Acta Paediatr 81: 177-81. 1992
Congenital dislocation of the hip: a prospective study comparing ultrasound and clinical examination K Rosendahl, T Markestad and R T Lie Departments of Diagnostic Radiology and Pediatrics, and Section ,fi>rMed. Infiirmatics and Stari.stics, University Hospital, Bergen, Norway
Rosendahl K, Markestad T , Lie RT. Congenital dislocation of the hip; a prospective study comparing ultrasound and clinical examination. Acta Paediatr 1992;81:177-81. Stockholm. ISSN 0803-5253 Screening for congenital dislocation of the hip by standard clinical methods and ultrasound was compared prospectively in 1503 newborns (1291 girls and 212 boys). A total of 82.8% of the hips (78.8Y0 of the infants) had well developed acetabulae, 14.5% (17.2% of the infants) were shallow (immature) and 2.7% (4.1Yo of the infants) were dysplastic. Within 1-3 months 96.7% of the infants with clinically stable, but immature hips normalized, while 3.3Y0 did not improve or worsened, and therapy was therefore initiated. Indications for treatment included dysplastic and/or clinically unstable hips, and a higher number of newborns were treated during the study period than in 1982-85 (31.2 vs 19.7 per 1000, p=0.0002). Thirty-seven percent of the patients had both clinical and ultrasound findings compatible with congenital dislocation of the hip, while the decision to treat was based on clinical findings alone in 25.0% and on ultrasound findings in 38.0%. Infants born during the study period of nine months had a low incidence of late congenital dislocation of the hip compared with our earlier reported results from 1982-85 (0.9 vs 3.5 per 1000, p=0.012). The study demonstrated major discrepancies between clinical and ultrasound evaluation of hips in the newborn, and the role of ultrasound in the screening for congenital disclocation of the hip requires further evaluation. 0 Clinical examination, congenital dislocation of the hip, newborns, ultrasound K Rosendahl, Department of Pediatric Radiology, Haukeland Sykehus. 5021 Bergen, Norway
Despite the introduction of clinical screening for early detection of congenital dislocation of the hip (CDH), the annual incidence of late cases has gradually increased in many western countries ( 1 - 9 , and is now commonly reported to be approximately 2 per 1000 live births in Norway (6, 7). The main reason for this increase has not yet been established, but inadequate examination techniques, lack of experience or reduced alertness on the part of the examiners have been suggested (8). On the other hand, there may be a clinically silent predislocation stage based on an anatomical abnormality which progresses to dislocation when weight-bearing begins (3, 9). Other authors emphasize the pitfalls of interpreting radiographs, hence the possibility of overdiagnosing late cases (1, 10). This may be relevant in Norway, where radiographic screening of risk groups at age 4-5 months is common practice (1, 6, 7). The complexity of CDH led to the introduction of ultrasound as an additional diagnostic tool ( I 1-16). The method has the advantages of being radiation-free and non-invasive, and has gained acceptance in many centers. Standard ultrasound criteria for initiating therapy and evaluation of the diagnostic accuracy of this method are, however, lacking (15-20). The aim of the present study was to determine the variation in ultrasound morphology in a defined population of newborn infants, to compare ultrasound features with clinical findings, and to evaluate whether
routine ultrasound examinations can reduce the incidence of late discovered CDH.
Methods The study was conducted during 1987 at the maternity hospital, University of Bergen. It was approved by the Regional Committee for Medical Research Ethics, and informed written consent was obtained from all participating mothers. The study population included all girls, and only boys with identifiable risk factors for CDH, defined as one first-degree relative, or more than one second-degree relative with CDH, breech presentation or clinical findings compatible with, or suggestive of, CDH. Infants with a birth weight less than 1500 g were excluded, and babies were not enrolled when the radiologist (KR) was on leave. Furthermore, the first 400 ultrasound examinations were performed to establish the technique, and were not included in the study. Of the 3457 live babies born between March 24 and December 31, 1503 babies were entered into the study. Sex and distribution of risk vs non-risk groups are shown in Table 1. The infants were examined clinically, once during the nursery period by one of eight physicians with at least two years' training in pediatrics. Most infants were examined within 24 h, a few within 24-48 h of delivery. Each hip was classified into one of four clinical groups: stable, unstable (significant movement, but not disloca-
178 K
Rosenduhl el ul.
ACTA PRDIATR 81 (1992)
Tuble 1. Sex and distribution of risk and non-risk groups. Risk was defined as one first-degree, o r two or more second-degree relatives with CDH, o r breech presentation. Risk*
Girls Boys
Pos. family history
Breech
Both
No risk
Total
112 19
38 36
5 3
929 60t
I084 I78
* Information regarding risk factors was missing for 207girlsand 34 boys. All were clinically normal, and all were sonographically normal (215) o r immature (26). t All were referred for ultrasound because of established or suspected instability.
