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https://doi.org/10.1177/18632521231152282
Journal of Children’s Orthopaedics
2023, Vol. 17(2) 97 –104
© The Author(s) 2023
DOI: 10.1177/18632521231152282
journals.sagepub.com/home/cho
JOURNAL OF
CHILDREN’S
ORTHOPAEDICS
Basic Science
Introduction
Many studies reporting increased anteversion are based
on surgical findings, anatomical specimens from still-
born infants, or infants with multiple congenital anom-
alies, including hip dislocation.1–3 Ortolani’s collection
is a unique collection of post-mortem infant specimens
that were dissected and evaluated by Ortolani, who
evaluated them to identify the cause of the “jerk sign”
or “segno dello scatto.”4 Ortolani and his son preserved
the collection until it was donated to the Institute of
Anatomy at the University of Padua in 2008.5 This
unique collection allowed the study of the anatomy of
non-teratological infant hips with varying degrees of
hip dysplasia.
1152282CHOXXX10.1177/18632521231152282Journal of Children’s OrthopaedicsHuayamave et al.
research-article2023
1 Department of Mechanical Engineering, Embry-Riddle Aeronautical
University, Daytona Beach, FL, USA
2 Department of Surgery, Oncology and Gastroenterology, University
of Padua, Padua, Italy
3 Department of Neuroscience, University of Padua, Padua,
Italy
4International Hip Dysplasia Institute, Orlando, FL, USA
5Pediatric Orthopaedics, Orlando Health, Orlando, FL, USA
Date received: 9 September 2022; accepted: 22 December 2022
Corresponding Author:
Victor Huayamave, Department of Mechanical Engineering,
Embry-Riddle Aeronautical University, 155 Lehman Engineering Center,
1 Aerospace Blvd, Daytona Beach, FL 32114, USA.
Email: huayamav@erau.edu
Femoral morphology in Ortolani’s
anatomical collection of developmental
dysplasia of the hip: Anteversion is
unrelated to severity of infantile dysplasia
Victor Huayamave1, Tamara Chambers1, Ilaria Fantoni2,
Carla Stecco3, Raffaele De Caro3, and Charles T. Price4,5
Abstract
Purpose: This study evaluated and quantified femoral anteversion and femoral head sphericity in healthy and dysplastic
hips of post-mortem infant specimens from Ortolani’s collection. Methods: Healthy hips and hips with cases of
dysplasia, with a large variety of severity, were preserved. Morphological measurements were taken on 14 specimens
(28 hips), with a mean age of 4.68 months. The degree of dysplasia was classified as mild (A) to severe (D); 11 hips were
Grade A, 6 hips were Grade B, 7 hips were Grade C, and 4 hips were Grade D. The femoral anteversion angle, the
minimum femoral head diameter, and the maximum femoral head diameter were measured. The minimum and maximum
femoral head diameters were used to estimate femoral head sphericity. Results: The mean femoral anteversion angle
was 30.81 degrees ± 11.07 degrees in cases and 29.69 degrees ± 12.69 degrees in controls. There were no significant
differences between the normal-to-mild group and moderate-to-severe group when comparing the femoral anteversion
angle (p = 0.836). The mean estimated sphericity was 1.08 mm ± 0.50 mm in cases and 0.81 mm ± 0.65 mm in controls,
with no statistically significant difference between the groups (p = 0.269). Conclusion: Ortolani’s collection showed
no significant differences between healthy and dysplastic hips in specimens under 1 year of age. While the femoral head
appeared slightly more flattened in dysplastic hips, it was not statistically significant. The findings in the unique collection
add to the knowledge of the pathoanatomy of infantile hip dysplasia. Clinical Relevance: Femoral anteversion may not
play a role in the etiology and pathogenesis of DDH.
