Hip dysplasia is an abnormality in the shape of the hip joint. The hip joint is the junction between the long leg bone called the femur and pelvis. The upper part of the femur is almost completely round and fits within a concave part of the pelvis called the acetabulum. The most common abnormality in hip dysplasia is that the acetabulum is not deep enough to accept the rounded part of the femur. This means that the hip joint does not function properly, which can interfere with walking and other activities involving the legs. Infant developmental hip dysplasia is hip dysplasia that occurs in otherwise normal newborn. While most newborns will have “loose” hip joints soon after birth, within a few weeks the head of the femur and the acetabulum should fit together properly. When they do not, it indicates hip dysplasia.
Diagnosing infant hip dysplasia
The American Academy of Pediatrics recommends that pediatricians screen for developmental hip dysplasia starting at the first office visit and continuing until the child walks normally. Since developmental hip dysplasia can occur as early as two weeks after birth, screening at the initial visit is particularly important.
Recommended screening tests
Birth to 3 months
- Hip instability
- Asymmetric leg creases
- Shortening of femur
3 to 12 months
- Significantly asymmetric leg creases
- Limited hip abduction while the leg is flexed
- Lateral, rotated posture while prone
- Klisic test
- Significant shortening of femur
In a walking child
- Excess of lordosis
- Prominent greater trochanter
- Trendelenburg gait
- Positive Trendelenburg sign
Diagnostic maneuvers
Barlow or Ortolani test. Hip instability is determined by a positive Barlow or Ortolani test. These tests are usually performed at the same time. The physician grasps the thighs near the hip and pull the legs together (Barlow) or away from the body (Ortolani) and attempts to feel if the hip joint is dislocated. The examiner will feel a “clunk” as the hip joint is dislocated and again as it is reduced (put back to normal).
Asymmetric leg creases are creases in the folds of the skin that appeared different on one leg compared to the other.
Galeazzi/Allis/Perkins sign An abnormally short femur may be tested by looking for a positive Galeazzi/Allis/Perkins sign. To look for the Galeazzi sign, the patient lays on their back with the knees bent, heels touching buttocks. Looking from the bottom of the bed, one knee will be obviously lower than the other. This is a positive Galeazzi sign (also known as and Allis sign or a Perkins sign). Hip abduction will be tested while the leg is flexed.
Hip abduction is the degree to which the leg can be pulled from the body at the hip joint. In children age 3 to 12 months, the child should have 75° of abduction or more while lying on her back if their pelvis is stabilised. If the hip cannot be abducted greater than 45°, this is most likely developmental hip dysplasia.
Lateral, rotated posture while prone is recognised when the child lies on her stomach and the femur is abnormally rotated to the outside.
The Klisic test requires close observation of a relative levels of bony protuberances on the pelvis and on the femur. In general, children with developmental hip dysplasia will have abnormally raised femurs compared to the normal place on the pelvis.
Lordosis is an excessive inward curving of the lower spine, which causes the chest to be raised and they had to tilt backwards.
The greater trochanter is a bony protuberance on the upper part of the femur. When feeling the upper part of the largest bone in the leg (femur) the greater trochanter is the most obvious bony structure felt. In developmental hip dysplasia the greater trochanter is abnormally prominent.
Trendelenburg gait or gluteus medius lurch is recognised by a lurching gait in which the weight of the torso moves too far to one side or the other. A positive Trendelenburg sign is similar in can be elicited by having the patient stand on one leg. The weight will be shifted abnormally over the lifted leg opposite the affected side.
Diagnostic imaging
Before six months of age, ultrasound is the most helpful imaging technique to make or confirm a diagnosis of developmental hip dysplasia.
A trained ultrasound technician will collect ultrasound images of the hip while the leg is moved into various positions. Abnormal anatomy on this test can help make the diagnosis of developmental hip dysplasia.
In children older than six months of age, and regular x-ray is the most helpful diagnostic test. Again, the child should have x-rays taken while thier legs are held in certain positions to get the clearest view of the hip joint.
Risk factors
Hip dysplasia is more likely if the fetus was in a breech position before 35 weeks of gestation, there is a history of developmental hip dysplasia, or if the child is female. For reasons that are unclear, first born children to a mother are more likely to have hip dysplasia. Moreover, any condition during pregnancy in which the fetus was crowded (e.g., too little amniotic fluid a.k.a. oligohydramnios) increases the risk of hip dysplasia.
Treatment
If a pediatrician suspects developmental hip dysplasia in an infant/child, the patient is usually referred to an orthopedic surgeon who has experience in diagnosing and treating this condition.
Two weeks or younger Since a bit of laxity or looseness in the hip joint is normal just after birth, there is usually no treatment needed for possible hip dysplasia before two weeks of age. In fact, it is usually inappropriate to treat a child for developmental hip dysplasia before two weeks of age 10 week old infant in Pavlik Harness[/caption]
Two weeks to six months Mild hip dysplasia may go untreated between two weeks and six months of age because the condition may resolve without treatment. Some orthopedic surgeons will use a Pavlik harness in this age group, which is a device that holds the legs and hips in a bent position and anchors them to the torso. Moderate or severe hip dysplasia is almost always treated with some sort of harness or abduction splint.
Six months to 18 months The primary treatment for children in this age range (or for those who did not achieve any benefit from a harness or splint) is reduction. Reduction involves forcibly moving the head of the femur into the acetabulum (i.e., the ball inside the socket). This can be done manually, without surgery, or an open procedure. Once the hip joint is reduced, the child must wear a spica cast that keeps the hips separated and in a fixed position.
Eighteen months and older In older children, closed reduction is unlikely to be successful, so most orthopedic surgeons will recommend open surgery to reduce the hip joint, followed by a cast.
Long-term expectations
Children who have had developmental hip dysplasia are at increased risk for having residual or recurrent hip dysplasia, even after successful treatment. They will need to undergo regular x-rays of the hip during development to check for abnormalities. Long-term success is more likely in children who were treated at younger ages versus older ages, which is why early diagnosis and treatment are so important.
References
- Clinical practice guideline: early detection of developmental dysplasia of the hip. Committee on Quality Improvement, Subcommittee on Developmental Dysplasia of the Hip. American Academy of Pediatrics. Pediatrics. Apr 2000;105(4 Pt 1):896-905.
- Luhmann SJ, Bassett GS, Gordon JE, Schootman M, Schoenecker PL. Reduction of a dislocation of the hip due to developmental dysplasia. Implications for the need for future surgery. J Bone Joint Surg Am. Feb 2003;85-A(2):239-243.
- Holman J, Carroll KL, Murray KA, Macleod LM, Roach JW. Long-term follow-up of open reduction surgery for developmental dislocation of the hip. J Pediatr Orthop. Mar 2012;32(2):121-124. doi:10.1097/BPO.0b013e3182471aad
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