Validity and application of Doiguchi's pelvic tilt measurement method.

BACKGROUND: The validity of Doiguchi's pelvic tilt measurement method has not been proven. The objective in our study was to validate the method. METHODS: Our investigation included 73 total hip arthroplasties (THAs) performed using our cup placement procedure from July 2020 to November 2021. Pelvic tilt formed by the pubic symphysis and sacral promontory (PTPS) in supine and lateral positions was calculated by two methods (the Doiguchi method and the digital reconstructed radiograph (DRR) method using a 3D computer templating system) based on the transverse and longitudinal diameters of the pelvic ring measured immediately before THA. RESULTS: There was a strong/moderate correlation in the values of PTPS between the Doiguchi and DRR methods. However, the value of PTPS calculated by the Doiguchi method was significantly lower than that calculated by DRR, and there was a partially direct match. On the other hand, there was no significant difference in the value of PT change from supine to lateral position between the Doiguchi and DRR methods. The PT changes based on both methods were strongly correlated, and the PT change calculated by the Doiguchi method was almost identical to that calculated by the DRR method. CONCLUSIONS: Doiguchi's pelvic tilt measurement method was validated for the first time. These results demonstrated that the ratio of the transverse and longitudinal diameters of the pelvic ring was an important factor defining the change in pelvic tilt. The slope in the linear function of the Doiguchi method was found to be almost the correct value, although the intercept of the linear function exhibited individual differences.

Bone morphogenetic protein-2 induces differentiation of multipotent C3H10T1/2 cells into osteoblasts, chondrocytes, and adipocytes in vivo and in vitro.

Mesenchymal stem cells capable of differentiating into multiple cell types are potentially useful therapeutically for regeneration of bone and cartilaginous tissues. Multipotent fibroblastic C3H10T1/2 cells are known to differentiate into osteoblasts, chondrocytes, and adipocytes in response to certain growth factors. In this study we compared the effects of bone morphogenetic protein (BMP)-2 on the differentiation of C3H10T1/2 and MC3T3-E1 preosteoblastic cells. Incubation of these cells with BMP-2 resulted in a dose- and time-dependent increase in alkaline phosphatase activity, but the increase in MC3T3-E1 cells was much higher than that in C3H10T1/2 cells. BMP-2 also induced differentiation of C3H10T1/2 cells but not MC3T3-E1 cells into chondrocytes and adipocytes. Reverse transcription-polymerase chain reaction analysis showed that these commitments were accompanied by the specific expression of osteocalcin, aggrecan, and PPARgamma. To investigate the in vivo differential property, these cells were inoculated with BMP-2 in a diffusion chamber and transplanted into the mouse peritoneal cavity for 4 weeks. The transplanted C3H10T1/2 cells formed mineralized bone containing chondrocytes and adipocytes, whereas MC3T3-E1 created only bony tissue. Our results indicate that BMP-2 can induce the differentiation of C3H10T1/2 into osteoblasts, chondrocytes, and adipocytes in both in vivo and in vitro conditions, and that C3H10T1/2 could be used to examine the BMP-2-induced regulatory mechanisms of mesenchymal differentiation.