Osteoarthritis of the knee
Epidemiology
One in four persons over the age of 18 report of chronic joint pain in at least one joint. Knee is the most frequent site (17%). Knee Osteoarthritis (OA) is the major cause of disability in elderly. The pooled global prevalence of OA was 16.0% in people aged 15 years and over, and 22.9% in people aged 40 years and over (Cui et al 2020). Women are more predisposed than men to having OA. Estimated cost of total knee arthroplasty is $11 billion per year (Losina et al 2009).
What is osteoarthritis?
OARSI is an international body of researchers dedicated to the understanding and advancement of osteoarthritic research. OARSI defines OA as “joints characterized by cell stress and extracellular matrix degradation initiated by micro- and macro- injury that activates maladaptive repair responses including pro-inflammatory pathways of innate immunity. The disease manifests first as molecular derangement (abnormal joint tissue metabolism) followed by anatomic and/or physiologic derangements (characterized by cartilage degradation bone remodeling, osteophyte formation, joint inflammation and loss of normal joint function) that can culminate in illness.
What causes OA of the knee?
Knee joint is typically composed and surrounded by cartilage, bone, capsule, ligament muscles and tendons. Stresses like abnormal mechanical loading, obesity, genetics, aging, prolonged immobilization and prior injury can contribute to cartilage thinning and/or erosion. A healthy cartilage acts as a cushion to protect joint surfaces from loading and friction. Excessive loading of the knee joint cartilage damages collagen fiber network leading to proteoglycan washout and loss of further ability to endure more compressive or shear forces.
This can trigger inflammatory processes in the initial stages of OA and consecutive progression of changes in cartilage, synovium and bone structures in advanced stages if condition is not addressed appropriately. Synovium, bone and nerves are the most common sources of pain experience in OA. Cartilage is not innervated and avascular. It requires modest amounts of compression through loading and muscle contraction to maintain structural integrity, health and nutrition for normal functioning of the joint.
What are the clinical signs of knee OA?
If you have any 3 of the following upon clinical inquiry clinically then you are likely to be diagnosed to have OA knee - Over 50 years old, stiffness lasting >30 minutes, joint crepitus, bony tenderness, bony enlargement, no palpable warmth.
Kellgren and Lawrence`s radiographic evidence is commonly used to confirm the diagnosis and grade the severity of OA ranging from grades I (mild reduction of joint space) to grade IV (severe OA). Knee is a tri-compartmental joint and OA can impact one or more compartments pathologically.
How can I treat OA knee?
All current clinical guidelines strongly recommend exercises for knee OA. An exercise program that is standardized, regularly performed and monitored is definitively known to help not only with pain reduction for 2 to 6 months but also improve function and quality of life.
Exercises that target stiffness and muscle weakness as a result of degenerative changes in the joint are a key towards improving circulation, soft tissue mobility and flexibility. This helps the patient to cope better while managing pain and loss of mobility of the joint.
Following are a few simple and basic exercises for beginners who are diagnosed with knee OA.
It is also essential to keep body weight under check for the exercises to work effectively as claimed by evidence. New research throws light on adipocytes being a causative factor in knee OA. Role of low impact and moderate intensity exercises such as regular walking can target weight control/loss and cartilage health in early stages of OA. Exercising at least 4 days per week is known to challenge the muscles enough to bring desired improvements in outcomes.
How can a Physical Therapist facilitate recovery other than giving an exercise program?
Role of manual therapy especially in early stages with education/awareness to enhance quality of life is known to show improved outcomes (Bannuru et al 2019, Kolasinski et al 2019).
Less than 40% patients with knee OA receive the first line of treatment. Patient education, physical exercise and weight loss (for overweight and obese individuals) constitute the first line of treatment (Lucas et al 2021).
Additionally, American College of Rheumatology guidelines conditionally support the use of kinesio-taping and acupuncture as adjuncts.
How can I track progress objectively?
The most common outcome measures used to assess and reassess status of knee osteoarthritis are Western Ontario and McMaster Universities Osteoarthritis Questionnaire (WOMAC) and Knee Injury and Osteoarthritis outcome score (KOOS). These scales assess pain, daily functions, stiffness, sports and knee related quality of life.
