1. MedPix Medical Image Database COW - Case of the Week Case Contributor: David Victor Bode Affiliation: Uniformed Services University

2. MedPix No: 9126 - History Pt Demographics: Age = 22 y.o. Gender = man 22-year-old college football player clipped on left side during play. Downloaded by (-1)

3. MedPix No: 9126 - EXAM & LABS Exam revealed a grossly swollen and contused left knee associated with medial joint line tenderness, pain with valgus stress, and a positive Lachman test.

4. AP radiograph of the left knee Anterior-posterior radiograph of the left knee reveals a 5mm elliptical ossific fragment adjacent and distal to the lateral tibial cortex and plateau, respectively, consistent with a Segond fracture. Downloaded by (-1)

5. Lateral Left Knee The lateral view reveals marked effusion indicated by widened lucency superior to the patella. Downloaded by (-1)

6. Sagittal Proton Dense Fat Suppressed MRI Left Knee In the sagittal views of the proton dense fat suppressed MRI, increased signal intensity running from anterior to posterior is observed obliterating what should be the anterior cruciate ligament (ACL) in addition to the ACL itself lying parallel to the tibia plateau removed from its proximal insertion, all of which indicate a complete tear; there also appears to be increased signal at the medial lateral aspect of the lateral femoral condyle, in addition to the posterior lateral aspect of the tibia, representing bone contusions. Downloaded by (-1)

7. Proton-density with fat saturation sagittal oblique MR image of the left knee Proton-density with fat saturation sagittal oblique MR image of the left knee shows a complete tear of the anterior cruciate ligament (ACL) at its proximal attachment and increased signal intensity in the normal location of the ligament consistent with post- traumatic change. The fibers that lie parallel with the tibial plateau are consistent with the torn ACL. Downloaded by (-1)

8. T2-weighted with fat sat coronal MR image T2-weighted with fat sat coronal MR image shows both the ossific fragment adjacent and distal to the lateral tibial plateau and the lateral femoral bone contusion. Downloaded by (-1)

9. FINDINGS Anterior-posterior radiograph of the left knee reveals a 5mm elliptical ossific fragment adjacent and distal to the lateral tibial cortex and plateau, respectively, consistent with a Segond fracture. The lateral radiograph shows increased density in the region of the suprapatellar bursa consistent with a knee effusion. Proton-density with fat saturation sagittal oblique MR image of the left knee shows a complete tear of the anterior cruciate ligament (ACL) at its proximal attachment and increased signal intensity in the normal location of the ligament consistent with post-traumatic change. The fibers that lie parallel with the tibial plateau are consistent with the torn ACL. High-signal-intensity bone contusions are present in the mid-lateral femoral condyle and posterolateral tibial plateau.T2-weighted with fat sat coronal MR image shows both the ossific fragment adjacent and distal to the lateral tibial plateau and the and the femoral bone contusion. Both menisci, the collateral ligaments, and the posterior cruciate ligament were intact on other images not shown.

10. DIFFERENTIAL DIAGNOSIS What is your Differential Diagnosis? ACL Tear - Segond Fracture

11. Diagnosis: ACL tear with associated Segond Fracture and Kissing Contusions Dx Confirmed by: Clinical

12. DISCUSSION