Meniscal ramp lesions: an illustrated review

Abstract

The purpose of this review is to describe the anatomy and lesions affecting the peripheral portion of posterior horn of medial menisci (ramp lesions), along with illustrations and MRI cases. We will correlate imaging features with arthroscopic classification of ramp lesions. Also, postoperative and chronic changes related to meniscocapsular tears will be presented, as well as biomechanical consequences and treatment approach.

Keywords: ACL tear; Arthroscopy; MRI; Meniscus; Ramp lesion.

Fig. 1

Posterior medial meniscus anatomy, with its corresponding structures. In (a), an illustrated open view of the medial compartment of the knee, in (b), a zoomed view of the posteromedial capsular-meniscal unit, and in (c), the corresponding MRI appearance on sagittal PD-weighted fat suppressed: meniscocapsular ligament (thin arrow), meniscotibial ligament (curved arrow) and posterior capsular attachment (star)

Fig. 2

Type 1 ramp lesion illustration, defined as meniscocapsular ligament tear

Fig. 3

Type 1 meniscal ramp lesion MRI Case. Sagittal (a) and axial T2-weighted fat-suppressed images show meniscocapsular tear (arrow) with tibial bone bruise, and the extension of meniscocapsular junction edema (arrowheads)

Fig. 4

Type 2 meniscal ramp lesion illustration, defined as partial superior peripheral posterior meniscal horn tear

Fig. 5

Type 2 meniscal ramp lesion MRI Case. Sequential sagittal T2-weighted fat-suppressed MR images show peripheral partial tear of posterior horn of medial meniscus (arrows) affecting the femoral articular surface, along with meniscocapsular ligament tear

Fig. 6

Type 3A meniscal ramp lesion illustration, defined as partial inferior peripheral posterior horn meniscal tear

Fig. 7

Type 3A meniscal ramp lesion MRI Case. Sagittal T2-weighted fat-suppressed images show peripheral vertical partial tear (arrow in a) extending to the tibial surface of the posterior horn of medial meniscus, with intact meniscotibial ligament (arrowhead in b)

Fig. 8

Type 3B meniscal ramp lesion illustration, defined as a partial inferior tear affecting the meniscotibial ligament

Fig. 9

Type 3B meniscal ramp lesion MRI Case. Sagittal (a) and axial (b) T2-weighetd fat-suppressed images show peripheral partial vertical tear affecting the tibial surface of the posterior horn of medial meniscus (arrow), along with meniscotibial ligament tear (curved arrow) and bone bruise; extension of vertical tear is seen in (b) (arrowheads)

Fig. 10

Type 4A meniscal ramp lesion illustration, defined as complete peripheral posterior horn meniscal tear

Fig. 11

Type 4A meniscal ramp lesion MRI Case. Sagittal (a) and axial (b) T2-weighted fat-suppressed MR image shows a type IV ramp lesion, with tear extending from femoral to tibial articular surfaces (arrow); tear extension is seen in (b) (arrowheads)

Fig. 12

Type 4B meniscal ramp lesion illustration, defined as complete meniscocapsular junction tear

Fig. 13

Type 4B meniscal ramp lesion MRI case. Sagittal (a) T2-weighted fat-suppressed MR image shows a type IV ramp lesion, with a complete meniscocapsular disruption of the posterior horn of medial meniscus. Axial (b) image shows a cross-sectional view of the extensive meniscocapsular disruption

Fig. 14

Type 5 meniscal ramp lesion illustration, defined as peripheral posterior horn meniscal double tear

Fig. 15

Type 5 meniscal ramp lesion MRI case. Sagittal PD-weighted fat-suppressed MR image (a, left) shows a postoperative ACL graft tear (arrow), and sagittal T2-weighted fat-suppressed (b, right) shows a double vertical peripheral tear through the posterior horn of medial meniscus (thin arrows). *Case courtesy of Dr. Diego Lemos (USA)

Fig. 16

Arthroscopic images presents intra-articular diagnosis of a Type 4 ramp lesion through a posteromedial portal (a). An all-inside meniscal repair was performed (b and c). Final suture aspect is seen in (d). *Case courtesy of Dr. Luis. E. P. Tirico (Brazil)

Fig. 17

(a) Sagittal fat-suppressed MR image shows a type 4 acute ramp lesion (arrow) and in (b) the postoperative appearance after 4 months of surgery (arrow)

Fig. 18

Sagittal T2-weighted fat-suppressed MR image (a) shows a zip lesion, with a rip between Wrisberg ligament (curved arrow) and posterior horn of lateral meniscus. Axial T2-weighetd fat-suppressed MR image (b) shows the lesion in a cross-sectional view (arrowheads)

Fig. 19

Sagittal T2-weighted fat-suppressed MR image (a) shows a double delta sign (thin arrow), typical for flipped meniscus. Axial image (b) shows anterior dislocation of the posterior horn of lateral meniscus (thin arrow)

Fig. 20

Sagittal (a), coronal (b) and axial (c) T2-weighetd fat-suppressed MR images show “ghost sign” on posterior medial meniscal root attachment (thin arrows). Full-thickness tear of the posterior medial meniscus root is clearly demonstrated in (b) and (c)