Bone bruise or fracture: what is the difference in the knee?

What each injury is

Bone is not solid all the way through. Inside the hard outer shell is a mesh of fine bone with marrow. In a bone bruise the tiny struts of that mesh are damaged and fill with fluid and blood, but the outer shell stays intact.

In a fracture the bone is broken through its surface. Around the knee this may be a tibial plateau fracture, a kneecap fracture or a small piece pulled off by a ligament.

Bone bruise and fracture side by side

• Seen on X-ray: bone bruise no; fracture usually yes, sometimes only on CT
• Seen on MRI: bone bruise yes, as bright swelling in the bone; fracture yes, as a line through it
• Typical cause: bone bruise from impact or from the bones knocking together when the ACL tears; fracture from a fall, car accident or high-energy blow
• Weight bearing: bone bruise usually allowed as pain permits; fracture often restricted for weeks
• Treatment: bone bruise protected activity and time; fracture a brace, cast or surgery depending on displacement
• Recovery: bone bruise often weeks to a few months; fracture usually longer, with follow-up X-rays

Why a bone bruise is a clue

The position of a bone bruise often tells the surgeon what happened. A typical pattern on the outer side of the knee strongly suggests an ACL tear, even if the ligament is hard to see. So a report saying only a bone bruise should still be read with the examination, to make sure a ligament or meniscus injury is not missed.

When to see a knee surgeon in Doha

Seek urgent care if you cannot bear weight, the knee looks deformed, or swelling is severe after a fall or accident. Book an assessment if a bone bruise is still painful after six to eight weeks, or if the knee also feels unstable. At Aman Hospital, Dr. Gelber reviews the MRI and X-rays together and advises how much load the bone can take.