Synovial fluid is part of the joint. And like any other part of the joint, if it changes, if it’s out of balance or no longer functions as it’s meant to, the cascade of joint disease starts to accelerate.

It’s basically defined as the collection of fluid confined within a joint space. The healthy synovial fluid within healthy joints functions as a biological lubricant as well as a biochemical carrier, through which nutrients and regulatory cytokines travel. It contains certain molecules that provide low-friction and low-wear properties to articulating cartilage surfaces. Without healthy synovial fluid in our joints, the wear on the cartilage surface will increase.

What is it?

Synovial fluid is physiologic and acts as a joint space lubricant. It is the nutrient source for cartilage, meniscus, labrum, etc. It’s produced as an ultrafiltrate of blood plasma, primarily composed of hyaluronan, lubricin, proteinase, collagenases, and prostaglandins, and is produced from fibroblast-like synovial cells.

A closer look

A healthy knee for example contains ~2mL of synovial fluid.

This consists of:

• Hyaluronic acid: A viscous glycosaminoglycan serves as a structural element and lubricant. HA is in high concentration within the healthy synovial fluid, it is a key component to the extracellular matrix of cartilage, supporting chondrocytes.
• Lubricin: The most lubricating and anti-adhesive molecule in the human body. It is a surface-active mucinous glycoprotein secreted in the synovial joint and plays an important role in cartilage integrity. Lubricin molecules coat the cartilage surface, providing boundary lubrication and preventing cell and protein adhesion.
• Proteinase: An enzyme that catalyzes proteolysis, the breakdown of proteins into smaller polypeptides or single amino acids.
• Collagenases: Enzymes that break the peptide bonds in collagen.
• Prostaglandins: Produced in nearly all cells and are part of the body’s way of dealing with injury and illness. They both sustain homeostatic functions and mediate pathogenic mechanisms, including the inflammatory response.

Choosing treatments to match pathology

Synovial fluid can change and create negative effects in the joint. Volume and content changes occur in response to trauma, inflammation, and bacterial, fungal, or viral penetrance. If a patient presents with acutely painful joints with suspicion of infection, inflammation or non-inflammatory causes of effusion, synovial fluid aspiration and analysis can be a really useful part of the overall analysis when considering direct treatment modality.

Strategies to maintain healthy synovial fluid

Synovial fluid can be heavily influenced by our day-to-day life with simple factors coming into play.

1. Stay Hydrated: It is essential for overall health but this includes joint health. Dehydration can reduce synovial fluid production.
2. Balanced Diet: Consume a well-balanced diet rich in omega-3 fatty acids, antioxidants, and nutrients like vitamins C and E. These nutrients support joint health and can indirectly contribute to synovial fluid production.
3. Regular Exercise: Engage in regular, low-impact exercises to stimulate the production of synovial fluid. Activities like swimming, walking, and cycling are beneficial for joint health.”Diet and activity uniquely altered SF metabolites attributed to amino acids, lipids, and steroids. Notably, a high-fat diet increased network connections to systemic biomarkers such as interleukin-1β and glucose intolerance. In contrast, exercise increased local joint-level network connections, especially among subchondral bone features and SF metabolites.” https://doi.org/10.1016/j.joca.2021.08.008
4. Joint Mobility Exercises: Perform specific exercises that target joint mobility. These exercises help in the distribution of synovial fluid within the joint capsule.
5. Maintain a Healthy Weight: Extra body weight can put additional stress on the joints, leading to inflammation and reduced synovial fluid production. Maintaining a healthy weight can alleviate this pressure.
6. Supplements: Some supplements may support joint health. Glucosamine and chondroitin sulfate are commonly used to promote joint lubrication and reduce stiffness. More data is needed but it can seen as part of an overall healthier approach to life. It is always better to support nutritional needs through diet when possible.
7. Heat Therapy: Applying heat to the affected joint can improve blood circulation and stimulate synovial fluid production. This can be done through warm compresses or hot baths.
8. Massage and Physiotherapy: Regular massage and physio help to improve joint flexibility, reduce stiffness, and promote synovial fluid circulation.
9. Avoid Prolonged Immobility: Prolonged periods of immobility can lead to decreased synovial fluid production. Take breaks, stretch, and move regularly throughout the day. A sedentary lifestyle is not a good idea for joint health.
10. Injection therapies: They can support a patient to increase activity again once the joint disease is present and the synovial fluid is compromised. This helps to halt the painful OA cycle and creates a positive one, allowing patients to be active and motivated to achieve 1-9

Look after your synovial fluid

We have excellent surgical strategies in the key areas to repair and preserve the joint. We can also brace a joint to offload pain and manage biomechanics. However, do patients understand the underlying causes of what leads to these issues in the first place? Can we improve our own synovial fluid, in turn improving overall joint health through good lifestyle choices?

Prevention is better than cure, a healthy active lifestyle, a good diet, good nutrition, staying hydrated, and as soon as you feel joint pain seek advice from a healthcare professional. Non-operative treatments can delay surgical intervention or in some cases prevent them altogether. But before any intervention, look after your body, it’s the only one you’ll get.