Location

Knee

Diagnosis

ACL tear – Segond fracture

Discussion

Frontal radiographs of the knee reveal a small fleck of bone adjacent to the lateral aspect of the lateral tibial plateau. This “lateral capsular sign” is a simple radiographic finding visible on the routine AP knee x-ray, indicating severe lateral capsular injury and alerting the examiner to the possibility of ACL tear. The fleck of bone represents an avulsion of the meniscotibial portion of the middle one-third of the lateral capsular ligament. It most commonly implies a disruption of the capsular ligament and the ACL. (MRI, Figure A, confirms diagnosis of ACL tear, as indicated on radiographs, Figures B,C).

Reference

Woods GW, Stanley RF, Tullos HS: Lateral capsular sign: X-ray clue to significant knee instability. Am J Sport Med 1979; 7:27-33.

Figures

Click thumbnail for larger image

Attachments:


kneesegundacltearmr.jpg (image/jpeg)


kneesegund2a.jpg (image/jpeg)


kneesegund2.jpg (image/jpeg)