Abstract
Background: Most reports on the results of the Bernese
periacetabular osteotomy for the treatment of developmental dysplasia of the
hip have been by the originators of the procedure. In 1997, we began to use
this osteotomy without direct training from the originators of the
procedure.
Methods: Seventy-three patients (eighty-three hips) underwent a
Bernese periacetabular osteotomy between 1997 and 2003 and were followed
prospectively with use of the Harris hip score to assess clinical results and
with use of anteroposterior pelvic and false-profile lateral plain radiographs
to assess radiographic results. The three-dimensional position of the
acetabulum was recorded preoperatively and postoperatively. The mean duration
of follow-up was forty-six months.
Results: The average Harris hip score improved from 54 to 87 points
(p < 0.001). Three hips (three patients) had a conversion to total hip
arthroplasty at two, three, and four years after the periacetabular osteotomy.
Preoperatively, fifty-four of the eighty-three acetabula were anteverted, and
twenty-nine were either retroverted or had neutral wall relationships.
Postoperatively, sixty-five hips (78%) were anteverted. Radiographically, in
preoperatively anteverted hips, the average center-edge angle improved from
3° to 29° (p < 0.0001), the average anterior center-edge angle
improved from 5° to 31° (p < 0.0001), and the acetabular index
improved from 25° to 5° (p < 0.0001). In preoperatively retroverted
or neutral hips, the average center-edge angle improved from 13° to
33° (p < 0.0001), the average anterior center-edge angle improved from
15° to 36° (p < 0.0001), and the acetabular index improved from
19° to 2° (p < 0.0001). Complications included four hematomas,
three transient femoral nerve palsies, two deep wound infections, and one
transient sciatic nerve palsy. Nine of the ten major complications and all
four of the failed osteotomies occurred in the first thirty hips in which the
index procedure was performed.
Conclusions: In our experience, the early results of the Bernese
periacetabular osteotomy have been encouraging, with a 92% survival rate at
thirty-six months. The occurrence of complications demonstrates a substantial
learning curve. Recognition of the true preoperative acetabular version and
reorientation of the acetabulum into an appropriately anteverted position have
become important factors in surgical decision-making.
Level of Evidence: Therapeutic Level IV. See Instructions
to Authors for a complete description of levels of evidence.
Redirectional acetabular osteotomy has been performed at our institution
since the early 1970s. Prior to 1997, the favored osteotomy for patients with
developmental dysplasia and nonarthritic hips was the triple innominate
osteotomy as described by
Steel1,2.
As our nine-year follow-up showed a 27% rate of conversion to total hip
arthroplasty, substantial perioperative morbidity, and postoperative limp in
these
patients3,4,
we began to use the Bernese periacetabular osteotomy in 1997 because of its
purported advantages.
The advantages of the Bernese periacetabular osteotomy include a single
incision and osteotomies that are performed close to the joint, allowing for
large corrections of the acetabulum. In addition, the maintenance of an intact
posterior column preserves the intrinsic stability of the
pelvis5. Since the
introduction of the Bernese periacetabular osteotomy, the clinical and
radiographic results of this procedure have been reported pre-dominately by
the Berne group, by surgeons who have trained in Berne, or for small series of
patients with unusual diagnoses other than developmental dysplasia of the
hip5-29.
To our knowledge, a consecutive series of periacetabular osteotomies performed
by a single surgeon who was not trained in Berne has not been reported in the
English-language literature.
The purpose of the present report is to describe the early clinical and
radiographic results for a consecutive series of patients in whom the Bernese
periacetabular osteotomy was performed by a single surgeon for the treatment
of symptomatic acetabular dysplasia. Because the series represents our
learning curve, we wished to determine if our surgical technique, results, and
avoidance of complications improved with time. Finally, because of the recent
recognition of the importance of assessing acetabular version, we wanted to
critically examine the preoperative and postoperative three-dimensional
positions of the acetabulum in our patients.
This retrospective study was approved by our institutional review board.
