SYMPOSIUM: DEVELOPMENTAL DYSPLASIA OF THE HIP
Neonatal Incidence of Hip Dysplasia
Ten Years of Experience
Eli Peled MD, Mark Eidelman MD, Alexander Katzman MD,
Viktor Bialik MD
Published online: 21 February 2008
? The Association of Bone and Joint Surgeons 2008
well known, but its main disadvantage is that it might lead
to overdiagnosis, which might cause overtreatment. Vari-
ations in the incidence of developmental dysplasia of the
hip are well known. We ascertained the incidence of neo-
natal sonographic developmental dysplasia of the hip
without considering the development of those joints during
followup. All 45,497 neonates (90,994 hips) born in our
institute between January 1992 and December 2001 were
examined clinically and sonographically during the first 48
hours of life. Sonography was performed according to
Graf’s method, which considers mild hip sonographic
abnormalities as Type IIa. We evaluated the different
severity type incidence pattern and its influence on the total
incidence during and between the investigated years.
According to our study, sonographic Type IIa has major
The advantages of sonographic examination are
effects on the incidence of overall developmental dysplasia
of the hip with a correlation coefficient of 0.95, whereas
more severe sonographic abnormalities show relatively
stable incidence patterns.
Level of Evidence: Level I, prognostic study. See the
Guidelines for Authors for a complete description of levels
Developmental dysplasia of the hip (DDH) is one of the
most widely discussed abnormalities in neonates. Previ-
ously termed congenital dislocation of the hip, DDH
encompasses a group of related pediatric hip disorders,
including clinical instability of the hip (neonatal or early
postnatal), with or without anatomic dysplasia, subluxa-
tion, or dislocation. The definition of DDH is a complex
and difficult issue. The question is whether all neonates
with slight hip abnormalities can be considered as having
DDH or does it apply only to those hips that will remain
pathologic if not treated. DDH etiology is obscure and
seems multifactorial. DDH is associated with genetics,
family history, female gender, skeletal abnormalities, and
hormonal and environmental factors, making the definition
of the problem difficult. Determining the incidence of DDH
based on an uncertain definition is even more difficult, and
data on the subject in the literature vary widely [15, 16, 26,
28, 29, 31].
The literature on DDH incidence and the way it is
diagnosed has changed over the years [4, 6, 27]. At the
beginning, before the introduction of routine screening
programs for detecting DDH, incidence was estimated at
0% to 40%. Until the 1980s when routine screening for
DDH was performed clinically, incidence was 0.41% to
Each author certifies that he or she has no commercial associations
(eg, consultancies, stock ownership, equity interest, patent/licensing
arrangements, etc) that might pose a conflict of interest in connection
with the submitted article.
Each author certifies that his or her institution has waived or does not
require approval for the human protocol for this investigation and that
all investigations were conducted in conformity with ethical
principles of research.
Department of Orthopedic Surgery B, Rambam Health Care
Campus, Haifa, Israel
M. Eidelman, A. Katzman, V. Bialik (&)
Pediatric Orthopedics Unit, Rambam Health Care Campus,
PO Box 9602, Haifa 31096, Israel
E. Peled, M. Eidelman, A. Katzman, V. Bialik
Bruce Rappaport Faculty of Medicine, Technion-Israel Institute
of Technology, Haifa, Israel
Clin Orthop Relat Res (2008) 466:771–775
16.8%. Since the 1980s, after the introduction of sono-
graphic techniques for investigation of pediatric hip and
neonatal screening, incidence rose to 4.4% to 52%. This
wide range of numbers is, as suggested earlier, in part
attributable to the varying definitions and diversity between
inclusion and exclusion criteria in the protocols used by
It is now widely accepted ultrasound is the most sensi-
tive method to evaluate infant hips and is sometimes even
too sensitive [4, 10, 25]. It is an excellent tool for evalu-
ating acetabular development and for followup during and
after treatment. On the other hand, it is well known that
sonographic screening of the neonatal hip, combined with
clinical examination, can lead to overdiagnosis followed by
overtreatment when not used properly [4, 10, 25]. Two
principal methods for examining the infant hip by means of
sonography have been used recently. The method of Graf
 is more static but describes the exact anatomic struc-
tures of the hip. The method of Harcke et al.  is more
dynamic, resembling clinical examination under sono-
graphic control. Patel et al.  reported most infants with
DDH have no risk factors and selective ultrasound
screening failed to show benefit.
