The failure to diagnose congenital hip dysplasia (CDH) is the most common cause of legal suits involving the musculoskeletal system directed against pediatricians. Even more important, the consequences of late diagnosis or delayed treatment are devastating to the infant. Congenital hip dysplasia, if diagnosed during early infancy, can be effectively managed with the Pavlik harness in 90% of instances.1 This treatment is safe, inexpensive, and effective. If diagnosis is delayed beyond about 6 months, management is more complicated requiring traction, anesthesia, and prolonged casting. This involves considerably more risk, expense, and potential for long term disability. If the diagnosis is delayed until walking age, operative treatment is often necessary and, even with good management, it is unlikely the hip will become normal and degenerative arthritis during adult life is probable.
This potential for disability coupled with the difficulty in early diagnosis make hip dysplasia a major problem. The detection of hip instability during infancy is probably the most difficult examination of the musculoskeletal system. Even after two decades as a pediatric orthopedist with special interest in hip problems, I find it necessary to "back-up" a negative physical examination with additional exams or radiographic study if the hips are at risk for dysplasia.
Two instructive cases show that the value of early diagnosis can be jeopardized by ineffective treatment.
Case 1. This patient was delivered breech at term by cesarean section. Hip instability was diagnosed at birth and "treatment" was started by the pediatrician with "triple diapering." This treatment was continued for several months. At 1 year of age, shortening of the left leg was noticed by a colleague and radiography demonstrated a dislocated left hip (Figure IA). The patient then was treated with 3 weeks of in-hospital traction, followed by closed reduction under anesthesia and spica cast immobilization. The cast immobilization was continued for 3 months followed by full time bracing for an additional 3 months. At age 30 months, radiography showed persisting dysplasia necessitating acetabular reconstruction (Figure IB). A suit is pending against the pediatrician for failure to employ proper management.
Case 2. This patient was born following a normal pregnancy and delivery. Hip instability was noticed shortly after birth and a radiograph was made (Figure 2A). "Treatment" was started with "triple diapering." At age 3 months, the infant was seen in our clinic due to persisting shortening of the right leg. The physical Figure 1. Case I shows the outcome of an infant "treated" by triple diapering. A. Radiograph at I2 months shows the dislocated hip on the left. B. Persisting hip dysplasia at 30 months.
Figure 1. Case I shows the outcome of an infant "treated" by triple diapering. A. Radiograph at I2 months shows the dislocated hip on the left. B. Persisting hip dysplasia at 30 months.
diagnosis but jeopardized the outcome by applying "triple diaper treatment." Such management is somewhat akin to prescribing "corrective shoes." Both treatments are ineffective but in the case of CDH, the delay in instituting effective treatment may be catastrophic. The following suggestions may help improve the pediatrician 's effectiveness in diagnosing and managing hip dysplasia.
Figure 2. Case 2 shows the outcome of a newborn treated by triple diapering and radiographic features of a dislocated hip before ossification of the femoral head- A. Radiograph at 2 weeks of age. The status of the hip is questionable. Radiography is often not definitive in early infancy. B. Radiograph at 3 months.
DIAGNOSING AND MANAGING HIP DYSPLASIA
1. Carefully Screen Every Newborn for Hip Dysplasia
Careful screening is important and difficult to perform, but it is not definitive.2 The results can be made more accurate by following several steps. The infant should be examined while relaxed as crying invalidates a negative examination. Ideally, the infant should have been recently fed and be lying on the mothers lap. The pediatrician's hands should be warm. Be very gentle; do not apply force. Examine one hip at a time. With one hand, stabilize the pelvis by holding it with the thumb and fingers around the sacrum and pubis. With the other hand, hold the thigh with the thumb over the knee and index finger around the greater trochanter. Gently apply an up and down force to demonstrate instability. Repeat this several times with the hip adducted and in a neutral position. Hip instability is demonstrated by a "clunk" or "jerk" as the hip slides over the posterior edge of the socket. If the dislocation is irreducible, the only finding will be a sense of translation or movement between the thigh and pelvis. As this examination is not definitive,3,4 repeated examinations to rule out hip dysplasia are necessary throughout the first year. Be certain to document the examinations in the patient's chart.
Figure 2C. A tracing of the radiograph of B with the necessary markings for measurement The horizontal line is drawn through the triradiate cartilage. The vertical line is drawn at right angles to the horizontal line and intersects the lateral margin of the acetabulum. The acetabular line intersects with the horizontal tine and provides the acetabular index (AI). Note that on the dislocated right side the acetabular index is greater and the femoral shaft is displaced laterally to the vertical line.
2. Examine the Hip for Dysplasia at Each Visit
Be aware that clinical manifestation of hip dysplasia changes with age (Figure 3). In the newborn, instability is the primary and often only manifestation. With time, the adductors become contracted and motion is limited. With dislocation, the affected limb is shortened. If diagnosis is very late, the child will walk with a limp. An understanding of these changes is essential for hip dysplasia screening in the older infant. Be certain to record all hip examinations.
3. Study the High Risk Infant with a Screening Radiograph
The risk of congenital hip dislocation is higher in certain situations (Table).5,6 Infants at risk for hip dysplasia should be examined with special care, and a negative physical examination should be confirmed by some imaging study. Although ultrasound7 or magnetic resonance imaging8 will be the standard for screening in the future, radiographic imaging is still the accepted standard. This is usually accomplished with a single anterior-posterior radiograph made at 10 to 12 weeks of age. This age is recommended because ossification of the hip is sufficiently advanced to make radiographs definitive and there is still time for management with a Pavlik harness. The exposure should be made with the hips slightly flexed and the pelvis flat. To assess the hips for dysplasia certain measurements are necessary (Figure 2C). First draw a horizontal reference line "H" through the clear space of the triradiate cartilage. Then draw a second line along the acetabular roof. The angle between these first two lines is called the acetabular index (Al). Finally, draw a vertical line "V" at right angles to the horizontal reference line that intercepts the lateral most margin of the acetabulum.
