Assess the Blood-Oxygen-Level-Dependent (BOLD) Signal Changes in the Brain by Paracetamol as Measured by Functional Magnetic Resonance Imaging (fMRI) in Subjects With Osteoarthritis (OA)

BOLD response to painful pressure stimuli was evaluated using fMRI. Voxel-wise BOLD scores were reported on a Z-scale (Gaussian,mean=0,SD=1); range -3 (worst score, lowest connectivity) to +3 (best score, highest connectivity). The software derived scores compared the intensity reading in the region to a template, specifically the Montreal Neurological Institute (MNI) Echo-Planar Image (EPI) template. The template provides, for each region, expected (mean/median) intensity for that region, along with expected variation. The BOLD score on the Z-scale represents how far the actual measured intensity is from the expected in the template. A score of 0 would correspond to the mean/median, a score of 1.65 would represent the 90-percentile, -1.65 the 10-percentile, and so on, according to a standard normal distribution.

BOLD response to painful pressure stimuli was evaluated using fMRI. Voxel-wise BOLD scores were reported on a Z-scale (Gaussian,mean=0,SD=1); range -3 (worst score, lowest connectivity) to +3 (best score, highest connectivity). The software derived scores compared the intensity reading in the region to a template, specifically the Montreal Neurological Institute (MNI) Echo-Planar Image (EPI) template. The template provides, for each region, expected (mean/median) intensity for that region, along with expected variation. The BOLD score on the Z-scale represents how far the actual measured intensity is from the expected in the template. A score of 0 would correspond to the mean/median, a score of 1.65 would represent the 90-percentile, -1.65 the 10-percentile, and so on, according to a standard normal distribution

Subjective NRS response for each participant was calculated as difference of pre-treatment NRS pain assessment before stimulus and post-treatment NRS pain assessment before stimulus. NRS responses was based on an 11 scale rating (0-10), with 0 corresponding to "No Pain" and 10 corresponding to "Extreme Pain or Pain as bad as you can imagine".

Subjective NRS response was calculated for each participant as difference of pre-treatment pain assessment after stimulus and post-treatment pre-scan pain assessment after stimulus on tibio-femoral joint. NRS responses was based on an 11 scale rating (0-10), with 0 corresponding to "No Pain" and 10 corresponding to "Extreme Pain or Pain as bad as you can imagine".

Subjective NRS response was calculated for each participant as difference of pre-treatment pain assessment after stimulus and post-treatment pre-scan pain assessment after stimulus on patello-femoral. NRS responses was based on an 11 scale rating (0-10), with 0 corresponding to "No Pain" and 10 corresponding to "Extreme Pain or Pain as bad as you can imagine".

Subjective NRS response for treatment effect on tibio-femoral stimulus after the fMRI scan was calculated for each participant as difference of pre-treatment pain assessment after stimulus and post-treatment post-scan pain assessment after stimulus on tibio-femoral. NRS responses was based on an 11 scale rating (0-10), with 0 corresponding to "No Pain" and 10 corresponding to "Extreme Pain or Pain as bad as you can imagine".

Subjective NRS response for each participant for treatment effect on tibio-femoral stimulus after the fMRI scan was calculated as difference of pre-treatment pain assessment after stimulus and post-treatment post-scan pain assessment after stimulus on patello-femoral. NRS responses was based on an 11 scale rating (0-10), with 0 corresponding to "No Pain" and 10 corresponding to "Extreme Pain or Pain as bad as you can imagine".