Excess weight (either body weight or the weight of the Projoint Plus Review objects that you carry around) intensifies the load on the supporting muscles and ligaments of your knee while you perform your daily chores. This increases the likelihood of injuries taking place and the process of degeneration of bones is also faster. This causes pain behind the knee.
When there is some inflammation in the joints of your knee, making forward and backward movement of the knee while walking or climbing stairs can be a cause of pain behind the knee. You must follow the guidelines of the physiotherapist closely, who will advise you on the correct posture to maintain while you are in the process of lifting and carrying unwieldy objects.
A weak hamstring is another cause of pain behind the knee as the hamstring muscles are instrumental in helping you to bend your knees. The quadriceps and hamstrings are the prominent muscle groups that are the workhorses helping us to move our legs and bend our knees.