Keywords: Ortolani’s collection, hip dysplasia, femoral anteversion
98 Journal of Children’s Orthopaedics 17(2)
The pathogenesis of developmental dysplasia of the hip
(DDH) is considered the result of both endogenous and
exogenous factors.6 Endogenous factors include primary
alterations in the joint morphology, such as acetabular dys-
morphism, excess femoral anteversion, and joint hyperlax-
ity.6 Exogenous factors consist of abnormal forces acting
on the hip in utero (i.e. oligohydramnios and feto-maternal
disproportion), during delivery (i.e. vaginal breech deliv-
ery), or after birth (i.e. swaddling).6,7 Reduced amniotic
fluid and first childbirth can be associated with increased
abdominal pressure. Breech presentation is thought to lead
to extreme hip flexion and knee extension with consequent
impairment of the fetus’s ability to move. The plasticity of
the femoral head also makes it susceptible to mechanical
factors.8 Predisposing factors include the shallow neonatal
cartilaginous acetabulum and soft tissue laxity accompa-
nying the labor and delivery process.9,10
A less understood factor is the variation of the femoral
anteversion angle. This angle at birth averages approxi-
mately 30 degrees in otherwise healthy infants and gradu-
ally decreases to an average of 10–20 degrees in
adulthood.11,12 An increase in femoral anteversion, particu-
larly when combined with increased acetabular antever-
sion, may contribute to hip instability.13 Inconsistent
findings regarding femoral anteversion have been reported
for patients with DDH. Some authors reported increased
femoral anteversion angles in patients with hip dyspla-
sia.11,13–15 Others found comparable anteversion angles
between healthy infants and children and those with
DDH.6,13,16–18 Jia et al.,13 in a computed tomography (CT)
study, found no differences in femoral anteversion angle
between healthy and dysplastic hips in Tönnis Type II and
III hips, while the anteversion angle was increased in
Tönnis Type IV dysplastic hips.
Reports of pathoanatomy of DDH have described
severe dislocations in stillborn infants or infants with addi-
tional congenital abnormalities.1–3 However, a limited
number of studies have described the femoral morphology
of otherwise healthy infants under 1 year of age. The study
seeks to add to the literature on femoral morphology in
infants with DDH by adding Ortolani’s collection to the
current state of knowledge. Therefore, the purpose of this
study was to report anatomical findings from Ortolani’s
collection. Specifically, the range of femoral anteversion
in these untreated infants was evaluated, providing the
basis for this study. Femoral head sphericity was also mea-
sured and included in this report.
Materials and methods
The specimens evaluated in this study are from infants
who died of infectious diseases, such as influenza and gas-
troenteritis, that were common in children during the pre-
antibiotic era. The specimens include healthy hips, those
with varying cases of dysplasia, ranging from mild to
severe, and those with and without hip instability.19 A total
of 14 of the 16 specimens from Ortolani’s collection were
used in the study. Two of the 16 specimens (or 4 hips) from
the collection did not meet the study’s inclusion criteria
due to poor conservation. The age of the specimens (Table
1) was estimated using measured femoral lengths and
growth charts.20,21 The calculated ages were consistent
with age-related femoral head diameter measurements in
the literature.20,22 There were 13 full-term specimens and
one pre-term specimen.
For all specimens, the degree of hip dysplasia was
assessed based on the rounding of the acetabular rim, the
acetabular shape and depth, the development of a false
acetabulum, and the morphology of the femoral head. The
specimens were independently classified by two orthope-
dic surgeons, and they were confirmed with the previous
classifications made by Ortolani. They were classified as
Grade A (normal hips), Grade B (hips with mild altera-
tions), Grade C (moderate, but clearly visible alterations),
and Grade D (severe alterations). Table 2 shows the mea-
surements used to assess normal and dysplastic hips.
Pelvic measurements were also taken from the samples for
completeness purposes (Figure 2(a)), but these measure-
ments were not used in the analysis.
The femoral anteversion angle was measured using two
different methods: the photographic method23,24 and the
Table 1. Specimen estimated age.
Specimen Femoral length (mm) Approximate age
1 – –
2 110.40 6.5 months
3 104.27 6 months
4 98.63 5 months
5 61.00 32 weeks gestation
6 99.35 5 months
7 – –
8 79.83 3 weeks
9 – –
10 110.00 6.5 months
11 90.50 3.5 months
12 94.87 4 months
13 90.46 3.5 months
14 103.10 6 months
Table 2. Femoral and acetabulum morphological
measurements.
Femur measurements Acetabulum measurements
Anteversion angle Depth
Maximum femoral head diameter Width
Minimum femoral head diameter Height
Length Anteversion angle
Inclination angle
Huayamave et al. 99
direct method.12 The anteversion angle was measured
using the photographic method in 8 of the 14 evaluated
specimens (or 16 hips). For the photographic method, the
femurs were placed on a table with both condyles in con-
tact with the table. A photograph was taken from the proxi-
mal end parallel to the shaft axis and was used to measure
femoral anteversion. The femoral anteversion angle was
expressed as the angle between the projections of the axis
of the femoral neck and the femoral condyles (Figure 1).
