Subchondroplasty in Sydney

What is subchondroplasty?

Subchondroplasty is a minimally invasive knee procedure used to treat selected bone marrow lesions, often called BMLs. These are areas of stress, swelling or oedema in the bone just beneath the cartilage surface, and they are usually seen on MRI rather than on a standard X-ray.

The word “subchondral” refers to the bone under the cartilage. When this bone becomes overloaded or develops a stress response, it can cause deep, localised pain with walking, standing, stairs or uneven ground. Subchondroplasty aims to support this stressed area by injecting a flowable calcium phosphate bone substitute into the lesion.

The material hardens inside the bone and acts as an internal scaffold. Over time, the body may gradually remodel the material and replace it with natural bone. It is not a treatment for every painful knee, and it is not a replacement for good patient selection, careful imaging review and structured rehabilitation.

Do you need subchondroplasty?

Subchondroplasty is usually considered when an MRI shows a specific bone marrow lesion that matches your symptoms. The pain is often described as deep, localised and worse with load-bearing activities rather than sharp surface-level pain alone.

You may be suitable if the lesion is well-defined, your symptoms match its location, non-surgical treatment has not provided enough improvement, and the surrounding joint is healthy enough to preserve. It may be less suitable if arthritis is advanced, the knee is unstable, there is severe malalignment, or pain is mainly coming from another structure such as widespread cartilage damage or a major meniscal problem.

At your consultation, your surgeon will take a detailed history, examine your knee and review your imaging. MRI is especially important because bone marrow lesions are often not visible on plain X-rays. The decision is not based on the MRI alone. It depends on whether the lesion explains your symptoms and whether subchondroplasty is the right option for your whole knee.

Benefits and risks

What you can expect it to achieve

• Target a painful bone marrow lesion seen on MRI
• Support weakened or stressed subchondral bone
• Reduce deep localised bone pain in suitable patients
• Improve walking tolerance and confidence with load-bearing activity
• Allow associated issues to be assessed during knee arthroscopy where required
• Potentially delay the need for larger surgery in carefully selected cases
• Support a structured return to activity through progressive rehabilitation

Risks to understand

• Common and temporary: swelling, bruising, stiffness, local bone discomfort and reduced strength in the early recovery period
• Uncommon: infection, blood clots, wound problems, nerve or blood vessel irritation, and anaesthetic complications
• Specific to subchondroplasty: temporary increase in bone pain, leakage of calcium phosphate material, incomplete symptom relief or pain from another untreated structure
• Longer-term: symptoms may return if arthritis progresses, alignment continues to overload the area, or the lesion is part of a broader joint problem

All surgery carries risk and outcomes vary between individuals. Subchondroplasty can be useful when a bone marrow lesion is the main pain generator, but it is not a cure for advanced arthritis and it is not appropriate for every MRI finding.

Subchondroplasty	Other knee treatments
Targets a specific bone marrow lesion	May target cartilage, meniscus, alignment, ligaments or whole-joint arthritis
Uses calcium phosphate bone substitute to support stressed bone	May involve cartilage repair, meniscal repair, osteotomy or replacement implants
Usually guided by MRI and intra-operative imaging	Depends on the diagnosis and treatment being performed
May be combined with arthroscopy	May be non-surgical, arthroscopic, realignment-based or replacement-based
Best for selected patients without advanced joint damage	Broader options are needed when arthritis or mechanical problems are more advanced

The procedure: what happens

Before surgery, you will have a pre-operative assessment to review your general health, medications, imaging and anaesthetic plan. Your surgeon will review the MRI carefully to identify the size and location of the bone marrow lesion and plan the safest path for treatment.

The operation is performed under general or spinal anaesthesia. In many cases, subchondroplasty is performed with knee arthroscopy. This allows the surgeon to inspect the joint surface, meniscus and ligaments and address related issues if appropriate.

The bone marrow lesion is targeted using imaging guidance, often fluoroscopy, which provides real-time X-ray images during the procedure. A small cannula is placed into the affected area of bone, and a flowable calcium phosphate bone substitute is injected in a controlled way.

The material fills the targeted region and hardens to provide internal support. The surgeon confirms placement, removes the instruments and closes or dresses the small incisions. The exact operating time depends on the lesion, the technique used and whether other procedures are performed at the same time.

After surgery

You will wake in the recovery room, where your pain, circulation and vital signs are monitored closely. Once you are comfortable and stable, you will begin your early recovery with nursing and physiotherapy support.

