The influence of osteoporosis on varus deformity of the knee

Abstract

Objective: Osteoporosis(OP) and osteoarthritis(OA) are the most common joint disorders affecting many people older than age 65. Varus deformity of the proximal tibia is seen in many patients with OA of knee. The aim of this study was to evaluate the influence of BMD on varus deformity of the knee. Method: We studied 59 patients(35 women and 24 men) with varus osteoarthritis of the knee to determine the influence of the BMD on varus deformity. BMD was measured in the L1-L4 spinal region using dual X-ray absorptiometry(DEXA). Standing anteroposterior(AP) radiographs were taken of each knees. Five angles were measured to assess the varus deformity of each knee: 1-femorotibial angle(FT), 2-femur condylar-femoral shaft (FC-FS) angle, 3-femur condylar-tibial plateau(FC-TP) angle, 4-tibial plateau-tibial shaft (TP-TS) angle, 5-medial tibial plateau varus(MTPV) angle. The knee radiographs were graded according to the Kellgren and Lawrence radiographic criteria. Results: There were no significant differences in the FT, FC-FS, FC-TP, TP-TS, MTPV angles between the genders. We found a lower BMD was associated with less MTPV angle. A positive correlation was noted between the MTPV and BMD. We also found significant relationship between BMD and radiographic stage of the knee OA. Conclusion: Our results suggest a lower BMD predisposes to trabecular microfractures and is an important factor for development and aggrevation of varus deformity of proximal tibia.