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two children with OI who had femoral neck fractures that
were successfully treated using 3.5 mm or 4.5 mm cannu-
lated screws placed under image intensifier control, sup-
plemented with a spica cast.
Tibial tubercle fractures have been reported in patients
with mild OI. Wiss and colleagues
112
noted two patients
with type I OI among a series of 15 children with dis-
placed fractures of the tibial tubercle. Frey et al.
113
described one patient with OI among a group of 19
patients with this fracture. Recently, Tamborlane et al.
114
reported the case of a 9-year-old boy who sustained bilat-
eral tibial tubercle fractures while running. Yoshino et al.
described bilateral Salter-Harris type II fractures sus-
tained by a 14-year-old boy with type I OI. Nine months
after these fractures went on to heal, the patient sustained
a displaced tibial tubercle fracture of the right knee.
There is insufficient evidence in the literature to con-
clude any association between tibial tubercle avulsions
and OI. It is possible that the coincidence is more com-
mon than recognized due to the difficulty in diagnosing
the mild form of the disorder. The treatment of a dis-
placed tibial tubercle fracture in an adolescent with OI is
generally similar to that of unaffected patients with open
reduction and internal fixation.
is prolonged, and that there was no evidence that this
would decrease non-unions. Their findings highlight the
need for weighing the risks and benefits of bisphospho-
nate therapy in each patient with OI.
Agarwal and Joseph
116
observed three non-unions
after following 135 osteotomies of the femur, tibia and
humerus. Multiple osteotomies in the same bone were
cited as a risk factor due to the potential for devascular-
ization that may arise from periosteal stripping of the
intercalary fragment. However, they observed that non-
unions in the setting of realignment osteotomies did not
present a clinical problem in their population, due to the
osseous stability afforded by the use of intramedullary
fixation using Rush rods. Consequently, their patients
with post-surgical non-union did not have pain, and did
not have diminished weight bearing or function. The
authors did not suggest further treatment to address this
type of non-union.
A persistent non-union in weight-bearing long bones
of the lower extremity can lead to bone deformity with
deformation of the intramedullary device, particularly if
the device is of small diameter, such as the male portion
of a telescoping rod system (
Figure 46.13
). In this set-
ting, removal of the device by “closed reduction” of the
non-union and bent device or by cutting of the device
through the non-union site, followed by realignment
osteotomy and repeat fixation, is the treatment of choice.
NON-UNION
Although most low-energy fractures in patients with
OI go on to heal uneventfully, some will fail to unite in
the expected timeframe. It is difficult to assess a true non-
union rate per fracture in these patients, because many
parents whose children have fractures with minimal
trauma do not seek formal medical attention. However,
non-union is more common in OI than in unaffected indi-
viduals, with particularly increased risk in patients with
Sillence type III OI. Vetter et al.
115
reported a 64% annual
incidence of pseudarthrosis in type III OI versus <15% in
types I and IV between the ages of 5 and 10 years. Both
Gamble et al.
74
and Agarwal et al.
116
found a 15-20%
prevalence of fracture non-union in heterogeneous
groups of OI patients over a 10-14-year period. Non-
unions can occur in two settings in this patient popula-
tion: after realignment osteotomy and after acute fracture.
Non-Union Following Fractures
Unlike non-unions that occur following an osteotomy,
non-unions after fractures generally present with pain
and instability. They have been noted after fracture fixa-
tion with plates
72,74
with fracture adjacent to the plate, or
in weight-bearing long bone fractures treated with inad-
equate immobilization, particularly in severely affected
patients.
74,115,116
In controlled studies, chronic bisphosphonate therapy
does not seem to increase the non-union rate in the set-
ting of acute fracture.
45,46
Non-unions following fractures
can be hypertrophic, atrophic or “gap” (associated with
segmental bone absence). Non-unions without a gap can
successfully be treated by intramedullary fixation auto-
genous bone graft.
74,106
Gamble et al.
74
had good success
treating predominantly hypertrophic non-unions with
excision of the non-union, shortening to achieve bony
apposition, placement of intramedullary fixation and
autogenous bone grafting. Gwynne-Jones
106
reported
successful treatment of an olecranon non-union with ten-
sion plating and bone grafting at 3 months post-injury.
Long-standing non-unions may lead to progressive
deformity with resultant shortening. To et al.
117
recently
reported on a case of long-standing femoral non-union
with severe angulation and shortening. They successfully
Non-Union Following Osteotomy
Non-union after osteotomy is thought to be uncom-
mon in children with OI. Munns et al.
46
demonstrated
that patients treated with pamidronate had a higher odds
ratio of non-union after osteotomy than those who did
not receive bisphosphonate. They suggested increasing
the bisphosphonate-free time around surgery, although
they acknowledged that the half-life of bisphosphonates
