The Latin breakdown:
“Arthro” = Joint
“Itis” = Inflammation
Osteoarthritis (OA) is a common, degenerative, painful disease with chronic onset and acute flare-ups [1]. This means it most commonly takes a long time to develop, but will also have periods of increased sensitivity and pain (acute flare-ups). This disease involves the whole synovial structure [1]– which is one of the reasons it is difficult to prevent and to manage. The synovial structure includes the attached connective tissue that covers tendons, muscles, bones and enclosed joints… which means it can majorly affect movement. The smooth articular surfaces become injured and inflamed, which result in lameness and compensation. The primary and secondary problems associated with managing arthritis are numerous.
Layers of a joint:
A: shows what a normal bone/joint looks like, B: diagram representing cartilage and the outer most edge of bone, C: demonstrates normal cartilage and subchondral bone, and D represents damaged cartilage and subchondral bone which is indicative of arthritis.
Features of joints and arthritis
1. The articular surface (the surface between two bones) is made of smooth and softer cartilage. This allows frictionless motion between bones at the joint.
2. Between these surfaces is a thick fluid made of hyaluronic acid and other chemicals which provide a frictionless and shock-absorptive liquid to cushion the joint ends.
3. The gradient of cells and tissues which develop from the core of the bone to the articular cartilage surface is highly interwoven [2]. This means it’s not distinct and the relation from the bone to the end of the joint is extensive. This gradient also represents a change in the elasticity/“softness” of the levels. This is marginal but does provide for some of the shock-absorptive properties of joints.
4. The “cracking” and loss of smooth surface observed in damaged tissue, and the loss of an even distribution of cells and tissue across the layers of joint tissue indicates arthritis. This alters the frictionless, smooth surface effectively, and becomes a downward cycle which increases joint inflammation and damage in turn.
Effects of/evidence of arthritis include [1]:
- Narrowing of joint space
- Osteophyte formation (joint mice, also known as little bony spurs that grow in or around the joint cavity).
- Subchondral sclerosis – This is the thickening of bone ends just under the cartilage
- Subchondral cyst – a fluid-filled space which appears at the end of a bone as a result of arthritis.
- Reduction in cartilage mineral density in early phases of arthritis
Chondrocytes are cartilage-producing cells. Losing them reduces the ability of the joint to repair and produce cartilage. Chondrocytes decrease in activity as the animal ages; however increased strain, damage and pressure to the joints, which could cause these microscopic fragments of cartilage to break, will increase the “wear and tear” associated with aging animals.
Âge -> cartilage degeneration
Increased workload -> cartilage degeneration
Cartilage degeneration -> increased joint damage, inflammation and pain
Joint damage and pain -> biomechanical compensations and discomfort
Causes of arthritis are not easily defined;
1. As a chronic disease, the precise moment that it starts happening is nearly impossible to define. However, some metabolic and physiological changes have been linked to early stages of OA.
2. As an acute onset, direct damage to cartilage in a sudden injury can result in a string of events which cause arthritis too.
A very brief overview of factors that can increase arthritis onset:
1. Joint conditioning when young
- Studies shown that growing and moving young horses “primes” their joints for good cartilage layers at their joints, and that these joints are better prepared for increased pressure later in life.
Injury
- Joint injury, soft tissue, bone fractures,
- Overcompensation (increased pressure on other joints)
2. Poor conformation
- Straight hocks (check out the blog: )
3. Discipline
- Racing, showjumping, cross country, dressage… all have different predisposition to arthritis in particular joints
4. Location of the joint
- Interestingly, different joints have been categorized in various studies to be far more prone to problems (sometimes labelled “radiographic lesions”). Bones of the distal limb, aka the Phalanges, are short, compact bones that appear to have evolved to take the brunt of force applied to limbs when moving [3]. Because of this function, these joints are exposed to the greatest force, and most likely to suffer arthritic changes as a result.
Common locations: (for those who paid attention, this would be the answer to the question posed on my social media this week!)
- The coffin joint of the forelimbs are the most commonly affected with arthritis. This is associated with the high level of force these joints absorb as the first point of contact with the ground.
- Hocks are the second most affected – this is so commonly related to conformation, back problems and as a result saddle and training problems.
- Hindlimb fetlocks are also highly affected, likely as a result of compensation from other problems.
Treating arthritis
NO TREATMENT WILL REVERSE THE EFFECTS OF ARTHRITIS, NOR SAVE THE JOINT ENTIRELY. TREATMENT OF ARTHRITIS MEANS TREATMENT OF SYMPTOMS. THIS MEANS ADDRESSING PAIN AND COMPENSATION, WHICH INVOLVES A VARIETY OF APPROACHES.
Treating arthritis at the level of the joint space and surface is reserved for the Veterinarian. Joint injections in the form of Hyaluronic acid and corticosteroids are commonly used to address inflammation (remember inflammation itself can and does cause pain and further problems) in the joint directly, and to aid in “plumping” the joint fluid already there: this is the Veterinarian’s domain. Pain management and lameness work-ups should all be used in the diagnosis and management of this chronic disease, particularly if you’re expecting your horse to work hard and compete.
