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Patellar complications constitute one of the
most common causes of failure of total knee
arthroplasty [5] and the leading reason for
surgical revision [7, 15]. Depending on the
series, the frequency is estimated at 1 to 50%
[9, 26]. Patellar complications are usually seen
as more or less patent patellar dislocation
with or without instability, fracture, patellar
loosening, or pain.
Disturbance of patellar blood supply,
modifications of patellar thichness or global AP
whidth, patellar maltracking are the main
origins of these complications.
Medial or lateral approach may have an
influence on the patella in terms of blood supply
or maltracking.
Approach and Blood
supply
Vascularization of the patella is given from the
Scapinelli’s periarticular circle which comes
from the genicular arteries, one branch of the
femora artery and recurrent branches from the
anterior tibialis a. and the posterior tibialis a.
[33]. The most important part of the blood flow
comes from the medial part which has three
practical consequences:
- Medial arthrotomy interrupts the medial
blood supply,
- Medial arthrotomy + lateral retinaculum
release does interrupt the large majority of the
patellar vascularization,
- Iterative surgery should use the same articular
approach as the index surgery as often as
possible.
Approach and Patellar
Tracking
Regarding maltracking, residual patellar
malposition, and its radiographic presentation
of patellar tilt and/or gliding, contributes to
such complications [4, 8, 30]. The proportion
of tilted patella varies from 0.8% according
to Brick and Scott [10] to 45% reported by
Bindelglass and Vince [8]. Lateral tilt is more
common [8, 10, 18, 19, 29] and has a worse
effect on prognosis. Laughlin [22]
demonstrated that external tilt tends to worsen
with time, unlike medial tilt which tends to
improve. The degree of tilt increases with
more pronounced patellar malposition
preoperatively [12].
Approach and Patella in
Total Knee Arthroplasty
P. Beaufils, M. Thaunat, D. Passeron,
P. Boisrenoult, N Pujol