196 / 460
Sulcus deepening trochleoplasty for the treatment of recurrent patellar dislocation…
195
satisfaction were corrected significantly and
were comparable to patients with no previous
surgery that underwent trochleoplasty. Radio
graphic presence of patellofemoral arthritis
was not recorded, although its appearance
requires even longer follow-up periods.
Subjective evaluation and overall satisfaction
of these multiply-operated patient group was
higher (p: NS) than patients with no previous
surgery, with no need for re-operation or
complications in this group.
On the other hand, trochleoplasty procedures
are not void of surgery-specific complications.
Early concerns on post-operative cartilage
viability have been studied by Schöttle
et al.
who recorded normal subchondral bone, viable
cartilage cells, bone flap healing and minimal
risk for cartilage deterioration [9]. Over or
undercorrection of normal trochlea geometry is
another concern. Again this is difficult to verify
since authors use different imaging parameters
to compare post-operatively. Fucentese
et al.
showed significant decrease of TT-TG distance
(17mm vs. 13mm), decrease of lateral patellar
tilt (32° vs. 13°) and patellar translation (8mm
vs. 0mm) after “Bereiter” trochleoplasty, in
which the sulcus angle does not change [6, 8],
but they recorded overcorrection of the
trochlear groove in 2 out of 17 cases [8]. Von
Knoch
et al.
showed significant correction the
crossing sign (which remained positive only in
2 cases), increase of the trochlear depth from
-0.1mm to 5.0mm, and decrease of the trochlear
bump from 3.9mm to 0.4mm [11]. Donell
et al.
also recorded significant reduction to normal
values of prominence height, TT-TG distance
and patellar tilt without measuring the sulcus
angle, which they considered inaccurate for
estimating trochlear dysplasia [7]. Although
they commented that the repetition of the
imaging at 1 year, showed that correction of the
patellar tilt angle was not achieved in a few
cases, they followed the same “à la carte”
rationale to reduce the risk of overcorrection
[7]. In our study, there was a significant
decrease of sulcus angle, TT-TG distance and
lateral tilt. The clinical importance of such
changes in radiographic findings is difficult to
evaluate, because of the multifactorial nature
of patellar instability. Yet, persistence of
instability and need for re-operation after
trochleoplasty procedures are rarely recorded
[3, 5, 11], and when they are present, authors
attribute it to other untreated pathology, i.e.
MPFL deficiency [6]. Similarly, in this study,
there was no case of post-operative patellar
instability.
Post-operative stiffness and arthrofibrosis are
potential complications after any knee
operation, and the conflicting results of its
occurrence by Verdonk (46%) [10], Donnell
(33%) [7], Utting (2%) [5] and Thaunat (5%)
[12], to its complete absence in the long-term
study of von Knoch [11], prevent safe
conclusions for the aetiology of trochleoplasty
in post-operative arthrofibrosis. In this study
there was no case of arthrofibrosis recorded.
Similarly, reports of post-operative pain
associated with trochleoplasty procedures vary
among authors and it is difficult to compare,
especially in the case of patients treated for
patellar pain rather than dislocation [10, 20].
Even when the procedure is performed for the
treatment of patellar dislocation, post-operative
pain is a concern. Pain complicates trochleo
plasty in previous studies from 15% [5] to 46%
[10] and up to 100% [12]. In the mid and long-
term evaluation, Von Knoch
et al.
[11] with an
8-year follow-up, recorded 49% of improve
ment of pain and 33% of increase, and
Fucentese
et al.
[6] with 4 years follow-up,
recorded increase of pain in 7% of their cases.
In this series, patients were treated with
trochleoplasty for recurrent patellar dislocation
and not for patellofemoral pain alone. Post-
operatively, 75% showed decrease in pain and
25% that their symptoms remained unchanged
or increased. The unpredictability of post-
operative pain [6] and its probably strongest
association with severe cartilage lesions on
both femoral and patellar side before surgery
have been recorded [5-7].
The most concerning, though, potential
complication of trochleoplasty procedures is
the late development of osteoarthritis. Recurrent
patellar dislocation can lead to degenerative
changes if left untreated [27], and trochlear
dysplasia can accelerate osteoarthritis as well
[2, 11, 27], but the role of corrective surgeries