Bone Bruise And Bone Marrow Lesion Knee Pain

If your knee scan report mentions a bone bruise, bone marrow oedema or a bone marrow lesion, it is describing the same finding: fluid and tiny areas of damage inside the bone just beneath the joint surface. Bone contusions and bone marrow edema are other names for it. What it means for you depends on how it got there.

A bruise from a fall or twist usually settles with the right loading. A lesion under worn cartilage behaves differently and is often why an arthritic knee hurts more than the X-ray suggests. At MTP Health, Dr Jonathan Negus and our physiotherapy team see both, and treat them differently.

Key Takeaways

• A bone bruise and a bone marrow lesion are the same change in the bone under the cartilage, but the cause decides what happens next.
• Bone has a nerve supply and cartilage does not, so a lesion can be the exact source of a deep ache.
• Traumatic bone bruises usually improve over six to twelve weeks, and protected loading beats complete rest.
• Degenerative lesions under thin cartilage may persist and are a recognised pain driver in knee osteoarthritis.
• Subchondroplasty is one option for a persistent, painful lesion in a joint still worth preserving. Physiotherapy comes first.

What A Bone Bruise Is

Beneath the cartilage that caps your thigh and shin bones, within the knee joint, sits dense subchondral bone, and under that a honeycomb of fine bony struts filled with marrow. When the honeycomb is overloaded, struts crack microscopically, vessels leak and fluid accumulation within the bone shows on magnetic resonance imaging as a bright, cloudy patch.

These changes cluster at predictable spots, most often the medial femoral condyle or lateral femoral condyle, and sometimes the lateral tibial plateau or anterior tibia, depending on the injury mechanism.

Bone bruise and bone marrow oedema are the names used after an injury; bone marrow lesion, or BML, is used when the change sits beneath worn cartilage. The tissue change in the underlying bone is similar; the outlook is not, which is why our orthopaedic and physiotherapy clinic on Sydney’s North Shore starts by asking how it got there, drawing on the clinical history as much as the MRI imaging.

Why The Bone Hurts

Cartilage has no nerve supply, so worn cartilage on its own is silent. Subchondral bone is richly supplied with nerves and sensitive to pressure. When the marrow oedema is present, pressure inside the bone rises and every step loads it.

The result is a deep, hard-to-point-to ache, worse with standing, walking and weight bearing activities, with motion pain that can throb at night after a busy day, and it often matches the exact spot on the scan. Pain severity tends to track how large the lesion is.

Bruise From An Injury

A traumatic bone bruise, or bone contusion, follows a specific event: a fall onto the knee, a heavy landing, a tackle in contact sports or a twist that jams the bone surfaces together.

It is common alongside ligament tears and meniscal injuries, and these associated injuries matter: bone bruising is seen in most ACL tears and other ACL injuries, where the same force that tears the anterior cruciate ligament also compresses bone. The knee may swell for a day or two, then settle into a weight-bearing ache that outlasts a normal sprain, and knee motion can feel guarded.

Healthy bone heals. Most bone bruises heal as the cracks knit, the fluid reabsorbs and the marrow returns to normal, a process of bone healing that protected loading supports. Bone that is completely rested loses strength, and bone that is pounded too early keeps re-injuring, so the middle path is protected loading that increases as pain allows and helps promote healing.

Lesions Under Worn Cartilage

When cartilage thins, the underlying bone takes more load and more shock. It responds with the same damage and fluid, but without a healing endpoint, because the excessive stress does not stop. These degenerative lesions, a form of subchondral pathology, usually sit on the most heavily loaded side of a knee with knee osteoarthritis, most often the inner compartment, over the medial femoral condyle or medial tibial plateau.

They correlate closely with how much an arthritic knee hurts, and larger or persistent lesions are associated with faster cartilage loss and future osteoarthritis in that compartment.

That does not make surgery inevitable, even when the X-ray is described as bone-on-bone knee arthritis, but from a clinical perspective the lesion should not be dismissed as incidental, because several factors, including alignment and the state of the cartilage surface, shape long term outcomes.

Healing Time And Loading

Most traumatic bone bruises improve within six to twelve weeks, larger ones and those alongside a ligament injury can take three to six months, and the MRI appearance often lags behind how the knee feels.

