Deep lateral notch sign and double notch sign in complete tears of the anterior cruciate ligament: MR imaging evaluation.

OBJECTIVE: To systematically compare the notches of the lateral femoral condyle (LFC) in patients with and without complete tears of the anterior cruciate ligament (ACL) in MR studies by (1) evaluating the dimensions of the lateral condylopatellar sulcus; (2) evaluating the presence and appearance of an extra or a double notch and its association with such tears. MATERIALS AND METHODS: This retrospective study was approved by our institutional review board, and informed written patient consent was waived. In 58 cases of complete ACL tears and 37 control cases with intact ACL, the number of notches on the LFC was determined, and the depth and anteroposterior (AP) length of each notch were measured in each third of the LFC. The chi-square test, t-test, and logistic regression model were used to analyze demographic data and image findings, as appropriate. RESULTS: Presence of more than one notch demonstrated a sensitivity of 17.2%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 43.5% for detecting a complete ACL tear. Lateral third depth measurement (p = 0.028) was a significant associated finding with a complete ACL tear. CONCLUSION: A deep notch in the lateral third of the LFC is a significant associated finding with a complete ACL tear when compared with an ACL-intact control group, and the presence of more than one notch is a specific but insensitive sign of such a tear.

Anatomic features of metatarsal heads that simulate erosive disease: cadaveric study using CT, radiography, and dissection with special emphasis on cross-sectional characterization of osseous anatomy.

OBJECTIVE: The purpose of our study was to characterize and describe normal osseous contours of the metatarsal heads that may simulate erosive changes. MATERIALS AND METHODS: CT of the metatarsal heads was performed in six human cadaveric feet, and 3D reformatted images were analyzed. Subsequently, five feet were sectioned in planes corresponding to those at imaging for anatomic correlation, and one foot was anatomically dissected for correlation. The normal anatomic osseous contours of the metatarsal heads were analyzed and described. RESULTS: Normal osseous anatomy of the greater (first) and lesser (second through fifth) metatarsal heads was identified. The normal osseous landmarks that simulate erosive changes were identified. Variations in the normal anatomic osseous contours, including those related to the medial and lateral condyles, were present in all specimens. The lateral condyle of the first metatarsal head was found to be more prominent than the medial condyle. In addition, anatomic variations in the normal osseous concavities of the lateral and medial aspects of each metatarsal head were measured. An intersesamoidal ridge, present on the plantar surface of the first metatarsal head, was identified in all specimens. CONCLUSION: The normal anatomic contours of the metatarsal head are a potential major source for diagnostic error when viewing sectional CT and MR images in patients with suspected erosive arthritis. These normal variations, although common and varied, produce characteristic findings that can be differentiated from bone erosions.