The Bernese periacetabular osteotomy for treatment
of adult hip dysplasia
Todd O. McKinley
Published online: 20 July 2010
Adult hip dysplasia (AHD) results in a hip joint that has a
suboptimal mechanical articulation secondary to deficient
or malaligned acetabular cartilage. Acetabular deficiency
and malalignment result in an abnormal force transfer
across the hip joint leading to pathologically elevated
cartilage stresses [1, 2]. Pathological cartilage stresses
accumulate over time affecting cartilage metabolism .
The normal anabolic/catabolic metabolic balance that
maintains healthy cartilage is uncoupled with increases in
catabolic enzymes. Production of proinflammatory
enzymes is increased. These metabolic and inflammatory
changes lead to joint pain and localized cartilage degener-
ation. Localized cartilage loss magnifies abnormal stress
transfer, establishing a pathomechanical cascade that leads
to further cartilage loss. A vicious cycle of cartilage loss
leading to increased stress in remaining cartilage, in turn
leading to further cartilage loss, and eventually ending in
joint-wide destruction of cartilage and endstage arthritis.
AHD is the most common cause of acetabular deficiency
and malalignment in adults, but other causes such as
acetabular retroversion, Perthes disease, and trauma, can
result in similar pathological anatomy.
Regardless of the etiology, the inciting event for the
pathomechanical cascade leading to hip joint arthritis is
abnormal stress transfer secondary to acetabular deficiency,
acetabular malalignment, or a combination of the two
factors. As AHD is the most common cause, this article will
focus on surgical correction of the acetabulum in AHD.
Typically, AHD is characterized by a shallow acetabulum
that does not fully cover the femoral head. There is lateral,
anterior, and posterior deficiency in coverage . Further-
more, the deficient acetabulum can be malaligned, typically
with excessive retroversion . The acetabular deficiency
and malalignment are unique to each patient, and need to be
meticulously scrutinized to determine optimal treatment.
Plain radiography in concert with advanced imaging
techniques including computerized tomography and mag-
netic resonance imaging afford the treating surgeon the
necessary information to understand the deformity.
The goal of surgery to treat AHD is to realign the
acetabulum into its optimal mechanical position. It is
important to recognize that acetabular realignment surgery
does not produce a normal acetabulum. This surgery
reorients the position of an abnormally shallow acetabulum
in an attempt to optimize stress transfer across the joint.
Surgeons have devised multiple operations to realign the
acetabulum. Previous acetabular osteotomies involved
cutting medial to the acetabulum through the superior
ramus, inferior to the acetabulum through the ischium, and
finally above the acetabulum into the greater sciatic notch.
These operations completely mobilized the acetabulum, but
they destabilized the pelvic ring by completely dividing the
posterior column from the pelvis. Prolonged recoveries and
nonunions led to the development of posterior column-
sparing osteotomies. These operations evolved to achieve
acetabular mobility to allow reorientation, but to do so
without destabilizing the pelvis. The Bernese periacetabular
osteotomy (PAO) as originally described by Reinhold Ganz
(this operation is often referred to as a “Ganz procedure”)
has become the most widely used posterior-column-sparing
acetabular osteotomy .
The mechanical goal of acetabular reorientation is to
decrease articular surface contact stresses by increasing the
contact area in affected hips [1, 2, 6]. Several investigators
T. O. McKinley (*)
Department of Orthopaedics and Rehabilitation,
University of Iowa Hospital,
200 Hawkins Drive,
Iowa, IA 52242, USA
Skeletal Radiol (2010) 39:1057–1059