Vol.2, No.5, 318-321 (2013) Case Reports in Clinical Medicine
http://dx.doi.org/10.4236/crcm.2013.25085
Etiology of the bifid (double) femoral head, with prior
history of developmental dysplasia of the hip
Leonard P. Seimon*, Christine Kohler-Ekstrand, Howard D. Dorfman
Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, USA;
*Corresponding Author: [e-mail]
Received 23 April 2013; revised 26 May 2013; accepted 3 June 2013
Copyright © 2013 Leonard P. Seimon et al. This is an open access article distributed under the Creative Commons Attribution Li-
cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Our patient presented with a double femoral
head, that is, two separate heads with individual
epiphyses, but a single contiguous metaphysis.
Two similar cases had been described in the
literature. The only common feature in these three
cases is that they had open reduction for De-
velopmental Dysplasia of the Hip (DDH) through
an anterior approach. No other pathology was
detected in these patients. A rabbit model was
created in which the cartilaginous anlage of the
rabbit femoral head was surgically split. After 2 -
4 weeks a bifid femoral head developed, mim-
icking that described in the literature. We sug-
gest that inadvertent damage to the femoral
head during surgery for DDH may in fact lead to
the development of a bifid femoral head. Prior
history of DDH should be considered when the
isolated bifid femoral head is identified.
Keywords: Bifid; Femoral Head; Etiology; Rabbit
Study
1. INTRODUCTION
Bifid femoral heads are an unusual and puzzling de-
formity. While the etiology of the deformity is unknown,
Ferguson [1], Rossman [2] and Salter [3] proposed that
since increased pressure or forced positions contribute to
the development of avascular necrosis of the hip, a tight
iliopsoas tendon, or focal necrosis through forced posi-
tions, may be responsible for the development of a bifid
femoral head. However, if a tight iliopsoas muscle is the
major factor in producing a bifid femoral head then the
condition should be common in the cerebral palsy popu-
lation. Yet it has never been described in those patients.
Variants of bifid femoral heads are described in the liter-
arure, such as seen in Perthe’s Disease and Meyer Dys-
plasia, and in a recent article by Osuji, et al. [4].
Two patients with bifid femoral heads, with prior his-
tory of surgical treatment for D.D.H. have been de-
scribed in the literature [1,2]. Ours is the third similar
case to be reported.
2. CASE REPORT
An 8-year-old girl presented for evaluation of left hip
pain. She felt this at times when walking, and also on
turning over in bed. Open reduction though an anterior
approach was performed for D.D.H. as an infant. She
walked with a mild limp, with the limb in neutral align-
ment, but ran rapidly with her limb internally rotated.
Radiographs revealed a split femoral head with a larger
anterior segment and a smaller posteromedial segment
(Figures 1 and 2). The smaller femoral head was con-
tained in the acetabulum with the hip in neutral align-
ment, and the larger head with the hip internally rotated.
This explained why she felt pain when walking, as the
smaller head was in the acetabulum. She internally ro-
tated her limb when running and had no pain, as the lar-
ger head was in the acetabulum. Intraoperatively the ili-
opsoas tendon was not significantly tight, and the labrum
was not deformed. The smaller head was excised. The
larger head was reduced by internal rotation into its most
optimal position in the acetabulum, and a derotational
osteotomy was performed with internal fixation (Figure
3). She made excellent progress. She had mild residual
shortening of the limb. She participated in sporting ac-
tivities and at 8-year follow-up, she was a cheerleader.
3. OBJECTIVE
The common thread in our patient, and the two prior
cases, is surgery at a very young age for developmental
dysplasia of the hip. We propose that the deformity may
be related to damage to the ossific nucleus of the femoral
head during surgery for DDH. We therefore devised an

L. P. Seimon et al. / Case Reports in Clinical Medici ne 2 (2013) 318-321 319
Figure 1. A-p view. Smaller head articulates in acetabulum.
Figure 2. Frog-lateral view.
Figure 3. Immediate post-excision of the smaller head, reduc-
tion of larger head and rotation osteotomy.
animal model to determine the effect of splitting the os-
sific nucleus, with a simple incision, on development of
the femoral head.
