Impact responses of the flexed human knee using a deformable impact interface.

Area of Science:

• Biomechanics
• Orthopedic Surgery
• Trauma Research

Background:

• Blunt impact to the patellofemoral joint causes diverse knee injuries.
• Current knee injury criteria are limited, primarily for car accidents and a single knee flexion angle.
• Injury severity and type depend on knee flexion angle and impactor stiffness.

Purpose of the Study:

• To evaluate if a deformable impact interface mitigates gross and microscopic knee injuries at various flexion angles.
• To compare injury outcomes between rigid and deformable impact interfaces.
• To inform the development of optimized knee injury protection.

Main Methods:

• Paired experiments on 18 human cadavers using contralateral knees.
• Impact tests conducted at three knee flexion angles: 60, 90, and 120 degrees.
• Comparison of impacts using a rigid interface versus a deformable honeycomb interface at equivalent loads.

Main Results:

• The deformable interface reduced gross bone fractures at approximately 5 kN across all tested flexion angles.
• A significant reduction in femoral condyle split fractures was not observed at 120 degrees flexion.
• Microscopic injuries were not effectively mitigated by the deformable interface at any flexion angle.

Conclusions:

• The tested deformable interface partially mitigated gross knee fractures but was ineffective against microscopic injuries.
• The chosen interface was not optimal for comprehensive knee injury protection.
• Further studies are required to develop superior knee impact interfaces for diverse injury types and flexion angles.