The patient is placed in the lateral decubitus position with the extremity
draped free on the table. No traction table or any other distraction device is
used. Intraoperative fluoroscopy or radiography is used to confirm the
appropriate osteotomy line. The skin incision
(Fig. 1) begins at the anterior
superior iliac spine and is curved downward and posteriorly for a distance of
2 cm, distal to the base of the greater trochanter, and then is curved upward
and back to the posterior superior iliac spine. The exposure is developed by
incising the gluteal fascia in the same line on the skin incision. The
anterior interval (Fig. 2)
between the tensor fasciae latae and the gluteus medius is identified and
dissection is carried out by separating the tensor fascia latae anteriorly and
the gluteus medius posteriorly, continuing distally to the greater trochanter.
Blood vessels in this interval are coagulated. A posterior dissection is
carried out by blunt digital splitting of the fibers of the gluteus maximus at
the level of the underlying posterior border of the gluteus medius muscle
(Fig. 3). The short external
rotator muscles are identified with the hip placed in internal rotation. The
piriformis, obturator internus, and gemelli are incised at their insertions,
and then the anterior and posterior borders of the gluteus medius with the
underlying gluteus minimus can be clearly visualized with and defined by the
periosteal elevators placed beneath them
(Fig. 4). After the osteotomy
line is marked, the greater trochanter is osteotomized obliquely at its base,
with care being taken to avoid injury to the femoral neck and to preserve the
insertion of the gluteus medius and minimus muscles. The greater trochanter
with its tendinous insertion is then retracted proximally to expose the entire
joint capsule (Fig. 5). The
reflected head of the rectus femoris is then incised at its insertion. The
lateral surface of the ilium extending from the anterior inferior iliac spine
to the greater sciatic notch as well as the entire superior joint capsule is
exposed with use of several Steinmann pins
(Fig. 5).
With use of fluoroscopy, a 2-mm-diameter Kirschner wire is inserted just
tangential to the superior joint capsule as a guide for the osteotomy
(Fig. 6). The dome-shaped
osteotomy line is then drawn with use of electrocautery
(Fig. 7). This line should run
just proximal to the capsular attachments. The angle of inclination for the
osteotomy line should be 10° or 20° upward in relation to the
transverse plane of the body. The dome-shaped osteotomy is performed with use
of a reciprocating power saw (Fig.
8). After the osteotomy is completed, the distal osseous fragment
is manually displaced medially and slightly posteriorly to improve lateral and
anterior femoral head coverage (Fig.
9). Two 2-mm-diameter Kirschner wires are then inserted from the
proximal part of the ilium into the ischium distally to fix the fragment in
position. Two or three cancellous screws are then inserted to reattach the
osteotomized greater trochanter (Fig.
10). The greater trochanter is advanced distally by 1 to 2.5 cm if
it is high-riding preoperatively. In hips in which a femoral valgus osteotomy
is performed simultaneously, a cable system is used for fixation of the
greater trochanter. A final check of the improvement of femoral head coverage
and the appropriate position of the greater trochanter is performed
fluoroscopically. The reflected head of the rectus femoris is sutured to the
straight head. One 3-mm suction drain is inserted, and the wound is closed in
layers.
CRITICAL CONCEPTSINDICATIONS:The performance of a Chiari pelvic osteotomy for the treatment of advanced
osteoarthritis due to hip dysplasia should be limited to patients with an age
of less than fifty years who refuse total hip arthroplasty after having
received preoperative information that a future revision arthroplasty is
likely and who accept a clinical outcome that is predicted to be less
favorable than that of total hip arthroplasty. The patient should also
understand that clinical functional improvement requires several months after
surgery.CONTRAINDICATIONS:Radiographic evidence of severe dysplasia and subluxation with a
preoperative center-edge angle of less than -10° or complete obliteration
of the joint space are contraindications to this procedure. Patients who are
unwilling to accept a clinical outcome that is inferior to that of total hip
arthroplasty also are not candidates for this procedure.PITFALLS:The osteotomy level is one of the important factors influencing the
outcome. The level of the osteotomy is considered to be appropriate when
placed between 0 and 10 mm from the superior osseous margin of the
acetabulum4.
Intraoperative use of fluoroscopy or radiographs is recommended. Chiari
emphasized that the risks of the osteotomy are more pronounced when it is
performed at too low a level because the proximal osteotomized fragment
presses ex-essively on the joint capsule, resulting in a poor
outcome1. Efforts
should be made to avoid an excessively low or high osteotomy.Sufficient displacement of the fragment for the improvement in femoral head
coverage is technically important. This also provides good acetabular bone
stock for subsequent total hip arthroplasty. A postoperative center-edge angle
of 30° to 35°, which usually requires 1.5 to 2.5 cm of medial
displacement of the distal fragment, is ideal for femoral head coverage.If the preoperative position of the greater trochanter is high-riding,
distal advancement of the trochanter to an anatomically normal position is
performed. Ideally, the proximal end of the greater trochanter should be at
the same level as the center of the femoral head.Preoperative education of the patient regarding the possibility of limited
functional improvement is necessary.AUTHOR UPDATE:In the original study, the osteotomized greater trochanter was reattached
with use of two or three metallic screws. Since January 2004, we have used
bioresorbable cancellous screws made of forged composites of hydroxyapatite
particles and polylactic acid (Super-Fixsorb; Takiron, Osaka,
Japan)5.