For 3 of the 14 specimens (or 6 hips), the anteversion
angle was measured using the direct method (i.e. a goni-
ometer). Two independent observers confirmed all femoral
anteversion measurements, and the mean value was deter-
mined. The femoral anteversion angle could not be mea-
sured for the last three specimens (six hips) because the
distal femoral condyles were absent (Figure 2(b)). The
maximum and minimum femoral head diameters were
measured using a digital caliper on all 14 specimens (28
hips) because all specimens had intact proximal femurs.9
The difference between the diameters was used to estimate
femoral head sphericity. For comparison purposes, the
specimens were then organized into two main groups. The
control group consisted of normal hips (Grade A) and hips
with mild hip dysplasia (Grade B). The cases group
included hips with moderate to severe cases of hip dyspla-
sia (Grades C and D). A summary of all measurements is
shown in Tables 3 and 4.
All statistical analysis was performed using IBM SPSS
Statistics 27.25 The study used a two-tailed independent
samples t-test, with a statistical significance set to p < 0.05,
to assess the between-group differences in the measure-
ments of the femoral anteversion angles and sphericity.
Figure 2. The width of the iliac crests (a), the left and right femurs from Specimen 1 did not have intact femoral condyles; thus,
the length of the femurs and the femoral anteversion angles were not measured (b), the acetabulum depth (c), and the acetabulum
width (d) were measured using a digital caliper.
Figure 1. A visual representation of how the femoral
anteversion angle (
θ
) was measured using a photographic
method.
Note: This is for visualization purposes only, and measurements from
the figure may not be accurate.
100 Journal of Children’s Orthopaedics 17(2)
Descriptive statistics are presented as the mean
value ± standard deviation.
Results
In this study, 28 hips with severity grades ranging
from Grade A to Grade D were assessed. The mean
estimated age of the 14 specimens (28 hips) was
4.68 months ± 1.80 months. The mean femoral anteversion
was 30.10 degrees ± 11.87 degrees. The mean minimum
and maximum femoral head diameters were
14.09 mm ± 3.65 and 15.01 mm ± 3.69, respectively. The
mean estimated femoral sphericity was 0.92 mm ± 0.60 mm.
Table 5 summarizes the measured parameters for the 14
specimens. The distribution of the femoral anteversion
angle, the minimum and maximum femoral head diameter,
and the sphericity for the cases and the controls are shown
in Figure 3.
For the femoral anteversion analysis, there were 8 hips
for the cases and 14 hips for the controls since femoral
anteversion could not be measured in 3 specimens (6 hips)
without femoral condyles. The mean femoral anteversion
angle was 30.81 degrees ± 11.07 degrees in cases (moder-
ate-to-severe group) and 29.69 degrees ± 12.69 degrees in
controls (normal-to-mild group). The femoral anteversion
angles did not show a statistically significant difference
between the two groupings based on severity (p = 0.836).
There were 11 moderate-to-severe cases and 17 normal-
to-mild hips (controls) when measuring the minimum and
maximum femoral diameters since all specimens had
intact proximal femurs. The mean maximal femoral head
diameter in the cases was 14.01 mm ± 3.75 mm compared
Table 3. Summary of the measurements for the controls.
Specimen Grade FAV (ο) D_min (mm) D_max (mm) Sphericity (mm)
2L A 17.50 17.00 17.90 0.90
2R A 11.75 16.95 17.72 0.77
4R A 42.25 13.29 14.10 0.81
5L A 14.00 4.75 4.99 0.24
6L A 21.00 16.50 18.11 1.61
6R A 12.50 16.98 18.37 1.39
10L A 37.50 16.30 16.70 0.40
10R A 24.00 16.90 17.70 0.80
11L A 32.00 10.80 11.00 0.20
13L A 33.50 14.40 14.40 0.00
14L A 38.00 13.50 15.80 2.30
1R B – 17.00 17.10 0.10
4L B 48.00 12.50 13.68 1.18
7R B – 20.60 21.40 0.80
9L B – 15.00 16.70 1.70
12R B 37.50 15.36 16.00 0.64
13R B 46.10 14.40 14.40 0.00
FAV: femoral anteversion angle; D_min: minimum femoral head diameter; D_max: maximum femoral head diameter; L: left femur; R: right femur.
Table 4. Summary of the measurements for the cases.
Specimen Grade FAV (ο) D_min (mm) D_max (mm) Sphericity (mm)
1L C – 14.10 15.60 1.50
3L C 26.60 15.46 16.77 1.31
3R C 32.90 16.15 16.57 0.42
7L C – 19.30 19.90 0.60
9R C – 14.78 15.68 0.90
11R C 32.50 10.10 11.00 0.90
12L C 38.00 14.60 15.80 1.20
5R D 10.50 7.60 8.10 0.50
8L D 22.00 7.50 9.50 2.00
8R D 46.50 9.00 9.90 0.90
14R D 37.50 13.70 15.30 1.60
FAV: femoral anteversion angle; D_min: minimum femoral head diameter; D_max: maximum femoral head diameter; L: left femur, R: right femur.
