OSTEOARTHRITIS
SCIENCE
WHAT IS
HYALURONIC ACID?
Hyaluronic acid (HA) is a polysaccharide that is nearly ubiquitous in the body, and is a molecule found within the synovial fluid (SF).
It is produced by the synovial cells and chondrocytes and plays a crucial role in protecting the articular cartilage by maintaining synovial fluid viscosity. In normal joints, the viscoelastic properties of synovial fluid rely on Hyaluronic Acid. This molecule is hydrophilic and viscous in aqueous solution. It has specific rheological properties (see “Cartilage” section) due to its high molecular weight and concentration that make it the ideal lubricant and an effective shock absorber.
The size and concentration of Hyaluronic Acid decreases with age. It has been shown that for each decade gain in age, Hyaluronic Acid concentration decreases by 10%, leading to degradation of the mechanical/viscoelastic properties of the endogenous synovial fluid. 1,2
In osteoarthritis (OA), the concentration and molecular weight of endogenous Hyaluronic Acid is significantly reduced. Osteoarthritis treatment with intra-articular (IA) Hyaluronic Acid involves injecting exogenous Hyaluronic Acid into the joint cavity. Treatment works by replenishing Hyaluronic Acid levels and stimulating production of endogenous Hyaluronic Acid. The injected exogenous Hyaluronic Acid can be produced via biofermentation using the bacteria streptococcus equi or extracted from rooster combs. 3-6
WHAT IS SORBITOL?
Sorbitol is a sugar alcohol that is found in fruit and plants.
In osteoarthritis (OA), hyaluronic acid (HA) (see “Hyaluronic Acid” section) is broken down by free radicals in a process called oxidative stress. This reduces synovial fluid (SF) viscoelasticity (see “Hyaluronic Acid” section) which is one of the factors leading to reduced mobility. 4
Sorbitol is a sugar alcohol that is found in fruit and plants. It is used in many products, such as in food, cosmetic creams, toothpaste and medications. Sorbitol acts as a free radical scavenger.
It neutralizes the free radicals that break down Hyaluronic Acid in Osteoarthritis, helping to maintain synovial fluid viscoelasticity. When hyaluronic acid is combined with high concentrations of sorbitol, it is protected from degradation, providing lasting relief from the symptoms of Osteoarthritis. 8-11
What I need to remember?
RHEOLOGY
OF SYNOVIAL FLUID
Rheology is the study of how a substance deforms and flows following the application of a force. Synovial fluid (SF) is a non-Newtonian fluid with unique rheological properties: 1
– Viscosity: the primary function of synovial fluid is to act as a natural lubricant, reducing friction between the articular cartilage of synovial joints during movement
– Elasticity: synovial fluid also acts as a shock absorber, protecting joint tissues from damage
The viscoelastic behavior of synovial fluid depends on the type of force applied. If a shear stress is applied, synovial fluid acts as a lubricant, becoming less viscous and enabling free and easy movements. However, if a compressive force is applied, it acts as a shock absorber, preventing injury to the joint. Therefore, synovial fluid is said to be viscoadaptive. 1,4,12,13
In healthy joints, synovial fluid switches from viscous to elastic during movement. The point at which this switch takes place is known as the crossover. The crossover is key as it enables the joint to adapt based on the type of movement. This way, the joints are able to glide seamlessly to protect the cartilage. In osteoarthritis (OA), the crossover no longer happens normally. As a result, the joint is less able to protect the cartilage, leading to intense pain. 4,12-14
INFLAMMATION
Osteoarthritis (OA) is a disorder that involves the whole joint.
It affects all joint tissues that communicate at the cellular level by releasing and responding to inflammatory mediators. 15 In Osteoarthritis, the joint tissue known as the synovium becomes inflamed.
The inflammatory mediators released, such as cytokines (e.g., TNF, IL-1β; see figure), damage the cartilage (see "Cartilage" section), the fibrous tissue that covers and protects the end of long bones at the joints. Furthermore, inflammation also impairs the ability of the cartilage to repair itself following damage. 15
Inflammation (see image) is responsible for several Osteoarthritis symptoms, including: 15,16
- Redness
- Joint swelling
- Joint pain
- Joint stiffness
- Loss of joint function
CARTILAGE
Cartilage is made up of unique cells called chondrocytes.