months of age if they were born after breech presentation or if they had a family history of CDH. The population in this part of the country shows great geographic stability. All cases of late discovered CDH (after one month of age) have for decades been referred to one orthopedic hospital, and in the present, as in a previous local study on children born between 1980-85 ( I ) , the incidence of late CDH was calculated from the number of cases referred to this hospital. To maintain standard clinical and radiological criteria for late diagnosed CDH when comparing incidence, the late cases from 1982-85 were re-evaluated. At the conclusion of the study, the study population had reached the age of 28 to 37 months. The gamma-coefficient was used to measure the agreement between the sonographic hip categories and the extent of clinical instability, and chi-square tests for group comparisons.
table), dislocatable (completely out of the acetabulum) and dislocated. Later on the same day, an ultrasound examination was performed by one person who was unaware of the clinical findings. Babies born during weekends had an ultrasound examination on Mondays, Results resulting in a maximum interval of 48 h between clinical As judged by ultrasound examination, 82.8% of the hips and ultrasound examinations. The results of ultrasound had a normal morphological appearance, 14.5% were scannings were referred to the pediatricians the follow- physiologically immature, and 2.7% were dysplastic ing morning, and in cases of sonographic immaturity or (Table 3). A larger proportion of the girls than of the dysplasia and/or clinical pathology, one senior pediatri- selected boys had immature or dysplastic hips (Table 3). The results of the sequential clinical and ultrasound cian re-examined the hips within 24 h of the ultrasound examination. evaluations of the infants are shown in Fig. 1. Of 2929 The ultrasound examinations were performed with a hips (in 1475 babies) initially judged as stable, 463 Toschiba Sal30A, and a 5-MHz linear transducer. Two ( 1 5.8%) were re-examined because of ultrasound immacoronal scans of each hip were obtained as docu- turity or dysplasia. Twenty-six hips in 19 babies were mentation. The hips were described morphologically found to be pathological on the repeat clinical examiaccording to Graf ( 1 I), and classified into one of three nation (15 were unstable but not dislocatable, 10 were categories: mature, immature and dysplastic (Table 2). dislocatable and one was dislocated). Three of these 19 Hips which were judged to be persistently dislocatable babies would have been treated anyhow, due to a or dislocated on clinical examinations were treated with clinically abnormal contralateral hip on first examiabduction splints independent of ultrasound findings. nation. On the other hand, 44 of 77 hips (57.1%) which were Unstable, but not completely dislocatable hips were not treated if the ultrasound morphology was normal orjust judged initially to be clinically abnormal, had a sonoimmature. Hips with sonographic dysplasia were graphically normal or just physiologically immature treated even if they were clinically stable on re-exami- morphological appearance. On clinical re-examination, nation. Clinically stable, but sonographically immature 15 of these hips (in nine babies) were stable, while 29 (in hips were followed by ultrasound and clinical exami- 15 babies) were still abnormal. nations every four weeks until normal, or until progress Of the hips with persistent clinical instability, but with or failure of improvement was demonstrated, and morphologically normal or immature acetabulae, 44 of therapy therefore initiated. 53 (71%) were diagnosed correctly at the first clinical In accordance with existing practice, neonates with examination, while this was true for only 33 of 51 (65%) normal hips were referred for an X-ray of the hips at 4-5 dysplastic hips ( p = 0.03). Table 2. Sonographic classification according to morphology ( I 1). Normal Immature
Normal hips (Graf type la/b) Physiological retardation of the acetabular ossification (Graf type 2a)
Dysplastic
Acetabular maturational deficit (Graf type 2a-), critical zone hip (Graf type 2c). decentering hip (Graf type 2d) and eccentric hip (Graf type 3a/b, 4)
Table 3. Distribution of the ultrasound types for 3006 hips (1503 infants). The boys represented a selected risk group. Girls ( I % ) Mature Immature Dysplastic Total
2105 (81.5) 403 ( I 5.6) 14 (2.9) 2582 ( 100)
BOYS(%)
Total (%)
385 (90.8) 33 (7.8) 6 (1.4) 424 (100)
2490 (82.8) 436 (14.5) 80 (2.7) 3006 ( 100)
Ulirasound in the ear1.v diugnosis of CDH
ACTA P R D I A T R 81 (1992)
179
n = 3006
12t CLI Nl CAL EXAM1NATl ON
PATHOLOGICAL n =I1
STABLE n 2929
NORMAL n 2466
u. s.
