Bone contusion (bone bruise) is a pathologic condition characterized by microtrabecular damage and edema in bone marrow resulting from trauma. It is invisible on radiographs — MRI is the specific diagnostic tool. It appears as hyperintense signal increase in bone marrow on STIR or T2 fat-suppressed sequences. Bone contusions are usually found with ligament injuries, meniscal tears, and chondral lesions, showing specific patterns reflecting injury mechanism: pivot-shift pattern (ACL tear — posterolateral tibial plateau + anterolateral femoral condyle), dashboard pattern (PCL tear — anterior proximal tibia), clip/valgus pattern (MCL injury — lateral compartment kissing contusion), hyperextension pattern (anterior tibial plateau + anterior femoral condyle). Bone contusion itself usually resolves in 6-12 weeks but detecting accompanying structural injuries is critical.
Age Range
10-60
Peak Age
25
Gender
Male predominant
Prevalence
Very Common
Bone contusion results from traumatic forces causing micro-level damage to trabecular bone structure. Trabecular microfractures, intramedullary vascular damage, and interstitial hemorrhage/edema occur together. Damage severity forms a spectrum: mild contusion with only interstitial edema, moderate with trabecular microfractures + edema, severe with subchondral depression fracture (surface collapse). Contusion patterns directly reflect injury mechanism because bone marrow edema forms where force is applied: in impaction contusion two opposing joint surfaces impact each other (kissing contusion), in compressive contusion force is applied perpendicular to joint surface, in distraction/avulsion contusion ligament traction force creates edema at bone surface. The pathophysiological basis of bone marrow edema appearing bright on STIR/T2 fat-sat is interstitial edema fluid filling bone marrow spaces after trauma. In normal bone marrow, fat cells are dominant giving bright T1 signal with short T1. Edema fluid (free water) seeping between fat cells after trauma produces bright signal on T2 with long T2 relaxation time. Fat suppression removes normal fat signal making edema visible with contrast enhancement. Bone contusion is invisible on radiographs because trabecular damage is at a micro level insufficient to change the overall density of mineralized bone structure — no macroscopic cortical fracture exists.
On STIR/T2 fat-sat MRI, specific localization patterns of bone contusions directly reflecting injury mechanism. Pivot-shift pattern (posterolateral tibial plateau + anterolateral femoral condyle) predicts ACL tear, dashboard pattern (anterior proximal tibia) predicts PCL tear, kissing pattern (lateral compartment opposing edema) predicts MCL/valgus injury, hyperextension pattern (anterior tibial plateau + anterior femoral condyle) predicts hyperextension injury. These patterns significantly increase the diagnostic value of bone contusion — recognizing the contusion pattern enables targeted search for associated ligament injury.
On STIR sequences, focal or geographic pattern hyperintense signal increase is seen in bone marrow. Edema is concentrated in the subchondral region and does not cross cortical bone boundaries. In pivot-shift pattern, edema in posterolateral tibial plateau and anterolateral femoral condyle; in dashboard pattern, anterior proximal tibia; in kissing pattern, symmetric edema in opposing femoral condyle and tibial plateau. Edema size is proportional to trauma severity.
Report Sentence
Subchondral bone marrow edema is seen in ___ on STIR sequences, consistent with traumatic bone contusion.
On T2 fat-sat sequences, subchondral bone marrow edema is seen in posterolateral tibial plateau and anterolateral-to-mid lateral femoral condyle. This specific localization reflects impaction of lateral femoral condyle against posterolateral tibial plateau during ACL tear. Pivot-shift contusion pattern has >90% specificity for ACL tear. Edema depth and extent is proportional to trauma severity.
Report Sentence
Bone marrow edema consistent with pivot-shift contusion pattern is seen in posterolateral tibial plateau and anterolateral femoral condyle, associated with ACL tear.
On T1-weighted sequences, normal high-signal bone marrow fat is replaced by focal low signal area in the bone contusion region. This finding reflects displacement of fat cells by interstitial edema. The combination of T1 low signal and T2/STIR hyperintense signal is characteristic of bone contusion and helps differentiate from neoplastic infiltration or infection (clinical context important).
Report Sentence
Focal loss of normal bone marrow signal in ___ region on T1-weighted sequences is seen, consistent with bone contusion in conjunction with hyperintense edema on T2/STIR.
On T2 fat-sat sequences, bone marrow edema is seen in the proximal anterior tibia. This pattern reflects the dashboard injury mechanism in PCL tear — direct impact to anterior tibial surface. Dashboard contusion has different localization from pivot-shift pattern and is a specific secondary finding for PCL tear.
Report Sentence
Bone marrow edema consistent with dashboard contusion pattern is seen in the anterior proximal tibia, supporting PCL injury mechanism.
On T2 fat-sat sequences, opposing (kissing) subchondral bone marrow edema is seen in lateral femoral condyle and lateral tibial plateau. This pattern reflects valgus stress mechanism (MCL injury) — showing compression of opposing joint surfaces in the lateral compartment. MCL injury and possible meniscal pathology on the medial side may accompany.
Report Sentence
Kissing contusion pattern bone marrow edema in the lateral femoral condyle and lateral tibial plateau is seen, reflecting valgus stress mechanism.
Criteria
Posterolateral tibial plateau + anterolateral femoral condyle bone edema
Distinct Features
90%+ association with ACL tear, non-contact pivot/deceleration mechanism, lateral meniscus tear frequently accompanies
Criteria
Anterior proximal tibia bone edema
Distinct Features
Associated with PCL tear, motor vehicle accident or fall on knee, posterior instability
Criteria
Opposing femoral condyle + tibial plateau symmetric bone edema
Distinct Features
Associated with MCL/valgus injury, direct blow from lateral side, high chondral damage risk
Distinguishing Feature
ACL tear is ligament pathology; bone contusion is bone marrow pathology — however pivot-shift contusion pattern specifically predicts ACL tear
Distinguishing Feature
Chondral lesion is cartilage surface damage; bone contusion is bone marrow edema under cartilage — severe contusion and chondral damage may coexist
Distinguishing Feature
MCL injury is extra-articular ligament pathology; kissing contusion pattern is the bone marrow correlate of MCL injury mechanism
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
3-monthIsolated bone contusion generally heals in 6-12 weeks with conservative treatment — pain management (NSAIDs, analgesia), activity modification, and gradual load increase. What is critical is not the contusion itself but detecting and treating accompanying structural injuries (ACL, PCL, MCL, meniscus, cartilage). Recognizing the contusion pattern enables targeted search for associated pathology. Subchondral depression fracture (severe contusion) heals more slowly with higher chondral damage risk — long-term follow-up may be needed. Return to sport should be planned after edema resolution is confirmed with follow-up MRI.
Bone contusions are usually self-limiting and resolve within 6-12 weeks. Their clinical significance lies in indicating associated structural damage (ACL/PCL/meniscus). The pivot shift contusion pattern is strong evidence for ACL tear. Severe contusions carry risk of progression to subchondral fracture and osteochondral damage.