what-when-how
In Depth Tutorials and Information
the joint and lead to arthritis. Depending on the sever-
ity of OI, deformity of the femur and tibia are common
and usually result in bowing of these bones with tor-
sional deformities. Children with these deformities are
often treated with rodding procedures in an attempt to
straighten the long bones of the leg.
13
Previous fractures that have healed and resulted in a
limb deformity may be the cause of OA and may also
require correction during the procedure.
those with little deformity. Patients with mild OI and
concomitant OA of the knee have a higher risk of intra-
operative fracture than do patients without OI, which
may take unawares a surgeon who expects a routine
case. When placing a hip replacement, bone fragility
may lead to intraoperative femur or acetabular frac-
tures. The surgeon should be capable of placing a cable
around the proximal femur. The surgeon should have
a fully coated prosthesis and longer stemmed pros-
thesis as a backup in case of periprosthetic femoral
fracture. Intraoperative acetabular fracture may occur
during cup placements and final impaction. This type
of fracture may be able to be treated with supplemen-
tal screw fixation of the cup. However, plate or screw
augmentation of the acetabular fracture may be neces-
sary to achieve a stable cup. In the knee, periprosthetic
fracture is less common during surgery, but care should
be taken during implant impaction; the use of cemented
implants may be preferable. Fractures are also possible
when installing a knee replacement.
There may be substantial deformity affecting the
pelvis, femur and acetabulum that may cause major
difficulty during hip replacement. The pelvis is often
narrow and may be triradiate, there may be acetabular
protrusion and there may be a shepherd's crook defor-
mity of the femur.
14,18
Violas et al.
19
found an overall
incidence of radiographic acetabular protrusio of 33%,
with the greatest incidence (69%) found in OI type
III and 54% found in OI type V. There is often a small
distorted proximal femur with anterolateral bowing,
reported as occurring in 46% to 86% of patients.
20
It
may be important to be aware of subtle vascular ana-
tomical abnormalities before beginning complex recon-
structive surgery. Darmanis and Bircher
9
reported one
case of hypoplastic iliopectineal fascia making dissec-
tion difficult without damaging the external iliac artery,
and Ziran et al.
11
reported a case of iatrogenic injury to
the femoral vessels, which was probably related to the
small amount of perivascular connective tissue.
Difficulties also are present for knee replacement
because of bone fragility, deformity and ligamentous
laxity. The proximal femoral bone stock may be so
poor that a construct of cemented stem within a femo-
ral allograft, a recognized technique in revision hip
arthroplasty,
21
may be needed. Full-length radiographs
showing the entire femur are important to understand
the deformity and indicate where hardware is located.
Standing radiographs can be helpful in determining
alignment. Kim et al.
12
reported that torsional defor-
mity of the tibia profoundly affected implant selection
and soft tissue balancing during total knee arthroplasty
and that one patient required intraoperative custom-
izing of an all-polyethylene tibial component to match
the deformity of the tibial metaphysis.
12
AN
ESTHETIC CONSIDERATIO
NS
Depending on the severity and type of OI, anesthetic
considerations may be extremely important in a deci-
sion for surgery. Endotracheal intubation may need
fiberoptic assistance to avoid fracture of the mandible
or the cervical spine or to prevent damage to the teeth.
Preoperative radiographs of the cervical spine in flexion
and extension are needed to assess for cervical spine
instability and platybasia.
2,14
Airway anomalies and
perioperative hyperthermia should be expected and
require an experienced anesthesia team.
15
Scoliosis
and kyphoscoliosis occur in OI types III and IV and
may be mild or severe,
2
which may affect cardiac and
pulmonary function.
One study found that 10% to 30% of patients with
OI have a bleeding diathesis; interactions between
platelets and endothelium are abnormal and there is
reduced capillary strength.
16
Preoperative coagulation
studies may be normal despite the presence of coagu-
lopathy, making the prediction of blood loss difficult.9
9
Perioperative cell salvage and desmopressin therapy
may be needed. Darmanis and Bircher
9
reported a
blood loss of 1500 and 1800 ml in two acetabular frac-
ture fixation procedures without arthroplasty in
patients with OI. Liporace et al.
10
reported that an ace-
tabular fracture stabilized with arthroplasty required
6 units of packed red blood cells and 4 units of fresh
frozen plasma intraoperatively, then 2 units of packed
red blood cells postoperatively. These amounts of blood
loss are similar to those of healthy patients undergoing
acetabular surgery or revision hip arthroplasty, sug-
gesting that major surgery can be safely undertaken in
patients with OI. Abnormal manifestations of bleeding
diathesis have been reported, such as thrombocytope-
nia, petechial rash, disseminated intravascular coagula-
tion and adult respiratory distress syndrome.
17
P
REOPERATIVE PLANNING
Preoperative planning is very important for patients
with OI undergoing hip or knee replacement, even for