CLINICAL REEXAMINATION
PATH. n=l
IMMATURE n = 416
OYSPLASTIC n=47
STABLE PATH. n = 4 0 9 n.7
STABLE PATH. n.29 n=18
NORMAL n.24
I M M ATU RE n = 20
DYSPLASTIC n =33
STABLE PATH. n=13 n=ll
STABLE PATH. n= 2 n=18
STABLE PATH. n=l n=32
Fix. 1. Results of the sequential clinical and ultrasound examinations in 1503 infants (n=number of hips, path. =pathological, including unstable. dislocatable and dislocated)
There was a close relationship between clinical findings (based on re-examination when applicable) and ultrasound morphology (gamma correlation coefficient 0.56, p < 0.0001, Table 4). However, of 1 17 hips judged to be in need of treatment (3.9% of all hips) only 50 (43%) had both clinical and ultrasound evidence of disease (Table 4). Since 31 newborns (36.9%) had bilateral disease, a total of 84 infants (76 girls and 8 boys) were treated with abduction splints from birth. This represents 28.5 per 1000 live births at the hospital during the study period. An additional eight infants (2.7 per 1000 live births) were treated from age four weeks because of lack of improvement of morphological immaturity on ultrasound, although all had normal clinical findings. A total of 3 1.2 per 1000 were thus treated. If the first clinical examination or ultrasound findings alone had been the basis for initiating treatment, the therapy rate would have been 16.6 and 23.4 per 1000, respectively. A total of 242 newborns (1 6.3%)had 361 persistently clinically stable, but physiologically immature hips, and Table 4. Association between clinical findings and ultrasound morphology (3006 hips). The clinical grading is based on the re-examination by a senior pediatrician if that result differed from the first evaluation. Infants judged to have stable hips and a normal ultrasound morphology were not re-examined clinically. Ultrasound morphology Normal
Immature
Dysplastic
2478 3 9 0
41 I
30 15 21
~~
Clinical findings Stable Unstable Dislocatable Dislocated
9 16 0
14
2 17 (90%)of these (206 girls and I 1 boys) attended the follow-up examinations. Eight girls were treated from age four weeks because of lack of improvement, the remaining 209 infants improved to normal spontaneously within 1-3 months. Two girls considered normal both clinically and by ultrasound examination in the neonatal period, developed slight, unilateral dysplasia diagnosed by routine radiography at age five and six months. One of these girls had an ultrasonographically immature hip as a newborn, but was judged to be normal after four weeks. In the unscreened population ( 1 260 boys and 182 girls) one girl was found to have slight unilateral dysplasia with subluxation as an incidental finding after presenting with symptoms of transient synovitis at age 14 months.
Discussion Whether dysplasia of the hip joint is the primary cause, and luxation its sequela (20,21), or whether dysplasia is secondary to abnormal joint laxity and dislocation (22), remains unanswered. However, in agreement with other authors ( 1 I , 23), we found that the ultrasound technique could visualize great variations in morphology of newborn hips, ranging from a well developed and mature acetabulum and a well centered femoral head, to a highly dysplastic fossa and an eccentric position of the femoral head. Since boys were only screened by ultrasound if risk factors for CDH or clinical instability was present, a true population-based distribution of ultrasound findings could only be identified for girls. Comparing our ultrasound results for girls with those of Langer (24), we
180
K Rosenduhl el ul
found a slightly higher proportion of completely normal hips (8 I .5 vs 73.7%), a smaller proportion of immature hips (15.6 vs 25.0%) and a higher proportion of dysplastic hips (2.7 vs 1.2%). Genetic variations as well as differences in interpretation of ultrasound findings may account for these discrepancies. It is remarkable that boys had a lower incidence of sonographically immature and dysplastic hips since only boys with known risk factors and/or clinically pathological hips were examined. This finding suggests that the incidence of ultrasound pathology in an unscreened newborn male population is considerably lower than that of a female population, which is in accordance with the fact that CDH is primarily a female disease (2, 3). The reported incidence of neonatal CDH ranges from 1.4 to 29 per 1000 live births (2, 3, 25). Genetic differences and variations in the definition of an unstable hip may contribute to this wide variability as may difficulties in interpreting clinical findings. The present study confirms previous observations that clinicians often judge hips differently. Unexpectedly, the detection rate of persistently unstable hips was higher on the first clinical examination for those with a normal ultrasound morphology compared with those with dysplastic hips. A possible explanation, which fits with our clinical impression from the results of this study, is that the flattened acetabular edge of the dysplastic hip may prevent the convincing palpable “clunk” described by Ortolani, and instead the examiner feels an indistinct sliding movement when the head of the femur moves out of and back into the acetabulum. In an unscreened population, approximately 0.7 to 2.2 per 1000 children will have dislocated hips in early childhood (2, 3, 25). Treatment rates, based on clinical neonatal screening, indicate substantial over-treatment or a high spontaneous cure rate. Using various dynamic ultrasound approaches, 8.2 to 35 per 1000 newborns have been judged to have CDH and in need of treatment ( 17, 18). Graf concluded that approximately 50 per 100 infants required treatment based on morphological criteria, but he did not provide true population-based data for this conclusion ( I I). Based on morphology, our study implied that 23.4 per 1000 newborns needed treatment. However, an additional 7.8 per 1000 babies were judged to have persistently dislocatable hips requiring treatment on clinical grounds despite normal ultrasound morphology. Infants horn during the study period of nine months had a low incidence of late CDH compared with our earlier reported results from 1982-85 (0.9 vs 3.5 per 1000, p = 0.0 12). The clinical diagnostic routines were similar in the two periods, but a larger number of infants were treated in the present study 31.2 vs 19.7 per 1000, p =0.0002), obviously because of the introduction of ultrasound screening. One of the three late diagnosed cases of CDH occurred in the population of 1442 infants ( 1 260 boys, 182 girls) who was not screened by ultrasound (0.7 per 1000). The vast majority of these infants
ACTA PA3DIATR 81 (1992)
were, however, at low risk for CDH. Increase in awareness and interest created by the research project may also have improved clinical diagnosis. In the present study a total of 3 1.2 per 1000 infants were treated within four weeks of age. Only 37.O‘K of the infants had clinical as well as ultrasound evidence of CDH, while the indication for treatment was based on the clinical finding of persistent dislocatable hips alone in 25.0% and on sonographic dysplasia alone in 38.0%. While the introduction of ultrasound has caused a decrease in neonatal treatment for CDH in some reports ( 1 8), we found an opposite effect, partially because we felt that persistently dislocatable hips on clinical examination could not be ignored even if ultrasound was normal. Ultrasound examination represents the first easily accessible and reliable imaging technique for studying the hip joints of newborn infants, and the present, as well as other studies, suggest that ultrasound performed by experienced personnel may become an important adjuvant in the diagnosis of CDH in newborns. The significance of various degrees of shallow acetabulae in the newborn, remains, however, to be established, and can only be determined by large, prospective studies paying careful attention to study design. Arknow/edgemenrs.-The authors thank K Maurseth, MD, for stimulating discussions and advice, Prof. E Sudmann, MD for re-evaluating some of the cases, Prof. JH Gothlin, MD, for encouraging this work, and Prof. P Bergsja, MD, and his staffat the Department ofobstetrics for their cooperation with the project.
