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CHAPTER
43
Scoliosis and Kyphosis in Osteogenesis
Imperfecta
Varun Puvanesarajah and Paul D. Sponseller
Johns Hopkins Department of Orthopaedic Surgery, Baltimore, MD, USA
INTRODUCTION
lateral radiographs, which are recommended in patients
with OI.
2
Physically, these pathologies are suspected to arise
from the weight of the cranium causing microfractures
and/or bending of underlying skeletal structures, which
are two processes that have an increased likelihood of
occurring in OI patients due to intrinsically weak bone.
3
In fact, higher incidences of basilar impression have been
observed in OI type IB and IVB, two of the more severe
subtypes that are not perinatally lethal. A review by
Sillence proposes that the increased incidence of basilar
impression in more severe OI type IV, as compared to OI
type III, may be due to development of an earlier upright
posture in patients with OI type IV.
4
This would lead to
cranial weight on the vertebral column at an earlier age.
Neurologic dysfunction is a possible effect of each
of the discussed craniovertebral junction abnormalities.
Neurologic dysfunction results from compression of the
brainstem or cerebellum, from vascular insufficiency,
and CSF low impediment.
3
Neurologic signs associated
with basilar impression or basilar invagination include
headaches (most common), ataxia (due to cerebellar
dysfunction), dysphagia, hearing problems, hypoto-
nia, trigeminal neuralgia (secondary to vertebrobasilar
artery compression) and signs associated with commu-
nicating hydrocephalus secondary to compression of the
midbrain by the dens occluding the Sylvian aqueduct.
4-6
Sudden death has also been described in patients with
basilar invagination due to rapid decompression of the
vasculature or compression of the brain stem damag-
ing the respiratory centers.
4,7
As several of these signs
and symptoms can occur with insidious onset, a careful,
periodic neurologic examination is indicated in patients
with OI.
4,6,8
Osteogenesis imperfecta (OI) is a rare congenital
disorder characterized by altered connective tissue
architecture, usually due to inherited type I collagen
mutations. OI patients present with numerous physi-
cal manifestations due to ligamentous laxity and bone
fragility. Deformities in any area of the spine may be
observed. Specific pathologies include craniocervical
junction abnormalities, scoliosis, kyphosis, osteoporotic
fractures, degenerative disc disease, spondylolisthesis,
and spondylolysis. Although this chapter will focus on
scoliosis and kyphosis, craniocervical junction abnor-
malities, spondylolysis, and spondylolisthesis will be
discussed as they can be associated with abnormal cur-
vature of the spine.
CRANIOCERVICAL JUNCTION
ABNORMALITIES
At the craniocervical junction, three main pathologies
can be found in osteogenesis imperfecta (OI) patients:
basilar invagination, basilar impression and platyba-
sia. Basilar impression is the process where the base of
the skull is deformed to the extent that upper vertebral
structures end up being positioned above the lower
border of the skull. In contrast, basilar invagination is a
state in which the atlas and dens progressively ascend
into the foramen magnum (
Figure 43.1
). Lastly, platy-
basia is abnormal flattening of the base of the skull. The
overall incidence of these pathologies in OI patients is
estimated to be around 22%.
1
Diagnosis of craniocervi-
cal junction abnormalities can be accomplished with
