Watson-Jones tenodesis for ankle instability. A mechanical analysis in amputation specimens

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Sports Medicine

Background:

• Ankle instability often results from lateral ligamentous injuries.
• The Watson-Jones tenodesis is a surgical technique used to address ankle instability.
• Understanding the biomechanical effects of this tenodesis is crucial for surgical outcomes.

Purpose of the Study:

• To evaluate the stabilizing efficacy of a modified Watson-Jones ankle tenodesis.
• To assess the impact of the tenodesis on hindfoot and talocalcaneal joint kinematics.
• To compare the biomechanical effects of the tenodesis against intact ligament function.

Main Methods:

• Utilized a kinesiologic testing device on 10 lower extremity amputation specimens.
• Induced instability by cutting lateral ligaments.
• Quantified joint motion and stability following the modified Watson-Jones tenodesis.

Main Results:

• Lateral ligamentous disruption caused maximal instability in hindfoot adduction.
• The tenodesis significantly restricted adduction and internal rotation compared to intact ligaments.
• Persistent instability in external rotation was observed, indicating incomplete restoration of function.

Conclusions:

• The modified Watson-Jones ankle tenodesis effectively prevents abnormal hindfoot inversion.
• The procedure does not fully restore normal hindfoot kinematics or stability, particularly in external rotation.
• Clinical observations regarding inversion control are confirmed, but full kinematic restoration is not achieved.