208 / 460
Recession wedge trochleoplasty for major trochlear dysplasia
207
perfectly with the V-shaped recipient bed.
Areas of slight cohesion between cut surfaces,
and the use of suture instead of screws to secure
the flap could slow down osseointegration.
However, these considerations are theoretical,
as chondrolysis has in fact never been observed
in deepening trochleoplasty. Articular cartilage
is avascular, and keeping thick flaps protects
subchondral bone and theoretically allows
early vascularization through the cancellous
bone. Schöttle, studying cartilage viability after
Bereiter trochleoplasty [27], found that tissue
in the trochlear groove remained viable,
conserving distinctive hyaline architecture and
composition with only a few minor changes in
the calcified layers.
The present study, however, has several
weaknesses. In the absence of a control group,
it was not possible to know whether the
additional procedure provided any additional
benefit. It was not possible to assess the role of
trochleoplasty in the patellofemoral stability, as
it was never isolated but systematically
associated to other corrections within the same
surgical step. The study was retrospective, with
short-term follow-up, and patients were
heterogeneous. Some had already had several
operations which had failed, or already showed
patellofemoral degeneration at the time of
surgery. Although multi-operated patients had
lower functional scores at last follow-up than
those operated for the first time, they too were
satisfied with their result. None of the patients
was completely pain-free at last follow-up,
although symptoms and functional activity
improved. Patients operated for pain-free
instability were satisfied overall, although all
reported slight pain at last follow-up. This pain
was mostly difficult to attribute directly to the
trochleoplasty, due to the multiplicity of
associated procedures. However, trochleoplasty
should be considered with caution in this
indication, not being actually necessary for
consistent success with surgical treatment of
recurrent patellar dislocation despite dysplastic
trochlea. Two authors reported the results of
reconstruction of the medial patellofemoral
ligament in patients with trochlear dysplasia
[28, 29]: there was no significant association
between severity of dysplasia and Kujala score
ineitherstudy.Finally,depressiontrochleoplasty
is not without disadvantages. It reduces but
does not abolish the bump and convex dome
shape of the trochlea, and the groove created is
not deep enough for the lateral facet to block
any further tendency of the patella to dislocate.
In the present series, it failed to stabilize the
patella in 2 cases, and 2 complications were
surgery-related and required surgical revision:
1 patient required arthrolysis for postoperative
knee stiffness and the other required arthro
scopic exostosectomy near the trochlea for a
persistent ridge.However, these2complications
were not directly related to the specific surgical
technique of depression trochleoplasty, and the
rate of complications and failure remained low
and quite similar to other trochleoplasty series
[6, 17, 20, 21]. While recession wedge
trochleoplasty was effective in reducing
anterior knee pain, it did not seem to halt the
progression of patellofemoral arthritis, although
follow-up was too short for any definite
conclusions to be drawn. At last follow-up,
6 knees showed osteoarthritic changes in the
patellofemoral compartment according to the
Iwano classification, which was similar to the
results obtained with deepening trochleoplasty
[4]; however, MRI or CT to determine
postoperative cartilage status were not
systematically performed at last follow-up, and
these results must be interpreted with caution.
Future studies with larger numbers of patients
and long-term follow-up would be needed to
confirm that surgical correction of trochlear
dysplasia can slow down late patellofemoral
degeneration.
Conclusions
Despite encouraging clinical results, correction
of trochlear dysplasia is usually not attempted
because it is technically difficult, introduces a
significant potential for complications and is
usually not necessary for a successful outcome.
However, this procedure should be considered
in case of painful instability with severely
dysplastic trochlea (trochlear dysplasia grade
B, C or D on Dejour’s classification, with
trochlear prominence >5mm) or in revision