Total Ankle Replacement Provides Symmetrical Postoperative Kinematics: A Biplane Fluoroscopy Imaging Study

Area of Science:

• Orthopedic surgery
• Biomechanics
• Medical imaging

Background:

• In vivo motion analysis of tibiotalar and subtalar joints after total ankle replacement (TAR) is lacking.
• Biplane fluoroscopy can assess joint kinematics and range of motion.

Purpose of the Study:

• To compare tibiotalar and subtalar joint motion in patients with TAR to their contralateral limb and healthy controls.
• To test the hypothesis that TAR affects joint kinematics.

Main Methods:

• Six patients with unilateral Zimmer TAR and six controls underwent biplane fluoroscopy during walking and double heel-rise.
• CT scans were used for model-based tracking of fluoroscopy data.
• Statistical parametric mapping analyzed kinematic differences.

Main Results:

• Patients with TAR showed symmetric tibiotalar and subtalar joint kinematics between limbs during tested activities.
• Compared to controls, TAR patients had reduced dorsi/plantarflexion range of motion, especially during late-stance walking and double heel-rise.
• Minor compensatory kinematic changes were observed in the tibiotalar joint of TAR patients versus controls.

Conclusions:

• Zimmer TAR patients exhibit symmetric joint kinematics but demonstrate some compensatory tibiotalar motion compared to controls.
• The lack of significant subtalar joint compensation may contribute to the low incidence of secondary subtalar osteoarthritis in some TAR designs.