Figure 3. The changing findings in congenital hip dislocation by age.
Hip dislocation is manifested by three radiographic features:
1 . The ossifie nucleus is either smaller than the normal side or absent;
2. The acetabular index is high, meaning the acetabular slope is more steep than normal; and
3. There is evidence of displacement producing subluxation or dislocation.
Displacement of the femur is present if the femoral shaft falls lateral to the V line, or the ossifie nucleus is lateral to the V line or above the H line.
In some cases hip dysplasia may be manifest only by shallowness of the acetabulum. Acetabular dysplasia is potentially serious and, if not resolved during growth, often leads to degenerative arthritis during adolescence or adult life. We assess the depth of the acetabulum in the infant by the Al. The acetabular index normally decreases throughout infancy as ossification of the acetabulum progresses.9 We consider normal range for the AI as within 2 standard deviations of the mean. By this criterion the normal value for Al in early infancy is usually less than 30° (Figure 4). Thirty to forty degrees are marginal values, and any value above 40° is clearly abnormal. By 24 months of age, the AI should be less than 25°. If simple acetabular dysplasia is detected during infancy, treatment by splinting is necessary to facilitate acetabular development. Treatment is continued until the Al becomes normal. In some instances, acetabular dysplasia persists and operative acetabular reconstruction is necessary in childhood.
Risks off Hip Dysplasia
4. Properly Treat for Hip Instability\
If instability is found, effective treatment is necessary. Double or triple diaper "treatment" is inadequate as it provides insufficient flexion (Figure 5). In fact, such "treatment" is probably worse than no treatment as it gives a false sense of security and wastes the rapid growth period of early infancy. The most effective and safe treatment of hip instability is the Pavlik harness (Figure 6).1
In congenital hip dislocation, the iliopsoas tendon becomes interposed between the femoral head and joint. The Pavlik harness is effective because it positions the hip in flexion. This flexed position displaces the iliopsoas tendon anteriorly and away from the joint allowing the femoral head to reduce. This reduction is facilitated by movement of the hip allowed in the Pavlik harness. We have learned that flexion is more important for hip reduction than abduction.
Figure 4. The changes in acetabular index with age. The dotted line is the mean and the ±2 standard deviation levels are plotted. (Adapted from Tonnis D: Normal values of the hip joint for the evaluation of x-rays in children and adults. Clin Orthop 1976; 119:39-47.)
Figure 5. The typical position of the hips in the infant treated with triple diapers. The lack of sufficient flexion makes this treatment ineffective.
5. When Uncertain Either Refer or Evaluate by Radiography
Uncertainty may be caused by finding hip "clicks." These clicks are often due to adventitial noises from the hip or the knee and commonly found in normal infants. They are different from "clunks," which denote instability. Sometimes clicks and clunks are confused and we commonly see infants with clicks referred by a pediatrician. A second cause of uncertainty is the finding of limited abduction without instability. This may be due to bilateral hip dislocations or simply benign adductor tightness. To resolve these uncertainties (if the infant is over 10-12 weeks of age) screen with a single anterior-posterior radiograph of the pelvis. If the infant is less than 8 weeks of age it may be wiser to obtain a consultation.
6. Do Not Disregard the Mother's Intuition
Take the mother's concerns seriously. Mothers seem to have a unique sense about the health of their baby which may be helpful in diagnosis. I have seen several infants in which the diagnosis of CDH was delayed despite repeated expressions of concern by the mother about her infant's hips. Her sense that something was wrong was later proven correct.
Figure 6. The Pavlik harness. This splint provides flexion and allows motion. It has become the treatment of choice for hip dysplasia in infants under 6 months of age.
In summary, congenital hip dysplasia remains a worldwide health problem, which has not been resolved by neonatal screening programs. The primary care physician's role is critical for early diagnosis. An understanding of the need for repeated examinations, the age related signs, and continued diligence is essential. The common use of the triple diaper treatment is not recommended.
1. Grill F., Bensahel H. Canadell J, et al: The Pavlik harness in the treatment of congenital dislocatine hip: Report on a multicenter study of the European Pediatric Orthopaedic Society. J Pediatr Ordwp 1988; 8:1-8.
2. Bialik V, Fishman J, Katar J. et al: Clinical assessment of hip instability in the newborn by an orthopedic surgeon and a pediatrician. ) FeJuUr Orthop 1986; 6: 703- 705.
3. Ilfeld FW, Westin GW, Makin M: Missed or developmental dislocation of the hip. CIm Orthop 1986; 203:276-281.
4. Morrissy RT, Cowic GH: Congenital dislocation of the hip. Early detection and prevention «if late complications. CBn Orthop 1987; 222:79-84.
5. Dunn PM: Perinatal observations on the etiology of congenital dislocation of the hip. Clin Ormup 1976; 119:11-22.
6. Wynne-Davics R: Acetabular dysplasia and familial joint laxity: Two etiological actors in congenital dislocation of the hip. A review of 589 patients and their families. J Bone Joint Surg 1970; 52B: 704-716.
7. Saies AD, foster BK, Lcquesne GW: The value of new ultrasound stress test in assessment and treatment of clinically detected hip instability. I Pedían Orthup 1988: 8:436-441.
8. Johnson WD, Wood BP, Jackman KV: Complete infantile and congenital hip dislocation: Assessment with MR imaging. Radiology 1988: 168:151-156.
9. Tonnis D. Normal values of the hip joint for the evaluation of x-rays in children and adults-Clin Orthop1976: 119:39-47.
Risks off Hip Dysplasia