References I . Stamnes 0.Markestad T, Hole J, Seime S. Hofteleddsluksasjon hos nyferdte. Tidsskr Nor Laegeforen 1986;106:2607-9 2. Palmen K. Sent diagnostiserad hoftledsluxation. Lakartidningen 1980;77:2786 3. Wilkinson JA. Congenital Disaplacement ofthe Hip Joint. Berlin, Heidelberg: Springer-Verlag. 1985 4. Khingberg MA, Chen R, Chemke J, Levin S. Rising rates of congenital dislocation of the hip. Lancet 1976;1:298 5 . Danielsson L, Palmen K, Sunden G, Fredin H. Medfadd hoftledsluxation-riktlinjer for behandling. Lakartidningen 1983; 80:20 6. Bjerkreim I, &Seth P. Congenital dislocation of the hip in Noway. Late diagnosis 1970-74. Acta Paediatr Scand 1978; 67:329-32 7. Hinderaker T, Reikeris 0. Kongenitt hofteleddsdysplasi i NordNorge. Tidsskr Nor Laegeforen 1988;108:2356-8 8. Jones DA. Importance of the clicking hip in screening - for congenital dislocation of the hip. Lance;1989;1:599-601 9. Cyvin KB. A follow-up study ofchildren with instability of the hip joint at birth. Acta Orthop Scand Suppl 1977;166: 10. Bowyer FM, Hoyle MD, McCall W, Evans GA. Radiological evaluation of asymmetrical limitation of hip abduction during the first year of life. Br J Radiol 1985;935-9 I I . Graf R. Sonographie der Sauglingshufte.Ein kompendiurn. 2.auflage. Stuttgart: Enke 1986 12. Zieger M. Ultrasound of the infant hip. Part 1. Pediatr Radiol 1986:16;483-87 13. Zieger M. Ultrasound of the infant hip. Part 2. Pediatr Radiol 1986:16;488-92
ACTA PRDIATR 81 (1992)
14. Zieger M, Schulz RD. Ultrasonography of the infant hip. Part 3. Pediatr Radiol 1987:17;226-32 15. Zieger M, Hilpert S. Ultrdsonography of the infant hip. Part 4. Pediatr Radiol 1987:17;470-3 16. Clarke NMP, Harcke HT. McHugh P, Lee MS, Borns PF, MacEven GD. Real-time ultrasound in the diagnosis of congenital dislocation and dysplasia of the hip. J Bone Joint Surg [Br] 1985;67-B:406-12 17. Gomes H, Menanteau B, Motte J, Robiliard P. Sonography of the neonatal hip: a dynamic approach. Ann Radiol 1987;30:503-10 18. Terjesen T, Bredland T, Eik-Nes S. Ultralydundersekelse av hofteledd hos nyfedte. Tidsskr Nor Laegeforen 1988:108;2349-5 I 19. Dahlstrem H, 0berg L, Friberg S. Sonography in CDH. Acta Orthop Scand 1986;57:402-6 20. Hilgenreiner H. Zur Fruhdiagnose und Fruhbehandlung der angeborenen Huftgelenkverrenkung. Med Klin 19252 I ;1385-88, 1425-29
Ulirusound in ihe early diugnosb of CDH
18 1
21. Hilgenreiner H. 10 Jahre Abduktionsscheine und Frubehandlung der angeborenen Huftverrenkung. Z Orthop 1935:63;344-83 22. Howorth B. Development of present knowledge of congenital displacement of the hip. Clin Orthop 1977;125:68 23. Clarke NMP, Clegg J, AI-Chalabi AN. Ultrasound screening of hips at risk for CDH. J Bone Joint Surg [Br] 1989;71:9-12 24. Langer R. Ultrasonic investigation of the hip in newborns in the diagnosis of congenital hip dislocation: classification and results of a screening program. Skeletal Radiol 1987;16:275-9 25. Asher MA. Screening for congenital dislocation of the hip, scoliosis, and other abnormalities affecting the musculosceletal system. Pediatr Clin North Am 1986;33: Received Oct. 18, 1990. Accepted April 8, 1991
Congenital dislocation of the hip: a prospective study comparing ultrasound and clinical examination K Rosendahl, T Markestad and R T Lie Departments of Diagnostic Radiology and Pediatrics, and Section ,fi>rMed. Infiirmatics and Stari.stics, University Hospital, Bergen, Norway
Rosendahl K, Markestad T , Lie RT. Congenital dislocation of the hip; a prospective study comparing ultrasound and clinical examination. Acta Paediatr 1992;81:177-81. Stockholm. ISSN 0803-5253 Screening for congenital dislocation of the hip by standard clinical methods and ultrasound was compared prospectively in 1503 newborns (1291 girls and 212 boys). A total of 82.8% of the hips (78.8Y0 of the infants) had well developed acetabulae, 14.5% (17.2% of the infants) were shallow (immature) and 2.7% (4.1Yo of the infants) were dysplastic. Within 1-3 months 96.7% of the infants with clinically stable, but immature hips normalized, while 3.3Y0 did not improve or worsened, and therapy was therefore initiated. Indications for treatment included dysplastic and/or clinically unstable hips, and a higher number of newborns were treated during the study period