Between 1997 and 2003, seventy-three patients (eighty-three hips) underwent
consecutive periacetabular osteotomies that were performed by the senior
author (C.L.P.). Although experienced in the anatomy of the pelvis and pelvic
redirectional osteotomy after having performed more than thirty Steel
innominate osteotomies, the senior author learned the periacetabular osteotomy
procedure by first assisting another surgeon who was experienced with the
procedure during multiple operations and then by performing the operation on
four cadavers with the assistance of the same experienced surgeon. The
experienced surgeon then assisted the senior author during the first several
operations in this series. In 2001, after several years of performing the
periacetabular osteotomy, further refinement and understanding of the
procedure were obtained during several visits, including those in which the
senior author assisted one of the originators of the operation during
surgery.
Follow-up data were obtained prospectively with a clinical questionnaire
and at yearly physical and radiographic examinations. The patient population
consisted of fifty-five female patients and eighteen male patients with an
average age of twenty-eight years (range, fifteen to forty-seven years). The
average height was 65 in (165 cm), and the average weight was 171 lb (78 kg).
The average body mass index was 28.5 (range, 17.1 to 33.9). Nine patients had
had at least one previous operation on the hip: four patients had had one
previous operation, and five had had multiple operations (range, two to
fifteen operations). Previous procedures included open reduction or
soft-tissue release, pinning of a slipped capital femoral epiphysis,
corrective osteotomy of the femur, and hip arthroscopy. Patients who had had a
previous pelvic osteotomy were excluded from the study. Seven female patients
and three male patients underwent a bilateral staged procedure. Forty-three
periacetabular osteotomies were performed on the right side, and forty were
performed on the left side.
The preoperative diagnosis was "classic" acetabular dysplasia
(characterized by an anteverted acetabulum with deficiency in anterior and
lateral coverage of the femoral head) in fifty-nine hips, acetabular dysplasia
with retroversion (characterized by deficient posterior coverage and relative
anterior overcoverage of the femoral head) in twenty-two hips
(Fig. 1), and acetabular
dysplasia with concomitant Legg-Calvé-Perthes disease in two hips. A
periacetabular osteotomy alone was performed in sixty-nine hips, a
periacetabular osteotomy with a varus proximal femoral osteotomy was performed
in eleven, a periacetabular osteotomy with a valgus proximal femoral osteotomy
was performed in two, and a periacetabular osteotomy with relative femoral
neck lengthening was performed in one.
All patients in our series had a preoperative magnetic resonance imaging
study. In addition, magnetic resonance arthrography has been utilized
routinely by us since 2001 to facilitate the diagnosis of labral or chondral
injury.
Operative Procedure
The Bernese periacetabular
osteotomy5,7-9
was performed through a modified Smith-Petersen approach with the patient
lying in the supine position on a radiolucent table. The abductor muscles were
left intact on the lateral aspect of the ilium. Image intensification was used
for the ischial, pubic, and iliac osteotomies as well as for confirmation of
final acetabular positioning and fixation.
Judgment of final acetabular positioning was performed by first adjusting
the angle of the image intensifier to ensure that the tip of the coccyx was 2
to 5 cm cephalad to the symphysis pubis and the rotation of the pelvis was
neutral. Superolateral coverage and anteversion were then estimated with
two-plane image intensification. Our radiographic criteria for optimum
placement of the osteotomized acetabulum were a horizontal sourcil and
appropriate acetabular anteversion, manifested by a posterior wall extending
lateral to the center of the femoral head and an anterior wall extending
medial to the center of the femoral head
(Fig. 1). Since the
preoperative version of the acetabulum was different for each patient, the
optimum placement of the osteotomized acetabular fragment was individualized.
Fixation was accomplished with three, four, or five large or small-fragment
cortical screws.
A combined general and epidural anesthetic was administered during
seventy-two of the eighty-three procedures. The mean estimated blood loss was
715 mL (range, 100 to 2500 mL). No drains were used. The anticoagulation
regimen included enoxaparin and compression boots. The administration of
enoxaparin was avoided for twelve hours before removal of the epidural
catheter and was delayed by at least four hours after removal of the epidural
catheter. At the time of discharge from the hospital, patients were managed
with aspirin for six weeks. Partial weight-bearing with two crutches was
encouraged for six weeks, and then full weight-bearing with one crutch or a
cane was encouraged for six weeks until walking could be accomplished without
a limp (generally at three months).
Prior to 2001, arthrotomy of the hip was performed only when preoperative
magnetic resonance imaging revealed evidence of acetabular labral abnormality.
