Here is the link https://www.maxhealthcare.in/blogs/tips-reduce-knee-pain-old-age
Walking - Inactivity is the primary cause of knee pain in most of the elderly population. As the activities and workload decrease with age, older people tend to stop their physical movement. To balance it, one must make it a routine to go for morning/evening walks to keep a check on the muscle strength and stamina. A sedentary lifestyle makes knees stiff and hence painful.
Knee press - Lie flat on the bed with your knee straight. Keep a rolled towel beneath your knee joint and press it against the towel and hold it for five seconds. It helps to improve the strength of quadricep muscles.
Heel press - Lie flat on the bed both your knees straight. Keep rolled towel beneath your ankle joint, and press it against the towel and hold it for five seconds. It helps to improve the strength of hamstring muscles.
Knee curl - Stand with your front facing the back of the chair. Place your feet slightly apart and shift your weight over the left leg. Keep your knee slightly bent and bend your right knee raising the right foot towards buttocks. Repeat 10 to 15 times. This will help to increase the flexibility of knee muscles.
Knee squats - Stand with your front facing the back of the chair place your feet slightly apart and bend your knees while keeping your back straight. This will allow you to strengthen your knees as a whole.