Wk 1, Case 4, Knee MR - Review

Patient History
11-year-old female complaining of posterior swelling and pain since twisting injury one week ago.

Findings

Cruciate ligaments: The ACL and PCL are intact.

Bones: Complex, thin and delicate multidirectional fracture coursing through the distal femoral metaphysis, along the medial and lateral aspects of the growth plate down to the epiphysis without intraarticular extension into the tibiofemoral compartments; focal cortical breakthrough along the femoral abductor tubercle with disruption and elevation of the overlying periosteum,large subperiosteal hematoma located at the posterolateral femoral metaphysis cortex which extends for a length of 5.1cm and measures 2.6 cm x 4cm in anteroposterior and transverse dimensions, respectively.

Also, nondisplaced spiral fracture that involves the proximal fibular epiphysis and styloid extending downward to involve the growth plate. Cortical breakthrough anterior and posteriorly with a posterolateral metaphyseal subperiosteal hematoma extending for about 3.5cm in craniocaudal length and measuring 1.9cm x 2.5cm anteroposteriorly and in transverse dimensions, respectively.

Medial Compartment: No osteochondral injuries or penetrating chondromalacia. Intact meniscus. Medial collateral ligament is intact.

Lateral Compartment: No osteochondral injuries or penetrating chondromalacia. No meniscal tears. High-grade sprains of the arcuate ligament, the popliteofibular ligament and fibular collateral ligament. The biceps femoris attachment remains intact.

Anterior Compartment: No patellofemoral dysplasia. Mildly depressed, nondisplaced, shouldered contusional osteochondral fracture of the medial trochlea. The medial patellofemoral ligament and lateral patellar retinaculum are intact.

General: Moderate joint effusion/hemarthrosis without internal debris or free bodies.

Diffuse periarticular soft tissue swelling.

Focal periosteal rupture of the posterolateral tibial metaphysis more conspicuous adjacent to the abductor tubercle associated with an ill-defined intramedullary collection measuring 3.4cm x 2.3cm x 2.3cm (AP, transverse and CC) that abuts the descending biceps femoris.

Extensor Compartment: Normal.

Flexor Compartment: Flexor muscles and neurovascular bundle are intact.

Impressions

1. Right knee twisting injury with the following remarkable findings.

2. Complex multidirectional fracture coursing through the distal femoral metaphysis, the medial and lateral aspects of the growth plate into the femoral condyles without intraarticular extension consistent with a Salter-Harris type 4 injury.

3. Large subperiosteal hematoma measuring 2.6cm x 4cm x 5.1cm extending along the posterolateral tibial metaphysis at the level of the femoral abductor tubercle extending into the soft tissues with an ill-defined organizing intramedullary collection measuring 3.4cm x 2.3cm x 2.3cm that abuts the descending biceps femoris. This might represent either an organizing abscess or an hematoma.

4. Nondisplaced spiral fracture involving the proximal fibular epiphysis and styloid extending downward to involve the growth plate in keeping with a Salter-Harris type 3 injury. Cortical breakthrough anterior and posteriorly with a posterolateral metaphyseal subperiosteal hematoma extending for about 3.5cm in craniocaudal length and measuring 1.9cm x 2.5cm anteroposteriorly and transverse dimensions.

5. Posterolateral corner injury with high-grade sprain of the arcuate ligament, the popliteofibular ligament and fibular collateral ligament.

6. Mildly depressed, nondisplaced, shouldered osteochondral fracture of the medial trochlea.

7. Moderate joint effusion/hemarthrosis.