An Open Debate on the Morphological Measurement Methodologies of the Infrapatellar Fat Pad to Determine Its Association with the Osteoarthritis Process.

Introduction: Knee osteoarthritis (OA) is a disease affecting all the neighboring articular tissues including the infrapatellar fat pad (IPFP). Although not yet as widely studied as other tissues in the knee, the IPFP has been recognized to have important metabolic activities and is a key player in OA.

Methods: In this commentary, we will briefly describe the different methodologies employed for the MRI morphological measurement of this tissue and depict the findings in regard to OA.

Results: The morphology of this tissue, monitored mainly with the use of magnetic resonance imaging (MRI), demonstrates changes during OA. However, studies of the IPFP morphological alterations and their association with the OA process have shown conflicting results, including a detrimental or beneficial role or no role at all. Although many reasons could explain such mixed findings, one might be the different methodologies used for the MRI measurement of area, volume, or signal intensity. In addition, several techniques are also employed for measuring the volume and signal intensity. An additional level of complexity is related to the presence within the IPFP of two different types of signal intensities, hyper-intensity, and hypo-intensity.

Conclusion: A consensus of a procedure to measure the morphology of the IPFP is urgently needed to fully appreciate the role of this tissue in the pathology of OA, as well as its uses for clinical decision-making.