A new accelerometer-based portable navigation system provides high accuracy of acetabular cup placement in total hip arthroplasty in both the lateral decubitus and supine positions.

INTRODUCTION: No studies have compared the accuracy of acetabular cup placement in total hip arthroplasty (THA) in the supine and lateral decubitus positions using the same portable navigation system. Thus, this study aimed to compare the accuracy of acetabular cup placement using a new accelerometer-based portable navigation system combined with an infrared stereo camera and inertial measurement unit between the supine and lateral decubitus positions. MATERIALS AND METHODS: This retrospective study compared 45 THAs performed in the supine position (supine group) and 44 THAs performed in the lateral decubitus position (lateral group) using the same portable navigation system. The primary outcome was the absolute errors of cup placement angles, defined as the absolute values of the differences between cup radiographic inclination and anteversion angles displayed on the navigation system and those measured on postoperative computed tomography images. RESULTS: No significant difference in the median absolute error of the cup inclination angle (supine group 1.7° [interquartile range 0.8°-3.1°] vs. lateral group 2.1° [interquartile range 1.0°-3.7°]; p = 0.07) was found between the two groups. Similarly, no significant difference in the median absolute error of the anteversion angle (supine group 1.9° [interquartile range 0.8°-3.4°] vs. lateral group 2.1° [interquartile range 0.9°-3.1°]; p = 0.42) was found. CONCLUSION: This new accelerometer-based portable navigation system may provide high accuracy of the cup placement in THA in the lateral decubitus and supine positions.

Fenofibrate induces PPARα and BMP2 expression to stimulate osteoblast differentiation.

The peroxisome proliferator-activated receptor (PPAR)-α agonist fenofibrate is used as a lipid-lowering agent to reduce cholesterol and triglyceride in blood. In this study, we investigated whether fenofibrate affects osteoblast differentiation of osteogenic precursor cells. Quantitative real-time PCR and alkaline phosphatase (ALP) staining assays revealed that fenofibrate can enhance the osteoblast differentiation of C3H10T1/2 and MC3T3-E1 cells. In contrast with fenofibrate, the PPARγ agonist rosiglitazone decreased or did not affect the expression of osteogenic genes in these cells. Fenofibrate dose- and time-dependently increased PPARα expression, and concomitantly increased the expression of bone morphogenetic protein 2 (BMP2). Knockdown of PPARα abolished fenofibrate-induced BMP2 expression, activity of the BMP2 promoter gene, and calcium deposition. The chromatin immunoprecipitation assay demonstrated that fenofibrate increased BMP2 expression by inducing direct binding of PPARα to the BMP2 promoter region. Taken together, we suggest that fenofibrate has a stimulatory effect on osteoblast differentiation via the elevation of PPARα levels and the PPARα-mediated BMP2 expression. Our findings provide fenofibrate as a useful agent for controlling hypercholesterolemic patients with osteoporosis.