We believe all neonates should be screened sono-
graphically and clinically examined. In the first 2-year
period of this program, we reported a sonographic inci-
dence of DDH of 5.5% . We suggested calling those
hips that underwent subsequent treatment ‘‘true DDH’’ and
this decreased the incidence to 0.5% .
We assessed 10 years of experience with clinical-sono-
graphic neonatal screening for DDH within the first 48
hours of life, without considering the development of those
joints in the following years.
Materials and Methods
Since January 1992, each neonate born at our hospital was
routinely examined clinically and sonographically for hip
abnormality within the first 48 hours of life by experienced
neonatologists (clinically) and pediatric orthopaedic sur-
geons (VB, ME) (sonographically) working independently.
From January 1993 until the end of 2001, we examined
45,497 neonates (90,994 hips) clinically and sonographi-
cally (Table 1). For this report we excluded 4620 patients
(9240 hips) in the first year we started using sonography
(1992), because some data were missing from our records
(Table 1). No other neonates were included in the study.
The sonographic investigation was performed by the
senior author (VB) or under his supervision. Since January
2000, another senior pediatric orthopaedic surgeon (ME)
performed the sonographic examinations, first under the
clinical examination by the pediatric orthopaedic surgeon
was performed only when the sonographic examination
revealed hip abnormality. We performed the clinical
examination as instituted by Ortolani  and Barlow .
and the sonographic investigation with Graf’s method [10,
11] using a 7.5-MHz transducer. Data on family history,
gender, other skeletal abnormalities, and so on, were not
evaluated, because this was not an epidemiologic study.
The sonographically abnormal hips were classified by
Graf’s classification [10, 11]. Graf’s method is based on an
exact anatomic description of the infant hip using sonog-
raphy and is divided into four major types (Types I–IV).
We considered Graf’s Types Ia and Ib as mature joints and
Type IIa as physiologically immature. For statistical pur-
poses, we considered Type IIa hips as ‘‘pathologic,’’
because they were not fully mature hips, progressing (at
least theoretically) to Type IIb or worse.
We first determined the yearly incidences of the different
DDH types per year. We evaluated the pattern of total DDH
incidence consisting of all the sonographically pathologic
hips during the investigated years. The incidence pattern of
each type was compared between the years as was the
relation and influence of each type on the total incidence.
We compared Type IIa with the other severity types (Types
IIc, D, III, IV) and their patterns through the years.
Statistical evaluation was with a ‘‘crosstabs’’ chi square.
The Pearson correlation coefficient was calculated.
In 1993, the total neonatal incidence of DDH, including
Graf Type IIa, was 5.26%, changing and decreasing
Table 1. Number of neonates and hips per year and DDH incidence
Year Number of neonatesNumber of hips DDH incidence*
1992 46209240 Excluded?
19954709 9418564 (5.99)
1996 45909180 484 (5.27)
199944118822 301 (3.41)
2000 42938586 303 (3.53)
2001 43038606 388 (4.51)
* Values are expressed as number of hips with DDH with percent in
parentheses;?data were excluded because some of the details were
missing;?total DDH incidence; DDH = developmental dysplasia of
772 Peled et al.Clinical Orthopaedics and Related Research
gradually (p \ 0.001) until it reached 3.41% in 1999
(Table 2). It increased (p = 0.08) again to 4.51% in 2001,
still lower (p\0.001) than it was in 1993. Assessing Graf
Type IIa separately, the incidence changed similarly, from
2.45% in 1993 decreasing (p = 0.01) to 1.48% in 1997 and
continuing to decrease (p = 0.003) to 1.03% in 1999. In
2000 and 2001, Type IIa incidence increased again, in
keeping with the total incidence. Nevertheless, Type IIa
incidence was still less than it was in 1993 (p\0.001). The
decrease in Type IIa incidence (p\0.001) over the years is
expressed by a linear regression line slope (Fig. 1). Sono-
graphic abnormalities other than Type IIa were stable and
did not change. Concerning Type IIa, the mean incidence
between 1993 and 1996 was 2.63%, decreasing (p\0.001)
to 1.31% in the second period. We found no changes
between the successive years except between 1996 and
1997 (p\0.013) and between 1998 and 1999 (p\0.003).
