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Preparing components
allocation
A proper cementing technique is necessary to
obtain a successful UKR. Resurfacing led to a
minimal amount of bone removed from the
tibial and femoral side. Consequently, the
prosthesis components have to lie on
subchondral bone, which is often sclerotic. To
permit a deeper penetration of the cement in
the cancellous bone, the subcondral bone has to
be prepared by drilling and sawing it,
superficially and perpendicularly to the cutting
surface. This shrewdness will improve cement
adhesion and prosthesis stability.
Consider the patello-
femoral joint
In performing an isolated UKR, the patello-
femoral joint should be always carefully
evaluated [13, 14].
We developed an algorithm to recognize when
performing patello-femoral replacement (PRF)
in association to UKR. 3 main criteria and
2 secondary criteria formed this algorithm.
The three main criteria are: patello-femoral
pain; patellar malalignement or lateral patello-
femoral wear on X-Rays axial view;
intraoperative findings of grade 3-4 patello-
femoral chondral degeneration. The two
secondary criteria are: female sex and body
mass index (BMI) >32 (fig. 4).
If 2 main criteria or 1 main criteria and
2 secondary ones are present, isolated UKR
will fail and UKR+PFR must be considered
(fig. 5).
Consider both tibio-
femoral compartments
Most surgeons consider small implants useful
in unicompartimental OA. In patients with high
functional demand and knees with no major
deformity and an efficient anterior cruciate
ligament, bi-compartimental OA should be
addressed with bi-unicompartimental knee
replacement (fig. 6) [15-16].
Evenwhen surgery starts for unicompartimental
replacement, the opposite compartment should
be evaluated. If extensively degenerated,
surgeon should be ready to perform bi-UKR.
Fig. 4: Algorithm to consider concomitant PF replacement associated to UKR.