Beginning in 2001, with the thirty-fourth case of our series, arthrotomy of
the hip was performed routinely. Overall, arthrotomy of the hip was performed
in conjunction with periacetabular osteotomy in forty-nine hips (59%). Partial
labral excision was performed in eleven hips, and an osteochondroplasty of the
femoral head-neck junction was performed to improve femoral head-neck offset
in thirty-five hips. Osteochondroplasty was performed if there was abutment of
the femoral head-neck junction against the newly positioned anterior
acetabular rim with =90° of hip flexion and =20° of internal
rotation of the femur or if there was obvious overgrowth at the femoral
head-neck junction resulting in loss of normal head-neck offset.
Clinical Evaluation
The Harris hip score was determined preoperatively, at six months and one
year postoperatively, and yearly thereafter. A physician assistant (J.A.E.)
who is a member of our adult reconstruction service performed the clinical
evaluations.
Radiographic Evaluation
The preoperative, six-week, six-month, and yearly postoperative radiographs
included an anteroposterior pelvic and false-profile lateral radiograph for
all patients. A preoperative radiograph made with the hip in abduction and
internal rotation was made to assess whether a concentric reduction of the
femoral head could be
achieved4.
Radiographs were evaluated by measuring the acetabular
index4, the
center-edge
angle30, the
anterior center-edge
angle4, and the
acetabular angle of
Sharp4.
Radiographs also were evaluated for congruence of the femoral head in the
acetabulum as well as for acetabular rim changes such as sclerosis and/or cyst
formation. Beginning in 2001, the orientation of the acetabulum was routinely
assessed for anteversion, retroversion, or neutral wall relationships
preoperatively and postoperatively as described by Ganz et
al.15,25,31.
The presence of osteoarthritis was graded on all radiographs according to
the criteria of
Tönnis32. The
presence of any iliac, ischial, and pubic nonunions also was recorded on the
yearly postoperative radiographs. The radiographic evaluation was performed by
a physician assistant (J.A.E.).
Statistical Methods
All data were analyzed with use of a commercially available software
package (FileMaker Pro 7.0 [FileMaker, Santa Clara, California] and Microsoft
Excel [Microsoft, Redmond, Washington]). Comparisons were performed with use
of the Student t test. The level of significance was set at p = 0.05.
Kaplan-Meier survival analysis was performed by an independent statistician,
with revision of the osteotomy or conversion to total hip arthroplasty as the
end point.
Clinical Results
The mean duration of follow-up was forty-six months (range, thirty to
eighty-eight months). The mean Harris hip score improved from 54 (range, 20 to
81) preoperatively to 86 (range, 49 to 100) at one year (p < 0.001) and to
87 (range, 49 to 100) at the time of the most recent follow-up (p < 0.001).
The mean Harris hip score for the patients with a preoperatively anteverted
acetabulum improved from 55 (range, 20 to 80) preoperatively to 87 (range, 49
to 100) at the time of the most recent follow-up (p < 0.001). The mean
Harris hip score for the patients with a retroverted or neutral acetabulum
improved from 54 (range, 25 to 76) preoperatively to 88 (range, 49 to 100) at
the time of the most recent follow-up (p < 0.001).
Complications included three transient femoral nerve palsies, one transient
sciatic nerve palsy, four hematomas, and two deep infections. In one patient,
an osteotome tip broke within the ischium and was left in place. The patient
remained asymptomatic. Two of the three femoral nerve palsies completely
resolved within the first year; the third patient with this complication had
residual weakness and numbness. The patient with the sciatic nerve palsy did
not have symptoms preoperatively and remained mildly symptomatic with painful
numbness but full motor function at the time of the most recent follow-up. The
four hematomas were treated with irrigation and débridement. The two
deep infections were treated with irrigation and dé-bridement and six
weeks of intravenous antibiotics.
Four hips in four patients were considered to have had a failure, defined
as conversion to total hip arthroplasty or revision osteotomy. Three hips had
a conversion to total hip arthroplasty at two, three, and four years
postoperatively because of pain and continued arthritic degeneration. Two of
these three hips had undergone irrigation and débridement, one because
of a hematoma and one because of a deep infection. The fourth patient who had
a failure underwent revision periacetabular osteotomy (performed by another
surgeon) because of pain and femoroacetabular impingement. All four of these
hips were among the first thirty hips in our group that underwent the index
procedure.
