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The 2019 Arthroscopy Association of Canada (AAC) guidelines provide suggestions for patients with knee OA, including the role of joint injections in improving pain, function, and stiffness in patients with mild to moderate knee OA.

These guidelines discuss the utility and cost-effectiveness of arthroscopic surgery as a treatment for OA of the knee. In these guidelines, they recommend an initial 6-9-month trial of appropriate and comprehensive conservative treatment for all patients before considering operative treatments.

Specifically, the guidelines for treatment of knee OA advise:

  • The use of knee injections is most effective in patients with mild to moderate knee OA (Kellgren-Lawrence grades 1-2). This is sooner than previously recommended.
  • Intra-articular corticosteroid injections have a role in providing short-term, moderate pain relief and the restoration of function, in a cost-effective manner for patients with early knee OA.
  • Intra-articular hyaluronic acid (HA) provides improvement in pain, function, and stiffness for up to 26 weeks after an injection in patients with mild to moderate knee OA. Furthermore, it is safe, with a low risk of adverse events.
  • Combination therapy of HA and corticosteroids has been shown to significantly reduce pain in knee OA, with a more rapid onset of action than HA alone.


Osteoarthritis is the most common form of arthritis and it’s affecting more and more Canadians every year. It’s estimated that by 2035, one in four Canadians with be diagnosed with OA – a disease of the whole joint that leads to the breakdown of joint cartilage and the underlying bone.

OA is sometimes described as degenerative or “wear-and-tear” arthritis. Recent studies suggest there may be an inflammatory component to OA, so it may not just be age-related or caused by overuse. In normal joints, cartilage – the tough elastic material that covers and protects the ends of bones – acts as a cushion and provides a smooth, gliding surface for joint motion. OA causes the cartilage to break down, leading to pain, swelling, and problems moving the joint. As it worsens over time, the cartilage wears away and bone rubs against bone, causing joint damage and increased pain.


OA usually progresses slowly over months or years and early symptoms tend to come and go. It commonly affects the knees, hips, first toes, wrists, thumbs, fingers, and spine. As damage progresses, symptoms can become more constant, occurring at rest and disturbing sleep.

There are a number of methods for classifying the clinical severity of OA, which is important in directing appropriate treatment. The most commonly used is Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) that assesses OA based on pain, stiffness, and physical function.

There are also different methods for determining the severity of OA through imaging.

As X-ray is readily available, the Kellgren-Lawrence grading scale is routinely used to gauge OA disease severity. It is determined by assessing joint space narrowing and bony growths, and is divided into five stages – graded from 0 to 4. The Whole-Organ Magnetic Resonance Imaging Score (WORMS) method grades OA on MRI including articular cartilage, bone marrow alterations, and soft tissue changes around the joint.


STAGE 0 – Joint is healthy and there are no signs of OA.

STAGE 1 – There may be tiny, early changes of the cartilage in the joint, but no appreciable joint narrowing or spurring. At this stage, there is only minor wear on joint components and you rarely experience pain or discomfort.

STAGE 2 – This is considered mild OA. X-rays may show bone spurs, but cartilage is still thick enough to prevent joint space narrowing. Cartilage may be frayed and there may be mild bone marrow alterations. Synovial fluid, which helps lubricate and cushion joints, is typically still present at sufficient levels for normal joint motion. It’s often at this stage where you may first begin experiencing symptoms. They could include pain after a long day of walking or running, greater stiffness in the joint when it’s not used for several hours, or tenderness when kneeling or bending.

STAGE 3 – Classified as moderate OA, cartilage between bones begins to thin, so the space between the bones begins to narrow. This may be associated with larger bone spurs, more bone marrow swelling or cyst formation, and more fluid in the joint. You may experience frequent pain when using the joint, or stiffness after long periods of inactivity or when waking up in the morning. Joints may swell after extended periods of motion, as well.

STAGE 4 – At this stage, OA is considered severe and you may experience great pain and discomfort when using the affected joint, or during rest. The joint space between bones is dramatically reduced, there are bulky bone spurs and the cartilage is often completely gone, leaving the joint stiff and possibly immobile. Synovial fluid can be decreased dramatically, no longer reducing the friction between the bones; or can be increased causing swelling and limiting range of motion of the joint.

Osteoarthritis is a chronic (long-term) disease and, although there is no cure, these newer guidelines suggest earlier treatment and management may slow the disease. Earlier treatment will reduce your symptoms and make it possible for you to lead a full and active life. It’s important to thoroughly discuss all your options with your health care practitioner.

For more information on pain management procedures, please speak to your health care practitioner.



Arthritis Foundation (2021) “Osteoarthritis Symptoms and Diagnosis.” Accessed October 5, 2022.

Arthritis Society Canada (2022) “Osteoarthritis.” Accessed October 5, 2022.

Arthroscopy Association of Canada (2019) “Arthroscopy Association of Canada Position Statement on Intra-articular Injections for Knee Osteoarthritis.” Orthopaedic Journal of Sports Medicine. 7 (7). Accessed October 5, 2022.

Holland, Kimberly (2021) “Stages of Osteoarthritis (OA) of the Knee.” Accessed October 5, 2022.

Bennington-Castro, J. (2020) “What Is Osteoarthritis? Symptoms, Causes, Diagnosis, Treatment, and Prevention.” Accessed October 5, 2022.

Osteoarthritis Research Society International (2019) “OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis.” Osteoarthritis Cartilage. Nov; 27(11):1578-1589. Accessed October 5, 2022.


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