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PIVOT SHIFT TEST: HOW DOES IT WORK
63
CLINICAL GRADING AND
FACTORS AFFECTING
PIVOT SHIFT
Pivot shift can be graded clinically according
to the amount of pathological motion observed
and is used in IKDC score.
0-
Normal
1-
Subtle change in motion or glide
2-
Distinct reduction or clunk
3-
Significant clunk with locking (impingement
of the posterolateral tibial plateau against
lateral femoral condyle)
Other simplistic way to describe pivot shift is
to divide it into low grade or high grade. Low
grade includes both grade 0 and 1 of IKDC
where as high grade includes grade 2 and 3.
There are various anatomical and structural
factors, which play role in exaggerating or
masking the pivot shift grading. They are
summarized in Table 1.
QUANTIFICATION OF THE
TEST-INSTRUMENTED
ASSESSMENT OF ROTATORY
KNEE INSTABILITY
To eliminate subjective grading, attempts have
been made in developing devices to objectively
quantify the pivot shift test. The primary reason
for the difficulty to establish an evaluation
system is the complexity of the pivot shift
movement that is composed of a six degree-of-
freedom tibial internal-external (i-e) rotation,
varus-valgus (v-v) rotation, and anterior-
posterior (a-p) translation. Computer assisted
surgical navigation systems and electro
magnetic tracking devices are among the
technologies that can provide kinematic data
during the pivot shift test [7]. These
technologies provide accurate kinematic data,
but limitations exist such as invasiveness,
bulkiness, and cost. In recent years, non-
invasive technologies have been developed
that can help clinicians to objectively quantify
the pivot shift test. These technologies measure
different aspects of bony motion during the
pivot shift test. We have been using two these
systems image analysis and inertial sensor
technology.
IMAGE ANALYSIS
TECHNOLOGY
While performing the pivot shift, anterior tibial
translation in lateral compartment of the knee
is more than that of the medial compartment.
This translation correlates with the subjective
grading of the pivot shift [8]. Based on this
finding, we developed PIVOT software that
uses a computer tablet’s camera to record the
motion of markers attached to the lateral aspect
of the knee during the pivot shift maneuver
Table 1:
Anatomical & Morphological factors affecting Pivot shift test
Factors leading to increased Pivot shift test
Factors masking Pivot shift test
Lateral Meniscus injury
Illiotibial band injury
Anterolateral capsule injury
Posterolateral corner injury
Increased lateral tibial plateau posterior slope
Small size of lateral tibial plateau
Medial Collateral ligament injury
Illiotibial band laxity
Patient guarding/Haemarthrosis
Flexion contracture of knee
Osteoarthritis