Infrapatellar fat pad pressure and volume changes of the anterior compartment during knee motion: possible clinical consequences to the anterior knee pain syndrome

Abstract

This biomechanical study was performed to measure tissue pressure in the infrapatellar fat pad and the volume changes of the anterior knee compartment during knee flexion-extension motion. Knee motion from 120 degrees of flexion to full extension was simulated on ten fresh frozen human knee specimens (six from males, four from females, average age 44 years) using a hydraulic kinematic simulator (30, 40, and 50 Nm extension moment). Infrapatellar tissue pressure was measured using a closed cell sensor. Infrapatellar volume change in the anterior knee compartment was evaluated subsequent to removal of the fat pad using a water-filled bladder. We found a significant increase of the infrapatellar tissue pressure during knee flexion, at flexion angles of <20 degrees and >100 degrees . The average tissue pressure ranged from 343 (+/-223) mbar at 0 degrees to 60 (+/-64) mbar at 60 degrees of flexion. The smallest volume in the anterior knee compartment was measured at full extension and 120 degrees of flexion, whereas the maximum volume was observed at 50 degrees of flexion. In conclusion, the data suggest a biomechanical function of the infrapatellar fat pad at flexion angles of <20 degrees and >100 degrees , which suggests a role of the infrapatellar fat pad in stabilizing the patella in the extremes of knee motion.

Signal intensity alteration in the infrapatellar fat pad at baseline for the prediction of knee symptoms and structure in older adults: a cohort study

“…Some preliminary studies reported that signs of inflammation in IPFP (assessed using dynamic contrast-enhanced MRI) were cross-sectionally associated with knee pain in obese patients with knee OA,43 and inflammation and oedema of IPFP contributed to knee pain43 44 Oedema within IPFP could increase pressure and lead to irritation of nearby tissues such as knee capsule and nociceptive nerve fibres that contain substance-P,45 46 resulting in increased knee pain. Our current study reported that, cross-sectionally, IPFP signal intensity alteration was positively associated with knee pain (especially when going upstairs/downstairs, at night while in bed and when sitting or lying).…”

Expected Prevalence From the Differential Diagnosis of Anterior Knee Pain in Adolescent Female Athletes During Preparticipation Screening

“…29,33 Symptomatically, irritation of the fat pad (often called the Hoffa syndrome) produces a dull, aching pain that is exacerbated by squatting, kneeling, climbing stairs, or prolonged sitting. 27,29,34,35 We found a prevalence of fat pad irritation of 0.4%.…”

The influence of patellar bracing on patellar and knee load-distribution and kinematics: an experimental cadaver study

“…In previous biomechanical studies we showed that an infrapatellar fat pad edema significantly increases tissue pressure inside the anterior knee compartment [1,2]. In a further immunohistochemical study, a high number of pain afferent substance-P nerve were found inside the fat pad adjacent to vessels [3], which we interpreted as a possible mechanism for inducing anterior knee pain following a possible chronic neurohistogenic fat pad edema.…”