Our preferred method includes fixation of the greater trochanter with
vertical wires, allowing good apposition of the trochanteric fragment,
combined with the trochanteric claw plate to increase
rigidity4.
The original incision is used to expose the greater trochanter. Once the
anterior part of the gluteus medius has been located, the vastus lateralis is
incised posteriorly with use of an inverted L-shaped incision to expose the
subtrochanteric region. The trochanter then is elevated through the nonunion
site. Dislocation of the prosthesis usually is not required. The trochanteric
fragment and its femoral bed are cleaned of all fibrous or granulation tissue
to expose bleeding cancellous bone. If satisfactory apposition of the
trochanter to its osseous bed cannot be achieved, both surfaces are shaped
with an oscillating saw to obtain adequate apposition. If the trochanter
cannot be brought down to the desired position, the fibrous tissue located
deep to the gluteus muscles is excised and the gluteus minimus is mobilized
from the ilium above the acetabular rim. In our experience, this release
usually has been sufficient to obtain good osseous contact with the hip in no
more than 20° of abduction.
Wiring Techniques
As we found the adjunctive use of vertical wires crucial to obtaining
union, different methods have been developed to pass the vertical wires.
INDICATIONS:
The indications for fixation of an ununited greater trochanter with the
trochanteric claw plate following total hip arthroplasty depend mainly on the
functional impairment and the magnitude of the proximal migration of the
trochanteric fragment. Because of the reported consequences of a migrated
ununited greater
trochanter5,6,
we developed a treatment algorithm (Fig.
7) based primarily on the degree of limp and the amount of
proximal migration. Pain is considered only when the patient has a mild
limp.
CONTRAINDICATIONS:
When dealing with uncemented femoral components, the surgeon should take
care not to compromise the stem fixation when passing the wires. In these
situations, either the wires should be placed around the femur without passing
them into the medullary canal or the plate should be used alone.
PITFALLS:
Prior to any attempt to fix the greater trochanter, especially in cases of
delayed surgery, efforts should be made to release the abductor muscles of all
fibrous tissue to facilitate placement of the greater trochanter in the
desired position without excessive tension. Abduction of the hip of up to
20° can be used to help position the fragment.
Great attention should be paid when passing the two horizontal wires that
fix the proximal part of the plate. The wires should be passed distal to the
lesser trochanter and crossed (one over the anterior claw and one over the
posterior claw) to increase compression.
Before the distal part of the plate is fixed with 4.5-mm screws, after
drilling has been performed, a tap should be used throughout the cement mantle
to avoid screw breakage. Moreover, the screw holes should be placed to avoid
direct contact with the femoral stem.
The vertical and horizontal wires used to fix the plate should be
monofilament wires to avoid the fragmentation and localized osteolysis that
have been described with use of multifilament wires.
AUTHOR UPDATE:
In the original study, some patients had been treated with the claw plate
alone. Whenever possible, we use the adjunctive vertical wires to increase the
osseous contact between the two fragments. The role of the plate is to
increase the rigidity of the fixation in order to prevent fatigue failure.
Currently, we frequently use a thicker plate with three claws. However,
this plate is not as easily bent and the anatomy of the patient should match
the plate, or the two-claw plate should be used.
In our department, the transtrochanteric approach is used routinely, for
both primary and revision surgery. When there is a substantial risk of
nonunion, such as when revision surgery is being performed
(Figs. 8-A and 8-B), or when
the patient may not be able to bear partial weight for six weeks, we use
vertical wires and a trochanteric claw plate to prevent nonunion.
This technique of fixation combining wires and a claw plate can also be
used for the treatment of a fracture of the greater trochanter following total
hip arthroplasty.
The most usual wiring technique consists of drilling two 2.6-mm holes
anterior and posterior to the femoral stem from the lateral cortex to the
medial cortex, 3 to 4 cm distal to the trochanteric bed. Two monofilament 316L
stainless-steel 12-gauge wires are passed through each of these holes. These
wires then are passed over the superior edge of the trochanteric fragment. The
ends of the anterior and posterior wires are then joined with several twists.
This maneuver replaces them in the middle of the lateral femoral cortex and
avoids cutting through the bone (Figs. 1-A,
1-B, and 1-C).
If the femoral stem is bulky or if the anterior and posterior cortices are
too thin, two anteroposterior holes can be drilled in the lateral cortex. Two
wires then are passed in each of these holes and around the medial cortex to
arise at the level of the femoral neck. Finally, they are passed over the
trochanteric fragment (Figs. 2-A,
2-B, 2-C, and
2-D).
If the lateral cortex is too thin for this technique to be used, the
diaphyseal fixation of the wires can be performed around the subtrochanteric
region. Two anterior and two posterior wires are knotted with use of a short
but tightened twist. The long ends of the wires then are passed around the
medial cortex to arise over the trochanteric fragment
(Figs. 3-A and 3-B).
Whichever wiring technique is used, the wires are knotted in the
subtrochanteric region and the twists are impacted into bone to avoid
bursitis.
Trochanteric Claw Plate Fixation
The proximal end of the trochanteric plate has two or three claws that
capture the trochanteric fragment, and the distal end has two convex flanges
that appose to the femoral cortex (Fig.
4). Each of these arms has one hole for fixation to the femur with
a 4.5-mm screw. The device is available in four sizes (70, 80, 90, and 100
mm).
The fixation is completed with use of the trochanteric claw plate according
to the following steps. The distal part of the plate should end about 4 cm
distal to the trochanteric bed. It has to be contoured to closely match the
anatomy of the femur in some patients. Two cerclage wires are then passed from
front to back around the femoral diaphysis distal to the lesser trochanter.
The claws of the plate are pushed into the thickness of the gluteus medius
tendon until they are in contact with the trochanteric fragment. One cerclage
wire is then passed over the anterior claw, and the other is passed over the
posterior claw. When the cerclage wires are tightly knotted, the obliquity of
the wires brings the claws down into close contact with the trochanteric
fragment and firmly applies the plate against the lateral cortex. The fixation
is completed with two 4.5-mm screws placed anterior and posterior to the
femoral stem (Figs. 5-A, 5-B,
6A, 6B, and 6C).
This method of rigid fixation allows immediate postoperative motion
exercises. Patients are free to walk with two supports after three days. Full
weight-bearing is delayed until union is obtained, usually after the third
postoperative month.