Huayamave et al. 101
to 15.65 mm ± 3.62 mm in controls. The mean minimum
femoral head diameter in the cases was 12.94 mm ± 3.83 mm
and 14.84 mm ± 3.43 mm in controls. The difference
between the maximum and minimum femoral head
diameter was 1.08 mm ± 0.50 mm in cases and
0.81 mm ± 0.65 mm in controls. The difference in spheric-
ity between cases and controls was not statistically sig-
nificant (p = 0.269).
Discussion
Ortolani’s collection is unique because of its noteworthy
number of specimens and historical value. The collection
includes the original specimens on which Professor
Ortolani studied the morphological alterations typical of
DDH and the anatomical explanation of the “segno dello
scatto,” which he pointed out as a pathognomonic “jerk
sign” of dysplastic hips. A major value of this anatomical
collection is that it includes all DDH grades instead of
focusing solely on hip dislocations. The specimens were
from babies ranging from birth to 1 year of age, which
Table 5. Summary of data: estimated age, femoral length,
femoral anteversion angle (FAV), minimum femoral head
diameter (D_min), maximum femoral head diameter (D_max),
and sphericity.
Parameter Unit Mean SD
Age Months 4.68 1.80
FAV Degrees 30.10 11.87
D_min mm 14.09 3.65
D_max mm 15.01 3.69
Sphericity mm 0.92 0.60
SD: standard deviation; FAV: femoral anteversion angle; D_min:
minimum femoral head diameter; D_max: maximum femoral head
diameter.
Figure 3. The distribution of femoral anteversion (FAV), minimum femoral head diameter (D_min), maximum femoral head
diameter (D_max), and sphericity for the cases and the controls are given.
102 Journal of Children’s Orthopaedics 17(2)
allows evaluation of the early characteristics of the
untreated condition before the onset of weight-bearing.
The specimens were from otherwise healthy babies who
died of unrelated reasons, primarily infectious diseases
common during the pre-antibiotic era, allowing DDH to be
studied without confounding factors related to associated
conditions. The collection includes the variations of typi-
cal hip dysplasia cases before intervention as a valid sub-
strate for the characterization of anatomical alterations
during the development of hip dysplasia.
Based on the findings of femoral anteversion in
Ortolani’s collection, our analysis suggests that increased
femoral anteversion is not part of the etiology or pathogen-
esis of DDH. The results also suggest that femoral antever-
sion has some individual variability in healthy and
dysplastic hips. The mean femoral anteversion angle for
all 28 hips was 30.1 degrees and showed no significant dif-
ference between moderate to severe cases (30.8 degrees)
and normal to mild cases (29.69 degrees). The results of
the femoral anteversion of Ortolani’s collection are consis-
tent with research findings of infants with DDH that are
otherwise healthy. The average values found in both
groups agree with the findings from CT scans obtained by
Edelson et al.16 In addition, Mootha et al.18 found no differ-
ences in femoral anteversion between healthy and dysplas-
tic hips in an magnetic resonance imaging (MRI) study of
children aged 12–48 months. Li et al.17 found similar
femoral anteversion between cases and controls in adult
dysplastic hips. Our results are also in agreement with
normal mean anteversion angles of 30–32 degrees reported
in the literature in infants without DDH.11,14 There are
studies where increased femoral anteversion was found in
infants,14 children,11 and adults17,26–28 with dysplastic hips.
McKibbin based his findings on a single full-term, frank
breech infant who died shortly after a difficult extraction
and found the increased femoral anteversion present in an
infant with bilateral hip dislocations.14 Fabry et al.11 found
a 17 degree increase in femoral anteversion in dysplastic
hips of children older than 1 year of age when compared
with a similar group of non-dysplastic hips. In addition,
femoral anteversion increased in subjects with unilateral
dislocation of the unaffected hip with an average value of
44.62 degrees.11 In adult dysplastic hips, Li et al.17 reported
increased femoral anteversion only for dysplastic hips
with the onset of osteoarthritis, which may play a role in
developing anomalous joint stresses.
