The use of functional analysis in evaluating knee kinematics

Area of Science:

• Orthopedics
• Biomechanics
• Biomedical Engineering

Background:

• Total knee arthroplasty (TKA) aims to restore knee function, but outcomes can be limited by understanding in vivo knee kinematics.
• Knee joint motion is complex, involving six degrees of freedom, and its behavior during activities like walking and stair climbing is critical for TKA success.

Purpose of the Study:

• To investigate the activity-dependent six-degrees-of-freedom (6-DOF) knee kinematics during ambulatory activities.
• To evaluate the impact of in vivo knee kinematics on total knee arthroplasty (TKA) function, implant wear, and deep flexion capabilities.

Main Methods:

• Collected in vivo knee motion data during walking, stair climbing, and deep flexion activities.
• Compared knee kinematics between healthy subjects and TKA patients during stair climbing.
• Utilized patient-derived walking kinematics as input for a knee wear simulator.
• Analyzed femoral rotation during deep flexion activities.

Main Results:

• Knee kinematics were found to be highly dependent on the specific ambulatory activity.
• Preserving posterior cruciate ligament function during stair climbing is important for TKA patients.
• Patient-derived walking kinematics led to increased wear in a simulator compared to standard inputs, linked to slip velocity.
• Deep flexion requires significant femoral rotation, which may be a challenge in TKA.

Conclusions:

• In vivo knee kinematics are activity-specific and essential for understanding TKA performance.
• Accurate simulation of in vivo knee motion is vital for predicting and reducing implant wear.
• Further research into in vivo knee kinematics will enhance the design and treatment strategies for arthritic knees and TKA.