into the socket, reinforcing the proper positioning in a natural and unstrained way . The movement and the muscular activity will also stimulate the blood flow, which in turn will also speed up the process of turning the cartilage into bone.
When the baby is placed in a harness, there will naturally be less of this type of movement, as the baby will be fixated in the position, unless a special physical therapy is included in the treatment of DDH. Nevertheless, it seems that no scientific investigations have been conducted this far on whether proper ergonomic carrying might be as effective (or more) as placing the baby in a harness.
Carrying one’s baby can be done for many reasons. It is certainly good to know that it will, on top of the many other benefits, also help the baby develop healthy hip joints.
Resources: Guille JT, Pizzutillo PD, MacEwen GD. Developmental Dysplasia of the Hip From Birth to Six Months. J. Am. Acad. Ortho. Surg., July/August 2000; 8: 232 - 242. Vitale MG and Skaggs DL. Developmental Dysplasia of the Hip From Six Months to Four Years of Age. J. Am. Acad. Ortho. Surg., November/December 2001; 9: 401 - 411. Lehmann, HP, Hinton R, Morello P, Santoli J in conjunction with the Committee on Quality Improvement and Subcommittee on Developmental Dysplasia of the Hip. Developmental Dysplasia of the Hip Practice Guideline: Technical Report. Pediatrics 2000;105;e57 E. Fettweis. Über das Tragen von Babys und Kleinkindern in Tüchern oder Tragehilfen. Orthopädische Praxis 46, 2, 2010 (In German) Evelin Kirkilionis. Ein Baby will getragen sein. Alles über geeignete Tragehilfen und die Vorteile des Tragens. Kosel. (In German)