Biomechanical and Kinematic Influences of a Total Infrapatellar Fat Pad Resection on the Knee

Abstract

Background This biomechanical study was performed to evaluate the consequences of total infrapatellar fat pad resection on knee kinematics and patellar contact pressure. Hypothesis Resection of the infrapatellar fat pad produces significant changes in knee kinematics and patellar contact pressure. Study Design Biomechanical cadaveric study. Methods Isokinetic knee extension was simulated on 10 human knee cadaveric specimens (6 men, 4 women; mean age at death, 44 years). Joint kinematics were evaluated by an ultrasound-based 3D motion analysis system, and retro-patellar contact pressure was measured using an electronic pressure-sensitive film. All data were taken before and after resection of the infrapatellar fat pad and statistically analyzed. Results A total resection of the infrapatellar fat pad resulted in a significant decrease of the tibial external rotation relative to the femur between 63° of flexion and full knee extension (maximum: 3° rotation difference at 0° knee flexion, P = .011), combined with a significant medial translation of the patella between 29° and 69° of knee flexion (range, 0.9-1.3 mm, P = .017-.028). Retro-patellar contact pressure was significantly reduced (from 20% to 25%, P = .008-.021) at all flexion angles. Conclusion A resection of the infrapatellar fat influences patellar biomechanics and knee kinematics. Clinical Relevance The infrapatellar fat pad may have a biomechanical function and may play a role in anterior knee pain syndrome.