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Unicompartimental knee replacement (UKR)
has several well-known advantages over total
knee replacement (TKR): less invasiveness,
tissue sparing, respect of both cruciate
ligaments and consequently respect of native
knee kinematic, better knee function and less
morbidity [1-3]. Historically, UKR survivorship
was lower than TKR one [1, 4].
This was caused by wrong indications, partial
knowledge of knee kinematic, inadequate com
ponents designs and poor surgical technique.
To obtain a successful UKR, I’ve identified 10
top items to apply during UKR surgery.
Tibialand femoral cuts
The native orientation of the tibial plateau
should be respected. On the coronal plane, it is
perpendicular to the epiphyseal axis of the
tibia, not to its diaphyseal one. Moreover, the
two compartments have different obliquity in
the sagittal plane (slope) [5-7].
Because UKR necessitates of anterior cruciate
ligament (ACL) integrity, the native tibial
slope should be respected to obtain a normal
knee kinematic and not to overload or slacken
the ACL. Consequently, tibial cut should be
done according to the native orientation. The
coronal orientation of the tibial cut must be
perpendicular to the epiphyseal axis of the
tibia, not to the whole axis of the tibia, in order
to respect the height and obliquity of the joint
line and avoiding any consequent release. In
the sagittal plane, the cut should be 0-3° for
the lateral compartment and 3-6° for the
medial one.
The femur should be cut as less as possible
because UKRmust be considered as resurfacing
replacement. The thickness of the femoral
component we use is 2mm. So, we remove
only 2mm of cartilage and bone from the
femur. Femoral cut must be very conservative
in the lateral compartment because of condylar
hypoplasia in the valgus deformity. In this case,
the thickness of the lateral condyle should be
restored using a thicker femoral component.
This tip will correct axial alignment and joint
line obliquity.
Tibial component
design
The tibial plateau is different from medial to
lateral. Its lateral part is semicircular, its medial
one is asymmetrical instead, wider posteriorly
than anteriorly [8, 9].
What are the limits for
Unicompartimental Knee
Arthroplasty?
10 top tricks for an ideal UKA
S. Romagnoli, M. Marullo; M. Corbella