The incidence of OA increases with age. In those aged ≥70-years, the condition ranks seventh among causes for years lived with disability. However, some patients may present early (<50-years).¹

Presentations of OA include joint pain and loss of function. It should be noted that the disease is clinically very variable and can present merely as an asymptomatic incidental finding to a devastating and permanently disabling disease.²

The most commonly affected areas are the knees and hands. By 2050, knee OA will increase by 75%, hand OA by 50%, hip OA by 78.6%, and other (eg elbow, shoulder) by 95.1%.¹

Risk factors

Women have a higher risk of OA. In 2020, 61% of OA cases were in women versus 39% in men. Although it is not yet fully understood what drives these gender differences, researchers postulate that genetics, hormones, and anatomical disparities may play a role.¹

Modifiable risk factors include obesity and joint injury. Other factors that increase the risk of OA are physically demanding occupations, elite-level high-impact sports, surgery such as meniscectomy following injury, joint anatomy, and muscle weakness.^1,2

Classification of OA

OA can be classified into two categories:²

• Primary OA: The most common subset of the disease. Diagnosed in the absence of a predisposing trauma or disease but is associated with the risk factors listed above.
• Secondary osteoarthritis: Occurs with a pre-existing joint abnormality. Predisposing conditions include trauma or injury, congenital joint disorders, inflammatory arthritis, avascular necrosis (results from the temporary or permanent loss of blood supply to the bone), infectious arthritis, Paget disease, osteopetrosis (a group of rare disorders that cause bones to grow abnormally and become overly dense), osteochondritis dissecans (a joint condition in which bone underneath the cartilage of a joint dies due to lack of blood flow), metabolic disorders (haemochromatosis, Wilson’s disease), haemoglobinopathy, Ehlers-Danlos or Marfan syndromes.

Signs and symptoms of OA

As mentioned, symptoms and signs may vary from patient to patient. Primary signs and symptoms include joint pain, stiffness, and limitations in locomotion. In addition, patients may present with muscle weakness and balance challenges.²

Furthermore, patients might encounter bony swelling, joint deformities, and instability (often described as joints 'giving way' or 'buckling,' indicative of muscle weakness).²

OA predominantly affects the proximal and distal interphalangeal joints, first carpometacarpal (CMC) joints, hips, knees, first metatarsophalangeal joints, and joints within the lower cervical and lumbar spine. OA can manifest as either monoarticular or polyarticular.²

Notably, joints may exhibit different stages of disease progression. The customary examination findings in OA encompass bony enlargements, crepitus, non-inflammatory effusions, and a restricted range of motion. Tenderness may be observed at joint lines, and passive motion can elicit pain.²

Classic physical examination discoveries specific to hand OA include the presence of Heberden's nodes (swellings on the posterolateral aspect of distal interphalangeal joints), Bouchard's nodes (swellings on the posterolateral aspect of proximal inter-phalangeal joints), and squaring at the base of the thumb (involving the first CMC joints).²

Evaluation and diagnosis

A thorough history and physical exam (with a focused musculoskeletal exam) should be performed on all patients. OA is a clinical diagnosis and can be established if the following are present:

• Pain worse with activity and better with rest
• Age >45-years
• Morning stiffness lasting <30-minutes
• Bony joint enlargement
• Limitation in range of motion.

Blood tests, including a complete blood test, erythrocyte sedimentation rate, rheumatoid factor, and antinuclear antibodies, typically yield normal results. These tests are often conducted to exclude the possibility of inflammatory arthritis.²

When synovial fluid is collected, the white blood cell count should be less than 2000microL, primarily consisting of mononuclear cells (non-inflammatory), aligning with an OA diagnosis.²

X-ray imaging of the affected joint can reveal OA-associated findings such as marginal osteophytes, narrowing of the joint space, subchondral sclerosis, and cysts. However, these radiographic findings do not necessarily correspond to the disease's severity and may not manifest in the early stages.²

While MRI is not typically part of the standard OA diagnostic workup, it can detect OA at earlier stages compared to conventional radiographs. Ultrasound is another modality that can identify synovial inflammation, effusion, and osteophytes, all of which can be indicative of OA.²

There are several classification systems for OA. In general, they include the effects on joints, the age of onset, radiographic appearance, presumed aetiology (primary vs secondary), and rate of progression. The American College of Rheumatology classification is the most widely used classification system. At this time, it is not possible to predict which patients will progress to severe OA and which patients will have their disease arrest at earlier stages.²

Treatment goals

The primary goals of OA treatment are to alleviate pain and mitigate functional impairment. A comprehensive approach to managing this condition incorporates both non-pharmacologic and pharmacologic interventions, with treatment strategies tailored to the severity of the disease.²

Conley et al (2023) reviewed 11 international guidelines to evaluate the quality of interventions in the management of OA and to provide a synthesis of high-quality recommendations. These are the do’s and don’ts that they identified:³

Do’s

• Exercise: Strengthening and aerobic exercises, as well as tai chi are recommended for managing knee, hip, polyarticular, and hand OA. Programmes should be personalised and progressively intensified based on patient preferences, capabilities, and available facilities.
• Education: Patient-centred education is essential for enhancing understanding of OA and its management options, including exercise therapy, ergonomic principles, and assistive devices.
• Non-steroidal anti-inflammatory drugs (NSAIDs): Use is recommended, unless contraindicated, with a preference for low doses and short-term use. Topical NSAIDs are considered safe and effective, especially for older adults with a few symptomatic joints. Monitoring of side effects is essential.
• Weight loss: Overweight or obese patients (body mass index [BMI] ≥25kg/m²) with hip and/or knee OA are encouraged to achieve a weight loss target of 5%–7.5% of body weight for symptomatic benefits.
• Hand orthosis: Recommended for OA of the carpometacarpal joint and conditionally recommended for other hand joints to provide symptom relief, improve function, and prevent degenerative progression.
• Patient-centred care: Individualised care and shared decision-making are advocated for patients with knee, hip, and hand OA.
• Surgery: Surgery should be considered for individuals with radiographic evidence of OA, marked disability, reduced quality of life, and unsuccessful prior treatments.