The pattern of incidence changed when comparing all
neonatal DDH with Type IIa during the investigated period
(Fig. 2). The constantly changing Type IIa incidence had a
major influence on the overall results, whereas Type IIc
and more severe sonographic hip abnormalities had
relatively stable patterns of incidence. We observed a
correlation (r = 0.95) between total incidence and Type IIa.
This study was constructed to ascertain sonographic DDH
incidence over a long period of time without considering
the later development and treatment of these hips or epi-
demiologic, demographic, or other factors. Sonography of
the pediatric hip is highly sensitive but can lead to over-
diagnosis. Using Graf’s method of sonography, even
minimal anatomic abnormalities can be detected, most of
which will not affect the later development of the hip,
which will go on to become normal. In a previous study,
we suggested overtreatment can be avoided with correct
The study was limited to assessing incidence only. We
did not ascertain any factors that might have influenced the
overall incidence of DDH or the relative incidences of the
various Graf types (eg, gender, presentation at delivery).
Table 2. Incidence of sonographic pathology distribution per year
Year Type IIa Type IIc Type DType IIIType IV
1993 239 (2.45) 159 (1.63)57 (0.58)41 (0.42) 18 (0.18)
1994 232 (2.68) 117 (1.35)49 (0.57) 16 (0.19)17 (0.20)
1995 283 (3.00) 126 (1.24)96 (1.02) 29 (0.31) 30 (0.32)
1996 221 (2.41)179 (1.95) 53 (0.58)20 (0.22) 11 (0.12)
1997 137 (1.48)143 (1.54)48 (0.52)30 (0.32)11 (0.12)
1998145 (1.54) 134 (1.42)47 (0.44) 21 (0.22)7 (0.07)
199991 (1.03) 107 (1.21)62 (0.70) 36 (0.41)5 (0.06)
2000 100 (1.16)116 (1.36) 51 (0.59)37 (0.37)4 (0.05)
2001128 (1.49)169 (1.96)46 (0.53)38 (0.44)7 (0.08)
Values are expressed as number of sonographically pathologic hips with percent in parentheses.
19931994 19951996 1997
1998 19992000 2001
Fig. 1 Sonographic incidence of Type IIa developmental dysplasia
of the hip is compared with other hip abnormalities in the assessed
period adding the regression lines, which demonstrate the pattern of
the incidence changes during the reported years.
19931994 19951996 1997
Fig. 2 The incidence of total developmental dysplasia of the hip is
compared with the incidence of Type IIa developmental dysplasia of
the hip per year adding their regression lines showing the pattern of
the changes during the reported years.
Volume 466, Number 4, April 2008Neonatal Incidence of Hip Dysplasia 773
We have no formal study to examine learning curves,
although we believe the data reflect in part a learning
Sonographic DDH incidence using Graf’s method as
reported in the literature varies between 4.44% and 51.8%
(Table 3) [2–5, 7–9, 14, 17, 18, 21–24, 27, 30]. Such inci-
dence rates differ from those reported in previous estimated
and clinical screening periods [2–5, 7–9, 14, 17, 18, 21–24,
27, 30]. and are essentially higher than what we call the true
incidence of DDH. In a previous study, we reported an
overall sonographic incidence of DDH as high as 5.51%.
From these, only 0.5% abnormal hips with sonographic
were defined as ‘‘true DDH’’ . These data confirm Bar-
low’s statement, suggesting 88% of unstable hips will
eventually become normal without treatment .
In 2000, another senior pediatric orthopaedic surgeon
(ME) joined our unit, and he performed the neonatal hip
screening, first under the supervision of the senior author.
