Knee Osteoarthritis Surgery: What Your Options Are at Every Age

Dr Adam Walker (PhD) — Director and Head of Rehabilitation, Gold Coast Knee Group

Physiotherapists are sometimes assumed to be anti-surgery. I am not, and I want to be clear about that before anything else.

Surgery plays a genuinely important role in knee osteoarthritis. For the right person, at the right time, it can make an enormous difference.

The problem is not that surgery exists. It is that most people are given a binary — try physio, and if that fails, have a knee replacement — when the actual landscape is far more varied than that, and what is appropriate changes considerably with your age.

This article maps that landscape. It comes out of a presentation by Dr Francois Tudor, Specialist Knee Orthopaedic Surgeon at SEQSEM, at our Mastering Knee OA for GPs evening, reshaped for people trying to work out where they sit.

It is written particularly for anyone who has been round the loop a few times — years of pain, a stack of scans, and a growing sense that nobody has explained the whole picture.

Age is a Sliding Scale, Not a Switch

Not all knees are the same, and neither are all people with osteoarthritis.

The single most useful organising idea is that surgical options move along a spectrum with age — from preserving the joint at one end to replacing it at the other. Where you sit on that spectrum shapes which conversations are worth having.

Before any of it: education, exercise, activity and managing your inflammatory load sit underneath all of this for everyone. That is the base, covered in the three critical ingredients of knee arthritis management. Nothing below replaces it.

Under 40: Prevention and Preservation

This age group is the trickiest, and it is also where the most is at stake.

Most osteoarthritis here is post-traumatic — the legacy of an old ACL injury, a meniscal tear, or an alignment problem that has been quietly loading one part of the joint for years.

The surgical strategies are about protecting what is there:

Meniscus repairs

Particularly for root and radial tears, which can rapidly accelerate joint degeneration if left alone. Success rates are high — up to 95% when combined with an ACL reconstruction.

We have written in detail about which tear patterns matter in meniscus tear surgery versus rehab for young adults.

Ligament reconstruction

Addressing instability early reduces how the joint gets loaded, and therefore the long-term wear. It suits people with recurrent episodes of the knee giving way, or a positive pivot-shift on examination.

Osteotomy

For people whose legs are not aligned neutrally — bow-legged or knock-kneed — realigning the bone redistributes force away from the compartment taking the punishment.

Cartilage procedures

Microfracture, osteochondral grafts, and cartilage implantation for focal defects. These are very case-specific and generally reserved for younger, active people.

The goal in this decade is prevention. Catch these knees early and you can potentially delay, or even avoid, the progression to full osteoarthritis. That is a meaningfully different objective from anything further down the list.

40 to 55: The Grey Zone

This is where it gets complicated, and where most of the frustration lives.

Some people in this bracket still have a knee worth preserving. Others are well into the osteoarthritis trenches. Two people the same age can be in completely different situations, which is exactly why blanket advice fails here.

The options include:

High tibial osteotomy

Particularly valuable for osteoarthritis on the inner side of the knee combined with malalignment. It suits active people who want to stay active and push a joint replacement further down the line.

Meniscus allograft transplantation

Where the meniscus has been completely removed and symptoms persist, transplanting a donor meniscus can restore the shock absorption that was lost. It is performed in very specific cases, where the rest of the joint still looks good.

Radiofrequency ablation and genicular nerve blocks

Pain relief without structural intervention. Often used as a bridge, or for people who are not yet surgical candidates. More on these in knee injections for osteoarthritis.

Targeted bracing and injections

Cortisone for acute flares, and PRP to reduce inflammation.

Why replacement is usually delayed here

There is a hard number behind this, and it is the reason surgeons are cautious with younger patients.

The revision rate for joint replacement is high in people under 50 — around 25% at five years, compared with 5% at ten years for those who have it done over 50.

A revision is a second, harder operation on a knee that has already been through one. Delaying the first replacement is not about making you wait. It is about not spending the operation too early.

Over 55: The Replacement Window

Once osteoarthritis has progressed and the other options are exhausted, joint replacement enters the conversation properly. Even then it is not one procedure.

Unicompartmental knee replacement

Ideal where the arthritis is isolated to one side of the knee — inner or outer. It is less invasive, recovery is faster, and it preserves more of your own bone.

Total knee replacement

The gold standard for end-stage osteoarthritis affecting multiple compartments. Outcomes continue to improve with modern surgical technique and better rehabilitation.

And here is the part most people are never told: improving the outcome of a knee replacement begins months before the operation. What you do in the lead-up genuinely changes what you get out of it. We have covered that in knee replacement recovery.

Questions Worth Taking to a Surgical Appointment

A surgical opinion is far more useful when you arrive with the right questions. These are the ones that tend to change the conversation:

1. Which compartments of my knee are actually affected? Isolated arthritis on one side opens options that whole-joint arthritis does not.

2. Is my leg alignment contributing? If it is, realignment may be on the table, and that changes the timeline considerably.

3. Given my age, what is the expected lifespan of this implant, and what happens after that? Revision is the part rarely discussed upfront and it matters most for younger patients.