Don’ts:

• Avoid therapeutic ultrasound and certain pharmacologic interventions: Therapeutic ultrasound is not recommended for knee, hip, or polyarticular OA. Avoid using bisphosphonates, colchicine, hydroxychloroquine, methotrexate, and biologic disease-modifying antirheumatic drugs for knee, hip, and hand OA.
• Glucosamine and chondroitin: Avoid using glucosamine and chondroitin for knee, hip, and polyarticular OA, with conditional use only for knee OA pending further research.
• Postsurgical continuous passive motion and cryotherapy devices: Avoid continuous passive motion after total joint replacement for knee and hip OA, as it offers no improvement in outcomes. Cryotherapy devices are not recommended for total knee arthroplasty, except for total shoulder replacement with conditional use.

Are natural alternatives effective in the treatment of OA?

Due to the side effect profile of NSAIDs, patients often look to alternative or natural options to safely manage their pain. Over the last few years, avocado soybean unsaponifiable (ASU) and Boswellia acid have gained attention as potential alternative treatments for OA.^4,5

ASU comprises natural extracts derived from avocado and soybean oils, composed primarily of phytosterols like β-sitosterol, campesterol, and stigmasterol. ASU exhibits chondroprotective, anabolic, and anticatabolic properties, making it effective in inhibiting cartilage breakdown and promoting repair. It achieves this by inhibiting inflammatory cytokines like interleukin (IL)-1, IL-6, IL-8, tumour necrosis factor, and prostaglandin E2 through nuclear factor kappa β modulation.⁴

Additionally, ASU inhibits collagenase and stromelysin 1, increases tissue inhibitors of metalloproteinases (TIMP-1), and affects growth factors like transforming growth factor (TGF)-β1 and TGF-β2, which are crucial in cartilage repair. ASU also impacts cholesterol levels and oxidative stress, reducing oxidised low-density lipoproteins in serum, a factor linked to OA pathology.⁴

Clinical trials have demonstrated the symptomatic benefits of ASU in OA patients, reducing pain and stiffness while improving function. ASU's efficacy and safety have been assessed in various randomised, double-blind trials. It has been shown to decrease NSAID intake and improve function. Its impact on structural damage is less clear.⁴

The effect of ASU may vary based on factors such as BMI, disease severity, and activity level. Obesity-associated inflammation may influence ASU's efficacy, as it does with other treatments.⁴

Boswellic acid, derived from Boswellia serrata extract, has demonstrated significant pharmacological activity in treating inflammatory diseases such as rheumatoid arthritis, chronic bronchitis, asthma, ulcerative colitis, and Crohn's disease.⁵

The active compound within Boswellia extract, 3-O-Acetyl-11-keto-beta-boswellic acid, has been shown to have a potent inhibitory effect on 5-lipoxygenase, an enzyme involved in inflammation.⁵

Clinical studies have highlighted the anti-inflammatory, anti-arthritis, and pain-relieving properties of Boswellia serrata extract. In vitro experiments have indicated its ability to suppress the expression of inflammatory factors. Importantly, studies have demonstrated the safety of Boswellia serrata extract, even at higher doses, making it a promising alternative for inflammatory conditions.⁵

Numerous clinical trials have explored the efficacy of Boswellia and its extracts in OA treatment, with results suggesting pain relief, improved joint function, and reduced stiffness. Notably, these benefits often become noticeable after four weeks of continuous intervention with doses ranging from 100mg to 250mg. Safety assessments and toxicology experiments have indicated that Boswellia and its extract are generally safe for use.⁵

Yu et al conducted a systematic review and meta-analysis, involving seven randomised controlled trials. Their findings support the potential of Boswellia and its extract as a treatment option for OA. It highlights the benefits of pain relief, stiffness reduction, and improved joint function.⁵

Conclusion

Natural alternatives offer promising avenues for pain relief and improved joint function. ASU and Boswellia acid have emerged as noteworthy options. These natural remedies, with their anti-inflammatory properties and demonstrated efficacy, provide potential relief for OA patients, especially those seeking alternatives to NSAIDs.

References

1. GBD 2021 Osteoarthritis Collaborators. Global, regional, and national burden of osteoarthritis, 1990-2020 and projections to 2050: a systematic analysis for the Global Burden of Disease Study 2021. The Lancet Rheumatology, 2023.
2. Sen R, Hurley JA. [Updated 2023 Feb 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482326/
3. Conley B, Bunzli S, Bullen J, et al. Core Recommendations for Osteoarthritis Care: A Systematic Review of Clinical Practice Guidelines. Arthritis Care and Research, 2023.
4. Christiansen BA, Bhatti S, Goudarzi R, Emami S. Management of Osteoarthritis with Avocado/Soybean Unsaponifiables. Cartilage, 2015.
5. Yu G, Xiang W, Zhang T, Zeng L, Yang K, Li J. Effectiveness of Boswellia and Boswellia extract for osteoarthritis patients: a systematic review and meta-analysis. BMC Complement Med Ther,