Arthramid Joint Therapy

If you’re looking for a long-lasting, effective, and safe way to support your equine athlete’s joints, consider Arthramid. This therapy has been commonly used in horses and humans in Europe for many years. Henderson Equine Clinic has been using it since its FDA approval for use in the United States in 2020.

What Is ArthramidVet?

A non-resorbable, injectable, 2.5% polyacrylamide hydrogel (PAAG) cross-linked with water that is incorporated into the synovial membranes as a bioscaffold and spacer.

ArthramidVet is long lasting due to its stable, inert, non-absorbable, non-degradable, non-pyrogenic (no fever), and neuro-innocuous (not toxic to nerves) properties. It is extremely stable due to its high molecular PAA polymers that are cross-linked in a three-dimensional network that is hydrophilic (attracts water). Its hydrophilic characteristics increase its viscoelasticity making it resilient to compression and shear forces. It is used intra-articularly to treat early and late stages of osteoarthritis, as well as non-infectious causes of joint disease.

When Do We Choose ArthramidVet?

ArthramidVet is both a preventative and therapeutic treatment, without long term contraindications. It is safe and effective in both younger and older horses. Horses of almost any age and athletic level who have inflammation or injuries involving their joints, cartilage, tendon sheaths, or bursa (including the navicular bursa) will benefit from ArthramidVet. This includes horses that have:

Poor conformation predisposing them to arthritis: ArthramidVet will cushion and prevent inflammation, minimizing factors triggering Osteoarthritis
Synovitis or joint effusion: ArthramidVet will stimulate new cell growth and stabilize the joint capsule, decreasing inflammatory mediator release into the joint fluid
Bursitis or Tenosynovitis (swelling and inflammation in a bursa or tendon sheath), especially in young horses: ArthramidVet will stimulate new cell growth and stabilize the synovial membrane, decreasing inflammatory mediator release into the synovial fluid
Injuries or past surgery that will predispose them to osteoarthritis in the future: ArthramidVet minimizes degenerative progression from those injuries / surgeries
Osteoarthritis, mild or severe: ArthramidVet will provide cushion and joint stability, to treat current lameness problems as well as prevent worsening of osteoarthritis
Cartilage defects: ArthramidVet will help fill the gaps in the cartilage, minimizing further cartilage degeneration

Between 67-85% of horses (depending on the disease state of the joint) treated with ArthramidVet have a successful resolution of joint lameness. Horses with joint pain, synovitis, joint effusion, lameness, a history of joint injection-related reactions, or that suffer from metabolic conditions (where steroids are contraindicated) respond favorably to intra-articular injection of ArthramidVet. We have seen very good results in high-motion joints, such as the upper hock joint, stifle, shoulder, elbow, fetlock, coffin, pastern, and hip joints. Studies on efficacy and safety of Intra-articular injections of ArthramidVet into cervical joints are currently being performed.

The efficacy often lasts for 1-2 years, longer than most other intra-articular therapies. ArthramidVet is more effective and safer for joint cartilage. Not only does it reduce the pain of swelling and inflammation (like a steroid), it also helps the joint to heal and restore proper function; all without the cartilage degrading side effects seen with steroid injections. However, If necessary under certain conditions, ArthramidVet can be combined with steroids or Ortho-biologic injections to resolve inflammation sooner, facilitating the integration of ArthramidVet into the synovial membrane.

How Does It Work?

ArthramidVet first adheres to and then integrates into the joint's synovial membrane (the membrane around the joint space that produces synovial fluid). This integration occurs at the sub intima layer, by migration and growth of new cells, blood vessels, and collagen fibers into the joint lining. Full integration takes approximately two to four weeks.

Once integrated, ArthramidVet acts as an inert, biocompatible tissue scaffold and porous spacer, providing a long lasting increase in joint capsule elasticity and tensile strength. This stabilizes the joint capsule, supports and cushions the joint, and helps preserve the synovial membrane, allowing the joint capsule to deform and compress while under load, weight bearing, without stretching the capsule and triggering its mechanoreceptor and nociceptor mediated pain response. The increased capacity for load bearing with concurrent decrease in pain stimulation results in increased freedom of motion and improved joint health. The reduction in capsular damage and subsequent inflammatory products results in an improved quality of joint fluid and better joint health.

In addition, the cellular growth stimulated by the ArthramidVet integration encourages the cell lining of the synovial membrane to cover itself in a new hypercellular layer, which is able to produce even more synovial fluid to support the joint naturally. To read more about how Arthramid affects joint inflammation at a cellular level, please see the bottom of this article.

What Can I Expect During ArthramidVet Treatment?

Due to the viscous nature of Arthramid Vet, it does not cross the synovial membrane or pass through the synovial plica. It must be injected directly into the joint, with the needle completely penetrating through the joint capsule. Confirmation of this proper placement is achieved via ultrasound guided injection of the joint. The needle is actually visualized penetrating the joint capsule, passing through the plica or proliferative synovial membranes and entering the joint; then the Arthramid Vet itself is visualized entering the joint and mixing with the joint fluid. Confirmation of proper placement is critical to ensure results. There will be no improvement in lameness or prevention of progression of the disease state if the product is not placed completely inside the joint capsule.

