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Introduction
Lateral patellar dislocation is a common knee
injury in the skeletally immature adolescent
with a high recurrence rate in patients younger
than 14 years [5, 9, 10, 12, 24]. The stabilising
role of the MPFL as the main restraining force
to lateral displacement of the patella has been
emphasized by many authors [2, 4, 20]. In
adults reconstruction of the patellofemoral
ligament has shown good results [1, 4, 7, 21].
Since it has been shown historically in children,
that operative procedures like lateral release,
medial reefing and the Roux-Goldthwait
procedure have a high failure rate reconstruction
of the MPFL has been advocated in skeletally
immature patients as well [19]. Due to the
adjacent physis different non anatomical
techniques have been described for children [6,
12, 24]. But many authors emphasized the need
of an anatomical reconstruction with tightening
of the MPFL in knee flexion when the femoral
origin is placed too proximally [4, 13, 25, 26].
Additionally several authors have shown, that
the femoral insertion of the MPFL is distal to
the femoral physis [3, 14, 15, 16, 18]. As the
importance of an anatomical repair respecting
the femoral and patellar insertion of the
ligament has been proven, this technical report
describes the technique of an anatomical,
physeal-sparing reconstruction of the MPFL in
children with open growth plates.
Methods
Before surgery every patient’s knee was
examined clinically under anesthesia and a
diagnostic arthroscopy is performed to rule out
intraarticular pathology.
Following the diagnostic arthroscopy an
oblique incision is made along the pes
anserinus. After exposing the fascia the gracilis
tendon is harvested proximally using a tendon
stripper. Distally the tendon is sharply detached
from the tibia. The tendon is prepared with a
Vicryl suture on both ends and stored within a
moist swab.
A longitudinal incision is made over the medial
proximal two-thirds of the patella. The medial
border of the patella is exposed subperiosteally
avoiding injury of the joint capsule. A 4-mm
drill is used to create a V-shaped tunnel at the
superomedial half of the patella with sufficient
distance between tunnels to avoid fracturing.
The graft can then be inserted into the tunnel
forming a loop through the patella (fig. 1).
By blunt dissection the interval between the
capsule and the vastus medialis obliquus is
developed to the femoral insertion of the
MPFL. Using the indirect radiographic method
described by Schöttle
et al.
[22] the anatomical
femoral insertion of the MPFL is identified
Anatomical positioning of
the medial patellofemoral
ligament in children
M. Nelitz, S. Lippacher