Knee Arthritis (Osteoarthritis): Causes, Symptoms, Diagnosis and Treatment in Bristol

Knee osteoarthritis is the most common reason patients come to see me. The range is enormous – from someone who has noticed a bit of stiffness after a long walk, to someone who can barely get around the house. What often surprises people is that the x-ray severity and the symptom severity don't always match, and that the pattern of arthritis in the knee matters just as much as the amount when it comes to deciding what to do about it.

I see knee arthritis at every stage. The options span physiotherapy, braces and injections, through to knee-preservation surgery like osteotomy, and joint replacement – partial, total, or robotic-assisted depending on the situation. The key is matching the right treatment to the right knee at the right time.

What is knee osteoarthritis?

The joint surfaces of the knee are lined with smooth cartilage that helps the joint glide and spreads load. With osteoarthritis, this cartilage gradually thins and roughens. The underlying bone becomes irritated and develops spurs. The joint lining can become inflamed, producing excess fluid, which is what causes the swelling many patients describe.

I always explain to patients that osteoarthritis is not simply "wear and tear" – it is a whole-joint condition involving cartilage, bone, the synovium (joint lining), lubricating joint fluid, and often the meniscus and ligaments too. That distinction matters because it shapes how I approach treatment.

What causes knee osteoarthritis?

Usually it is a combination of factors rather than one single cause:

Age: OA becomes much more common after 40, and increasingly so with each decade
Body weight: higher weight means more load through the knee with every step – this is one of the most modifiable risk factors
Previous injury: a torn meniscus, ACL rupture, fracture or cartilage injury can set the joint up for earlier arthritis. This is one of the main reasons I am so focused on meniscal preservation and ACL reconstruction in younger patients
Genetics: there is a strong family element – I frequently hear "my mum/dad had a knee replacement"
Sex: OA is more common in women
Alignment: a bow-leg (varus) overloads the inner compartment; a knock-knee (valgus) overloads the outer. This is directly relevant to whether osteotomy might be an option
Meniscus deficiency: when meniscal tissue has been lost – whether from an old tear or a previous partial meniscectomy – the cartilage underneath takes more load and can wear faster. This is a pattern I see regularly in patients who had keyhole surgery years ago
Occupational and sporting loads: decades of heavy manual work or high-impact sport can contribute

Sometimes there is no clear trigger at all – the arthritis simply develops gradually over time.

Symptoms

Knee arthritis can present very differently from one person to the next. The most common symptoms I hear about are:

Pain – typically worse with activity and towards the end of the day, though some people get pain at rest or at night as things progress
Stiffness – especially first thing in the morning or after sitting, usually easing after a few minutes of movement
Swelling – often after doing more than usual, sometimes persistent
Reduced walking distance or difficulty on stairs and hills
Grinding or creaking – this worries people, but on its own it is not always a sign of severe arthritis
Loss of confidence in the knee, or a feeling it might give way
Sleep disturbance once pain becomes more persistent

When to seek urgent assessment

You should seek urgent advice if you have sudden severe pain, a hot or red knee with fever, inability to weight-bear, a locked knee, or a major new swelling following injury. These may indicate something other than simple osteoarthritis.

Assessment and diagnosis

Getting the diagnosis right matters enormously, because the treatment I recommend depends on which part of the knee is affected, how severe the arthritis is, and what your goals are. I start with a thorough history – where exactly the pain is, what sets it off, how it affects your day-to-day life. Then I examine the knee: range of motion, tenderness, swelling, stability, alignment and how you walk.

I almost always get weight-bearing x-rays, because they show the joint space under load – a non-weight-bearing x-ray can be misleading. If I am considering osteotomy, I will also request long-leg alignment films to measure the mechanical axis. An MRI is useful when the clinical picture does not match the x-rays, or when I need more detail on the cartilage, meniscus or ligaments to decide between treatment options.

There is no routine blood test for osteoarthritis. I only request bloods if I suspect inflammatory arthritis or another diagnosis.

Why the arthritis pattern matters

This is something I spend a lot of time explaining in clinic. Knee osteoarthritis often affects one compartment more than the others, and the pattern drives the treatment decision:

Medial compartment OA (inner side) – the most common pattern, and typically associated with bow-leg alignment. This is the classic pattern for medial partial knee replacement or high tibial osteotomy
Lateral compartment OA (outer side) – less common, sometimes linked with knock-knee alignment. Distal femoral osteotomy or lateral partial replacement may be options
Patellofemoral OA (kneecap joint) – pain around or behind the kneecap, typically worse on stairs, slopes and getting out of a chair
Multi-compartment OA – arthritis across more than one compartment, where total knee replacement tends to be the more reliable surgical option

Understanding which compartments are involved – and which are spared – is central to deciding whether knee-preservation surgery is possible or whether a partial or total replacement is the best path.

