Relationship between shaft bowing in the femur and tibia and bone mineral density in women with varus knee osteoarthritis

Abstract

s / Osteoarthritis and Cartilage 20 (2012) S54–S296 S219 Figure 3. Predicted versus true rotation for the 6 pelvises under study.Ă 433 RELATIONSHIP BETWEEN SHAFT BOWING IN THE FEMUR AND TIBIA AND BONE MINERAL DENSITY IN WOMEN WITH VARUS KNEE OSTEOARTHRITIS Y. Akamatsu , N. Mitsugi , H. Kobayashi , K. Kumagai , Y. Kusayama , T. Saito . Yokohama City Univ. Sch. of Med., Yokohama, Japan; Yokohama City Univ. Med. Ctr., Yokohama, Japan Purpose: Anterior and lateral shaft bowing of the femur and tibia in patients with varus knee osteoarthritis (OA) results in malalignment of the whole lower extremity, when the preoperative planning in total knee arthroplasty or high tibial osteotomy is performed on the knee radiograph. Previous studies reported that femoral shaft bowing in women was different from that in men. To our knowledge, no studies investigating the relationship between shaft bowing in the femur and tibia and bone mineral density (BMD) have been reported. We hypothesized that anterior and lateral shaft bowing in the femur and tibia was related with age, body mass index (BMI), and BMD in women with varus knee OA. The main aim of our study was to assess the relationship between anterior and lateral shaft bowing in the femur and tibia and BMD in women with varus knee OA. Methods: We enrolled 52 women between April 2010 and March 2011 at our institution. All patients had symptomatic primary varus knee OA. Anteroposterior and lateral whole leg radiographs were taken with the patients in a standing position. Femoral and tibial shaft was divided into five equal parts. In the coronal and sagittal planes, anterior and lateral shaft bowing of the femur and tibia were defined as the angulations between midlines drawn in the second and forth parts from the proximal femur and tibia. The Kellgren and Lawrence grades were grade 2 in 3 knees, grade 3 in 7 knees, and grade 4 in 42 knees. Limb alignment was expressed as the femorotibial angle (FTA) obtained from the anteroposterior radiograph. BMD values were measured in L2-L4 vertebrae and the femoral neck using a QDR-4500 (Hologic Inc., Bedford, MA, USA). The lumbar spine and femoral neck BMDs were analyzed using standard software. BMI was calculated as an index of obesity. Data are expressed as means and standard deviation. Significance was set at p < 0.05. We used Pearson's correlation coefficients to investigate the relationship between two continuous variables (bowing, age, BMI, and BMDs). Results: Mean age and BMI were 72.4 8.9 years and 26.6 4.4 kg/m2, respectively. Mean FTA was 183.6 3.4 degree. Anterior femoral Anterior and lateral bowing in the femoral and tibial shaft and multivariate factors. Variables Anterior femoral bowing Lateral femor Age 0.317 (p1⁄40.022) 0.156 (p1⁄40. Body mass index 0.109 (p1⁄40.442) 0.045 (p1⁄40.75 Lumbar spine BMD 0.160 (p1⁄40.258) 0.252 (p1⁄40. Femoral neck BMD 0.345 (p1⁄40.012) 0.076 (p1⁄40. shaft bowing was positively correlated with age and negatively correlated with femoral neck BMD (r 1⁄4 0.317, p 1⁄4 0.022, and r 1⁄4 0.345, p 1⁄4 0.012, respectively). Lateral femoral shaft bowing was not related with multivariate factors. Anterior tibial shaft bowing demonstrated a positive correlation with BMI (r 1⁄4 0.283, p 1⁄4 0.042). Lateral tibial shaft bowing was positively correlated with age and negatively correlated with femoral neck BMD (r 1⁄4 0.364, p 1⁄4 0.008, and r 1⁄4 0.293, p 1⁄4 0.035, respectively). Conclusions: Karakas and Harma stated that anterior femoral shaft bowing was related with age. Our results showed that anterior femoral shaft bowing was correlated with age and femoral neck BMD. Contrary to our expectation, lateral femoral shaft bowing was not related with femoral neck BMD. Only anterior tibial shaft bowing was affected by BMI. Also, the relationship between anterior tibial shaft bowing and lumbar spine BMD might be associated with degenerative changes of the lumbar spine. Lateral tibial shaft bowing was correlated with age and femoral neck BMD, although anterior tibial shaft bowing was not related with femoral neck BMD. In Japanese, these results in the tibia might be associated with congenital tibia vara. The results from our small number of patients should be considered preliminary. However, if shaft bowing in the femur and tibia were related with BMD, the use of medication for osteoporosis might be a proper conservative approach to treatment. 434 DOES ANKLE CARTILAGE ADAPT TO STRONG ALTERATIONS IN LOADING ENVIRONMENT AFTER TRANSPLANTATION TO THE KNEE (VAN NEES ROTATIONPLASTY)? S. Maschek , F. Eckstein , W. Wirth , G. Gradl , C. Kirchhoff , K. Wortler , R. von Eisenhart-Rothe . 1 Paracelsus Med. Univ., Salzburg, Austria; Chondrometrics GmbH, Ainring, Germany; 3 Technical Univ.,