Ankle Instability

A. Douglas Spitalny, DPM FACFAS

NAVIGATE:
  • Ankle instability can be diagnosed easily with simply a history of instability
  • Assessing instability clinically is a little more challenging
  • Instabilty needs to be quantified via stress radiography
  • Stress radiography involves anterior drawer - tests Anterior talofibular ligament
  • Stress radiography involves talar tilt - tests Calcaneofibular ligament


Clinical anterior drawer

Positive "pucker sign"
Stress radiography can be performed either manually or with a Telos device

Manual stress - anterior drawer

Telos device - anterior drawer
Talar tilt
- ankle is inverted to stretch the calcaneofibular ligament
- tilt is measured in degrees
- 0 - 15 is normal
- > 15 abnormal

Talar tilt of the talus

Technique for measuring talar tilt
Anterior Drawer Measuring Techniques
- Concentric Circles
- Parallel Lines
- Posterior displacement

New Method
- Anatomic

Normal Measurements on non-stressed lateral
- Men - 10mm
- Women - 8mm

Stress Measurements
S - N = degree of instability

0 - 5 normal
5 - 10 mild instability
10 - 15 unstable

Measure from the edge of the fibula to the vertical ridge of the lateral talar process

Anterior drawer measurement on lateral radiograph
19mm - 10mm = 9mm