What is the Donjoy Fortilax Knee? The Donjoy Fortilax Knee Elastic offers support & compression for knee injuries while helping to alleviate the symptoms of mild osteoarthritis. The Fortilax is best utilised following acute pain, usually as a result of trauma or direct impact where discomfort is isolated & rapid, although is limited in duration or chronic problems which can last more than six months. This ultra-light support (less than 500g) is perfect for daily living or conservative non-contact sports & features a unique Lycra fabric blend for added comfort with an enhanced compressive fit: Meniscus (cartilage) damage General instability Swelling Proprioceptive & neuromuscular stimulation What size do I need? The thigh circumference should be taken 15 cm above the patella mid-line & where your sizing falls between measurements, please select the next size up: X-Small: 35-38 cm or 13-15.5 inches Small: 39-42 cm or 15.5-16.5 inches Medium: 43-46 cm or 17-18 inches Large: 47-49 cm or 18.5-19.5 inches X-Large: 50-53 cm or 19.5-21 inches XX-Large: 54-57 cm or 21-22.5 inches This product is not suitable for contact, extreme or water-based sporting activities. Please Note if buying from abroad: These products are sent direct from the manufacturer & so lead times will be significantly longer than normal if you purchase this item from outside the UK