Age / Sex : 54 / M

Chief complaint : knee pain for 8 months (exacerbated during deep flexion)

What is your diagnosis?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy : 이재혁(Yi Jaehyuck) 계명대동산병원(KEIMYUNG UNIVERSITY DONGSAN HOSPITAL)

Lateral meniscus posterior root tear (with meniscofemoral ligament tear)

Discussion

Findings

Marginal blurring & T2 hyperintensity of LMPR & MFL

Discussion

• Lateral meniscus posterior root tear (LMPRT)

  - usually traumatic & associated with ACL injury (7–12% of patients with ACL injury); only 0.8% isolated injury

    * cf. medial meniscus posterior root injury: mainly degenerative

  - Meniscofemoral ligament (MFL): significant role (+) in load transmission of the lateral femorotibial compartment

  - if complete tear of LMPR (+),↑lateral compartment peak contact pressure by a mean of 43 % & ↓ maximum lateral compartment contact area by a mena of 47%

• Arthroscopic classification of LMPRT (Forkel and Petersenet. 2012)

  - type 1: avulsion of the root with an intact meniscofemoral ligament (MFL)

  - type 2: radial tear of the root with an intact MFL

  - type 3: root avulsion or radial tear with rupture or absence of the MFL

• MRI findings

  - ‘ghost meniscus sign’ on sagittal fluid-sensitive images

  - LM extrusion: relatively infrequent (more frequent in patients with MFL tear)

1. Matthias J. Feucht et al. Knee Surg Sports Traumatol Arthrosc 2015;23:119–125


2. Andrew R. Palisch et al. RadioGraphics 2016;36:1792–1806