Quantification of patellofemoral joint reaction forces during functional activities using a subject-specific...

Area of Science:

• Biomechanics
• Medical Imaging
• Kinesiology

Background:

• Patellofemoral joint reaction forces (PFJRFs) are crucial for understanding knee function and injury.
• Quantifying PFJRFs in vivo during functional tasks remains challenging.

Purpose of the Study:

• To describe an imaging-based, subject-specific model for quantifying PFJRFs.
• To validate this model in healthy individuals during various functional tasks.

Main Methods:

• Developed a 3D imaging-based model using MRI data of the knee and thigh.
• Collected kinematic, kinetic, and EMG data during walking, running, stair ascent, and stair descent.
• Utilized an optimization routine to compute 3D vasti muscle forces and PFJRFs.

Main Results:

• Peak PFJRFs were highest during running (58.2 N/kg-bwt), followed by stair ascent (33.9 N/kg-bwt), stair descent (27.9 N/kg-bwt), and walking (10.1 N/kg-bwt).
• No significant sex differences in PFJRFs were observed.
• PFJRFs consistently directed posterior, superior, and lateral, with the posterior component being dominant.

Conclusions:

• The developed 3D-imaging based model effectively estimates PFJRF magnitude and direction during functional activities.
• This model offers a valuable tool for research in biomechanics and clinical assessment of knee conditions.