A popular rule of thumb is that every kilo of weight loss is equivalent to four less kilos of pressure on a knee afflicted with joint osteoarthritis. For obese people in particular, this can make a world of difference for common activities like walking. A combination of low-impact cardiovascular training (e.g. swimming, cycling), specific muscle strengthening exercises around the knee and healthy eating will slim you down and make physical work more fulfilling.
Depending on your current level of knee stability, your physiotherapist will suggest a variety of exercises:
While overweight people have special physiotherapy needs, the information here is relevant for anyone who is recovering from back or knee injuries. Besides maintaining a suitable weight, ensure that regular movement (including back, knee specific exercises), and proper rest are all part of your winning rehabilitation formula.