Osteoarthritis is a progressive chronic degenerative joint disease with the main pathology being the destruction of joint cartilage, inflammation of the synovial membrane or sclerosis of the underlying bone. The main goal in treatment is pain reduction and halting the disease progression.
Although intra articular injection of viscosupplementations has been shown to be safe and efficacious, controversy continues to exist with regards to their usage. The uncertainty is likely secondary to inconsistency with guidelines and literature. Intra articular injection of hyaluronic acid can delay the surgical intervention in knee osteoarthritis and can be considered for long term therapy and also for pain reduction and joint function improvement.
A wide variety of treatments for osteoarthritis of the knee are available:
Non-pharmacological treatments: include education, exercise, lifestyle changes and physical therapies. TENS and acupuncture can also provide symptomatic pain relief.Pharmacological treatments: include pain killers, mainly non-steroidal anti- inflammatory drugs (NSAIDs), paracetamol and opioids.
Pharmacological treatments: include painkillers, mainly non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol and opioids.
Interventional treatments (Injections): include Intra-articular corticosteroid injections, which often provide transient symptom relief and viscosupplementation which may provide longer lasting pain relief.
Viscosupplementation is an injection of Hyaluronic Acid (HA). Hyaluronic Acid is a major component of the synovial fluid and of the cartilage and is one of the most important components of the extracellular matrix. HA is a high-molecular-weight glycosaminoglycan composed of repeating disaccharides of glucuronic acid and N-acetylglucosamine.
Osteoarthritis of the knee not only affects the quality of the synovial fluid but also the concentration and molecular weight of HA. This can lead to pain and loss of function in the knee joint. Injection of hyaluronic acid may help in the recovery of the concentration, molecular weight characteristics in the extracellular matrix and the viscoelasticity of the synovial fluid. This, in turn, results in improved pain control, articular function, and mobility.
There are many studies that compare hyaluronic acid to placebo. Some of these studies concluded that viscosupplementation of HA is effective in improving symptoms and function and decreases the pain with a modest difference versus placebo. But there are also studies that did not find or doubt this difference. Further research is needed to confirm that there is a certain difference in efficacy of viscosupplementation versus placebo. The American Academy of Orthopaedic Surgeons (AAOS) currently does not recommend viscosupplementation.
The long-term benefits of the corticosteroid use are still questionable. There are few clinical trials which compare the effectiveness of corticosteroids and hyaluronic acid intra-articular injections. Ray et al. compared the duration of effectiveness of the viscosupplementaion and the nonsteroidal anti-inflammatory drugs and corticosteroid injections. The study result manifested the longer pain relief with viscosupplementation than corticosteroid group (approximately 26 weeks) especially when it is administered in the early stages of the OA. Comparing the duration of effectiveness of corticosteroids and hyaluronic acid injection, hyaluronic acid is superior in pain relief duration, with corticosteroid administration every 2 months and hylauronic acid injection every 3 months.
Viscosupplementation is considered a safe procedure, but like any medical procedure, it does carry some risks and side effects. Patients undergoing viscosupplementation may experience mild discomfort immediately after the procedure. Typical side effects at the injection site include localized swelling, skin warmth and redness, soreness, and joint stiffness. Allergic reactions, some which can be potentially severe, have been reported during the use of viscosupplementation.