Abstract
Chronic ankle instability arises from three interacting contributing factors: mechanical
ankle instability, functional ankle instability, and perceived ankle instability.
To decide on the
most appropriate individual recommendation for therapeutic options, it is necessary
to assess which of the two main aetiologies – functional vs. mechanical – is dominant
in causing the
perceived impairment. It is essential to perform a thorough analysis and diagnosis,
even though quantifying mechanical ankle instability is still a challenge in the clinical
approach to
this common pathology. When diagnosing mechanical instability, the most established
procedure is physical examination, although this unfortunately does not allow the
deficit to be
quantified. Additional options include stress-ultrasound, 3D stress-MRI (3SAM), ankle
arthrometry, marker-based 3D motion analysis, and diagnostic ankle arthroscopy. Of
these the latter is
considered the gold standard, even though it is an invasive procedure, it may not
be performed for diagnostic reasons only, and it also does not allow the mechanical
instability to be
quantified. For diagnosing functional instability there are non-instrumented tests
such as the Star Excursion Balance Test or Y-Balance Test, posturography/stabilometry,
and gait and
running analysis, possibly combined with EMG acquisition and isokinetic strength testing.
To date, the standard of care is conservative management of ankle instability, and
the therapy should include sensorimotor training, strength training of the periarticular
muscles,
balance training, and gait and running exercises on different surfaces. However, it
is increasingly clear that a certain degree of mechanical instability cannot be compensated
for by
functional training. Thus, it is the goal of differential diagnostics to identify
those patients and guide them to mechanical therapy, including ankle bracing, taping,
and surgical
ligament reconstruction.
Keywords Diagnosing ankle instability - ankle sprain - mechanical ankle instability - functional
ankle instability
