Evaluation of arthrometer for ankle instability: a cadaveric study

Area of Science:

• Orthopedics
• Biomechanics
• Medical Devices

Background:

• Traditional stress tests for ankle instability often rely on radiography, with debated reliability and sensitivity.
• A novel non-radiographic ankle arthrometer was developed for objective mechanical stability assessment.
• This device was validated against stress radiographs in a cadaver model.

Purpose of the Study:

• To evaluate the efficacy of a non-radiographic ankle arthrometer in assessing mechanical ankle stability.
• To compare the arthrometer's measurements with radiographic methods.
• To determine the sensitivity and specificity of the device in differentiating stable and unstable ankles.

Main Methods:

• Nine cadaver ankle specimens were tested with varying plantarflexion and anterior drawer loads.
• Ligamentous structures (anterior talofibular, calcaneofibular, posterior talofibular) were sequentially sectioned.
• Anterior drawer displacement was measured using a transducer and radiography; stiffness was calculated from the load-deformation curve.

Main Results:

• The ankle arthrometer successfully differentiated stable and unstable ankles via displacement and stiffness analyses (p = 0.012 and 0.003).
• Arthrometer measurements showed significant correlation with stress radiographs (p = 0.000 to 0.027).
• The transducer demonstrated high sensitivity (96.3%) for anterior drawer instability, with 44.4% specificity; stiffness analysis achieved 91.7% sensitivity and 62.5% specificity.

Conclusions:

• The non-radiographic ankle arthrometer effectively measured talar anterior subluxation in a cadaver model.
• The device is highly sensitive in distinguishing between stable and unstable ankles without radiography.
• This technology could enhance diagnostic accuracy and clinical decision-making for chronic ankle instability.