Wk 4, Case 5 - Review

Patient History
14-year-old with anterior knee pain and swelling after a football injury.

Findings
Menisci:

Medial Meniscus: Intact.

Lateral Meniscus: Intact.

Ligaments:

Anterior Cruciate Ligament: Intact.

Posterior Cruciate Ligament: Intact.

Medial Collateral Ligament: Slightly thickened, contused proximal tibial collateral ligament associated with subtle periligamentous edema/contusion.

Lateral Collateral Ligament: Thickened proximal fibular collateral ligament associated with periligamentous edema, consistent with low-grade sprain.

Posterolateral Corner Structures: Diffuse swelling of the arcuate ligament, associated with periligamentous edema, consistent with low-grade sprain. Diffuse moderate edema surrounding the popliteus myotendinous unit without macro tear or fiber waviness, consistent with a low grade (grade 1) myotendinous strain. Popliteofibular ligament intact but mildly swollen. Popliteal fascicles intact.

Posteromedial Corner Structures: Intact.

Extensor Mechanism:

Patellar Tendon: Intact.

Distal Quadriceps Tendon: Intact.

Medial Patellofemoral Ligament: Diffusely stretched, likely due to large knee joint effusion/arthrosis, but intact.

Medial and Lateral Patellar Retinacula: Diffusely stretched bilaterally is due to large hemarthrosis.

Hoffa Fat Pad: Mildly thickened infrapatellar plica. Otherwise unremarkable.

Articulations:

Patellofemoral Compartment: Low-grade trochlear dysplasia with trochlear sulcus insufficiency (Dejour A). Slightly lateralized patella could be attributed to the large hemarthrosis versus patellofemoral ligament injury. Borderline TT-TG distance measuring 1.5 cm. Incidental chronic, lateral, peripherally sclerotic, trochlear osteochondritis dissecans, measuring 2.4 x 1.2 cm diameter and 0.6 cm in depth. Overlying cartilage intact but demonstrates low-grade chondromalacia. No hyperintense fluid cleft to suggest potentially unstable fragment. No displaced fragment.

Medial Compartment: Normal.

Lateral Compartment: Normal.

General:

Bones: Diffuse direct medullary(enchondral) bone impaction fracture involving the medial aspect of the medial femoral epicondyle with associated high-grade confluent osteoedema/contusion extending through the medial femoral condyle epiphysis and metaphysis. No cortical depression.

Further subcortical contusion with osteoedema is noted at the posterolateral aspect of the medial femoral condyle.

Low-grade osteoedema consistent with contusion involving the inferior posterior margin of the lateral tibial epiphysis supporting a varus mechanism of injury.

Incidental note is made of mild lateral femoral condylar dysplasia, in addition to trochlear dysplasia.

Effusion: Large suprapatellar effusion/hemarthrosis with reactive capsular synovitis.

Baker’s Cyst: None.

Loose Bodies: None.

Soft tissue and Neurovascular: Unremarkable.

Conclusion
Evidence for recent varus mechanism of injury with medial impaction and the following findings:

1.Extensive direct impaction fracture of the medial femoral epicondyle with osteoedema extending to involve the medial femoral epiphysis and metaphysis.
2.Low-grade posterolateral corner sprain involving the arcuate ligament, popliteus myotendinous unit, popliteofibular ligament and proximal fibular collateral ligament. No high-grade injury, disruption or evidence for posterolateral instability.
3.Large knee joint effusion/hemarthrosis.
4.Incidental unrelated chronic anterolateral trochlear osteochondritis dissecans on a background of trochlear and lateral femoral condyle dysplasia. No evidence for unstable or displaced fragment.