Objective: The study was performed to test the hypothesis that cemented and uncemented implants influenced the measurement of proximal femur BMD.
Methods: 10 patients underwent THA with cemented or uncemented implants due to developmental dysplasia of the hip, femoral neck fracture or femoral head necrosis from January 2015 to July 2015 were included. The patients' BMD of L1-L4 and femoral neck were measured preoperative. We measured the BMD of proximal femur after divided it into Gruen zone 1-Gruen zone 71 day before the operation, 1 week after the operation and 3 months after the operation, respectively.
Results: 5 patients (3male, 2female) used uncemented implants, mean age were 61y. Another 5 patients use cemented implants, mean age were 80y. The mean preoperative BMD of uncemented group were G1: 0.762 ± 0.432 g/cm2; G2: 1.572 ± 0.570 g/cm2; G3: 1.973 ± 0.314 g/cm2; G4: 1.962 ± 0.314 g/cm2; G5: 1.900 ± 0.672 g/cm2; G6: 1.547 ± 0.966 g/cm2; G7: 1.038 ± 0.268 g/cm2. And the mean preoperative BMD of cemented group were G1: 0.548 ± 0.204 g/cm2; G2: 1.260 ± 0.498 g/cm2; G3: 1.552 ± 1.000 g/cm2; G4: 1.492 ± 0.832 g/cm2; G5:1.454 ± 0.672 g/cm2; G6: 0.988 ± 0.062 g/cm2; G7: 0.704 ± 0.398 g/cm2. The mean BMD of uncemented group increased 1 week after the operation, especially in Gruen zone 1,2,6 and 7. The mean BMD of cemented group increased in all 7 zones obviously. But there is not statistical significance between preoperative group and postoperative group in both groups (p < 0.05). The mean BMD measured 3 months after the operation decreased comparing to 1 week after the operation, but there is not statistical significance (p < 0.05).
Conclusion: The proximal femoral neck BMD increased postoperative comparing to preoperative. The implants and the bone cement may affect the measurement of proximal femoral neck by DEXA.
|