The location of the knee pain can be a useful guide. Pain in the front portion of the knee can be caused by bursitis (inflammation of the lining of the joint, possible due to injury), arthritis, or injury to the patella cartilage (front portion of the knee). Pain on either sides of the knee is usually related to meniscal tears, injuries to the collateral ligaments, and even to arthritis. Pain in the back of the knee can be caused by arthritis or Bakers cysts (cystic accumulation of synovial fluid, also causes a swelling). So as you can see, arthritis can cause an overall knee pain. Ligament injury causes pain to worsen on walking, bending and stretching the knee. Meniscii too if torn or injured, result in joint instability—that is you are not confident the knee joint will take your weight. Often the person feels a popping sensation on moving the joint. It can also be tendinitis due to inflammation of tendon at the knee joint. You will need X-rays and MRIs of the knee to find the exact. Treatment will follow correct diagnosis. Your orthopedic specialist will help you with that. Meanwhile do not bear weight on that leg, give it rest, apply ice pack, and take an anti-inflammatory pain killer. Take care!
Thanks so much ...very helpful