Biomechanical and kinematic influences of a total infrapatellar fat pad resection on the knee

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: lsokinetic 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 63degrees of flexion and full knee extension (maximum: 30 rotation difference at 0degrees knee flexion, P = .011), combined with a significant medial translation of the patella between 29degrees and 69degrees 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.