At the beginning of 2001, he started to investigate neonatal
hip sonography independently and, to be on the safe side,
considered Type Ib hips as Type IIa. This, in our opinion,
explains the increased incidence pattern of DDH from
3.53% to 4.51% in this period based mainly on Type IIa hip
incidence changes. Our results are very similar to those
published by Toma et al.  describing the incidence of
DDH according to US investigations as 4.7% and Type IIa
incidence as 3.36%.
Our continuing study confirms our earlier contention
that the diagnosis of neonatal hip abnormalities carried out
during the first days of life are different from true DDH
incidence. They are higher but can serve as a baseline for
furtherfollowup until repeated
investigation shows a necessity for treatment.
Our data suggest the differences in the incidence pattern
of DDH during the years studied were influenced by Type
IIa and not by ‘‘changing’’ of the incidence itself. Sono-
graphic incidence of all types except Graf’s Type IIa did
not change and is close to that reported previously [4, 12].
It is well known that ultrasonographic investigation
depends on the examiner’s skill and equipment quality. We
believe the difficulties are mainly with hips associated with
mild or very mild sonographic abnormalities, defined as
Type IIa according to Graf’s classification. More severe
sonographic hip abnormalities are recognized more easily,
even by the less experienced investigator. We believe the
data suggest an understanding of mild hip sonographic
abnormality (Type IIa hips) needs a longer period of
training until the investigator achieves enough experience
in performing neonatal hip sonography.
the preparation of the manuscript and Mrs Ronit Leiba for help with
the statistical analysis. We are very grateful to the medical staff of the
Neonatal Unit who performed all the routine clinical examinations.
We thank Mrs Myrna Perlmutter for her help in
1. Barlow TG. Early diagnosis and treatment of congenital dislo-
cation of the hip. J Bone Joint Surg Br. 1962;44:292–301.
2. Baronciani D, Atti G, Andiloro F, Bartesaghi A, Gagliardi L,
Passamonti C, Petrone M. Screening for developmental dysplasia
of the hip: from theory to practice. Collaborative Group DDH
Project. Pediatrics. 1997;99:E5.
3. Bialik V, Berant M. ‘Immunity’ of Ethiopian Jews to develop-
mental dysplasia of the hip: a preliminary sonographic study.
J Pediatr Orthop B. 1997;6:253–254.
4. Bialik V, Bialik GM, Blazer S, Sujov P, Wiener F, Berant M.
Developmental dysplasia of the hip: a new approach to incidence.
5. Dorn U, Hattwich M. Initial experience using routine hip
sonography in newborn infants [in German]. Wien Klin
6. Edelstein J. Congenital dislocation of the hip in Bantu. J Bone
Joint Surg Br. 1966;48:397.
7. Exner GU. Ultrasound screening for hip dysplasia in neonates.
J Pediatr Orthop. 1988;8:656–660.
8. Falliner A, Hahne HJ, Hassenpflug J. Ultrasound screening of
neonatal hips. Monatsschr Kinderheilkd. 1996;144:1223–1229.
9. Ganger R, Grill F, Leodolter S. Ultrasound screening of the hip in
10. Graf R. Guide to Sonography of the Infant Hip. Stuttgart,
Germany: George Thieme Verlag; 1987.
11. Graf R, Tschauner C, Klapsch W. Progress in prevention of late
developmental dislocation of the hip by sonographic newborn hip
‘screening’: results of a comparative follow-up study. J Pediatr
Table 3. Sonographic incidence as reported by various studies
Dorn and Hattwich  1987 31.861866
Exner  198815.3 1230
Ganger et al. 1988 49.872582
Pauer et al. 198814.97 21,082
Szoke et al. 1988 51.854000
Hauck and Seyfert  1990323000
Lotito et al. 1990 20.7
Reibel et al.  1990 22.64290
Tonnis et al. 199032.64 5174
Rosendahl et al. 1992 20.683006
Reibel et al. 199530.52
Falliner et al.  199615.1
Baronciani et al. 1997 49.79296
Bialik and Berant  19974.44
Bialik et al.  19995.51 18,060
Toma et al. 2001 4.722,652
Kowalczyk et al. 2005 5.71944
DDH = developmental dysplasia of the hip.
