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Osteoarthritis (OA) 骨关节炎 (Reading & Sharing)

Pathophysiology of Osteoarthritis

Osteoarthritis (OA) is primarily a disease of cartilage. Cartilage is a tissue with viscoelastic and compressive properties. It is predominantly composed of type II collagen and proteoglycans. In a normal condition the extracellular matrix undergoes a dynamic remodeling process in which low levels of degradative and synthetic enzyme activities are balanced. When OA is present, the matrix degrading enzymes will become overexpressed. This results in loss of collagen and proteoglycans from the matrix (Ling & Bathon, 2012). Once the articular cartilage breaks down, the progressive formation of osteophytes (bone spurs) protrude into the joint space decreasing joint movement. Some factors that may cause OA may include mechanical injury, genetic and hormonal factors or previous joint damage. Risk factors may include older age, sex, obesity, and bone deformities.

Clinical manifestations of OA usually consist of pain, stiffness and functional impairment. Movement or exercise may aggravate the joint pain. The affected joint may have a decreased range of motion and may appear enlarged. OA often occurs in weight-bearing joints such as hips, knees, cervical and lumbar spine although the interphalangeal and distal interphalangeal joints may also be involved.

Incidence and Prevalence

Osteoarthritis is a disease that is more common in women with advancing age. It affects more than 30 million individuals in the United States (Ferri, 2018). According to Badlissi (2017), the Framingham Osteoarthritis Study showed that the prevalence of radiographic OA increases with age from 27% in people younger than 60 years to 44% to those older than 70 years. The prevalence of OA increases as a result of ageing population and increase in related factors such as obesity. According to the United Nations, by 2050 individuals aged over 60 will represent more than 20% of the world’s population, and 15% will have symptoms of OA (WHO, 2017).

Physical Assessment and Examination

Patient with OA present with primary symptoms of joint pain, locomotor restriction, and joint pain. Those symptoms could be presented in one or a few joints in middle-aged or older person. Other manifestations of OA in patients include sequelae such as weakness and poor balance or muscle weakness (Doherty and Abhishek, 2017). On examination the patient may present with joint tenderness and swelling, crepitus with motion, or Bouchard’s and Heberden’s nodes of the joints of the hand (Ferri, 2018).

Accurate history and thorough examination of the patient must be conducted followed by special tests that are meant to confirm the diagnosis of OA. Currently there is no single reliable diagnosis because the used diagnostic tools have low sensitivity and specificity (WHO, 2017). In patients presenting with real symptoms, radiography is the main diagnostic technique that can be used to confirm the condition (Roach & Tilley, 2017). However, if the process in any way linked to crystal deposition disease or secondary to an inflammatory arthropathy, a complete workup which includes urate levels, erythrocyte sedimentation rate, full blood count, rheumatoid factor and autoantibody screen may be recommended (Roach & Tilley, 2017). Other diagnostic procedures such as MRI scan and x-ray may be used where possible.

There are many physical examination (PE) procedures to assess knee function; however, none of them are specific to knee OA (Iversen et al, 2016). The Osteoarthritis Research Society International recommends the use of six functional performance measures to assess function in adults with OA (Iversen et al, 2016). A body of evidence from the literature has proven that the use of selected physical examination procedures, muscle flexibility, and strength of the hip and knee when evaluating OA patients is effective in patient assessment.

Treatment Plan and Education

When treating OA, the main goal is educating the patient about the disease and ways to improve joint pain and stiffness. There is no cure for OA, but with a combination of different modalities treatment it can provide adequate pain control and preserve quality of life for patients that suffer this disease (Ferri, 2018).

Treatment may include non-pharmacologic and pharmacologic therapies, complementary, and surgery. The most safest and less-invasive form of treatment should always be prioritized before proceeding to other invasive and expensive therapies. To begin with, nonpharmacological therapies often commences with exercise. AN RCT study compared supervised home-based exercise with no exercise in 786 patients with osteoarthritis of the knee (Sinusas, 2012). The exercise program entailed muscle strengthening and range of motion exercise. The research established statistically significant improvements in confirmed arthritis symptoms score at six, 12, 18, and 24 months (Sinusas, 2012). Since obesity has been a major predisposing factor to OA, studies on systematic reviews have concluded that weight loss of 5 percent from baseline was enough to reduce disability (Sinusas, 2012). Sprinting and bracing are additional non-pharmacological treatments that can help support unstable and painful knee.

The main pharmacological treatment for mild OA is acetaminophen, which has been found to be inexpensive, safe, and effective (Sinusas, 2012). A review from the Cochrane library conducted in 2006 found that the acetaminophen medication is better than placebo for treating mild OA and is equivalent to nonsteroidal anti-inflammatory drugs (NISAIDS), but with less adverse effects on the gastrointestinal tract (Sinusas, 2012). According to the U.S Food and Drug Administration, OA patients should not take more than 4, 000 mg of acetaminophen a day. In cases where acetaminophen fails to control OA, NSAID therapy is recommended (Sinusas, 2012). OA should always be educated on diets for OA management, how to avoid complications, when to seek doctor’s attention and how to engage in nonpharmacological treatments such exercise plus their benefits.

According to Badlissi (2017), in conjunction with local analgesia, intra-arrticular corticosteroid injections with methylprednisolone 4-80 mg intra-articularly as a single dose or triamcinolone acetonide 2.5 to 40 mg intra-articularly as a single dose could also be used as a primary option of treatment. It further states, that patients with persistent pain despite multiple treatment or with severe disability, surgery may an option to replace the hip and knee.

Follow-up

Patients are to be monitored for the progression of the disease and treatment plan. Patient should consult with their physician if pain persist in their joints on most days for more than 1 month. Patients on NSAIDS or COX-2 inhibitors, should be seen every 3 to 6 months to monitor their renal function, CBC, and liver function tests. Patients with persistent or limitation in their daily activities, should be referred to a rheumatologist and/or orthopedist for further evaluation or possible joint replacement or other surgical options available (Badlissi, 2017).

 

References:

Badlissi, F. (2017). Osteoarthritis epidemiology – Epocrates online. Retrieved from https://online.epocrates.com/diseases/19223/Osteoarthritis/Epidemiology

Doherty, M., & Abhishek, A. (2017). Clinical manifestations and diagnosis of osteoarthritis. Retrieved from https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-osteoarthritis?

Ferri, F. F. (2018). Ferri’s clinical advisor 2018. Philadelphia, PA: Elsevier.

Iversen, M. D., Price, L. L., von Heideken, J., Harvey, W. F., & Wang, C. (2016). Physical examination findings and their relationship with performance-based function in adults with knee osteoarthritis. BMC musculoskeletal disorders17(1), 273.

Ling, S. M., & Bathon, J. M. (2012, March 27). Osteoarthritis: Pathophysiology. Retrieved from https://www.hopkinsarthritis.org/arthritis-info/osteoarthritis/oa-pathophysiology/

Roach, H. I., & Tilley, S. (2017). The pathogenesis of osteoarthritis. In Bone and osteoarthritis (pp. 1-18). Springer, London.

Sinusas, K. (2012). Osteoarthritis: diagnosis and treatment. American family physician85(1).

World Health Organization (2017). 6.12 Osteoarthritis. Available at: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwiy2ZHo3rnZAhXMWxQKHdLTBMEQFgg0MAE&url=http%3A%2F%2Fwww.who.int%2Fmedicines%2Fareas%2Fpriority_medicines%2FCh6_12Osteo.pdf&usg=AOvVaw0CLvPq7d-AhRyy_Kdc95iH

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