Characteristics

• Common finding on MRI scans of post-traumatic joints – particularly the knee with ligament injury, e.g. in the lateral femoral condyle in ACL deficiency and posterolateral tibial plateau bruising is a marker of joint derangement at the time of ACL injury.

• Also known as marrow oedema syndrome and microfracture syndrome.

• Numerous patterns of bruising identified.

• Most commonly affects the lateral femoral condyle.

• May represent damage to the articular cartilage at the time of injury – hence the use of the term ‘microfracture’.

Clinical features

• Symptoms often related to the underlying ligamentous disruption – see ‘Knee injuries’.

• Bony pain and tenderness often related to the underlying bone bruising.

• Lasts up to 12 months frequently becoming more pronounced at 6–12 weeks following injury.

• Long-term outcome is unknown.

Radiological features

• Usually normal AP and lateral knee X-ray – occasionally an avulsion fracture of the lateral tibial plateau, at the site of attachment of the lateral capsular ligament, is seen; this is known as a Segond fracture and is frequently associated with an ACL injury.

• Bone bruising is manifest as high signal intensity on T2 weighting and STIR MRI.

• MRI: assess for ligamentous and meniscal pathology.

Management

• Treat as per the underlying ligamentous injury.

• Possibly restrict weight bearing.

• Persistent pain may require analgesia, e.g. after an MCL injury has settled down.