ORIGINAL ARTICLE
Importance of sagittal MR imaging in nontraumatic femoral
head osteonecrosis in children
Alice S. Ha
&
Lawrence Wells
&
Diego Jaramillo
Received: 31 March 2008 / Revised: 6 July 2008 /Accepted: 23 July 2008 / Published online: 19 August 2008
#
Springer-Verlag 2008
Abstract
Background In nontraumatic femoral head osteonecrosis,
characterization of femoral head collapse is important in
staging disease progression and planning treatment. Few
prior studies have quantitatively compared the ability of
sagittal and coronal MR images to detect femoral head
collapse.
Objective We hypothesized that sagittal MR images show a
greater degree and angular span of femoral head collapse
than coronal images.
Materials and methods We reviewed 38 hip MRI scans of
nontraumatic femoral head osteonecrosis from 34 pediatric
patients. In both sagittal and coronal images, the maximal
extent and angular location along with the angular span of
the femoral head collapse were measured. Differences were
evaluated using a paired t-test. The extent of bone and
cartilage loss from the femoral head was evaluated.
Results Sagittal MR images showed 29% maximal femoral
head radius collapse, whereas coronal images showed 16%
collapse (P<0.001). Sagittal images showed a larger angular
span of collapse (115°) than coronal images (55°, P<0.001).
Sagittal images showed greater epiphyseal bone loss in the
anterior than in the posterior portion (P<0.001), whereas
coronal images did not show a significant difference in
bone loss between the medial and lateral portion (P=0.32).
Conclusion Sagittal images show greater femoral head
collapse than coronal images in nontraumatic femoral head
osteonecrosis.
Keywords Femoral
.
Osteonecrosis
.
Sagittal
.
MRI
.
Children
Introduction
There are multiple risk factors for nontraumatic osteonec-
rosis of the femoral head in children including sickle cell
disease, leukemia, inherited coagulation disorders, and
corticosteroid therapy. When osteonecrosis is idiopathic, it
is termed Legg-Calvé-Perthes disease. Although multiple
staging systems have been designed to classify femoral
osteonecrosis [1, 2], there are four key common elements
that have been shown to worsen clinical outcome: (1)
presence of femoral head collapse, (2) increased size of the
necrotic segment, (3) greater amount of femoral head
depression, and (4) acetabular involvement [3]. Correct
staging of the disease is critical in clinical management of
femoral head osteonecrosis. Patients with advanced disease
and severe femoral head collapse might need total hip
joint replacement as adults. On the other hand, patients with
less collapse can benefit from medical therapy with
bisphosphonates or joint preservation surgeries such as
core decompression, vascularized fibular grafts and various
osteotomies [4, 5].
Osteonecrosis of the femoral head leading to deformity
is a three-dimensional problem. The tendency of the
Pediatr Radiol (2008) 38:1195–1200
DOI 10.1007/s00247-008-0979-6
A. S. Ha
Department of Radiology,
Hospital of the University of Pennsylvania,
Philadelphia, PA, USA
L. Wells
Department of Orthopedic Surgery,
Children’s Hospital of Philadelphia,
Philadelphia, PA, USA
D. Jaramillo (*)
Department of Radiology, Children’s Hospital of Philadelphia,
34th and Spruce Street,
Philadelphia, PA 19104, USA
e-mail: jaramillo@email.chop.edu