what-when-how
In Depth Tutorials and Information
Treatment of spondylolysis and spondylolisthesis in
OI patients is under-reported in the literature, although
management principles generally mirror those used in
patients with normal bone quality. As in the general pop-
ulation, conservative treatment (using periods of rest,
analgesics and orthotic support as needed) is indicated
as a starting point. Ivo et al. reported two patients with
OI and lumbar spine hyperlordosis with elongation of
lumbar pedicles resulting in spondylolisthesis.
10
Patients
did not complain of low back pain nor did they demon-
strate neurologic symptoms. A conservative treatment
strategy was adopted and no surgery was performed
despite radiographic evidence of spondylolisthesis.
Similarly, there are few reports of surgical treatment
of spondylolysis and spondylolisthesis in the litera-
ture. However, several authors have described success
with fusion procedures.
10,15
In these few cases, fusion
of involved segments with spondylolisthesis allowed
functional improvement in patients with OI. Although
surgical intervention has proven successful, treatment
strategies should be conservative with surgery only
necessary in situations where rapid progression of spi-
nal deformity takes place. For further information on
both spondylolysis and spondylolisthesis please see
Chapter 44.
dentinogenesis imperfecta is higher compared to the
incidence in patients with type I classification.3
3
Another
study observed that progression of scoliosis is signifi-
cantly correlated with the patient's body mass index
(BMI).
28
BMI plays an important role as increased weight
places more mechanical stress on vertebrae, increasing
the likelihood of vertebral deformity. The same study
observed that progression of scoliosis is inversely corre-
lated with bone mineral density, a finding confirmed by
other studies.
Vertebral body shape and attainment of motor mile-
stones represent more complex risk factors associated
with scoliosis in OI patients. A study by Ishikawa et al.
observed that the presence of six or more biconcave ver-
tebrae before puberty was a significant risk factor for
development of scoliosis. In their cohort of 44 patients,
Ishikawa et al. demonstrated that this criterion predicted
development of severe scoliosis (>50°).
23
Lastly, the age
at which key motor milestones are achieved has been
proven to be associated with scoliosis development in
OI patients. Reaching the motor milestone “supported
sitting” earlier in life was associated with a delayed inci-
dence of pathologic spine curvature independent of the
OI severity.
29-31
This may be due to superior bone quality
and spinal muscular balance in these patients.
Clinically, it is well known that scoliosis can lead to
significantly compromised pulmonary function. This
has important consequences for OI patients. A postmor-
tem study of OI patients showed that OI patients have a
higher probability of dying from respiratory disease as
compared to the general population - 81.6% of deaths
in type III OI patients were attributed to respiratory
disease, while 39% of deaths in type I and type IV OI
patients were related to respiratory disease. In compari-
son, 15.7% of deaths in the general population are related
to respiratory disease.
7
Given the increased mortality associated with respira-
tory compromise in OI patients, it is important that sco-
liosis in an OI patient is monitored to prevent a decline
in pulmonary function. A study by Widmann et al. found
that in OI patients, Cobb angles greater than 60° were
associated with a relatively large decrease in vital capac-
ity (reported vital capacities were on average 41% of the
expected value). In contrast, those OI patients with Cobb
angles below 60° had vital capacities that were main-
tained at a mean of 78% of the expected value. These
data may help inform surgeons on the necessity of surgi-
cal treatment to either halt or slow decline in pulmonary
function secondary to scoliosis. A discussion about the
possible role of surgery should occur with most patients
whose curves exceed about 50° to prevent eventual pul-
monary deterioration.
24,32
It is also important to consider
that in OI patients, respiratory function may decline as a
result of rib fractures, muscle weakness or abnormal pul-
monary collagen.
33-35
SCOLIOSIS AND KYPHOSIS
Prevalence, Risk Factors and Consequences
Scoliosis is relatively common in OI, with a reported
incidence varying between 39 and 80%.
16-21
In a pedi-
atric population, Benson et al. noted a 26% incidence of
scoliosis in children under the age of 5. This incidence
increased dramatically to as much as 82% in older chil-
dren, though not all cases are severe enough to require
treatment.
22
Other studies have confirmed that increas-
ing age is associated with an increased risk of curves
developing and progressing.
23,24
Kyphosis is also often seen in patients with OI.
Abelin et al. observed an increased thoracic kyphosis
in pediatric OI patients. This increased T1-T12 kypho-
sis was observed in the absence of significant T4-T12
change, suggesting that thoracic kyphosis observed in
OI patients may be seen more often in the upper tho-
racic spine. An increased kyphosis may be a direct result
of spine compression fractures and vertebral under-
growth.
25
Although kyphosis is generally seen in the tho-
racic and lumbar spine,
26
cervical kyphosis has also been
reported in OI.
27
Other than age, there are numerous risk factors that
predict curve development and progression. One risk
factor is the severity of disease. One study found that
the incidence of scoliosis in Sillence type III/IV with