Treatment by the Veterinary Physiotherapist is in support of the comfort and functionality of the horse, and to reduce pain caused by the acute flare-ups.
Target 1: The pain.
This is a wide-ranging target for this disease. Pain is likely to be in the affected joint… this will however be followed by that dark shadow that follows pain: compensation. This is likely to be causing pain elsewhere. Increased bracing activity of muscles in other limbs, or bracing the limb itself mean muscles are prone to fatigue quickly: causing further injury risk, discomfort and pain. On top of that, the increased muscle activity elsewhere is likely to increase the pressure on their associated joints, tendons and muscles, which can cause pain and even increase the rate of arthritis onset.
Furthermore, and I can’t stress this enough, pain will hinder muscle development and strengthening. If your horse’s pain and comfort levels are not being adequately managed, your training will be an uphill battle.
Training is hard enough as it is.
Monitor your horse’s comfort and improve your awareness of their indicators of fatigue.
LASER: is a fantastic tool for addressing painful and inflamed sites. This means muscle knots resulting from fatigue can be addressed without too much manual force. This is an advantage as chronic diseases can heighten the pain felt in the body. Horses with increased pain sensation rarely enjoy manual pressure and handling, therefore using a LASER to very effectively treat pain on a biochemical level, which can then improve the sensation and allow manual handling afterwards makes it a powerful tool for these cases.
Manual therapy: Massage, myofascial release and stretching offer release of the tight muscles developing from compensation, plus an element of strengthening and improved suppleness when the time is right. Increased blood flow, soft manipulation of tight muscles, movement of lymphatic fluid and gentle, physical treatment of muscle knots and tension all benefit the heightened state of discomfort the horse will be feeling.
Target 2: The joint.
Reducing further inflammation and maintaining the condition of the joint remaining is crucial. This is where the Vet’s involvement and direction is crucial. However, there are some powerful modalities a Veterinary Physiotherapist can offer to help your horse
LASER has been shown to increase the rate of production by chondrocytes: meaning increased cartilage production. This makes this an excellent choice to use at joint articulation sites, as it may help to power the chondrocytes that are remaining at the damaged joints.
CRYOTHERAPY: Ice applied to an inflamed joint after work reduces heat and the further damage that can cause. Ice further acts as a local mild painkiller after a certain period. It should not be applied for more than 20 minutes duration after work. Arthritic joints generally don’t like moving or being moved; so applying ice prior to work is not ideal, for pre-work preparation, HEAT therapy is more beneficial to these cases. Heat will increase the blood flow and lymphatic fluid movement to the joint, increasing its comfort and functionality in preparation for work.
Target 3: Maintaining and improving function.
Treating to maintain and improve function will increase the strength and condition of muscles, which should hopefully reduce the severity of acute flare-ups. Massage, stretching, myofascial release accompanied by a targeted remedial exercise program of controlled exercises will then allow strengthening of the body. As mentioned previously, pain hinders correct development and strengthening of muscles... improving muscle condition will improve comfort.
H wave is a powerful muscle stimulation tool which can create muscle contractions without fatigue. Increased blood flow, contraction and relaxation of whole muscles and lymphatic fluid movement vastly improve the biochemical concentrations of sore muscles. In addition, a direct reduction in pain sensation has also been recorded. Pain causes compensation which causes faulty muscle contraction sequences. Forcibly activating contraction in targeted muscles gives your Physiotherapist a powerful tool to re-train muscles which have changed their sequence, as well as bringing the horse’s attention to those muscles being treated. H-wave is also useful in neurological cases, and while arthritic horses hopefully are not suffering neurological symptoms, bringing their attention to the contraction of what are likely to be poorly used or dysfunctional muscles, could help them to improve the neurological pathways and therefore retrain the movement patterns… reducing the extensive compensations.
LASER can be applied similarly to target pain: muscle fatigue, knots, tension and pain will all greatly benefit this treatment.
Stretches target increased (or maintained) Range of Motion of joints, increase flexibility and the strengthening of muscles. These should be prescribed and performed on a case-by-case basis.
All the science aside, two of the most important approaches to managing arthritis and or injuries that I have learned over several experiences: Patience and confidence.
YOUR HORSE WILL NOT FORGET THEIR TRAINING JUST BECAUSE YOU GIVE THEM AN EASY DAY WHEN THEY FEEL STIFF OR SORE. Give them the benefit of the doubt. Your training is good enough, your horse remembers enough, you will get more out of training on the days they feel good if you let them recover effectively on the days they don’t.
Thanks for reading! there‘s so much more that can be written about arthritis, hopefully this fits as an introduction. Let us know your experiences in managing arthritis!
Take care!
Genevieve Xx
Apologies for the lack of reference list; uploading this from my iPad means I cant make the reference list yet, however it will be updated by the end of the weekend!