Functional morphologic features of the human knee: an evolutionary perspective

Area of Science:

• Evolutionary biology
• Biomechanics
• Orthopedic surgery

Background:

• The knee's complex structure has ancient evolutionary origins, dating back over 300 million years to lobe-finned fish.
• Ligaments and menisci function as critical components in the knee's biomechanical transmission system.

Purpose of the Study:

• To investigate the functional morphology and kinematics of the human knee.
• To analyze the anatomical asymmetries between the medial and lateral compartments.
• To explore how understanding these complexities can improve orthopedic device design.

Main Methods:

• Utilized advanced imaging techniques, including cine-computed tomography (CT) and magnetic resonance imaging (MRI).
• Examined intact cadaveric knee specimens to observe motion during flexion.
• Quantified femorotibial contact point displacement and compartment-specific kinematics.

Main Results:

• Observed a combined rolling and gliding motion in the knee joint.
• Identified posterior displacement of the femorotibial contact point with increasing flexion, significantly greater in the lateral compartment.
• Confirmed anatomical adaptations in the lateral compartment that accommodate increased motion.
• Documented inherent asymmetry in knee kinematics, leading to tibial internal rotation during flexion.

Conclusions:

• The knee's functional morphology exhibits significant evolutionary depth and inherent asymmetry.
• Understanding the differential kinematics between medial and lateral compartments is crucial.
• Improved designs for knee joint replacements and bracing systems can result from considering these functional morphologic features.