Adjacent Joint Kinematics After Ankle Arthrodesis During Cadaveric Gait Simulation

Area of Science:

• Biomechanics
• Orthopedic Surgery
• Human Anatomy

Background:

• Ankle arthrodesis is a common treatment for end-stage ankle arthritis.
• Adjacent joint arthritis is a frequent complication following ankle fusion surgery.
• The underlying mechanism driving adjacent joint arthritis post-arthrodesis is not fully understood.

Purpose of the Study:

• To isolate and investigate the specific biomechanical effects of ankle arthrodesis on adjacent joint kinematics.
• To determine how ankle fusion alters subtalar and talonavicular joint motion during simulated walking.
• To differentiate the impact of arthrodesis itself from altered gait patterns in cadaveric models.

Main Methods:

• Utilized 8 cadaveric foot and ankle specimens.
• Employed a robotic gait simulator to replicate walking.
• Measured 3D subtalar and talonavicular joint kinematics before and after simulated ankle arthrodesis.
• Applied both healthy and arthrodesis-specific gait parameters as simulation inputs.

Main Results:

• Ankle arthrodesis consistently increased subtalar and talonavicular joint motion during early and midstance.
• This increase in adjacent joint motion occurred irrespective of the gait parameters used.
• During late stance, adjacent joint motion did not differ with healthy gait parameters but decreased with arthrodesis gait parameters.

Conclusions:

• Ankle arthrodesis leads to increased motion in the subtalar and talonavicular joints compared to normal kinematics.
• This elevated biomechanical burden on adjacent joints is a likely contributor to observed articular degeneration.
• The findings suggest that increased adjacent joint motion post-arthrodesis may explain clinical observations of joint degeneration.