than in 1982-85 (31.2 vs 19.7 per 1000, p=0.0002). Thirty-seven percent of the patients had both clinical and ultrasound findings compatible with congenital dislocation of the hip, while the decision to treat was based on clinical findings alone in 25.0% and on ultrasound findings in 38.0%. Infants born during the study period of nine months had a low incidence of late congenital dislocation of the hip compared with our earlier reported results from 1982-85 (0.9 vs 3.5 per 1000, p=0.012). The study demonstrated major discrepancies between clinical and ultrasound evaluation of hips in the newborn, and the role of ultrasound in the screening for congenital disclocation of the hip requires further evaluation. 0 Clinical examination, congenital dislocation of the hip, newborns, ultrasound K Rosendahl, Department of Pediatric Radiology, Haukeland Sykehus. 5021 Bergen, Norway
Despite the introduction of clinical screening for early detection of congenital dislocation of the hip (CDH), the annual incidence of late cases has gradually increased in many western countries ( 1 - 9 , and is now commonly reported to be approximately 2 per 1000 live births in Norway (6, 7). The main reason for this increase has not yet been established, but inadequate examination techniques, lack of experience or reduced alertness on the part of the examiners have been suggested (8). On the other hand, there may be a clinically silent predislocation stage based on an anatomical abnormality which progresses to dislocation when weight-bearing begins (3, 9). Other authors emphasize the pitfalls of interpreting radiographs, hence the possibility of overdiagnosing late cases (1, 10). This may be relevant in Norway, where radiographic screening of risk groups at age 4-5 months is common practice (1, 6, 7). The complexity of CDH led to the introduction of ultrasound as an additional diagnostic tool ( I 1-16). The method has the advantages of being radiation-free and non-invasive, and has gained acceptance in many centers. Standard ultrasound criteria for initiating therapy and evaluation of the diagnostic accuracy of this method are, however, lacking (15-20). The aim of the present study was to determine the variation in ultrasound morphology in a defined population of newborn infants, to compare ultrasound features with clinical findings, and to evaluate whether
routine ultrasound examinations can reduce the incidence of late discovered CDH.
Methods The study was conducted during 1987 at the maternity hospital, University of Bergen. It was approved by the Regional Committee for Medical Research Ethics, and informed written consent was obtained from all participating mothers. The study population included all girls, and only boys with identifiable risk factors for CDH, defined as one first-degree relative, or more than one second-degree relative with CDH, breech presentation or clinical findings compatible with, or suggestive of, CDH. Infants with a birth weight less than 1500 g were excluded, and babies were not enrolled when the radiologist (KR) was on leave. Furthermore, the first 400 ultrasound examinations were performed to establish the technique, and were not included in the study. Of the 3457 live babies born between March 24 and December 31, 1503 babies were entered into the study. Sex and distribution of risk vs non-risk groups are shown in Table 1. The infants were examined clinically, once during the nursery period by one of eight physicians with at least two years' training in pediatrics. Most infants were examined within 24 h, a few within 24-48 h of delivery. Each hip was classified into one of four clinical groups: stable, unstable (significant movement, but not disloca-
178 K
Rosenduhl el ul.
ACTA PRDIATR 81 (1992)
Tuble 1. Sex and distribution of risk and non-risk groups. Risk was defined as one first-degree, o r two or more second-degree relatives with CDH, o r breech presentation. Risk*
Girls Boys
Pos. family history
Breech
Both
No risk
Total
112 19
38 36
5 3
929 60t
I084 I78
* Information regarding risk factors was missing for 207girlsand 34 boys. All were clinically normal, and all were sonographically normal (215) o r immature (26). t All were referred for ultrasound because of established or suspected instability.