Bioabsorbable screws offer several advantages compared with metallic screws.
There is no need to remove the implant, problems associated with migration of
the screws can be avoided, and gradual stress transfer to the bone may permit
more complete bone-remodeling. However, poly-L-lactide screws carry a risk of
fracture when used to reattach the osteotomized greater
trochanter6. These
screws have a threaded diameter of 6.5 mm, a core diameter of 4.0 mm, an
unthreaded diameter of 4.5 mm, and a length of 35 to 70 mm. A screw-hole is
made to penetrate the medial femoral cortex with use of a 4.4-mm-diameter
drill-bit and is tapped to a threaded diameter of 6.6 mm. The screw is
inserted with use of a screwdriver so that it penetrates the medial cortex.
All screws have been inserted with a washer to increase interfragmental
compression. Three screws are routinely used. Thus far, good bone union has
been obtained within three to six months postoperatively in all hips without
displacement of the greater trochanteric fragment.
CRITICAL CONCEPTS
INDICATIONS:
The performance of a Chiari pelvic osteotomy for the treatment of advanced
osteoarthritis due to hip dysplasia should be limited to patients with an age
of less than fifty years who refuse total hip arthroplasty after having
received preoperative information that a future revision arthroplasty is
likely and who accept a clinical outcome that is predicted to be less
favorable than that of total hip arthroplasty. The patient should also
understand that clinical functional improvement requires several months after
surgery.
CONTRAINDICATIONS:
Radiographic evidence of severe dysplasia and subluxation with a
preoperative center-edge angle of less than -10° or complete obliteration
of the joint space are contraindications to this procedure. Patients who are
unwilling to accept a clinical outcome that is inferior to that of total hip
arthroplasty also are not candidates for this procedure.
PITFALLS:
The osteotomy level is one of the important factors influencing the
outcome. The level of the osteotomy is considered to be appropriate when
placed between 0 and 10 mm from the superior osseous margin of the
acetabulum4.
Intraoperative use of fluoroscopy or radiographs is recommended. Chiari
emphasized that the risks of the osteotomy are more pronounced when it is
performed at too low a level because the proximal osteotomized fragment
presses ex-essively on the joint capsule, resulting in a poor
outcome1. Efforts
should be made to avoid an excessively low or high osteotomy.
Sufficient displacement of the fragment for the improvement in femoral head
coverage is technically important. This also provides good acetabular bone
stock for subsequent total hip arthroplasty. A postoperative center-edge angle
of 30° to 35°, which usually requires 1.5 to 2.5 cm of medial
displacement of the distal fragment, is ideal for femoral head coverage.
If the preoperative position of the greater trochanter is high-riding,
distal advancement of the trochanter to an anatomically normal position is
performed. Ideally, the proximal end of the greater trochanter should be at
the same level as the center of the femoral head.
Preoperative education of the patient regarding the possibility of limited
functional improvement is necessary.
AUTHOR UPDATE:
In the original study, the osteotomized greater trochanter was reattached
with use of two or three metallic screws. Since January 2004, we have used
bioresorbable cancellous screws made of forged composites of hydroxyapatite
particles and polylactic acid (Super-Fixsorb; Takiron, Osaka,
Japan)5.
Bioabsorbable screws offer several advantages compared with metallic screws.
There is no need to remove the implant, problems associated with migration of
the screws can be avoided, and gradual stress transfer to the bone may permit
more complete bone-remodeling. However, poly-L-lactide screws carry a risk of
fracture when used to reattach the osteotomized greater
trochanter6. These
screws have a threaded diameter of 6.5 mm, a core diameter of 4.0 mm, an
unthreaded diameter of 4.5 mm, and a length of 35 to 70 mm. A screw-hole is
made to penetrate the medial femoral cortex with use of a 4.4-mm-diameter
drill-bit and is tapped to a threaded diameter of 6.6 mm. The screw is
inserted with use of a screwdriver so that it penetrates the medial cortex.
All screws have been inserted with a washer to increase interfragmental
compression. Three screws are routinely used. Thus far, good bone union has
been obtained within three to six months postoperatively in all hips without
displacement of the greater trochanteric fragment.
A femoral valgus osteotomy is performed if the femoral head is distorted
and preoperative radiographs show good congruity between the femoral head and
the acetabulum with the hip in an adducted position. The femoral osteotomy is
performed through a lateral approach in which the incision is enlarged by
adding a distal extension from the base of the greater trochanter, parallel to
the femur, for a distance of 6 to 8 cm. The femoral shaft is exposed by
detaching the vastus lateralis, and the osteotomy cut is performed with a
power saw. A laterally based triangular wedge is removed, and a 110° to
130°-angle plate is used for fixation
(Fig. 11).
Postoperative traction or cast immobilization is not used. After two weeks
of bed rest, the patient is allowed to use a wheelchair, and nonweight-bearing
walking is allowed as tolerated. Partial weight-bearing is begun four to six
weeks after surgery when a pelvic osteotomy alone has been performed and at
eight weeks when combined pelvic and femoral osteotomies have been performed.
Full weightbearing is started ten to twelve weeks postoperatively. The two
Kirschner wires are removed six weeks postoperatively with the patient under
local anesthesia.