4. Is there anything worth preserving here, or are we past that? A direct question that deserves a direct answer.

5. If I did nothing surgical for another two years, what would you expect to happen? Useful for separating a knee that is deteriorating from one that is simply painful.

None of these is confrontational, and a good surgeon will answer all five readily. The point is to leave the appointment understanding where you sit on the spectrum rather than only whether you were offered an operation.

What Happens Before and After Surgery

Whether you are 40 or 70, there is work that belongs either side of any operation, and it changes the result.

Timing is critical. People should go into surgery strong, mobile and well-informed. Those who prepare properly tend to have better outcomes, less pain afterwards, and a faster return to function.

The preparation looks like:

• Improving how much load the knee tolerates, through strength and conditioning

• Reducing systemic inflammation

• Getting realistic about what your imaging means, what pain means, and what to expect from the operation

• Trialling braces or injections where they are appropriate

• Being referred for a surgical opinion at the right time — not too early and, just as importantly, not too late

That last point cuts both ways. Being sent to a surgeon before anything else has been tried wastes everybody’s time. Being kept away from one for years while a knee that needed an operation deteriorates is the other failure, and it is less often discussed.

The Bottom Line

Knee osteoarthritis is not one condition, and there is no one-size-fits-all solution to it.

Under 40, the aim is prevention and preservation — repairing what can be repaired, correcting instability and alignment before the joint pays for them.

Between 40 and 55, it is a genuine grey zone where preserving the joint and buying time are the objectives, and where replacement is usually held back because of the revision rates in younger knees.

Over 55, replacement becomes appropriate for the right person — and even then it is a choice between procedures rather than a single default.

Everyone deserves to be heard, to have their own goals put first, and to get the right intervention at the right time. Whether that is protecting a 35-year-old ex-footballer’s meniscus or preparing a 70-year-old grandmother for a successful replacement, the timing and the preparation matter as much as the choice itself.

Trying to work out where you sit?

The most useful starting point is knowing how much room is left before surgery becomes the right answer — and what condition your knee would go into an operation in. Our Healthy Knee Program begins with a full knee assessment that measures exactly that, and we work alongside orthopaedic surgeons when a surgical opinion is the right next step.

We see patients across the Gold Coast at Robina, Currumbin and Benowa. You can get in touch with our team or phone 0408 051 943.

FAQs about Knee Osteoarthritis Surgery

❓ Am I too young for a knee replacement?

It is less about being too young and more about revision rates. In people under 50, around 25% of knee replacements need revising within five years, compared with about 5% at ten years for those who have it done over 50.

A revision is a harder operation on a knee that has already had one. That is why surgeons generally look at joint-preserving options first in younger patients.

❓ What are the alternatives to a knee replacement?

Considerably more than most people are told. Under 40 the options are largely preservation — meniscus repair, ligament reconstruction, osteotomy, cartilage procedures.

Between 40 and 55 there is high tibial osteotomy, meniscus allograft transplantation in specific cases, radiofrequency ablation, nerve blocks, targeted bracing and injections. All of that sits above a base of exercise, education and inflammation management.

❓ What is an osteotomy?

It is a procedure that realigns the bone to redistribute force away from the part of the joint bearing the most load. It suits people who are bow-legged or knock-kneed with arthritis concentrated on one side.

High tibial osteotomy is particularly valuable for arthritis on the inner side of the knee in active people who want to push a replacement further into the future.

❓ What is a partial knee replacement?

A unicompartmental knee replacement resurfaces only one side of the joint rather than the whole thing. It suits arthritis isolated to the inner or outer compartment.

It is less invasive, recovery is faster, and it preserves more of your own bone than a total replacement.

❓ Why does my age change what surgery is appropriate?

Because the objective changes. Under 40 the aim is preventing progression — protecting a joint that has decades of use ahead of it. Over 55 the aim is restoring function in a joint where the damage is established.

The 40 to 55 bracket is genuinely a grey zone, and two people the same age can be in very different situations depending on how much of the joint is still worth preserving.

❓ Does an old ACL or meniscus injury cause arthritis later?

Most osteoarthritis in people under 40 is post-traumatic, and old ACL injuries, meniscal tears and alignment problems are the usual histories behind it.

That is exactly why early treatment of instability and of particular tear patterns matters. Catching those knees early can delay or avoid the progression.

❓ When should I see a surgeon?

When the timing is right, which is a real judgement rather than a formality. Too early and you are having a conversation about an operation before anything else has been tried properly.

Too late is the failure people talk about less — years spent avoiding a surgical opinion while a knee that needed one deteriorates. A surgical opinion does not commit you to surgery.

❓ What should I do before knee surgery?

Go in strong, mobile and well-informed. People who prepare properly tend to have better outcomes, less pain and a faster return to function.

Practically: build load tolerance with strength and conditioning, reduce systemic inflammation, and get clear on what your imaging means and what to realistically expect from the operation.

❓ Is my physiotherapist against surgery?

This one should not be, and most are not. Surgery plays a very important role and can make an enormous difference for the right person at the right time.

The role of good rehabilitation is to make sure you get to that decision having genuinely tried the alternatives, and that you go into the operation in the best condition possible if you do have it.