Wk 2, Case 5, Knee MR - Review

Patient History

Hit in the knee playing football one week ago. Pain anterior and medial, swelling.

Findings

Cruciate ligaments: The ACL is torn at its midsubstance with a subtle passive anterior tibial translation. PCL is intact. No avulsion fractures.

Bones: Depressed osteochondral fracture of the lateral femoral condyle anterior weight-bearing surface at the level of the terminal sulcus.

Mildly depressed osteochondral fracture at the anterior and posterior weight-bearing surface of the lateral tibial rim.

Reactive osteoedema at the fibular styloid without avulsion fractures. No displaced fractures.

As incidental notice, a cortical-based well-circumscribed lobulated cystic-like structure at the posteromedial aspect of the proximal tibial metadiaphysis with a thin sclerotic rim and a narrow transition zone. No cortical breakthrough or periosteal reactions. Lesion measures up to 1.5cm in craniocaudal length. Findings are in keeping with a nonossifying fibroma (NOF).

Medial compartment: Thin and delicate full-depth vertical longitudinal tear along the meniscocapsular junction without proper meniscal tear in keeping with a ramp 1 lesion. Disruption of the meniscotibial and meniscofemoral ligaments. No osteochondral injuries. No osteoarthrosis or chondromalacia.

Full-thickness tears of the tibial collateral ligament at its origin on the femoral condyle and at its attachment on the tibial metadiaphysis.

Low-grade sprain at the origin of the medial patellofemoral ligament (MPFL) in the medial collateral ligament (MCL) without detachment, diffuse edema of the deep crural fascia and MCL bursitis. Also, mild reactive bursitis of the pes anserinus.

Lateral compartment: Thin and delicate vertical longitudinal tear along the Wrisberg ligament that extends along the posterior meniscal horn in keeping with a Wrisberg rip. No meniscal extrusion.

Full-thickness tears of the arcuate ligament, the fibular collateral ligament (FCL) biceps femoris and popliteofibular ligament (PFL) at the posterolateral corner associated with a high-grade sprain at the origin of the soleus muscle which contains a 1.1cm x 1cm x 0.7cm (AP, transverse and CC) intramuscular hematoma.

Anterior compartment: No patellofemoral dysplasia. No osteochondral defects, osteoarthrosis or chondromalacia. The lateral patellar retinaculum is intact. MPFL as described above.

Extensor compartment: Quadriceps and patellar tendons are normal.

Induration of the infrapatellar plica with linear edema in the Hoffa's fat pad which can be seen in maltracking.

Flexor compartment: Besides the lesions described above, no additional findings. The neurovascular bundle is intact.

Large joint effusion or hemarthrosis without internal debris or free bodies.

Diffuse periarticular soft tissue swelling.

Impressions

1. Right knee pivot shift injury with a completely torn ACL at its midsubstance with subtle passive anterior tibial translation.

2. Depressed osteochondral fractures of the terminal sulcus and outer aspect of the anterior and posterior lateral tibial plateau.

3. Wrisberg rip with a thin and delicate vertical longitudinal tear along the Wrisberg ligament that extends along the posterior meniscal horn.

4. Posterolateral corner injury with full-thickness tears of the arcuate ligament, FCL, biceps femoris and PFL associated with a proximal soleus high-grade sprain that contains a 1.1cm intramuscular hematoma.

5. Nondisplaced segond injury, series 401 images 18 and 19.

6. Ramp 1 lesion with disruption of the meniscotibial and meniscofemoral ligaments.

7. Grade 3 MCL sprain consisting of full-thickness tears of the proximal and distal tibial collateral ligament with low-grade sprain of the MPFL origin, MCL bursitis and mild reactive pes anserinus bursitis. Query whether distal MCL is entangled with the PES complex so-called knee pseudo-stener lesion.

8. Reactive osteoedema at the fibular styloid without avulsion fracture.

9. Large joint effusion or hemarthrosis