Articular cartilage is a strong and flexible fibrous tissue that covers and protects the ends of long bones at the joints. Cartilage thickness varies from joint to joint. For example, cartilage may be less than 1 mm thick in the wrist. In the knee, it can be as thick as 6 mm. 17
Cartilage is made up of unique cells called chondrocytes. These cells are constantly producing and breaking down a network of mostly collagen-based molecules called extracellular matrix (ECM). Cartilage ECM provides crucial structural support to nearby cells. Furthermore, the ECM also sends important biochemical and biomechanical signals needed for tissue growth and homeostasis. 18,19
In a young and healthy joint, the production and breakdown of ECM is finely balanced. In osteoarthritis (OA), this balance is lost. ECM is broken down faster than it is produced, and the cartilage lowers in quality and becomes thinner. As a result, the bones on either side of the joint may grind against each other during movement leading to intense pain. 18,19
TREATMENT AND
PAIN MANAGEMENT
The treatment goals of osteoarthritis (OA) are to reduce pain and improve joint function.
Non-pharmacological interventions:
- Appliances (canes, insoles, knee bracing, etc.) 21
- Electrotherapy (nerve stimulation) 22
- Manual therapy (applying manual forces to improve the range of motion) 21
- Occupational therapy 21
- Patient education 22
- Thermotherapy (applying heat or cold to joints to improve symptoms) 21
- Weight loss 21
Pharmacological interventions:
- Oral analgesics (e.g. acetaminophen) 21
- Topical treatments (e.g. the topical NSAID diclofenac) 23
- NSAIDs and highly selective COX-2 inhibitors (e.g. celecoxib) 21
- Intra-articular injections (e.g. corticosteroids hyaluronic acid) 21
The use of intra-articular (IA) hyaluronic acid (HA) is growing worldwide. Several clinical trials have reported intra-articular Hyaluronic Acid-related improvements in functional activity and pain management. 4
Intra-articular HA is as effective as NSAID for pain control, but with a better safety profile. 24 Furthermore, using IA high molecular weight HA is cost effective in OA management 25 and delays for total knee replacements in OA. 26
Surgery:
If non-pharmacological and pharmacological interventions fail to manage pain effectively, referral to a surgeon may be required. Surgical procedures include arthroscopy and osteotomy. These procedures can help delay the progression of Osteoarthritis joint replacement may also be considered in certain patients. 24
See next section for more information on treatment and pain management, where you will find a number of useful resources including the latest guidelines.
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What I need to remember?
If you are experiencing symptoms such as joint pain, stiffness and swelling,
talk to your doctor about whether you have osteoarthritis.
OTHER TREATMENT OPTIONS
Your doctor will talk to you about finding a plan that suits your needs. Doctors usually treat osteoarthritis with a combination of therapies:18
- Lifestyle modifications
- Exercise
- Weight Management
- Orthotic devices
- Medications
- Topical (placed directly on the skin)
- Oral (by mouth)
- Injections (shots)
- Dietary supplements
- Surgery
Lifestyle modifications:
There are several ways of relieving osteoarthritis symptoms without using medications. 19-20
Exercise:
Although it might seem counterintuitive, physical activity can help osteoarthritis. Not only will appropriate activities decrease osteoarthritis pain, they can improve motion and function. Your doctor may recommend activities such as walking, swimming, water aerobics. Find out more here.
Weight management:
A weight loss program may be recommended, if needed, particularly if osteoarthritis affects weight-bearing joints (such as the knee, hip, spine, or ankle). Excess weight puts stress on your joints so removing that stress can relieve symptoms.
Orthotic devices:
These support (“assistive”) devices, such as a knee brace or shoe insert, can help by taking strain off joints.
Medications:
There are different types of medication that may help osteoarthritis: 20,21
Topical (placed directly on the skin):
Topical pain relievers can be applied directly on the skin over the affected joints. These medicines include capsaicin cream, lidocaine and diclofenac gel.
Oral (by mouth):
Oral pain relievers such as paracetemol are common first treatments. So are nonsteroidal anti-inflammatory drugs (often called NSAIDs), which decrease swelling and pain.
Injections (shots):
Joint injections with hyaluronic acid can also give months of pain relief from osteoarthritis. Find out more here.
Dietary supplements:
Many over-the-counter nutrition supplements have been used for osteoarthritis treatment. Most lack good research data to support their effectiveness and safety. Consult your doctor or pharmacist before using any of these supplements. This is especially true when you are combining these supplements with prescribed drugs.
Surgery:
Surgical treatment is an option for severe osteoarthritis, however not everyone can have surgery: 20
Surgical intervention can be considered when the joint has serious damage, or when medical treatment fails to relieve pain and there is major loss of function. Surgical options for osteoarthritis include joint replacement.
What I need to remember?
True of false?
You can’t or shouldn’t exercise once you’ve got osteoarthritis.
Choose an answer
The Truth: You should be physically active when you have arthritis. Not only will appropriate activities decrease your osteoarthritis pain, they can improve range of motion, function, and reduce disability.
Did you know ?
What is the percentage of people affected by osteoarthritis over 65 years old?
Choose an answer
Did you know ?
What is the percentage of people affected by osteoarthritis over 65 years old?
Choose an answer