After injection, the horse will be placed on 48 hours of stall rest followed by limited, low impact, restricted exercise that slowly increases to lower intensity training over the following two to four weeks, as prescribed by the treating veterinarian. This allows for the full integration of the ArthramidVet into the synovial membrane. A gradual decrease in lameness as well as a decrease in positive flexion tests are seen in the first one to seven days after treatment and the clinical improvement will continue over the next 3-4 weeks. ArthramidVet does not act like a steroid injection, and because of the gradual progression of improvement it’s best to plan your horse’s Arthramid injections well in advance of your planned show season (or period of increased exercise demand).

In general, 67 to 82% of treated horses will become sound, depending on the diseased state of the joint. 10 to 15% of the treated horses will improve but not have a 100% resolution of lameness. This incomplete resolution is often dose dependent, resulting when the volume of ArthramidVet injected was not large enough to integrate with all the damaged sites. These horses typically respond to a second injection, administered 4-6 weeks after the initial treatment. In severe osteoarthritic cases, ArthramidVet may be injected at four to six week intervals.

With ArthramidVet, you may notice a gradual reduction of lameness as early as the first week, but because the product takes 2-4 weeks to fully integrate into the joint capsule, you will see greater impacts on performance later in the process. We recommend a recheck exam 4-6 weeks after the first injection, and if your horse has only partially responded to the medication, we may recommend a second larger injection of ArthamidVet.

How Much Does Arthramid Cost?

Each Arthramid treatment is generally more expensive than a treatment of other joint treatments. This is partly because of the cost of the product itself, but also because of the expenses associated with the ultrasound-guided injection. Cost is also dependent on the amount of product used and how much sedation is necessary to complete the procedure. However, one treatment of Arthramid can be effective for at least two to three times as long as other joint treatments. Investing in Arthramid treatments generally results in lower long term maintenance costs as well as an extended athletic career for your performance horse, than using steroids and/or biologics alone.

The cost of the product itself depends on how many syringes are used. Arthramid comes in 1 mL syringes, and each joint can fit a different number of syringes. Keep in mind that individual horses may have joint abnormalities that require different amounts of Arthramid than this chart. The veterinarian will determine how many syringes are recommended based on the location and the severity of joint pathology in your individual horse.

The In Depth Mechanisms of Joint Disease

To understand the actual mechanisms of joint disease and ArthramidVet’s effect on it, a simple understanding of the inflammatory cascade is necessary. The inflammatory cascade is triggered by tissue damage, either from chronic low grade wear and tear or sudden impact. In joints, the damaged tissue is generally the synovial membrane, cartilage, or bone itself. Once damaged, the inflammatory cascade is triggered and inflammatory mediators are released from multiple cells (macrocytes, synoviocytes, and connective tissue cells). These mediators increase inflammation and inflammation within the joint, which results in:

1) effusion, swelling of the joint: The Joint capsule and synovial lining both contain mechanoreceptors and nociceptors.

Mechanoreceptors are sensory receptors that respond to mechanical pressure or distortion (commonly caused by trauma and joint swelling). They are innervated by sensory neurons that convert mechanical pressure into electrical signals that, in animals, are sent to the central nervous system where it creates the sensation of pain
Nociceptors are sensory neurons that respond to the damaging or potentially damaging stimuli of inflammation and chemical mediators of inflammation by sending "possible threat" signals to the spinal cord and the brain. The brain creates the sensation of pain

Both synovitis (inflammation of the joint lining) and capsulitis (inflammation of the joint capsule) stimulate chemical nociceptors (through inflammatory mediators) and mechanical nociceptors (through swelling and joint distention stretching the structures) in the joint and joint capsule which result in joint pain. Any degree of joint pain inhibits muscle contraction (and therefore joint motion) in a protective response. This decrease in joint motion allows the inflammatory mediators to remain in contact with the cartilage longer and further damage the joint. Finally, the reduction of pain removes the muscle inhibition, restoring normal motion and improving joint health.

2) decreased joint capsule elasticity: A reduction or complete loss of its ability to deform and transfer load results in higher forces passing through the joint. Joint capsule stiffness also results in pain due to stimulation of these mechanoreceptors and nociceptors.

3) enzymatic degradation: of the inflammatory mediators on the joint fluid and tissues resulting in a decreased concentration and poorer quality of proteoglycans

4) Bertilich damage: which increases the concentration of water in the cartilage and joint fluid and decreases the chondrocytes such that there is a reduced resistance to shear force in the cartilage and an increased possibility of cartilage fragments.

5) Cartilage fragments result in increased joint damage and further stimulation of the inflammatory cascade and an increasing, escalating, downward cycle

The inflammatory cascade and the resulting downward cycle, if uninterrupted, results in higher forces on the bone and less resistance to those forces intra-articularly, causing the bone to attempt to stabilize the joint with bony deposits (such as subchondral bone sclerosis, osteophytes, and osteoarthritic changes). ArthramidVet improves the joint capsule elasticity and improves the quality of proteoglycans and joint fluid as well as cushions the joint to protect against shear forces.