months of age if they were born after breech presentation or if they had a family history of CDH. The population in this part of the country shows great geographic stability. All cases of late discovered CDH (after one month of age) have for decades been referred to one orthopedic hospital, and in the present, as in a previous local study on children born between 1980-85 ( I ) , the incidence of late CDH was calculated from the number of cases referred to this hospital. To maintain standard clinical and radiological criteria for late diagnosed CDH when comparing incidence, the late cases from 1982-85 were re-evaluated. At the conclusion of the study, the study population had reached the age of 28 to 37 months. The gamma-coefficient was used to measure the agreement between the sonographic hip categories and the extent of clinical instability, and chi-square tests for group comparisons.
table), dislocatable (completely out of the acetabulum) and dislocated. Later on the same day, an ultrasound examination was performed by one person who was unaware of the clinical findings. Babies born during weekends had an ultrasound examination on Mondays, Results resulting in a maximum interval of 48 h between clinical As judged by ultrasound examination, 82.8% of the hips and ultrasound examinations. The results of ultrasound had a normal morphological appearance, 14.5% were scannings were referred to the pediatricians the follow- physiologically immature, and 2.7% were dysplastic ing morning, and in cases of sonographic immaturity or (Table 3). A larger proportion of the girls than of the dysplasia and/or clinical pathology, one senior pediatri- selected boys had immature or dysplastic hips (Table 3). The results of the sequential clinical and ultrasound cian re-examined the hips within 24 h of the ultrasound examination. evaluations of the infants are shown in Fig. 1. Of 2929 The ultrasound examinations were performed with a hips (in 1475 babies) initially judged as stable, 463 Toschiba Sal30A, and a 5-MHz linear transducer. Two ( 1 5.8%) were re-examined because of ultrasound immacoronal scans of each hip were obtained as docu- turity or dysplasia. Twenty-six hips in 19 babies were mentation. The hips were described morphologically found to be pathological on the repeat clinical examiaccording to Graf ( 1 I), and classified into one of three nation (15 were unstable but not dislocatable, 10 were categories: mature, immature and dysplastic (Table 2). dislocatable and one was dislocated). Three of these 19 Hips which were judged to be persistently dislocatable babies would have been treated anyhow, due to a or dislocated on clinical examinations were treated with clinically abnormal contralateral hip on first examiabduction splints independent of ultrasound findings. nation. On the other hand, 44 of 77 hips (57.1%) which were Unstable, but not completely dislocatable hips were not treated if the ultrasound morphology was normal orjust judged initially to be clinically abnormal, had a sonoimmature. Hips with sonographic dysplasia were graphically normal or just physiologically immature treated even if they were clinically stable on re-exami- morphological appearance. On clinical re-examination, nation. Clinically stable, but sonographically immature 15 of these hips (in nine babies) were stable, while 29 (in hips were followed by ultrasound and clinical exami- 15 babies) were still abnormal. nations every four weeks until normal, or until progress Of the hips with persistent clinical instability, but with or failure of improvement was demonstrated, and morphologically normal or immature acetabulae, 44 of therapy therefore initiated. 53 (71%) were diagnosed correctly at the first clinical In accordance with existing practice, neonates with examination, while this was true for only 33 of 51 (65%) normal hips were referred for an X-ray of the hips at 4-5 dysplastic hips ( p = 0.03). Table 2. Sonographic classification according to morphology ( I 1). Normal Immature
Normal hips (Graf type la/b) Physiological retardation of the acetabular ossification (Graf type 2a)
Dysplastic
Acetabular maturational deficit (Graf type 2a-), critical zone hip (Graf type 2c). decentering hip (Graf type 2d) and eccentric hip (Graf type 3a/b, 4)
Table 3. Distribution of the ultrasound types for 3006 hips (1503 infants). The boys represented a selected risk group. Girls ( I % ) Mature Immature Dysplastic Total
2105 (81.5) 403 ( I 5.6) 14 (2.9) 2582 ( 100)
BOYS(%)
Total (%)
385 (90.8) 33 (7.8) 6 (1.4) 424 (100)
2490 (82.8) 436 (14.5) 80 (2.7) 3006 ( 100)
Ulirasound in the ear1.v diugnosis of CDH
ACTA P R D I A T R 81 (1992)
179
n = 3006
12t CLI Nl CAL EXAM1NATl ON
PATHOLOGICAL n =I1
STABLE n 2929
NORMAL n 2466
u. s.
