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Introduction
Numerous anatomic factors have been shown
to contribute to episodic patellar dislocation
(EPD), including injury to the medial patello
femoral ligament (MPFL) [8] trochlear
dysplasia [4, 5] increased tibial tubercle-
trochlear groove (TT-TG) distance [7], abnormal
patellar tilt, and patella alta [6, 16, 19, 25].
Traditionally an under-appreciated contributor
to patellar instability, patella alta has been noted
to be present in 24% of patients with EPD but in
only 3% of normal controls [5]. Further, patella
alta has been shown to be a risk factor for
recurrent instability in patients with EPD
following conservative treatment [13] or
isolated MPFL reconstruction [23].
The reason for the association between patella
alta and EPD is not entirely clear and is likely
multifactorial. Patella alta has been shown to
cause decreased contact between the patella
and trochlea [14, 21, 24] contributing to
decreased resistance to lateral translation of the
patella in these patients [20, 25]. It has also
been suggested that increased patellar tendon
length itself is the culprit, with increased length
allowing a pathologic increase in coronal plane
motion of the patella [16].
One study identified increased patellar tendon
length (greater than 52mm) rather than a “too
proximal” position of the tibial tubercle in
patients with patella alta and EPD [16]. It may
thus be desirable to address the length of the
patellar tendon itself rather than simply altering
its insertion site through tibial tubercle distaliza
tion. One potential method for shortening an
abnormally long patellar tendon is to distalize
the tibial tubercle and tenodese the distal
portion of the patellar tendon into the original
location of the tibial tubercle. We have
described good results of this technique in a
recently published case series [15]. The goal of
this presentation is to explore indications and
technique for patellar tendon tenodesis and
review available outcomes data.
Indications for
Patellar Tendon
Tenodesis
It must be stressed that patellar tendon
tenodesis associated with a distalization of the
tibial tubercle is indicated in only a small
fraction of patients treated for EPD. Patients
undergoing evaluation for EPD should undergo
a careful assessment of their anatomy and all
predisposing factors for patellar dislocation as
has been described in detail by H. Dejour
et al.
[5]. Those with significant patella alta (defined
by a Caton-Deschamps index [1] greater than
1.2) should be considered for tibial tubercle
distalization.
Patellar Tendon Tenodesis
for the Treatment
of PatellaAlta
R.A. Magnussen, C. Mayer, E. Servien,
G. Demey, M. Jacobi, S. Lustig, P. Neyret