Conservative management of OA can be very effective
Surgical approaches for our patients include joint prosthesis, alteration in joint mechanics with osteotomies, and less invasive approaches using arthroscopy.
However, there is increased interest and a significant amount of research being done on less invasive forms of managing osteoarthritis (OA), controlling pain, and restoring function. These include rehabilitation, nutritional management, regenerative medicine, drug therapy, oral and injectable chondroprotectants, and anti-inflammatories.
For nonsurgical options in the treatment of osteoarthritis, multimodal approaches for pain control and improved function are often the most effective. However, for those patients where weight management, response to oral analgesics, and anti-inflammatories are no longer effective, the use of intra-articular (IA) injections can be considered.
What is osteoarthritis?
Osteoarthritis is defined as a reduction or loss of viable articular cartilage. Once this tissue is damaged, it has a limited capacity for self-healing. Some of the pathological changes that occur result in a reduction in synovial fluid and its viscoelastic properties. This loss alters the fluid’s viscosity and concentration, resulting in less lubrication and joint protection, and subsequent joint pain.
Hyaluronic acid (HA) is a component of the joint fluid that provides a form of viscosupplementation (i.e. joint lubrication), which reduces inflammation. Further, it is considered to have cartilage-repair properties. By binding to CD44 receptors on chondrocytes, HA induces cellular and extracellular matrix production, and is thought to inhibit mediators of inflammation. As a result, patients receiving intra-articular HA demonstrate improved function, less pain, and histologically, a reduction of cartilage pathology.
In our hospital, we use intra-articular high molecular-weight HA in dogs, most often given several weeks apart. In our experience, as well as reported findings, more than 80 percent of dogs show improvement after six months of treatment.
We currently use HA by itself in mild OA cases and add autologous platelet-rich plasma (PRP) and/or corticosteroids IA for more severe cases or those that show a poor response to single-agent injectables.
Intra-articular corticosteroids have been widely used in humans and have been shown in many applications to have a positive effect on reducing pain, albeit short-lived. Corticosteroids act on the inflammatory cascade through a reduction of arachidonic acid release.
Intra-articular corticosteroids reduce inflammation and decrease pain, permitting improved range of motion and, in turn, facilitating rehabilitative exercises that result in faster recovery time. Their disadvantages may include joint infection, extra-articular injection (which causes systemic signs of corticosteroid use), and injection pain.
In our hospital, we commonly use triamcinolone acetonide for patients with mild to moderate OA and reduced function. This medication is typically effective for about two weeks, during which rehabilitation exercises can be efficiently provided to improve muscle tone and range of motion.
Longer-acting Depo-Medrol can be used for more chronic and severe cases of end-stage joint disease. It typically results in pain relief in 12 to 24 hours, and can last for weeks to months. It is thought Depo-Medrol IA could be detrimental to articular cartilage. However, corticosteroids are generally considered safe and effective for repeated use every several months, with no significant loss of articular space identified. Lack of treatment response is often a result of failure of IA space injection.
PRP can be utilized by itself or in conjunction with HA in the treatment of osteoarthritis. It has been shown to have positive effects regarding angiogenesis and cartilage remodeling, as well as cytokine recruitment and chemotaxis. Further, it is a potent source of growth factors, including:
- platelet-derived growth factor (PDGF);
- epidermal growth factor (EGF);
- vascular endothelial growth factor (VEGF);
- transforming growth factor BETA; and
- basic fibroblast growth factor (bFGF).
All are found in the alpha granules of platelets and have been reported to both promote healing directly and recruit stem cells to local sites, facilitating repair.
The concentrated platelets found in PRP contain reservoirs of bioactive proteins and growth factors that inhibit inflammatory mediators (resulting in reduced pain) and improve articular function in osteoarthritis. Approximately 15 ml of blood is collected and processed through a series of steps of centrifugation to obtain PRP. The concentration of platelets and growth factors is increased three to seven fold, with no red blood cells, no neutrophils, and low monocytes. For osteoarthritis, PRP can be injected IA, either guided by fluoroscopy or digital radiography, depending on the patient and treatment site.
The intra-articular injection of PRP is a potentially promising therapy for OA in dogs. The growth factors found in platelets have demonstrated enhanced regenerative processes in arthritic joints. Intra-articular injection of PRP is a generally low-cost, simple procedure requiring blood collection and platelet extraction, followed by injection into the affected joint.
Rehabilitation offers a range of modalities that can be beneficial to patients suffering from varying severities of OA to provide them with pain control, maintenance of muscular integrity, and continued functional lives.
Hydrotherapy is useful for multiple conditions, and works to promote active range of motion with minimized weight-bearing. This therapy has the benefit of treating several areas at one time, which is helpful for patients affected by OA in multiple joints versus one focalized area. There are different forms of hydrotherapy that can be offered to patients, depending on their status. Underwater treadmills, whirlpools, and pools are the most common and provide the greatest control.
The combination of thermal effects, buoyancy, hydrostatic pressure, cohesion, and turbulence that water provides make hydrotherapy a unique modality for treating OA. This allows the therapist to work in a controlled environment where resistance can be appropriately adjusted for each case. As the patient progresses through the disease process, hydrotherapy treatments can be easily altered to meet their needs and abilities.
Range of motion can be significantly affected in OA patients, and the combination of hydrotherapeutic elements listed in the previous paragraph can help improve it. Overall range of motion, and in particular flexion, is greater during swimming than when walking; however, general extension is reduced with swimming.
In a human study done by Suomi and Lindauer, 1997, 17 women experiencing arthritis participated in three weekly 45-minute aquatic-training sessions over six weeks. The outcome resulted in greater increase in range of motion and strength versus the control group, which did not participate in any organized exercise.
Through regular sessions, the quality of range of motion should continue to improve. Along with greater range of motion, muscle tone, lengthening, and strengthening will increase to help support weak joints on dry land and provide the patient with improved quality of life and function.
Extracorporeal shock wave therapy (ESWT) is a useful modality in treating chronic and acute conditions (e.g. inflammation, tendinopathies) in postoperative patients, and also has become increasingly popular in treating osteoarthritis. ESWT uses high-energy shock waves comprising acoustic waves of various frequencies. Shock waves can travel to various tissue depths and target specific areas at different densities, both deep and superficial, which can be helpful when treating smaller, more delicate areas and joints.