Are MR imaging signs of meniscocapsular separation valid?

Abstract

The PPV for the MR diagnosis of meniscocapsular separation is low; the reported MR signs correlate poorly with arthroscopic findings.

Normal and abnormal medial meniscocapsular structures: MR imaging and sonography in cadavers.

“…Although this finding may not be used when the fat layer between meniscus and MCL is absent, the fat layer is present in most cases along the anterior portion of the MCL and, in about half the cases, along the mid portion of the MCL. Another potential problem is that the outer meniscal margin as vi sualized on MR images may not correspond to the true margin of the meniscus as seen histo logically becausethe peripheral 10â€"30% of the meniscus usually has vascular penetration, whereas the inner portion is avascular [3,7,9]. Therefore, the MR appearance of the inner and outer zones of the meniscus may be quite dif ferent.…”

“…However, precise criteria for apply ing this sign have never been described. Rubin et al [3] reported that this sign is insensitive be cause displacements of up to 10 mm may be seen in the absence of meniscocapsular separa tion, whereas patients with meniscocapsular separation may not have any such displace ment. Our results support this finding because none of the cases with meniscocapsular separa tion showed any meniscal displacement.…”

“…Our results show that when no other causes such as bursitis are apparent, a distance greater than 2 mm should suggest the presence of a meniscocapsularseparation. Although tears of the meniscotibial and me rnscofemoralextensionsmay be associated with meniscocapsular separation, Rubin et al [3] re ported that they are not accurate as signs of me niscocapsular separation.We found that on conventional MR images, the MFE could be seen anteriorly (six of seven cases) but not along the mid portion of the MCL. However, after in traarticular administration of a contrast agent, the MFE was clearly seen along the anterior portion and mid portion of the MCL.…”

“…However, a recent report [3] suggests that these findings are not ac curate for diagnosis of meniscocapsular separa tion. The low accuracy is likely related in part to the limited understanding about the normal anatomy of this region as depicted on MR im ages.…”

Continuing education mri spectrum of medial collateral ligament injuries and pitfalls in diagnosis

“…16, 17). This could also be mistaken for evidence of an MCL sprain (10,11). Deeper involvement may include peripheral meniscal tears.…”