Knee – ACL tear

CASE HISTORY

14-year-old male with left knee pain for about one week with the majority of the pain being lateral. Patient had a football injury. No history of surgery.

TECHNICAL FACTORS

Long- and short-axis fat- and water-weighted images were performed.

KEY IMAGES

CASE FINDINGS

Patellofemoral joint alignment demonstrates mild lateral patellar tilt with a thinned attenuated medial patellofemoral ligament with partial-thickness tearing at its insertion upon the patella and at its origin from the medial femoral condyle. No substantive patellofemoral chondromalacia. Quadriceps and patellar tendons are intact. Moderate-sized joint effusion mildly complex likely reflecting a component of hemarthrosis. No Baker’s cyst.
 
Near full-thickness tearing of the medial collateral ligament proper. Partial-thickness tear of the meniscofemoral attachment. Prominent edema and hemorrhage are noted surrounding the medial collateral ligament complex. Partial-thickness tearing of the fibular collateral ligament with surrounding edema consistent with a grade 2 LCL sprain. No evidence of macrofracture. Microtrabecular fracture along the lateral femoral sulcus with mild depression and along the posterolateral tibial plateau without substantive depression consistent with a pivot shift mechanism of injury. Mild edema along the tip of the fibula likely reflecting stress reaction from posterolateral corner injury. Vertical posterior 2cm meniscocapsular sprain posterolateral horn.
 
Full-thickness ACL rupture with surrounding edema and hemorrhage. PCL is intact.
 
No medial meniscal tear or discoid meniscus. No substantive medial compartment chondromalacia. No lateral meniscal tear or discoid meniscus. No substantive lateral compartment chondromalacia.
 
Prominent hemorrhage and edema noted extending along the popliteus tendon at the posterolateral corner. The superior and inferior popliteomeniscal fascicles are not well visualized and likely torn. Partial-thickness interstitial tearing of the popliteofibular ligament. Partial-thickness tearing of the arcuate ligament posteriorly. Tear of the lower meniscopopliteal segment.  

CASE CONCLUSION

• Full-thickness ACL tear with a pivot shift bone injury pattern along the lateral femoral sulcus and posterolateral tibial plateau with mild depression along the lateral femoral sulcus and subtle cortical irregularity along the posterior tibial plateau. Vertical posterior 2cm meniscocapsular sprain posterolateral horn.
• Grade 3 MCL sprain with infolding and corrugation of MCL fibers and grade 2 LCL sprain
• Injury of the posterolateral corner with partial-thickness tearing of the popliteofibular ligament and arcuate ligament with hemorrhage and edema extending into the popliteus hiatus and stress-related edema along the tip of the proximal fibula. Tear of the lower meniscopopliteal segment.  No fibular fracture.
• Thinning and attenuation of the medial patellofemoral ligament with partial-thickness tearing at its patellar and femoral insertions with mild lateral patellar tilt.
• Moderate-sized mildly complex joint effusion likely reflecting hemarthrosis.