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A philosophy and technique for reconstruction of the medial patellofemoral ligament
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should be to create a “favourable anisometry”
in the reconstructed ligament.13 In cases of
severe patella alta, it may be impossible to
achieve a “favourable anisometry” as non-
isometry increases progressively with the
height of the patella. In these cases, a
distalisation of the patella might be necessary
to improve the isometry.
In contrast to theMPFL, the lateral retinaculum
is lax in extension and tightens in flexion [14,
15]. In nearly all patella dislocations there is
damage to the MPFL. In our own series, 70%
had damage at the patellar insertion while the
remaining 30% were damaged at the femoral
origin. In all cases, however, there was some
interstitial damage to the whole ligament.
These findings correspond with that of Garth
[17] but differ from the MRI findings of
Sallay [16].
Management
In the majority of patients who present with
patellar dislocation, there is underlying
pathology such as ligamentous hyperlaxity,
trochlear dysplasia and patella alta [18]. This
underlying pathology predisposes the patient to
an acute overload of the soft-tissue stabilisers
and rupture of the MPFL with patella
dislocation. Primary repair has a high failure
rate: in our own series, 31% of the cases
suffered redislocations in a four-year follow-up
period. This corresponds with the results
published by Nikku [19]. Most cases of primary
dislocations are now treated non-surgically
with a brace that allows full flexion but restricts
the last 30% of extension. By restricting full
extension, the MPFL is relaxed and may heal in
a more favourable length. In exceptional cases,
a primary reconstruction or direct repair of the
MPFL and medial retinaculum would be
considered. The principle of our repair
philosophy is to reconstruct the MPFL with
stronger tissue than before to compensate for
the underlying predisposing pathology and
without changing the original position of the
patella and its original conformity with its
underlying trochlea. The normal MPFL fails at
208N with an elasticity of 8N/mm [20]. A
double gracilis fails at 1550N with an elasticity
of 336N/mm [21]. At present, we prefer a
double gracilis graft that, although stronger
than the MPFL, is not as strong and stiff as a
double semitendinosus tendon. Pre-operative
evaluation consists of a proper clinical
examination with specific attention to dynamic
patella tracking, patella height and possible P-F
chondral damage. The contra-lateral patella is
also properly evaluated, as the principle is to
restore the injured knee to the predislocation
situation. Standard X-rays of the knee are done
including a true lateral with the quads
maximally contracted. This lateral X-ray is
used to evaluate patellar height according to
the Bernageau technique [22]. On MRI images,
the ratio described by Biedert [23] can be used.
The only surgery to be considered in addition
to a MPFL reconstruction is a distal tibial
tubercle transfer in cases of severe patella alta.
Surgical technique of
MPFL reconstruction
Three 3cm long incisions are made over the
gracilis tendon, over the medial edge of the
patella and over the medial femoral epicondyle
(fig. 3). The gracilis tendon is harvested with a
routine technique. At the incision over the
medial edge of the patella, an incision is made
through the second fascial layer. From here a
dissecting scissors is used to tunnel between
the second and third fascial layers towards the
medial epicondyle. At the medial epicondyle,
the second fascial layer is again incised over
the tip of the scissors (fig. 4).
A guide wire is inserted slightly proximally on
the anterior slope of the epicondyle. In the
proximal third of the medial edge of the patella,
two 3mm drill holes are made approximately
10 to 12mm apart. These drill holes should be
on the edge of the patella. Larger drill holes
and holes that go into the centre of the patella
might act as stress raisers, which can lead to a
stress fracture of the patella and should
therefore be avoided. A tape is now placed
around the guide wire at the medial epicondyle,
then between the second and third fascial layers
and through the drill holes at the medial edge of