The synovit-rim of the anterior horn of the meniscus is a sign of an acl-lesion.

Synovitis of the centripitale part of the anterior horn on the mediale meniscus is a well known phenomenon observed in a large number of knee arthroscopies.
The phenomenon is apparent either by a slight synovial rim along the centripitale part of the meniscus or a total coverage of the anterior horns. The Synovial rim with mediale menisks anterior horn is seen in all complete cases and in some where the partial acl rupture is large.
The purpose of this study is to ascertain if there is a connection between the synovial overgrowth of the anterior horn of the meniscus and an acl-rupture.

Method and Material

From 1.1.98 to 31.12.98 all arthroscopies were classified according to whether they were soley acl lesions, acl-lesions combined with synovial over-growth or synovial overgrowth without accompanying acl-lesion. Arthroscopies were performed on 561 knees.
These were carried out by means of an infero-lateral entry using a Storz 30° optic with the occasional addition of a 70° optic.
Lidocain 1% without adrenalin and ca. 12ml. was used as infiltration anaestesia.
ACL lesion was tested with Lachmann test when acl was regarded directly. Too much movement was registrered. The anterior horn was inspected. Synovial rim was registrered.

Result:

8 knee has a synovial rim without visible acl lesion
11 knee has an acl lesion without visible synovial rim.
202 knee has a combination og acl lesion and synovial rim

Discussion:

Ebstrup & Bojsen-Møller descriebe femur-tibias relation in in- and out rotation. Also under stress in valgus/varus stress. They use the displacement of the hyperboloids axle to descriebe the condition.
Forced rotation or valgus/varus will give rise to a high stress, so an acl rupture will occur.
Two other condition under speed will occur.

a. Tibia and femur will be pressed neare another beceause of the force of paralellogram.

b. The rotation of the femur against tibia will continue after the rupture has occured.

c. The result of that will be that the anterior horn of the meniscus will be forced in between tibia and femur and a compression of the anterior horn is the result.

The result will be a meniscus lesion. It can range from a sligth synovial rim along the interior border to a total rupture of the horn.

Ohkoshi et al. Make a describsion of that, but do not combinate the lesion with an acl-lesion.
The synovial rim along the interior rim of the meniscus is therefore always a sign of an acl lession.