Knee Osteoarthritis: Exercise, Injections, and Surgery Compared

Your knee aches on the stairs, feels stiff when you get up, and sometimes swells after a long walk. You may have been told it is arthritis, or wear and tear. Knee osteoarthritis is very common, especially after age 45. There are many treatments, and some work much better than others. This guide compares the options using what major guidelines recommend.

What knee osteoarthritis is

Osteoarthritis (OA) is the most common type of arthritis [3]. It affects the whole joint, including cartilage (the smooth tissue covering the ends of bones), bone, ligaments, and the joint lining. Over time, cartilage thins and the bone underneath changes.

Common symptoms include:

• Pain with activity that eases with rest
• Brief stiffness in the morning or after sitting
• Swelling
• A grinding or crackling feeling
• Less movement in the knee

Risk factors include older age, extra body weight, past knee injury, joint shape, genes, and jobs with heavy knee use.

What your doctor looks at

Diagnosis

The UK NICE guideline says clinicians can diagnose OA without tests if a person [2]:

• Is 45 or older
• Has activity-related joint pain
• Has no morning stiffness, or stiffness that lasts 30 minutes or less

X-rays are not needed for most people. They may be used if symptoms are unusual, if another condition is suspected, or before surgery. X-ray findings often do not match how much pain a person feels.

The ACR guideline

The American College of Rheumatology and Arthritis Foundation 2019 guideline is a key US reference [1]. NICE (2022) is often used in Canada and the UK [2]. Their main recommendations are summarized below.

Treatments compared

Exercise

Both guidelines place exercise at the centre of care [1] [2]. Options include:

• Strengthening exercises for the thigh and hip muscles
• Low-impact aerobic exercise, such as walking, cycling, or swimming
• Water-based exercise
• Tai chi

The ACR strongly recommends exercise for everyone with knee OA [1]. NICE recommends offering a tailored exercise program, often with a physiotherapist [2].

Weight loss

For people who are overweight or have obesity, the ACR strongly recommends weight loss [1]. Losing 5 percent or more of body weight is linked to better pain and function, and more loss brings more benefit [1].

Other self-management

The ACR strongly recommends [1]:

• Self-management and education programs
• A cane, if needed
• A tibiofemoral knee brace (a brace that supports the main knee joint) for some people

Pain relief medications

• Topical NSAIDs, such as diclofenac gel: strongly recommended for knee OA and often tried first, since less of the drug reaches the bloodstream [1] [2]
• Oral NSAIDs, such as ibuprofen or naproxen: strongly recommended, at the lowest dose for the shortest time needed, because of risks to the stomach, kidneys, and heart [1] [4]
• Acetaminophen: the ACR gives it only a conditional recommendation, and NICE advises against routine use [1] [2]
• Duloxetine: conditionally recommended by the ACR [1]
• Opioids: NICE advises against strong opioids for OA [2]

Injections

• Corticosteroid (steroid) injections: strongly recommended by the ACR for knee OA [1]. NICE notes they offer short-term relief, often 2 to 10 weeks [2].
• Hyaluronic acid injections: the ACR conditionally recommends against them for knee OA, and NICE advises against them [1] [2].
• Platelet-rich plasma (PRP) and stem cell injections: the ACR strongly recommends against them, citing lack of standard preparations and weak evidence [1].

Supplements

The ACR strongly recommends against glucosamine and chondroitin for knee OA [1]. NICE also advises against glucosamine [2].

Surgery

• Arthroscopic surgery (keyhole surgery to wash out or trim the joint): NICE advises against it for OA unless there is a clear history of the knee locking [2].
• Total knee replacement: an option when pain and stiffness remain severe and affect quality of life despite non-surgical treatment [2]. Most people have less pain and better function after surgery, but recovery takes months and there are risks such as infection and blood clots.
• Partial knee replacement or osteotomy (reshaping a bone): options for some people with damage in only one part of the knee.

Canada and US notes

Access to physiotherapy and wait times for knee replacement differ between provinces and states. Coverage for injections and topical NSAIDs also varies. Topical diclofenac is available without a prescription in both countries.

Questions to ask your clinician

• Do my symptoms fit osteoarthritis, or should we look for another cause?
• What type of exercise is best for my knee, and can I see a physiotherapist?
• Is an NSAID safe for me, given my heart, kidneys, and stomach?
• Would a steroid injection help, and how often can I have one?
• What do the guidelines say about the injections or supplements I have heard about?
• At what point should I think about knee replacement?
• What would recovery look like for me?

When to get care quickly

Go to the emergency department or get same-day care if:

• Your knee is hot, red, and very swollen, especially with fever, which can be a sign of joint infection
• You cannot put weight on your leg after an injury
• Your calf is swollen, warm, and painful, especially after surgery, which can be a sign of a blood clot
• You have sudden shortness of breath or chest pain, which needs a 911 call

Bottom line

Exercise and weight loss, when needed, are the foundation of care for knee osteoarthritis. Topical and oral NSAIDs and steroid injections can help with pain. Guidelines advise against hyaluronic acid in most cases and against PRP, stem cells, and glucosamine. Knee replacement is an option for severe symptoms when other treatments are no longer enough.

Primary AI can show you the guideline and study sources behind this topic in plain language, so you can bring better questions to your appointment.