CLINICAL REEXAMINATION
PATH. n=l
IMMATURE n = 416
OYSPLASTIC n=47
STABLE PATH. n = 4 0 9 n.7
STABLE PATH. n.29 n=18
NORMAL n.24
I M M ATU RE n = 20
DYSPLASTIC n =33
STABLE PATH. n=13 n=ll
STABLE PATH. n= 2 n=18
STABLE PATH. n=l n=32
Fix. 1. Results of the sequential clinical and ultrasound examinations in 1503 infants (n=number of hips, path. =pathological, including unstable. dislocatable and dislocated)
There was a close relationship between clinical findings (based on re-examination when applicable) and ultrasound morphology (gamma correlation coefficient 0.56, p < 0.0001, Table 4). However, of 1 17 hips judged to be in need of treatment (3.9% of all hips) only 50 (43%) had both clinical and ultrasound evidence of disease (Table 4). Since 31 newborns (36.9%) had bilateral disease, a total of 84 infants (76 girls and 8 boys) were treated with abduction splints from birth. This represents 28.5 per 1000 live births at the hospital during the study period. An additional eight infants (2.7 per 1000 live births) were treated from age four weeks because of lack of improvement of morphological immaturity on ultrasound, although all had normal clinical findings. A total of 3 1.2 per 1000 were thus treated. If the first clinical examination or ultrasound findings alone had been the basis for initiating treatment, the therapy rate would have been 16.6 and 23.4 per 1000, respectively. A total of 242 newborns (1 6.3%)had 361 persistently clinically stable, but physiologically immature hips, and Table 4. Association between clinical findings and ultrasound morphology (3006 hips). The clinical grading is based on the re-examination by a senior pediatrician if that result differed from the first evaluation. Infants judged to have stable hips and a normal ultrasound morphology were not re-examined clinically. Ultrasound morphology Normal
Immature
Dysplastic
2478 3 9 0
41 I
30 15 21
~~
Clinical findings Stable Unstable Dislocatable Dislocated
9 16 0
14
2 17 (90%)of these (206 girls and I 1 boys) attended the follow-up examinations. Eight girls were treated from age four weeks because of lack of improvement, the remaining 209 infants improved to normal spontaneously within 1-3 months. Two girls considered normal both clinically and by ultrasound examination in the neonatal period, developed slight, unilateral dysplasia diagnosed by routine radiography at age five and six months. One of these girls had an ultrasonographically immature hip as a newborn, but was judged to be normal after four weeks. In the unscreened population ( 1 260 boys and 182 girls) one girl was found to have slight unilateral dysplasia with subluxation as an incidental finding after presenting with symptoms of transient synovitis at age 14 months.
Discussion Whether dysplasia of the hip joint is the primary cause, and luxation its sequela (20,21), or whether dysplasia is secondary to abnormal joint laxity and dislocation (22), remains unanswered. However, in agreement with other authors ( 1 I , 23), we found that the ultrasound technique could visualize great variations in morphology of newborn hips, ranging from a well developed and mature acetabulum and a well centered femoral head, to a highly dysplastic fossa and an eccentric position of the femoral head. Since boys were only screened by ultrasound if risk factors for CDH or clinical instability was present, a true population-based distribution of ultrasound findings could only be identified for girls. Comparing our ultrasound results for girls with those of Langer (24), we
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found a slightly higher proportion of completely normal hips (8 I .5 vs 73.7%), a smaller proportion of immature hips (15.6 vs 25.0%) and a higher proportion of dysplastic hips (2.7 vs 1.2%). Genetic variations as well as differences in interpretation of ultrasound findings may account for these discrepancies. It is remarkable that boys had a lower incidence of sonographically immature and dysplastic hips since only boys with known risk factors and/or clinically pathological hips were examined. This finding suggests that the incidence of ultrasound pathology in an unscreened newborn male population is considerably lower than that of a female population, which is in accordance with the fact that CDH is primarily a female disease (2, 3). The reported incidence of neonatal CDH ranges from 1.4 to 29 per 1000 live births (2, 3, 25). Genetic differences and variations in the definition of an unstable hip may contribute to this wide variability as may difficulties in interpreting clinical findings. The present study confirms previous observations that clinicians often judge hips differently. Unexpectedly, the detection rate of persistently unstable hips was higher on the first clinical examination for those with a normal ultrasound morphology compared with those with dysplastic hips. A possible explanation, which fits with our clinical impression from the results of this study, is that the flattened acetabular edge of the dysplastic hip may prevent the convincing palpable “clunk” described by Ortolani, and instead the examiner feels an indistinct sliding movement when the head of the femur moves out of and back into the acetabulum. In an unscreened population, approximately 0.7 to 2.2 per 1000 children will have dislocated hips in early childhood (2, 3, 25). Treatment rates, based on clinical neonatal screening, indicate substantial over-treatment or a high spontaneous cure rate. Using various dynamic ultrasound approaches, 8.2 to 35 per 1000 newborns have been judged to have CDH and in need of treatment ( 17, 18). Graf concluded that approximately 50 per 100 infants required treatment based on morphological criteria, but he did not provide true population-based data for this conclusion ( I I). Based on morphology, our study implied that 23.4 per 1000 newborns needed treatment. However, an additional 7.8 per 1000 babies were judged to have persistently dislocatable hips requiring treatment on clinical grounds despite normal ultrasound morphology. Infants horn during the study period of nine months had a low incidence of late CDH compared with our earlier reported results from 1982-85 (0.9 vs 3.5 per 1000, p = 0.0 12). The clinical diagnostic routines were similar in the two periods, but a larger number of infants were treated in the present study 31.2 vs 19.7 per 1000, p =0.0002), obviously because of the introduction of ultrasound screening. One of the three late diagnosed cases of CDH occurred in the population of 1442 infants ( 1 260 boys, 182 girls) who was not screened by ultrasound (0.7 per 1000). The vast majority of these infants
ACTA PA3DIATR 81 (1992)
were, however, at low risk for CDH. Increase in awareness and interest created by the research project may also have improved clinical diagnosis. In the present study a total of 3 1.2 per 1000 infants were treated within four weeks of age. Only 37.O‘K of the infants had clinical as well as ultrasound evidence of CDH, while the indication for treatment was based on the clinical finding of persistent dislocatable hips alone in 25.0% and on sonographic dysplasia alone in 38.0%. While the introduction of ultrasound has caused a decrease in neonatal treatment for CDH in some reports ( 1 8), we found an opposite effect, partially because we felt that persistently dislocatable hips on clinical examination could not be ignored even if ultrasound was normal. Ultrasound examination represents the first easily accessible and reliable imaging technique for studying the hip joints of newborn infants, and the present, as well as other studies, suggest that ultrasound performed by experienced personnel may become an important adjuvant in the diagnosis of CDH in newborns. The significance of various degrees of shallow acetabulae in the newborn, remains, however, to be established, and can only be determined by large, prospective studies paying careful attention to study design. Arknow/edgemenrs.-The authors thank K Maurseth, MD, for stimulating discussions and advice, Prof. E Sudmann, MD for re-evaluating some of the cases, Prof. JH Gothlin, MD, for encouraging this work, and Prof. P Bergsja, MD, and his staffat the Department ofobstetrics for their cooperation with the project.