774Peled et al.Clinical Orthopaedics and Related Research
12. Grill F, Muller D. Results of hip ultrasonographic screening in
Austria [in German]. Orthopade. 1997;26:25–32.
13. Harcke HT, Clarke NM, Lee MS, Borns PF, MacEwen GD.
Examination of the infant hip with real-time ultrasonography.
J Ultrasound Med. 1984;3:131–137.
14. Hauck W, Seyfert UT. Ultrasound study of the newborn hip:
results and consequences [in German]. Z Orthop Ihre Grenzgeb.
15. Klisic PJ. Congenital dislocation of the hip—a misleading term:
brief report. J Bone Joint Surg Br. 1989;71:136.
16. Kokavec M, Makai F, Maresch P. Present status of screening and
prevention of developmental dysplasia of the hip in the Slovak
Republic. J Pediatr Orthop B. 2003;12:106–108.
17. Kowalczyk B, Felus J, Kwinta P. Developmental dysplasia of the
hip: the problem in the diagnosis process in our own experience
[in Polish]. Med Wieku Rozwoj. 2005;9:395–406.
18. Lotito FM, Riccio R, Peluso M, Giustardi A. Ultrasound
screening for neonatal dysplasia of the hip. Riv Ital Pediatr.
19. Ortolani M. Congenital hip dysplasia in the light of early and very
early diagnosis. Clin Orthop Relat Res. 1976;119:6–10.
20. Patel H. the Canadian Task Force on Preventive Health Care.
Preventive health care, 2001 update: screening, management of
the hip in newborns. CMAJ. 2001;164:1669–1677.
21. Pauer M, Rossak K, Meilchen J. Hip screening of newborn
infants. Type classification, therapy and follow-up [in German].
Z Orthop Ihre Grenzgeb. 1988;126:260–265.
22. Reibel T, Herzig N, Nasir R. Neonatales Huft-Screening.
Monatsschr Kinderheilkd. 1995;143:268–273.
23. Reibel T, Nasir R, Kaeding M, Eckart L. Worsening found by
continuous observation of the hip joints in neonatal screening.
Monatsschr Kinderheilkd. 1990;138:664–669.
24. Rosendahl K, Markestad T, Lie RT. Ultrasound in the early
diagnosis of congenital dislocation of the hip: the significance of
hip stability versus acetabular morphology. Pediatr Radiol.
25. Rosendahl K, Markestad T, Lie RT. Ultrasound screening for
developmental dysplasia of the hip in neonate: the effect on treat-
ment rate and prevalence of late cases. Pediatrics. 1994;94:47–52.
26. Svec A, Kokavec M. Sonograficky skrining—moderny trend v
prevencii vyvojovej dysplazie koxy. Detsky Lekar Marec.
27. Szoke N, Kuhl L, Heinrichs J. Ultrasound examination in the
diagnosis of congenital hip dysplasia of newborns. J Pediatr
28. Tachdjian MO. Congenital dysplasia of the hip. In: Tachdjian
MO, ed. Pediatric Orthopedics. Vol 1, 2nd ed. Philadelphia, PA:
WB Saunders; 1990:297–526.
29. Toma P, Valle M, Rossi U, Bruneughi GM. Paediatric hip—
ultrasound screening for developmental dysplasia of the hip: a
review. Eur J Ultrasound. 2001;14:45–55.
30. Tonnis D, Storch K, Ulbrich H. Results of newborn screening for
CDH with and without sonography and correlation of risk factors.
J Pediatr Orthop. 1990;10:145–152.
31. Weinstein SL. Developmental hip dysplasia, dislocation. In:
Morrissy RT, Weinstein SL, eds. Lovell and Winter’s Pediatric
Orthopaedics. 4th ed. Philadelphia, PA: Lippincott-Raven; 1996:
Volume 466, Number 4, April 2008Neonatal Incidence of Hip Dysplasia 775