Fig. 5

H&E stained sections of the patellofemoral joint in studied groups. The first column represents low power × 40 (scale bar = 500 microns). The second column shows the high power of the round dashed area to represent the infrapatellar fat pad (IPF) changes (× 100, scalebar = 200 microns). The third column is the high power of the squared dashed area to show the articular cartilage thickness (double-headed arrow) and subchondral bone (SCB) (× 200, scalebar = 100 microns). The control (CN) group shows a normal architecture of the joint, IPF is formed of fat with no synovitis or fibrosis, and articular cartilage is thick with preserved zones. The subchondral bone is thin. The OA group shows joint deformities of articular cartilage (yellow arrow). The IPF shows inflammation (black arrow) with severe fibrosis (red arrow) and no fat cells are seen (score 6). Articular cartilage is thinned out and composed of a fibrous cap. SCB is thick and sclerosed. The changes were improved in the LOS and DIZE groups. The LOS group shows improved inflammation in IPF with residual fibrosis (black arrow). High power shows increased thickness of cartilage with residual mild surface irregularities and thin SCB. Meanwhile, the DIZE group showed smooth cartilaginous surfaces of the patellofemoral joint and resolved inflammation and fibrosis in IPF. Articular cartilage showed organized chondrocytes with no clustering or proliferation, and thin SCB. Yellow arrow = joint deformities, SCB = subchondral bone, black arrow = inflammation, red arrow = fibrosis, double head arrow = articular cartilage thickness