Objective: To study the influence of aging, menopause and knee retrograde osteoarthritis on femoral neck strength (FS) and muscle force (MF) of women.
Methods: A total of 306 healthy women aged 15 - 74 were stratified according to age and menstruation status, among which 76 menopausal women suffered from knee osteoarthritis. The bone mineral density (BMD) of lumbar vertebrae (L2 - 4) and femoral neck was measured by DEXA among all subjects. The FS and MF were measured by the Mobility Evaluation System (MES).
Results: (1) Influence of aging: FS and MF were at the peak in the group aged 15 - 19 and then decreased with the increase of age. Comparing with those in 15 -19 age group, the FS and MF values of the group aged 60 -74 decreased by 26.2% and 46.9% with the annual decrease rates of 0.55% and 0.99% respectively. (2) Influence of menopause: In the group aged 40 - 55, the FS and MF values of the postmenopausal ones were 9.4% and 21.7% lower than those in the women with normal menstruation respectively. ( 3) Influence of osteoarthritis: The women with knee osteoarthritis had lower FS and MF than those with normal knees; however, only the difference in MF was statistically significant (t = 5.33, P < 0.001). (4) Multiple regression suggested that MF and femoral neck BMD have positive correlation with FS, whereas age and BMI have negative correlation with FS.
Conclusion: FS and MF decrease annually with the increase of age and such decrease, especially that of MF, is aggravated with the onset of menopause. The menopausal women with knee osteoarthritis have lower FS and MF in comparison with normal controls. It is critical to maintain muscle mass and to enhance muscle force for the prevention and treatment of knee retrograde osteoarthritis.