Kaplan-Meier analysis revealed a survival rate of 92% at thirty-six months
with revision periacetabular osteotomy or conversion to total hip arthroplasty
as the end point (Fig. 2).
In the last fifty-three hips that underwent the index procedure, there was
only one complication (a transient femoral nerve palsy), which did not
adversely affect an eventual good outcome. Thirteen femoral osteotomies were
performed in combination with our first forty-one periacetabular osteotomies,
and only one was performed in combination with our most recent forty-two
periacetabular osteotomies.
Radiographic Results
All eighty-three hips had complete preoperative, postoperative, and
follow-up radiographs. Preoperatively, fifty-four acetabula were anteverted
and twenty-nine were retroverted or had neutral wall relationships. The
preoperative and postoperative acetabular wall relationships are shown in
Table I. Improvements in the
various radiographic indices are shown in
Table II.
The integrity of the Shenton line was broken in thirty-five of the
eighty-three hips preoperatively, and it remained broken in thirty-seven hips
postoperatively. The femoral head was not concentrically located in the
acetabulum in thirty-seven of the eighty-three hips preoperatively, whereas
only four hips exhibited a nonconcentric reduction postoperatively. Two of
these hips (one in a patient with spastic cerebral palsy and the other in a
patient with an aspherical femoral head) went on to subsequent total hip
arthroplasty. The latter two patients continued to function well.
Radiographic evidence of osteoarthritis, as graded on the Tönnis
scale, did not progress in fifty-eight of the eighty-three hips. Twenty-three
hips had one grade of progression, and three had two grades of progression. In
the three patients who went on to have a total hip arthroplasty, one had one
grade of progression and two had two grades of progression (from I to III)
before undergoing arthroplasty at three or four years postoperatively.
Ten nonunions of the pubis and one nonunion of the ischium were diagnosed
radiographically. The one hip with an ischial nonunion also had a pubic
nonunion and underwent a second operation for additional bone-grafting and
fixation, with eventual union of both sites. Eight of the remaining nine pubic
nonunions were asymptomatic at the time of the most recent follow-up, and most
were in hips with large corrections. One of these nine pubic nonunions was
symptomatic, but the patient did not wish to undergo a reoperation.
Our early results with the Bernese periacetabular osteotomy are of interest
because none of the authors trained directly in Berne and the series
represents our learning curve with what is considered to be a technically
difficult
operation5,7-9,33.
Moreover, during this series, we incorporated newer knowledge into our
evaluation and treatment regimen. For example, there recently has been
increased recognition that the acetabulum may be retroverted or in neutral
version in many patients with developmental
dysplasia15,16,25,27,31.
The prevalence of acetabular retroversion in our series is similar to that in
the recent studies by Li and Ganz (232 hips) and Mast et al. (153 hips), who
reported that as many as one-third of hips that underwent periacetabular
osteotomy were preoperatively
retroverted15,16.
We now recognize the importance of determining the version of the acetabulum
preoperatively and restoring normal anteversion with the osteotomy if
possible. In addition, during the time of our series, there was increased
recognition of the importance of concomitant labral abnormalities and
descriptions of conditions that predispose the hip to femoroacetabular
impingement27,34.
Over the seven-year period of this series, we substantially changed our
preoperative and intraoperative approach to identify and treat these problems
as part of the periacetabular osteotomy procedure.
Beginning in 2001, critical analysis of the anterior and posterior
acetabular wall relationships and recognition of the presence of
femoroacetabular impingement became an important part of our preoperative
evaluation and intraoperative plan. Our surgical goal for all periacetabular
osteotomies is to place the acetabular fragment in an appropriately anteverted
position and to improve femoral head-neck offset by means of
osteochondroplasty of the femoral head-neck junction. Importantly, in hips
with anteversion, which typically have a combined anterolateral deficiency of
coverage, we correct the acetabular fragment to produce a horizontal sourcil
with an anterior wall that is medial to the posterior wall of the acetabulum
as seen on an anteroposterior radiograph of the pelvis
(Fig. 1). In our series,
fifty-four hips were anteverted preoperatively and 74% (forty) of these
fifty-four hips were correctly positioned into anteversion
postoperatively.
