If you have osteoarthritis in one or both knees and are planning a hiking tour or holiday, you should listen to you body and heed what it tells you. By no means should you blithely march off. “Osteoarthritic knees are more sensitive. But if you treat them well, you can still do a lot with them in many cases,” says Dr Karl-Heinz Frosch, director of the Department of Trauma Surgery and Orthopaedics at Hamburg-Eppendorf University Medical Centre in Germany. Osteoarthritis is a wear-and-tear condition in which the cartilage cushioning the ends of the bones in the joint gradually breaks down, causi…