Abstract
Medial meniscus posterior root tears (MMPRTs) are a significant source of pain and
dysfunction. The purpose of this study was to evaluate changes in the medial compartment
of the knee over time following the diagnosis of a MMPRT on MRI. A retrospective review
of the institutional database was performed for patients with an initial MRI diagnosis
of a MMPRT. Patients were included if they had a subsequent follow-up MRI on the same
knee. Patients with surgical intervention, including debridement or repair, were excluded.
MRIs were evaluated by two board-certified musculoskeletal radiologists. MMPRTs were
defined using the LaPrade classification, and the medial compartment articular cartilage
was graded using the modified Outerbridge classification. MRIs were reviewed for meniscus
extrusion, subchondral bone edema, and insufficiency fractures. Patients were divided
into two groups for the analysis to account for differences in MRI time intervals.
Group 1 had a follow-up MRI within 12 months of initial imaging (subacute group) and
Group 2 had a follow-up MRI greater than 12 months after initial imaging (chronic
group). Forty-one knees and 82 MRIs were analyzed, including 20 knees/40 MRIs (13
females, 7 males) in the subacute group and 21 knees/42 MRIs (14 females, 7 males)
in the chronic group. Subacute patients had a mean age of 59.5 ± 8.8 years and a mean
interval of 4.8 ± 2.6 months between MRIs compared with 53.6 ± 11.0 years and 38.2 ± 20.8
months, respectively, for the chronic group. Meniscal extrusion, femoral modified
Outerbridge grade, and tibial modified Outerbridge grade worsened between initial
and final MRI in both groups (p < 0.05). In both groups, there were no significant differences between initial and
final MRIs with regard to the LaPrade classification, insufficiency fracture, or subchondral
cysts of the tibia. Progressive meniscus extrusion and medial compartment articular
cartilage degeneration were seen in patients with MMPRTs within a year from diagnosis.
Keywords
medial meniscus posterior root tear - meniscus - root tear