We correct the retroverted acetabulum, which typically has a deficiency of
posterior coverage, relative anterior over-coverage, and a relatively
horizontal sourcil, by moving the posterior wall lateral to the center of the
femoral head with corresponding medial movement of the anterior wall while
maintaining a horizontal sourcil. This anteversion maneuver improves anterior
hip clearance, which may reduce the potential for femoroacetabular
impingement. A retroverted acetabulum typically does not require enhancement
of lateral acetabular coverage.
Postoperatively, twenty-five (86%) of the twenty-nine hips in our series
that were retroverted or neutral preoperatively were correctly repositioned
into anteversion. As we gained experience and were able to incorporate newer
knowledge into our treatment regimen, we were able to more accurately redirect
the acetabulum. Seventeen of the eighteen hips that were under-corrected, that
is, those that had neutral wall relationships or acetabular retroversion on
postoperative radiographs, were among the first thirty-four hips that
underwent the index procedure. Only one of the last forty-nine hips to undergo
the procedure was left in a retroverted or neutral position. This latter hip
was in a patient who had spastic cerebral palsy and had undergone multiple
previous hip operations. Overall, as emphasized by Siebenrock et
al.27, a more
thorough preoperative identification of the true three-dimensional position of
the acetabulum has improved our ability to balance the dysplastic
horseshoe-shaped acetabulum over the femoral head.
In the original description of the operation from the Berne group, most
complications occurred in the first twenty hips that underwent the
procedure5,28.
Our data also reflect such a learning curve as all of the hips that had a
failure were among the first thirty that underwent the procedure. Similarly,
nine of the ten major complications, including transient femoral nerve palsy
(two hips), sciatic nerve palsy (one hip), postoperative hematoma (four hips),
and deep infection (two hips), occurred in the first thirty hips that
underwent the procedure, while only one major complication occurred in the
subsequent fifty-three hips that underwent the procedure. Furthermore,
thirteen concomitant proximal femoral osteotomies were performed in the first
forty-one hips that underwent the procedure, but only one femoral osteotomy
was performed in the last forty-two hips that underwent the procedure. This
finding reflects our increased level of comfort and ability to correct the
dysplastic deformity with acetabular reorientation alone.
Eleven (22%) of the forty-nine hips in which an arthrotomy was performed
showed evidence of labral abnormality. These findings are in agreement with
the 21% rate of labral tears as reported by Siebenrock et
al.28. In that
series, patients with labral tears had a worse
outcome28. However,
at the time of the most recent follow-up, the average Harris hip score for the
eleven patients with a known labral tear in our series was 90 points and none
of these patients had radiographic signs of progression of arthrosis. The
ultimate outcome for these patients and the optimal treatment of a torn labrum
will require additional studies.
In summary, on the basis of our surgical experience and the incorporation
of newer information regarding acetabular wall relationships, femoral
acetabular impingement, and the importance of detecting and treating labral
abnormalities, our preoperative evaluation routinely includes plain
radiographs that are used to determine the version of the acetabulum and
whether a congruent hip can be achieved with redirection. We now perform
magnetic resonance arthrography for all patients to determine whether or not
there is labral abnormality and to try to determine the integrity of the
articular surfaces. We consider Tönnis grade-II (or greater) arthrosis,
evidence of incongruity between the femoral head and the acetabulum on the
preoperative abduction-internal rotation radiograph, and substantial
acetabular articular cartilage degeneration on preoperative magnetic resonance
arthrography as contraindications to periacetabular osteotomy.
Our current operative goal is to restore normal anatomic anteversion. We
routinely perform arthrotomy, and, if a torn acetabular labrum is noted, we
perform either a limited partial resection or, if the labrum is detached from
the acetabular rim, we débride the rim to bleeding bone and reattach
the labrum to the rim with use of suture anchors. If there is residual femoral
acetabular impingement after appropriate repositioning of the acetabulum, we
correct it by performing a chondro-osseous débridement of the femoral
head-neck junction to allow for impingement-free movement with the hip in
90° of flexion and slight internal rotation. ?
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