4. METHODS
Approval for the following study was received from
IRB.
Eight New Zealand White (NZW) rabbits underwent
bisection of the right femoral ossific nucleus at 13 or 15
days of age. At this ag e, the 5 mm rabbit femoral head is
visible and surgical technique is thus reproducible [5].
Through a medial approach the right cartilaginous femo-
ral head was exposed and bisected under direct visualize-
tion, and the joint capsu le and wound closed. Th e left hip
was used as the control. Radiographs of both hips were
obtained at 2 - 4 weeks intervals until the rabbits were
euthanized at maturity, around 4 months. Both femoral
heads and both respective acetabulae were resected and
inspecte d grossly and histolog i c ally.
5. RESULTS
Two anesthetic deaths reduced the sample number to
six rabbits. One had to be sacrificed before maturity be-
cause of illness. In three of the rabbits radiographs dem-
onstrated double femoral heads, and in all three the sec-
ondary femoral head articulated with a pseudo-aceta-
bulum (Figure 4). In the remaining three rabbits the op-
erated-on femoral head was normal in one, demonstrated
an elongated neck in the second and had an SCFE-like
pattern in the third. The femoral heads with their respec-
tive acetabulae were dissected. A thick joint capsule was
present around the bifid femoral heads, with a flexion
contracture in the double-headed femurs, but no tight
structures were visible.
Gross sections of each specimen revealed two truly bi-
fid femoral heads (Figure 5), with each head lined with
cartilage and separate epiphyses (Figure 6). The third
double head, suspected by radiographic evidence, was
determined to be only a spicule of bone without any car-
tilaginous surface.
Figure 4. Two separate femoral heads with respective acetabuli
in rabbit specimen.

L. P. Seimon et al. / Case Reports in Clinical Medici ne 2 (2013) 318-321
320
Figure 5. Gross specimen of double femoral heads and aceta-
buli.
Figure 6. Gross section: two femoral heads with articular car-
tilage, single physis.
Histology showed all controls to have hemispherical
heads. Two bifid femoral heads were present (Figure 7).
One of these specimens showed a couple of dead bone
spicules at the cleft site, however this was due to remod-
eling and not consistent with osteonecrosis. Another spe-
cimen showed one head with a second head-like struc-
ture, which was actually composed of compact bone with-
out a physis. The fourth specimen demonstracted an
elongated epiphysis without any scar tissue. The fifth
specimen had a widened acetabulum and the last speci-
men had irregularities in the piriformis fossa and femoral
neck with abundant scar tissue.
6. DISCUSSION
Bifurcation of the femoral head is a rare entity, with
few reports in the literature [1,2,4]. Our patient is the
third to be reported who had prior surgery for DDH. In
order to evaluate the hypothesis that surgical trauma
during surgery for DDH may be related to the develop-
Figure 7. Histology of two separate femoral heads, single phy-
sis.
ment of a bifid femoral head, an animal model was cre-
ated. A bifid femoral head was demonstrated in 2 of 6
rabbits who underwent surgical bisection of the femoral
head. Another specimen was similar on radiographic
findings, howeve r the histology revealed only on e femo-
ral head with a compact bone spicule similar to an exo-
stosis.
The question remains: why did not all of the femoral
heads become bifid post-surgery? The specimens without
pathology in the femoral head may have been caused by
surgical error. Additionally, the ossific nucleus may not
have formed in 13 - 15 days since it has been shown by
Heikel [6] that the rabbit ossific nucleus presents in only
43 of 57 animals at 6 - 10 days. Alternatively, the surgi-
cal insult may have healed and remodeled.
7. CONCLUSIONS
Bifid femoral heads can be induced by splitting the
ossific nucleus in immature rabbits. This should be kept
in mind when performing surgery around the ossific nu-
cleus in immature patients. Focal necrosis and tight sur-
rounding structures are not the etiology of the true bifid
femoral head.
In children in whom a bifid femoral head is id entified,
a history of surgery at a young age, for DDH, should be
sought.
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doi:10.1097/BPO.0b013e3181b76985