The Journal of Bone and Joint Surgery

Image Quiz

Identify These Injured Knee Structures—An MRI Quiz
(continued)

Answers

For larger view place cursor on image

Fig. 7

Fig. 35

Anterior cruciate ligament (Figs. 7 and 35): Evaluation of the anterior cruciate ligament is one of the primary indications for magnetic resonance imaging of the knee. It is important to know the primary and secondary signs of an anterior cruciate tear (Table V).

Table V. Anterior Cruciate Ligament Tears
Primary Signs of Tear
Nonvisualization of ligament
Complete disruption of a ligament segment
Abnormal signal within ligament
Alteration of normal linear configuration of ligament
Alteration of normal ligament orientation nearly parallel or at acute angle to notch roof
Secondary Signs of Tear
Bone contusions
Deepening of lateral femoral condyle notch or sulcus
Anterior translation of tibia >5 mm from posterior margin of femoral condyle
Buckling of posterior cruciate ligament
Posterior displacement of posterior horn of lateral meniscus

Fig. 36

Fig. 37

Posterior cruciate ligament (Figs. 36 and 37): The posterior cruciate ligament is seen well on sagittal T1-weighted and T2-weighted images. Magnetic resonance imaging allows evaluation of both sprains and tears of the posterior cruciate ligament^15-17.

Fig. 38

Fig. 39

Fig. 40

Fig. 41

Fig. 42

Fig. 43

Collateral ligaments (Figs. 38, 39, 40, and 41): The collateral ligaments are best seen on coronal T1-weighted and T2-weighted images. Increased signal intensity on T2-weighted images is compatible with edema and indicates the acuteness of the injury. T1-weighted images can be used to follow the contour of the ligaments and to differentiate a ligamentous sprain from a complete (grade-III) tear (Table VI).

Table VI. Collateral Ligament Tears
Grade	Pathological Findings
I	Periligamentous edema; ligament grossly intact
II	Partial tear with edema
III	Complete tear

Reference

1. Khanna AJ, Cosgarea AJ, Mont MA, Andres BM, Domb BG, Evans PJ, Bluemke DA, Frassica FJ. Magnetic resonance imaging of the knee. Current techniques and spectrum of disease. J Bone Joint Surg Am. 2001;83(Suppl 2, Pt 2):128-41.