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Understanding Your Knee Pain

During the course of my time treating patients at Revolution Physical Therapy Weight Loss, I have encountered several who have been given the diagnosis of osteoarthritis, most commonly in the knees.  Depending on the extent of the knee pain, it may limit a patient’s mobility and quality of life. So what does this mean for exercise, especially with regards to the weight loss program? In order to answer that question it would be helpful to examine the aspects of the diagnosis and prognosis of osteoarthritis related knee pain.

What: The Knee Joint

Synovial joints such at the knee and shoulder are important parts of the musculoskeletal system at which point two bones articulate (come into contact) with one another. The ends of these bones are lined with hyaline articular cartilage, which creates a smooth surface for load transfer during motion (Ateshian & Mow, 2005). The main function of cartilage at joints is to distribute the load equally across the surface of the bones and decrease friction during motion (Eckstein et al, 2006).  This allows us to perform many activities uninhibited: walking, running, jumping, climbing stairs, etc. In the presence of osteoarthritis, patients are more aware of their knees than previously, however this does not mean they are doomed. 

How: The Process of Osteoarthritis

First of all, it is important to recognize the diagnostic process. Osteoarthritis is typically diagnosed with radiograph (x-ray), the results of which are not necessarily indicative of damage (Hunter & Eckstein, 2009). Imaging provides physicians and the medical community with information regarding the state of your joints, but is not the sole factor in diagnosis. It is important to remember that an image is a static snapshot of an area of your body, but does not necessarily indicate factors at play while your body is in motion.

In cases of osteoarthritis, synovial joints undergo structural and functional failure due to loss/erosion of cartilage, bony alterations, and meniscal degeneration (Nuki, 1999). This means that there are several physiological alterations that occur within the joint that may cause pain. Osteoarthritis is a result of excessive mechanical stress specifically in the context of systemic susceptibility, which is related to genetic factors, age, ethnicity, diet and female gender (Hunter & Eckstein, 2009). Therefore, not only does an individual have to undergo the process of joint changes, but one must also be susceptible to this process. A concept similar to that of predisposing factors associated with other disease processes.

 Factors such as abnormal joint mechanics, muscle weakness, and structural changes at the joint itself can increase the potential for osteoarthritic progression and can be affected by joint loading (Hunter & Eckstein, 2009). The good news is that muscle weakness and abnormal joint mechanics are not permanent and can be improved over time with physical therapy and exercise. Resistance exercises increase muscle strength over time, which in turn gives greater support to the joints. Abnormal joint motion can be altered by feedback from a physical therapist or simple changes in squat form to execute a basic sit to stand motion.

Joint loading can occur through joint injury (acute or repetitive overuse) or increased weight gain related to obesity. For example, during walking body weight is transferred to the knees, and each additional kilogram of body mass increases the compressive load over the knee by about 4 kilograms, or about 8.8 pounds (Messier at el 2005). If you do the math, a weight gain of 20-30 pounds over the course of a year increases the compressive force through the knees by about 80-100 pounds. Weight gain can also be modified with proper exercise, nutrition and motivation, as seen in a well-rounded program offered at Revolution. 

Why: Just Keep Moving!

Although there is an increasing awareness of the importance of exercise within the general population, the majority of individuals also believe that exercise is additionally damaging to one’s joints, especially in the lower extremities (Hunter & Eckstein, 2009). It is a common misconception regarding lower body joint pain and mobility. However, there is no strong evidence to suggest that vigorous low-impact exercise is associated with an accelerated rate of development of osteoarthritis (Hunter & Eckstein, 2009). In fact there are benefits from low-impact exercise (such as cycling and aquatic exercise) in comparison to high-impact (running, jumping) exercise. It allows patients to maintain cardiovascular health, increase joint mobility and stay healthy, while avoiding the potentially damaging effects of high-impact exercise (Hunter & Eckstein, 2009).

Individuals with osteoarthritis are likely to experience a sensation of joint stiffness, especially in the morning and after prolonged sitting. This is because the joints have been still for a long amount of time. It is important to keep moving and be aware that gentle walking is not going to cause any additional damage. In fact, not moving can have deleterious effects just as much as high-impact activity. Research has shown that cartilage undergoes a process of atrophy (thinning) in the absence of mechanical stimulation, such that there is a decrease in cartilage volume or thickness with reduced weight bearing (Eckstein et al, 2006). This means that without consistent activity, the cartilage that allows for that smooth motion at the joints may depreciate.

The joints of the body are constructed in such a way to manage increased mechanical loads over lifetimes without deteriorating (Ateshian & Mow, 2005). We are built to last and withstand lots of motion. Motion is lotion and it helps to lubricate our joints in order to be able to keep moving. A diagnosis of osteoarthritis is not a moratorium on your lifestyle and activity. Proper education regarding exercise and a strengthening program supervised by a physical therapist or licensed clinician can set you up for success with your weight loss program or your general return to activity.  

 

1.     Ateshian G, Mow VC (2005) Friction, lubrication, and wear of articular cartilage and diarthrodial joints. In Basic Orthopaedic Biomechanics and Mechanobiology, 3rd ed (ed Mow VC, Huskes R), pp. 447-494). Philadelphia: Lippincott, Williams & Wilkins.

2.     Eckstein F, Hudelmaier M, Putz R (2006) The effected of exercise on human articular cartilage. Journal of Anatomy, 208, 491-512.