What is Knee Osteoarthritis?

by Anu Lima, Registered P.T.

There is a lot of confusion and frustration with what to do when you have a diagnosis of knee osteoarthritis (OA). The same diagnosis of “moderate arthritis” can look and read vastly different from one person to another on xray. What do the sentences on an xray report even mean when the summary at the bottom of the report reads one thing: osteoarthritis. What we know is structural changes do not match clinical symptoms.

With medical words that evoke feelings of hopelessness like “chronic” and “disease” to the dismissive and inaccurate descriptors of “bone on bone” , and “wear and tear”, no wonder so many people with OA are fearful of moving or further damaging their joints. Education is key, especially when working together with a physiotherapist to achieve goals that are set around your lifestyle.

From the most recent research, test your knowledge. (Teoli, A. 2019)

1) Knee osteoarthritis is just wear and tear

False. There is no simple catchphrase to describe OA. There is a breakdown of the extracellular matrix that causes a cascade of effects. The primary molecular derangement leads to a secondary maladaptive repair responses, ie. an inflammatory response. Osteoarthritis can described as:

A progressive loss and disruption of articular cartilage
Thickening of subchondral bone
Formation of osteophytes
Degeneration of ligaments and menisci of the knee
Hypertrophy of the joint capsule
Variable degrees of inflammation of the synovium (Chen et al., 2017)

2) Knee osteoarthritis is a condition of the elderly

False. OA is on the rise and is described as a “mismatch disease” (Berenbaum et al 2018). It has doubled in prevalence since the mid 20th century and it has been found to have different mechanisms of initiation. The idea of chronic metaflammation is new and is caused by: increased obesity levels, physical inactivity, and a diet consisting of processed foods. This alone can initiate OA. The following are risk factors:

Knee malalignment (valgus, varus)
Decreased knee extensor strength (Hamstrings, gluteal muscles)
Previous knee injury – 50% of people with meniscal and ligament injuries will have OA 10-20 years later (Lohmander et al., 2007)
Occupational risks
Chronic metaflammation – adipose (fat) tissue is an endocrine organ that can secrete adipocytokines (Cohelo et al 2013). Elevated levels of adipocytokines have been found in the synovial fluid and plasma of OA patients. This may disrupt cartilage homeostasis.
Obesity - 8kg extra as a young adult will lead to a 70% increased risk for OA later.

3) Knee osteoarthritis can be prevented

True. Primary prevention would be in adolescence to decrease obesity and prevent injury. Secondary prevention would involve detection and treatment for those at risk. Tertiary prevention would occur after the OA has begun. This is when physiotherapists tend to see patients.

The advice that doctors give to lose weight is twofold: for the mechanical and the metaflammation factors.

Physiotherapists can work in many ways to help offload painful structures. My main focus is to change the way you move through adaptive movement patterns with subtle functional movement (ie. the way you weightbear through your big toe because you have been limping or the way your opposite hip may be overworking to protect the knee). Strengthening comes later once these movement patterns have been “unlearned”. There will be baseline postural stability exercises and knee strengthening exercises given. Self mobilization and trigger point release exercises will be prescribed for flare-up periods. Once this new groundwork of how your own body is working has been “understood” by your brain, balance and strengthening comes a lot easier than by just “pushing through pain”. The body is strong and adaptable. Pain is modifiable.

4) Those with more severe osteoarthritis have higher pain levels

False. Pain is an experience, not a sensation. Tissue damage is not necessary to experience pain (ref to my pain article)

5) Loading is bad for the knee

False Loading is required for normal knee joint and muscle function. Adaptation is normal for our bodies and we can condition ourselves to load our joints.

6) Running causes knee osteoarthritis

False. Running conditions the cartilage and does not initiate OA. (Miller, 2017). If the body is adapted to running and the mechanical factors are addressed (ie. varus/valgus knees) there is not an issue.

7) A clinical diagnosis of osteoarthritis can be made without an xray

True. The NICE guidelines, EULAR guidelines, and ACR guidelines all allow diagnoses without an xray. The NICE guidelines for objective measures are as follows:

Age 45 or older
Activity related joint pain
Early morning stiffness that lasts less than 30minutes.

8) Exercise will cause further damage in osteoarthritis

False. There have been so many studies proving the effectiveness of exercise and OA that the last one was done in 2002!

9) Partial meniscectomy will reduce the risk of osteoarthritis 20 years later

False. Partial or full menisectomy will increase the risk of OA. Any knee injury (ligament, meniscus) will increase the risk of OA. There is still no proof on which ACL approach is best – surgical or non surgical.

10) Knee replacement is inevitable for patients with osteoarthritis

False. Although there is a small percentage of individuals that exercise is not indicated for, most surgeons prefer to advise on rehabilitation first before putting you on the waitlist for replacement.