Knee osteoarthritis (OA) is one of the leading causes of disability worldwide. Over 40% of people develop some degree of knee arthritis, and currently, a New Zealander’s lifetime risk of undergoing a knee replacement is 18%. Knee replacement surgery can be a very successful procedure: whereas previously a diagnosis of knee osteoarthritis used to mean progressive pain and disability, now most patients can expect to remain active well into their retirement.

However, a significant percentage (up to 20%) of patients report dissatisfaction after knee replacement. Careful patient selection and pre-operative optimisation are critical to achieving the best outcome. Proceeding directly to knee replacement is often the wrong thing to do – a better outcome may be achieved initially with a targeted rehabilitation program.

Severity of Osteoarthritis on X-ray is key

Multiple studies have shown that patients undergoing total knee replacement for a mild grade of osteoarthritis have a poorer outcome. This may because their expectations were too high, or that there are other, non-structural, causes for the patient’s symptoms. Joint dysfunction due to muscle weakness or neuropathic pain may worsen after major surgery such as knee replacement.

Patients with a Kellergen-Lawrence grade <2 (ie no ‘bone on bone’ arthritis – Figures 1 and 2) should always undergo a targeted rehabilitation program before considering surgery. Strategies such as exercise, NSAIDs, and weight loss offer proven and sustainable benefits for symptom control. Regular high cadence, low resistance cycling is particularly effective. Additionally, studies in obese patients suggest weight loss through a combination of diet and exercise can lead to a 50% reduction in arthritic knee pain.

Figure 1

‘Early’ Osteoarthritis with mild joint space narrowing only

Figure 2

Severe ‘bone on bone’ medial compartment arthritis, potentially a good candidate for knee replacement if symptoms warrant surgery.


Injection therapy is also an option in patients with refractory symptoms but only mild radiographic change. Corticosteroid injections provide on average 2-3 months of relief, although multiple injections have negative effects on cartilage. Visco-supplementation injections and platelet rich plasma (PRP) injections do not have this effect, and may provide longer term relief. Despite their cost (approx $500) many patients may prefer a single injection than regular NSAID use.

The Value of Preoperative Exercise and Optimisation

Even in patients with severe arthritis, preoperative exercise prior to knee replacement can improve outcomes. In a 2017 meta-analysis, Moyer et al combined the results of 35 studies including almost 3,000 patients, and found ‘prehabilitation’ led to significant improvements in pain, function, and length of stay.

Weight loss can also decrease the risk of major complications following surgery. A body mass index (BMI) >40 is associated with an increased risk of deep infection, wound drainage, and cardiovascular complications following knee replacement. Studies show patients who lose >5% body weight pre-operatively will significantly lower their perioperative risk.

Multimodal management

Whatever the grade of arthritis, management should be targeted to each individual patient. The Axis Osteoarthritis Clinic involves a multi-disciplinary approach including Sport and Exercise Physicians, Orthopaedic surgeons, a dietician and clinical exercise physiologist. In this way we hope to be able to deliver high-quality care for patients with a range of joint symptoms.



Axis Osteoarthritis Clinic

Are you or one of your patients suffering from osteoarthritis? Is the pain, swelling, stiffness, or potentially worse, symptoms significantly impacting your ability to undertake physical activity? Our specialist Arthritis Clinic could provide you with improvements you’ve been searching for.

Our clinic brings together a range of medical and allied health specialists to provide a comprehensive treatment plan, looking to optimise the non-surgical management (including exercise and diet) of osteoarthritis.

If this sounds like something you or your patient could benefit from, make an appointment to come in and see us.

To make an appointment call 09 521 9846



By Mr Simon Young on