Age / Sex : 19 / M

Age / Sex: 19/M

Chief complaint: Left knee pain, especially during hyperextension.

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

* Send Application Answers to In Sook Lee, MD ([email protected])

Courtesy : Lee Guen Young/ Kim Baek Hyun, Korea University Ansan Hospital

Anterior meniscofemoral ligament of medial meniscus (anteromedial meniscofemoral ligament).

Discussion

Findings:

MRI: Linear dark SI band is seen at intercondylar notch, parallel to ACL on T2-weighted fat-supressed sagital image. It arises from anterior horn of medial meniscus and runs in intercondylar notch on sequential proton-density coronal and axial images. It attaches to medial cortex of lateral femoral condyle, just anterior to the ACL.

Differential Diagnosis: (1) displaced meniscal fragment

                      (2) Intact ACL

Diagnosis: Anterior meniscofemoral ligament of medial meniscus (anteromedial meniscofemoral ligament).

Discussion: Anomalous insertion of the anterior horn of the medial meniscus (without attachment to the tibial plateau) is rare. Some types of this anomalous insertion (for example, the anterior horn of the medial meniscus arises from ACL or transverse ligament) were reported previously. Anterior meniscofemoral ligament of medial meniscus is the rarest form of the anomalous insertion (Anderson et al. reported the incidence as 0.44% during 10 years after 2745 knee arthroscopies). Clinical significance and treatment of this lesion have been still controversial: some authors suggested that this lesion was related to knee pain and many patients were relieved after resection, but the others disagreed to that. According to previous reports, anterior meniscofemoral ligament of medial meniscus was detected in retrospective review after arthroscopy, so the radiologists should know about this lesion and try to see this anomalous insertion.

References:

(1) Soejima T, et al. Anteromedial meniscofemoral ligament. Arthroscopy 2003;19:90-5.

(2) Anderson AF, et al. The anterior meniscofemoral ligament of the medial meniscus: case series. Am J Sports Med 2004;32:1035-40.

(3) Nakajima T, et al. Symptomatic anomalous insertion of the medial meniscus. Arthroscopy 2005;21:629.