Copyright © 2008 by The Journal of Bone and Joint Surgery, Inc.
Commentary & Perspective
Commentary & Perspective by
Reinhold Ganz, MD*,
University of Bern, Gümligen, Switzerland
Posted March 2008
The authors sought to minimize the tissue trauma associated with
the Bernese periacetabular osteotomy through the use of a new approach. The execution
of the osteotomies was constantly monitored with fluoroscopy. The approach was
used in 125 consecutive hips over a period of twenty-nine months; ninety-four
hips were finally selected to comprise a well-defined study group, with a
follow-up that ranged from 2.0 to 4.3 years. All patients had undergone surgery
with hypotensive epidural anesthesia. The duration of surgery averaged 73.1 minutes;
the median perioperative blood loss was 250 mL, and the mean reduction of
hemoglobin was 33 g/L. There were no major vascular or nerve complications, no observed
instances of unintended extension of the osteotomy, and no wound infections requiring
surgical intervention. All procedures were performed by one surgeon, and no
particular learning curve was identified. The median length of the hospital
stay was eight days.
Concerning radiographic outcome, the median center-edge
angle improved from 15° preoperatively to 34° postoperatively, and the median
acetabular index angle of Tönnis decreased from 17° preoperatively to 3°
postoperatively. There were two hips with Tönnis grade-1 osteoarthritis that
had to be converted to total hip arthroplasty 1.8 years and 2.7 years after the
index surgery.
The authors concluded that their minimally invasive approach
for periacetabular osteotomy is safe, relatively fast, associated with minimal
tissue trauma and blood loss, and highly satisfactory with regard to acetabular
correction.
There is little question that the technique of any procedure
has room for improvement and that the initiative taken by this group of authors
may well prove to become, as a whole or in parts, a step forward in the surgery
of spatial correction of the human acetabulum. However, important conclusions
of this paper are really assumptions and have not been proven with the data presented.
The only quantified information with regard to minimal invasion is a skin
incision of 7 cm. Only a magnetic resonance imaging study would allow some
quantification of true invasion of tissues and/or muscles by comparing muscle
integrity during open dissection with a knife with muscle integrity during
blunt dissection with a periosteal elevator. Furthermore, the reduced overall
blood loss is probably more related to the hypotensive anesthesia than to the
minimal incision surgery. Blood loss during open dissection for periacetabular
osteotomy is also minimal, so blood loss during execution of the osteotomies
should be the same whether the exposure is minimal or classic. A mean operative
time of 73.1 minutes for acetabular reorientation for minor or moderate
dysplasia is short. An experienced surgeon performing an open dissection may
need twenty to twenty-five minutes more for a hip with similar morphological
characteristics; however, that amount of time includes the time needed to chart
the position of the acetabulum with use of intraoperative anteroposterior
pelvic radiographs for more spatial precision and also includes the time needed
to perform capsulotomy and intraarticular revision, which are necessary in
seven of ten cases. The length of hospital stay is similar for both procedures.
The authors repeatedly assert the importance of gaining an
accurate spatial correction of the osteotomized acetabulum (a lateral center-edge
angle of 30° to 40° and a Tönnis angle that is never <0°). Acetabular
version is mentioned as important; however, no preoperative or postoperative
information about prevalence and amount is given. They conclude that their
technique allows for optimal correction, and they present data for the frontal
plane in Table 2 with preoperative and postoperative overall values. However,
in electronic Figures E7-A and E7-B, in which the authors report the preoperative
and postoperative angles of each hip, there are several undercorrections and
overcorrections, some of which are substantial enough to be considered a complication
of the procedure. In addition, one might question the reason(s) for the need to
perform two early conversions to total hip arthroplasty of two hips with Tönnis
grade-1 osteoarthritis, since this grade of osteoarthritis is unlikely to be
associated with rapid degeneration after a satisfactory acetabular correction.
A final remark deals with a recommendation made toward the
end of the paper. The authors are basically saying that, in order to shorten
the learning curve associated with their technique, an inexperienced surgeon
should first learn the open technique of performing periacetabular osteotomy before
learning the described new technique, even though the new technique is contrasted
to the open procedure as being markedly different in many technical aspects. A
statement such as this may even give rise to an ethical discussion.
In summary, the primary conclusions that the new approach
for periacetabular osteotomy is minimally invasive and satisfactory with regard
to correction are not sufficiently proven by the data provided.
*The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of his immediate family, is affiliated or associated.
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