References I . Stamnes 0.Markestad T, Hole J, Seime S. Hofteleddsluksasjon hos nyferdte. Tidsskr Nor Laegeforen 1986;106:2607-9 2. Palmen K. Sent diagnostiserad hoftledsluxation. Lakartidningen 1980;77:2786 3. Wilkinson JA. Congenital Disaplacement ofthe Hip Joint. Berlin, Heidelberg: Springer-Verlag. 1985 4. Khingberg MA, Chen R, Chemke J, Levin S. Rising rates of congenital dislocation of the hip. Lancet 1976;1:298 5 . Danielsson L, Palmen K, Sunden G, Fredin H. Medfadd hoftledsluxation-riktlinjer for behandling. Lakartidningen 1983; 80:20 6. Bjerkreim I, &Seth P. Congenital dislocation of the hip in Noway. Late diagnosis 1970-74. Acta Paediatr Scand 1978; 67:329-32 7. Hinderaker T, Reikeris 0. Kongenitt hofteleddsdysplasi i NordNorge. Tidsskr Nor Laegeforen 1988;108:2356-8 8. Jones DA. Importance of the clicking hip in screening - for congenital dislocation of the hip. Lance;1989;1:599-601 9. Cyvin KB. A follow-up study ofchildren with instability of the hip joint at birth. Acta Orthop Scand Suppl 1977;166: 10. Bowyer FM, Hoyle MD, McCall W, Evans GA. Radiological evaluation of asymmetrical limitation of hip abduction during the first year of life. Br J Radiol 1985;935-9 I I . Graf R. Sonographie der Sauglingshufte.Ein kompendiurn. 2.auflage. Stuttgart: Enke 1986 12. Zieger M. Ultrasound of the infant hip. Part 1. Pediatr Radiol 1986:16;483-87 13. Zieger M. Ultrasound of the infant hip. Part 2. Pediatr Radiol 1986:16;488-92
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14. Zieger M, Schulz RD. Ultrasonography of the infant hip. Part 3. Pediatr Radiol 1987:17;226-32 15. Zieger M, Hilpert S. Ultrdsonography of the infant hip. Part 4. Pediatr Radiol 1987:17;470-3 16. Clarke NMP, Harcke HT. McHugh P, Lee MS, Borns PF, MacEven GD. Real-time ultrasound in the diagnosis of congenital dislocation and dysplasia of the hip. J Bone Joint Surg [Br] 1985;67-B:406-12 17. Gomes H, Menanteau B, Motte J, Robiliard P. Sonography of the neonatal hip: a dynamic approach. Ann Radiol 1987;30:503-10 18. Terjesen T, Bredland T, Eik-Nes S. Ultralydundersekelse av hofteledd hos nyfedte. Tidsskr Nor Laegeforen 1988:108;2349-5 I 19. Dahlstrem H, 0berg L, Friberg S. Sonography in CDH. Acta Orthop Scand 1986;57:402-6 20. Hilgenreiner H. Zur Fruhdiagnose und Fruhbehandlung der angeborenen Huftgelenkverrenkung. Med Klin 19252 I ;1385-88, 1425-29
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21. Hilgenreiner H. 10 Jahre Abduktionsscheine und Frubehandlung der angeborenen Huftverrenkung. Z Orthop 1935:63;344-83 22. Howorth B. Development of present knowledge of congenital displacement of the hip. Clin Orthop 1977;125:68 23. Clarke NMP, Clegg J, AI-Chalabi AN. Ultrasound screening of hips at risk for CDH. J Bone Joint Surg [Br] 1989;71:9-12 24. Langer R. Ultrasonic investigation of the hip in newborns in the diagnosis of congenital hip dislocation: classification and results of a screening program. Skeletal Radiol 1987;16:275-9 25. Asher MA. Screening for congenital dislocation of the hip, scoliosis, and other abnormalities affecting the musculosceletal system. Pediatr Clin North Am 1986;33: Received Oct. 18, 1990. Accepted April 8, 1991
