The Influence Of Osteoporosis On Varus Osteoarthritis Of The Knee

Objective: To investigate the effect of osteoporosis on varus osteoarthritis of the knee (KOA). Methods: 35 cases with varus osteoarthritis of the knee were diagnosed and treated in our department at the First Affiliated Hospital of Suzhou University from July 2007 to December 2008. Among them 15 were male, 20 were female, 23 were unilateral and 18 were bilateral. The average age of male was 64 (50 to78),while for female it was 65 (51 to 81);The shortest course of the disease was 1 year and the longest was 18 years, with an average of 8.6 years. The diagnostic criteria we have taken here was should be consistent with degenerative OA diagnosis and the Kellgren-Lawrence grade≥II. The exclusion criteria were: subjects with rheumatoid arthritis,post-traumatic arthritis, synovial osteochondromatosis secondary to osteoarthritis, recurrent patellar dislocation secondary to osteoarthritis, discoid cartilage secondary to osteoarthritis, etc. All subjects were diagnosed according to the osteoarthritis criteria which was recommended by The American Rheumatism Association and the osteoarthritis level was decided by the X-ray grading criteria pronounced by Kellgren and Lawrence. Subjects were on weight-bearing while anteroposterior knee radiography was performed. Separately measured femorotibial (FT) angle between the anatomical axis of the femur and that of the tibia; the femoral condylar-femoral shaft (FC-FS) angle between the anatomical axis of the femur and the tangent to the subchondral plate of the femoral condyles; the femoral condylar-tibial plateau (FC-TP) angle between the tangents to the subchondral plates of the femoral and tibial condyles; and the tibial plateau-tibial shaft (TP-TS) angle between the tangent to the subchondral plate of the tibia and the anatomical axis of the tibia and other related indicators. A dual-energy X-ray absorptiometry(DEXA), was carried out on subjects intertrochanteric femoral Ward's triangle bone as the mineral density scan, and the measurements of bone mineral density was recorded. Datas were analyzed using the Statistical Package for Social Sciences 13.0(SPSS 13.0). Results : The BMD of intertrochanteric femoral Ward's triangle bone and the BMD to BMI ratio were significantly larger in the men than in the women,There were no significant differences in the FT, FC-FS and the FC-TP angles between the genders, but the TP-TS and TP-TS/FT angles were significantly larger in the women, whereas the FC-TP/FT angle was greater in the men. Varus osteoarthritis of the knee in the men is mainly expressed in the joint space by the varus deformity, while in the women, it is reflected mainly in the proximal medial tibial plateau varus. Conclusion:Our results suggest that female subjects with lower bone mineral density may easily be susceptible to proximal tibial plateau fracture of the trabecular microstructure, thereby increasing the medial tibial plateau articular cartilage of the stress, resulting in the proximal tibial varus deformity; while in male ,because of increased bone mineral density can prevent tibial plateau proximal trabecular micro-fracture and collapse, therefore, the clinical results mainly by the joint space-based on varus alignment. However, reduced or increased bone density does not prevent knee osteoarthritis disease process itself.