DISCUSSION
When asked to stand on one leg, and follow a standard
routine to ensure hip abductor muscle contraction on the
same side, patients may respond to the standardised
Trendelenburg test in one of three ways. Only one
response is normal; the other two are abnormal. An
ability to assume the normal response must be absolute,
and if the pelvis drops on the non-stance side within 30
seconds the Trendelenburg test is positive. The use of a
timer is an essential part of the Trendelenburg test, and,
indeed, makes it an objective measure of severity of
altered hip mechanics.
However, the presence of pain, poor balance and
either lack of co-operation or understanding by the
patient can lead to false-positive tests, because the test cannot be properly performed. The reason for falsenegative
tests is that the subject uses muscles above the
pelvis to elevate the non-weight-bearing side of the pelvis,
or shifts the torso well over the weight-bearing side;
these can be called “trick movements”. Variable
responses were noted in some patients less than seven
years of age, and the test is of no value in children under
four. Nevertheless, if the Trendelenburg test is carefully
performed, it is an accurate clinical sign with prognostic
implications.
Inman (1947) measured the torque strength about
the hip with the pelvis in different postures with respect
to the ground. Our electromyographic results confirm his
findings that little abductor muscle strength/activity is
necessary to maintain a balanced posture with the pelvis
dropped (as in Response 3) on the non-weight-bearing
side. As the pelvis rises on this side there is increase of
abductor muscle activity provided that the torso is
centred over the hip.
Functional assessment of a joint is important in the
clinical assessment of patients. Observation of gait is
probably performed less often than is desirable because
of limitation of space. The Trendelenburg test allows for
functional assessment in a confined space, and is a more valuable clinical sign than many static tests. It can also
be easily recorded on film or videotape.
It is our belief that a patient who has an abnormal
response to the Trendelenburg test as described in this
paper has an inefficient gait, and therefore becomes
easily fatigued. With a little practice, the test is not difficult
to perform and interpret. Timing is an essential part
of the test; it provides an objective measure of improvement
or deterioration in the neuromuscular or mechanical
function of the hip.
Trendelenburg’s original observations were precise
and clear, and his interpretations accurate. We Support
the need for meticulous clinical examination in order to
provide correct diagnosis and we recommend the use of
the standardised timed Trendelenburg test in the assess- ment offunction and malfunction ofthe hip