Osteoarthritis (OA) is the most common chronic musculoskeletal disorder in the world, with more than 500 million people affected worldwide (6% of the global population) (Hunter, March, & Chew, 2020). It is twice as common in women than men and increases in incidence with age, specifically after 60 years of age (Poole, 1999). Radiographic evidence of OA can be seen in the majority over the age of 65 and in about 80% over 75 (Ardin & Nevitt, 2006). In the United States, OA is the second leading cause of work disability in men over 50 years of age, and accounts for more hospitalizations than rheumatoid arthritis (Ardin & Nevitt, 2006). From 1990 to 2019, the number of people affected by OA globally has increased by almost 50%. In 2019, OA was the 15th highest cause of disability worldwide, accounting for 2% of the global population (Ardin & Nevitt, 2006). This vast impact resonating in so many people highlights the importance of informing people about the development and progression of this disease. Discussing risk and protective factors along with all available treatment options will ensure people are aware of the pathogenesis of the disease and inform their decision towards an appropriate lifestyle that lowers their risk. 

OA is regarded as a disease affecting the whole joint due to a combination of both cellular and biomechanical stressors that leads to cartilage softening and loss of thickness; this creates nearly insurmountable physical difficulties among adults. It may plummet quality of life as it is the leading cause of activity limitation, such as having difficulty walking or getting out of bed in the morning pain-free, and absenteeism among working adults, and often results in significant decline in joint mobility (Man & Mologhianu, 2014). In particular, the risk of mobility impairments caused by knee OA is greater than any other medical condition in adults over the age of 65 (Guccione et al., 1994). OA is hallmarked by the pain it induces and this pain is exasperated in joints, which serve as the foundation for day to day mobility.  

Although certain risk factors for OA are not modifiable, such as older age, female gender, prior injuries, and family history, there are some that are amenable (Ardin & Nevitt, 2006). Making the necessary lifestyle changes can decrease someone’s risk of OA and even serve as a protective factor. Nutrition has been found to play a role in OA progression and severity. Increased dietary intake of antioxidants, such as vitamin C found in oranges and bell peppers and vitamin E found in nuts and oils, are thought to be protective because they fight oxygen radicals (Ardin & Nevitt, 2006). Oxygen radicals are extremely reactive chemical molecules that can damage cartilage (McAlindon et al., 1996a). By consuming a diet high in fruits and vegetables, which are loaded with antioxidants, these damages can be mitigated. A longitudinal population study found that consuming high amounts of dietary vitamin C led to slowed progression of knee OA , reduced frequency of new knee pain, and served as a protective factor against future risks among seniors (McAlindon et al., 1996a). In contrast, low vitamin D intake was associated with a threefold increase in risk of OA progression; it also predicted loss of cartilage and loss of joint space (McAlindon et al., 1996b). 

Research has also shown that an emerging protective factor for OA is estrogen replacement therapy, which provides a significant reduction in risk for OA in postmenopausal women. In a cross-sectional study, 4,366 Caucasian women over the age of 64 had mild or moderate-severe x-ray findings of OA in at least one hip. 17% of participants were current users of oral estrogen and had a significantly lower than expected risk of x-ray findings of OA. Estrogen was found to have a protective effect against severe development of OA in one or both sides of the body (Nevitt et al., 1996). 

Exercise regimens are shown to provide pain relief and improvement in mobility in patients with lower limb OA (Uthman et al., 2013). It was found that combining strength and aerobic exercises (either on land or in water) conferred the best result in terms of improving pain and joint function (Uthman et al., 2013). Animal studies show that prolonged immobilization (no exercise/movement) leads to thinning of the articular cartilage, which exacerbates OA (Vanwanseele, Lucchinetti, & Stüssi, 2002). Since animal models, such as mice, are biologically similar to humans and experience a lot of the same diseases, these findings can be assumed to be beneficial to humans.

Obesity is among the strongest risk factors for OA (Felson et al., 2000). The most promising evidence showing major risk reduction in development and severity of OA is weight loss (Felson et al., 1992). Obesity is a significant risk factor because its prevalence is very high among the global population, as is OA, which is why it is important to focus on (Hunter et al., 2020). In 2016, 13% of the world’s population (adults over 18 years) were considered obese (World Health Organization, 2020). 36.5% of American adults were classified as obese between 2011 and 2014, with a high prevalence of obesity observed in 37% of adults over the age of 60 (Ogden et al., 2015). This is especially concerning considering there is already a high prevalence of OA among older populations, with obesity being a major risk factor. There are barriers associated with overcoming obesity, which may explain why obesity prevalence has only increased throughout the years (Ogden et al., 2015). The most significant barriers include situational barriers (i.e. parties, ceremonies, vacations), stress, depression, social pressure, and food cravings (Sharifi, Mahdavi, & Ebhrahimi-Mameghani, 2013). Many people report that life circumstances and external barriers prevent adherence to weight loss programs as well as stress and depression causing overconsumption of food (Sharifi et al., 2013).

Research shows that weight loss reduces the risk of developing symptomatic OA and reduces symptoms in those with OA (Felson et al., 1992). A case-control study found that a 5 kg weight loss could result in 24% of surgical cases of knee OA being avoided (Coggon et al., 2001). This evidence was found through screening images that depicted a 4- to 5-fold increased risk of knee OA in obese individuals (Oliveria et al., 1999). This occurs through overloading the knee and hip joints, which leads to cartilage breakdown and failure of ligaments to provide structural support; every one-pound increase in weight increases the pressure on the knee by 2-3 pounds (Felson et al., 2000). Even a 5.1% weight reduction confers the benefit of pain reduction and diminished physical disability in OA patients (Christensen et al., 2000).

As common as OA is among the global population, most people are not aware. It is important to understand the risk factors and disease progression in order to make the necessary lifestyle changes early on to reduce your risk of OA or improve severity of existing symptoms.

References

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