Treatment options

I take a stepwise approach: starting with non-surgical treatment and only moving to surgery when symptoms remain genuinely limiting despite a proper trial of conservative care.

Activity and load management

Understanding what triggers flare-ups and learning to pace activity is genuinely useful. Low-impact exercise – walking plans, cycling (a static bike or turbo trainer is ideal), swimming – keeps the knee moving and the muscles working without pounding the joint.

Physiotherapy and strengthening

This is one of the most effective treatments for knee OA, and I recommend it for almost everyone. Good physiotherapy focuses on:

Quadriceps and hip strength – these muscles protect the joint and improve how it functions under load
Balance and movement control
Improving walking and stair mechanics
Progressive return to the activities you enjoy
Offloading braces or insoles, which can shift load away from the affected compartment

Weight management

I mention this because the evidence is strong: even modest weight loss meaningfully reduces load through the knee and can improve pain and function. It is one of the few things that changes the actual forces going through the joint.

Pain relief and anti-inflammatory medication

Medication can take the edge off symptoms and help you engage with physiotherapy. Options include simple painkillers and anti-inflammatory drugs, depending on your overall health.

Injections

Injections can provide a window of relief – sometimes to buy time, sometimes to help with a particular flare. The role depends on the severity and pattern of your arthritis and what we are trying to achieve.

When I consider surgery

I discuss surgery when symptoms are significantly affecting quality of life despite a genuine effort with non-surgical treatment. Which operation makes sense depends on the arthritis pattern and the condition of the whole knee.

Knee-preservation surgery

Osteotomy

Osteotomy is one of my particular interests. When malalignment is overloading one compartment – a bow-leg driving medial wear, or a knock-knee driving lateral wear – correcting that alignment can reduce pain and delay or avoid joint replacement. I perform both high tibial osteotomy (HTO) and distal femoral osteotomy (DFO) depending on where the deformity lies.

Meniscus surgery and meniscus preservation

Meniscus problems can worsen OA symptoms and joint mechanics. Depending on the situation, meniscal repair, root repair, partial meniscectomy, or meniscal transplant may be part of a wider knee-preservation strategy.

Cartilage treatment

When a focal cartilage defect is the main pain driver – rather than diffuse arthritis – procedures such as chondroplasty, OATS, ACI or osteochondral allograft can be considered. The distinction between a treatable focal defect and widespread arthritis is critical.

Joint replacement

When arthritis is advanced or affects multiple compartments, joint replacement tends to provide the most reliable and lasting improvement.

Partial knee replacement

If arthritis is confined to one compartment and the rest of the knee is healthy, a partial replacement can be an excellent option – faster recovery, a more natural-feeling knee, and preservation of healthy tissue. I offer medial, lateral and patellofemoral partial replacements.

Total knee replacement

When arthritis affects multiple compartments, or when the pattern is not suitable for a partial, total knee replacement is the more appropriate and reliable option.

Robotic-assisted knee replacement

For some patients, robotic assistance adds precision in planning and implant placement. I use Mako and CORI systems depending on the procedure type and the anatomy involved.

How I approach the decision with you

The best treatment depends on which compartments are affected, your alignment and knee stability, the state of your meniscus and cartilage, your activity goals, and your general health. I aim to give you a clear picture of the benefits, limitations and likely recovery for each realistic option so you can make a decision you feel confident about.

Frequently asked questions

Do x-rays always match symptoms?

No – and this catches a lot of people out. I regularly see patients with significant pain but relatively mild x-ray change, and others with advanced x-ray appearances who are managing well. Treatment decisions should be based on the full picture: your symptoms, how the knee functions, the examination findings and the imaging.

Can I still exercise with knee osteoarthritis?

Absolutely. Exercise is one of the most effective treatments. The goal is low-impact, progressive activity that builds strength and improves your knee's tolerance. I encourage patients to be guided by pain and swelling – some discomfort during exercise is acceptable, but if the knee is significantly worse for the next 24 hours, you have probably done too much.

When should I consider a knee replacement?

I typically discuss replacement when pain and function are significantly affected despite good non-surgical treatment, and when the arthritis pattern and severity suggest a replacement will provide the most reliable improvement. There is no single threshold – it is about your quality of life.

Is partial knee replacement better than total?

Neither is inherently "better" – each suits a different situation. Partial replacement can be excellent when arthritis is confined to one compartment. Total replacement is more appropriate when arthritis is widespread. The best option is the one that matches your arthritis pattern and your goals.

Can I be assessed for knee osteoarthritis in Bristol?

Yes. I see patients with knee arthritis at all stages, from early symptoms through to end-stage disease, at my clinics in Bristol. I can advise on non-surgical care, knee-preservation options such as osteotomy, and joint replacement where appropriate.