Femoral anteversion in older infants may vary,15 which
may explain why osteotomy is no longer routinely per-
formed during an open reduction in older children. A study
of older children undergoing corrective surgery also found
increased femoral anteversion, although there was great
individual variability.15 The variability was such that the
authors cautioned that femoral derotation should only be
performed when increased anteversion was present.15
Although femoral derotation osteotomy is often part of the
surgical procedure for hip dysplasia, there is no general
agreement about its necessity. Sankar et al.15 advised an
individualized treatment with derotation osteotomy for
anteversion greater than 50 degrees. Jia et al.13 suggested
derotation osteotomy in Tönnis IV type deformities in
cases with concomitant increased acetabular anteversion
and in cases where the hip is still unstable after pelvic oste-
otomy. It is widely accepted that increased anteversion
angles of untreated dislocated hips in older children may
reflect a remodeling failure secondary to an altered hip
position.18 The gradual decline in anteversion angle from
birth to maturity is unlikely to occur when the hip remains
dislocated. Our results suggest that the increase in femoral
anteversion may be a secondary phenomenon or the result
of an increased risk of failure of reduction in infants under
1 year of age.
One explanation for the increased femoral anteversion
found in older children with dislocated hips is that
increased anteversion may interfere with successful reduc-
tion. A biomechanical model has also suggested that
increased femoral anteversion may affect the successful
reduction of dislocated infant hips.29 Hunter et al.30 sug-
gested that increased anteversion could lead to difficulty
reducing unstable hips with the Pavlik harness. The
increase in femoral anteversion in infants of walking age
may be due to an increase in anteversion that inhibits spon-
taneous or guided reduction. The spontaneous reduction of
untreated infantile dislocation has been reported along with
spontaneous improvement of stable dysplasia cases.31,32
The forces that influence the spontaneous reduction of
anteversion derive primarily from muscle by their active
contraction and elastic connective tissues. Abnormally ori-
ented muscle forces could be associated with an abnormal
anteversion angle,33 which could be another possible
explanation for the increase in anteversion in older infants.
The sphericity, or the difference between the maximum
and minimum diameters of the femoral head, is slightly
larger in cases of DDH than in normal to mild hips. This
finding suggests that dysplastic femoral heads are more
ovoidal during infancy and before treatment. However,
these findings do not explain if it is a cause or consequence
of hip dysplasia. Ortolani considered head flattening a sec-
ondary change due to impingement against the acetabular
rim during natural hip movements.34
Important limitations of this study include the small
number of examined specimens, the uncertainty of mor-
phological to clinical findings, and the absence of other-
wise healthy control specimens from the same time. This
study did not investigate the effects of intra- and inter-
observer variability, although more than one observer
confirmed the measurements. In addition, the effect of
acetabular orientation combined with femoral anteversion
was not evaluated as a potential factor for instability or
pathogenesis of hip dysplasia. Regardless of these limita-
tions, the femoral anteversion angle in Ortolani’s collection
Huayamave et al. 103
is consistent with anteversion angles found in anatomical
studies of otherwise healthy infants. Our findings suggest
that femoral anteversion alone is an unlikely factor in the
pathogenesis of hip dysplasia. Future research on infantile
hip dislocations may help determine whether the increased
prevalence of femoral anteversion found in older children
is due to failure of remodeling or whether increased ante-
version predisposes to reduction failure. Either possibility
could help explain the increased femoral anteversion found
by Jia et al.35 in Tönnis Type IV dislocations but not in
Tönnis Types I, II, or III dysplasia.
Ortolani’s anatomical collection allows a unique over-
view of the premature pathological anatomy of hip dyspla-
sia. The findings can contribute to understanding DDH in
infants and provide information on possible anatomical
alterations. Measurements on the samples identified angles
and variability of femoral anteversion that were compara-
ble with anteversion angles in otherwise healthy infants.
The increase in femoral anteversion does not appear to be
a primary pathogenic factor in the development of DDH,
and the degree of femoral anteversion varies considerably
among samples.
Author contributions
V.H. performed measurements, statistical analysis, manuscript
preparation, and study design. T.C. contributed to statistical anal-
ysis and manuscript preparation. I.F. contributed to statistical
analysis and manuscript preparation. C.S. performed measure-
ments and manuscript preparation. R.D.C. performed measure-
ments and manuscript preparation. C.P. performed measurements,
manuscript preparation, and study design.
Compliance with ethical standards
This research does not involve human participants and/or animals
(i.e. compliance with Helsinki declaration). The nature of the
article does not require any approval from Institutional Review
Board/Ethics committee.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with
respect to the research, authorship, and/or publication of this
article.
Funding
The author(s) disclosed receipt of the following financial support
for the research, authorship, and/or publication of this article:
This study was supported by the International Hip Dysplasia
Institute, USA.
Informed consent
The nature of the article does not require any consent.
ORCID iDs
Victor Huayamave https://orcid.org/0000-0003-0837-6849
Tamara Chambers https://orcid.org/0000-0003-4730-4485
Charles T. Price https://orcid.org/0000-0001-9656-7762
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