Some discomfort in the treated area is expected in the first few days. Crutches may be recommended for a short period to reduce load while pain settles and walking confidence improves. Your exact instructions depend on the lesion location, the amount of material used and whether arthroscopy or another procedure was performed at the same time.

Subchondroplasty recovery and rehabilitation

Recovery after subchondroplasty is usually based on gradual improvement in pain, swelling, strength and load tolerance. Some people notice improvement over the first few weeks, while others improve more gradually over several months as the bone responds and confidence with activity returns.

Because subchondroplasty is often combined with arthroscopy, your recovery plan depends on the whole procedure rather than the injection alone. Rehabilitation aims to restore movement, rebuild strength, improve load-sharing across the knee and reduce the chance of the lesion being overloaded again.

Recovery timeline

Phase	Timeframe	What to expect
Protect & settle	Days 0–14	Crutches as needed, wound care, swelling control, gentle range-of-motion and short walking bouts
Early loading	Weeks 2–6	Walking progression, gentle strengthening, balance work and gradual return to daily tasks as symptoms allow
Build capacity	Weeks 6–12	Progressive strengthening, gait retraining, cycling and improved tolerance for stairs and longer walks
Strength & control	Months 3–6	More demanding strengthening, functional exercises and gradual return to selected recreational activities
Longer-term review	Months 6–12	Ongoing monitoring of symptoms, load tolerance and any underlying arthritis or mechanical contributors

Timeframes are a guide. Your surgeon and rehabilitation team will progress you based on the lesion, your symptoms, any associated procedures and your recovery goals.

Post-operative care

At home, the priorities are keeping the wounds clean and dry, controlling swelling, using pain medication safely, walking as instructed and completing your prescribed exercises. Some swelling and local discomfort is common early, but increasing redness, wound discharge, fever or worsening calf pain should be checked urgently.

Rehabilitation at MTP Health

This is where MTP Health is different. Your rehabilitation is delivered by our own physiotherapists and exercise physiologists, working in the same clinic as your surgeon. Your plan can begin before surgery and continue seamlessly afterwards, with everyone working from the same goals and shared clinical record.

Rehabilitation focuses on restoring movement, improving walking quality, rebuilding quadriceps and hip strength, improving balance and gradually increasing load tolerance. Your recovery may be supported by our post-operative rehabilitation, physiotherapy and exercise physiology services.

Returning to driving, work and sport

Return to driving depends on which knee was treated, whether you drive an automatic or manual car, your pain, swelling, weight-bearing status, reaction time and medication use. You must be able to safely perform an emergency stop and must no longer be taking strong pain medication. Please check with your surgeon and your insurer before driving.

Desk-based work may be possible relatively early if pain is controlled and transport is manageable. Physical work takes longer, particularly if it involves prolonged standing, stairs, kneeling, lifting, squatting or uneven ground.

Return to sport or higher-load activity is gradual. Low-impact activity is usually introduced before running, jumping or pivoting. The timing depends on symptoms, strength, confidence, the lesion location and whether there is underlying arthritis or another mechanical contributor.

Subchondroplasty cost in Sydney

The cost of subchondroplasty depends on your private health cover, hospital insurance, surgeon fees, anaesthetist fees, assistant fees, hospital charges, imaging, implant or bone substitute costs and whether arthroscopy or another procedure is performed at the same time.

If you are having surgery using private health cover, your out-of-pocket cost depends on your fund, policy, hospital arrangement and any gap charged by the surgical and anaesthetic teams. The anaesthetist is an independent practitioner and may charge a separate gap, so we provide their details and recommend checking their quote before surgery.

Because subchondroplasty may be performed alone or alongside arthroscopy, costs can vary. Your team will explain the expected fees, hospital arrangements and rebate pathway before surgery wherever possible.

If surgery is performed through the public system, there may be no out-of-pocket surgical cost, but waiting times can be long and depend on hospital access, urgency category and local availability.

Why have your subchondroplasty at MTP Health

MTP Health brings together fellowship-trained orthopaedic surgeons, careful surgical planning, physiotherapy and exercise physiology in one clinic. That matters because subchondroplasty is not just about filling an MRI finding — it is about working out whether that lesion is truly causing your symptoms and whether the rest of the knee is suitable.

Honest advice comes first. If your knee is better suited to non-surgical care, we will tell you. If the lesion is part of advanced arthritis or a bigger mechanical problem, we will explain why another option may be more reliable. If subchondroplasty is suitable, we will help you understand the procedure, recovery, risks and expected outcome clearly before you decide.

Your surgeon

Frequently asked questions