Factors associated with meniscal extrusion in knees with or at risk for osteoarthritis: the Multicenter Osteoarthritis study.
OBJECTIVE
To assess the associations of meniscal tears, knee mal-alignment, cartilage damage, knee effusion, and body mass index with meniscal extrusion.


METHODS
The Multicenter Osteoarthritis study is an observational study of individuals who have or are at risk for knee osteoarthritis (OA). The HIPAA-compliant protocol was approved by the institutional review boards of all participating centers, and written informed consent was obtained from all patients. All subjects with available baseline knee radiographs and magnetic resonance (MR) images were included. MR imaging assessment of meniscal morphologic characteristics, meniscal position, and cartilage morphologic characteristics with use of the Whole-Organ Magnetic Resonance Imaging Score system was performed by two musculoskeletal radiologists. Cross-sectional associations of severity of meniscal tears, knee malalignment, tibiofemoral cartilage damage, knee effusion, and body mass index with meniscal extrusion were assessed by using logistic regression, with multiadjustments when testing each predictor.


RESULTS
A total of 1527 subjects (2131 knees; 2116 medial and 2106 lateral menisci) were included. Medially, meniscal tears, varus malalignment, and cartilage damage were associated with meniscal extrusion, with odds ratios (ORs) of 6.3 (95% confidence interval [CI]: 5.0, 8.0), 1.3 (95% CI: 1.1, 1.7), and 1.8 (95% CI: 1.4, 2.2), respectively. Laterally, meniscal tears, valgus malalignment, and cartilage damage were associated with meniscal extrusion, with ORs of 10.3 (95% CI: 7.1, 14.9), 2.2 (95% CI: 1.5, 3.2), and 2.0 (95% CI: 1.3, 2.9), respectively.


CONCLUSIONS
Meniscal tears are not the only factors associated with meniscal extrusion; other factors include knee malalignment and cartilage damage. Meniscal extrusion is probably an effect of the complex interactions among joint tissues and mechanical stresses involved in the OA process.
Department of Radiology, Boston University School of Medicine, Boston, MA 02118, USA. micrema@bu.edu
Michel D
MD
Crema
Frank W
FW
Roemer
David T
DT
Felson
Martin
M
Englund
Ke
K
Wang
Mohamed
M
Jarraya
Michael C
MC
Nevitt
Monica D
MD
Marra
James C
JC
Torner
Cora E
CE
Lewis
Ali
A
Guermazi
D000368:Aged; D000407:Alabama; D018450:Disease Progression; D005260:Female; D006801:Humans; D007484:Iowa; D016015:Logistic Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008592:Menisci, Tibial / Q000000981:diagnostic imaging / Q000473:pathology*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011446:Prospective Studies; D011859:Radiography; D012307:Risk Factors; D012720:Severity of Illness Index