We found moderate evidence that combined heavy lifting and kneeling is a risk factor for knee OA, with odds ratios (OR) varying from 1.8 to 7.9, and limited evidence for heavy lifting (OR=1.4???7.3), kneeling (OR=1.5???6.9), stair climbing (OR=1.6???5.1), and occupational groups (OR=1.4???4.7) as risk factors.