During that window the MTP Health physiotherapy and exercise physiology team protects the bruised area from impact while keeping you moving, uses physical therapy to rebuild quadriceps and hip strength, unwind compensatory movement patterns, reduce pain and reduce inflammation, and progresses walking, stairs and then running or sport in a graded sequence.

Return to impact is decided on symptoms and strength, not a date. For degenerative lesions the goal shifts to reducing load through that compartment long term, and most patients improve with this approach.

How MTP Health Assesses It

A lesion on a report is not a diagnosis by itself; some are found in knees that do not hurt at all. Dr Jonathan Negus assesses the whole picture: how the pain started, where it sits, any associated meniscal or ligament injury, leg alignment and how the lesion relates to the cartilage above it.

That decides whether you have a bruise that needs time, a lesion that needs load management, or a persistent pain driver in a joint still worth keeping. Early diagnosis and clear treatment planning matter, because these knee conditions behave very differently.

Dr Negus confirms the diagnosis and rules out anything that changes the plan; our physiotherapists and exercise physiologists then deliver the personalised treatment plan and loading program that does most of the work for most people.

When Subchondroplasty Is Considered

Subchondroplasty injects a calcium phosphate bone substitute into the lesion under X-ray guidance, usually during a knee arthroscopy so any loose cartilage or meniscal fragment can be addressed at the same time. This surgical procedure fills the damaged honeycomb, is gradually replaced by your own bone, and aims to reduce pressure and pain from that spot.

It is not a treatment for arthritis as a whole, nor the first step, and orthopedic surgeons reserve this surgical intervention for a specific group. Dr Negus may discuss it when a degenerative lesion stays painful after a genuine period of physiotherapy-led load management, the cartilage over it is worn but not absent, and alignment is not driving the overload.

Where alignment is the main problem an osteotomy may fit better; where the compartment is bone on bone in advanced osteoarthritis, a partial knee replacement or other joint replacement is usually more reliable. Among the treatment options, risks include infection, ongoing pain and a temporary rise in discomfort while the bone remodels, so the decision is made together, with the non-surgical path always open.

Signs That Need Prompt Review

A simple bone bruise eases when you take weight off it. Seek review for knee pain sooner if it does not settle with offloading, you cannot bear weight, night pain is escalating despite rest, or the knee becomes hot and swollen.

In an older knee, sudden severe pain on the inner side without a clear injury can signal a subchondral insufficiency fracture, sometimes called a subchondral fracture, or osteonecrosis of the knee, also known as avascular necrosis or spontaneous osteonecrosis, rather than a bruise. Both need earlier specialist input and may need MRI scans, especially if symptoms persist.

Frequently Asked Questions (FAQs)

How long does a bone bruise in the knee take to heal?

Most improve within six to twelve weeks, and larger bruises or those linked to a ligament injury can take three to six months. The scan often looks abnormal for longer than the knee feels sore, so recovery is judged on function.

Can I walk or exercise on a bone bruise?

Usually yes, within limits set by pain. Walking and cycling are generally encouraged early, while running and jumping wait until the weight-bearing ache has settled. A physiotherapist can set the progression so the bone strengthens without being overloaded.

Is a bone marrow lesion the same as arthritis?

No. A bone marrow lesion is a change inside the bone beneath the cartilage, and it can occur with or without arthritis. In an arthritic knee it is often the main reason the joint hurts, so it is treated as a target in its own right.

Do bone marrow lesions go away on their own?

Traumatic lesions usually do, once the bone has healed. Degenerative lesions may shrink with reduced loading and stronger muscles, but can persist or recur because the underlying overload continues.

What is subchondroplasty and who is it for?

It injects a bone substitute into a painful lesion to support the bone while it remodels. It may suit people with a persistent degenerative lesion who have completed a proper course of physiotherapy and whose cartilage and alignment are still reasonable. It does not suit advanced, bone-on-bone arthritis.

Conclusion

A bone bruise and a bone marrow lesion look alike on a scan but lead to different plans. One needs time and graded loading. The other needs a longer view, with physiotherapy first and subchondroplasty or other surgery reserved for the lesion that will not settle. If your knee report has raised either term, book an assessment with MTP Health on (02) 9437 9794.