Chronic Pain and Osteoarthritis

The chronic pain associated with OA, in particular the severe pain experienced by nearly a quarter of OA sufferers, is one of the most common reasons for chronic opioid prescriptions. Additionally, OA is the highest cause of work loss in the United States.

In individuals with OA, protective cartilage on the ends of the bones gradually deteriorate, and the bones around the joints harden and form edges. These changes cause pain, swelling and difficulties moving the joint. OA can affect any joint, but it occurs most often in knees, hips, lower back and neck, small joints of the fingers and the bases of the thumb and big toe. OA also results in bony changes of the joints, such as bone spurs, deterioration of tendons and ligaments, and various degrees of joint inflammation. OA can cause pain severe enough that patients experience difficulty with simple daily movements such as walking, climbing stairs or even rising from a chair.

There is no cure for OA. As a result, current treatments are intended to address symptoms (in particular relief of pain and improvement in functional status) and with exercise that maintains muscle mass and supports the knee. Despite these currently-available therapies, many patients still suffer with chronic moderate-to-severe OA pain. When the patient can no longer tolerate the pain and disability, a surgical procedure can be performed which replaces the natural joint with an artificial joint.

Osteoarthritis of the Knee

Knee OA is the most common form of OA. It is estimated that approximately 18 million people in the United States are diagnosed with knee OA, and that number is expected to grow to in excess of 30 million by 2030.

In the case of the knee joint, as OA progresses the structure of the knee changes as cartilage erodes exposing bone and nerve fibers. The joint becomes inflamed and the lack of cartilage leads to stiffness and deterioration of movement and flexibility. Patients experience inflammatory pain and discomfort moving the joint. The pain is often severe, which can be debilitating and prevent people from carrying out daily activities.