BACKGROUND Stress shielding after total hip arthroplasty (THA) can induce bone mineral density (BMD) loss around the femoral implant. Several studies using drug have described methods to prevent BMD loss around implants following THA. Switching from teriparatide to alendronate was reported to increase lumbar BMD; on the other hands, it is unclear whether switching from teriparatide to alendronate is effective around the implant. The aim of this study is that changes in BMD is compared in patients switched from teriparatide to alendronate, in patients treated with alendronate alone, and in control patients without medication after total hip arthroplasty. PATIENTS AND METHODS Patients were randomized into three groups, those switched to alendronate after teriparatide (switch: n = 17), those receiving continuous alendronate (ALD: n = 15), and control untreated patients (control: n = 16) and followed up for 2 years after THA. Baseline periprosthetic BMD was measured by dual-energy X-ray absorptiometry (DEXA) 1 week after THA, followed by subsequent measurements at 1 and 2 years postoperatively. Lumbar BMD was also evaluated at preoperatively, 1 and 2 years postoperatively. RESULTS Two years after surgery, BMD (%) at zone 1 was significantly higher in the switch group than in the control group (P = 0.02). BMD (%) at zone 7 was significantly higher in the switch and ALD groups than in the control group (P = 0.01, P = 0.03). Lumbar BMD (%) anterior-posterior (AP) side was significantly higher in the switch group than in the ALD and control groups 2 years after surgery. On the other hand, lumbar BMD (%) lateral side was significantly higher in the switch and ALD groups than control group 2 years after surgery. CONCLUSIONS Switching therapy had a significant effect on BMD of the lumbar spine and zones 1 and 7 at 2 years postoperatively. At zone 1 in particular, it was found to be more effective than ALD alone. TRIAL REGISTRATION UMIN, registry number UMIN000016158. Registered 8 January 2015.

中文翻译：

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特立帕肽后换用阿仑膦酸盐预防全髋关节置换术后植入物周围BMD丢失的效果，随访2年：一项随机对照试验。

背景技术全髋关节置换术（THA）后的应力屏蔽可引起股骨植入物周围骨矿物质密度（BMD）的损失。一些使用药物的研究已经描述了防止THA后植入物周围BMD丢失的方法。据报道，从特立帕肽改为阿仑膦酸钠可增加腰椎骨密度。另一方面，目前尚不清楚在植入物周围从特立帕肽转换为阿仑膦酸盐是否有效。这项研究的目的是比较从特立帕肽转为阿仑膦酸盐的患者，仅接受阿仑膦酸盐治疗的患者以及在全髋关节置换术后未药物治疗的对照患者的BMD变化。患者与方法将患者随机分为三组，特立帕肽治疗后切换为阿仑膦酸盐（切换：n = 17），接受连续阿仑膦酸盐的患者（ALD：n = 15），对照组为未经治疗的患者（对照组：n = 16），THA后随访2年。在THA后1周，通过双能X线骨密度仪（DEXA）测量假体周围的BMD，然后在术后1年和2年进行后续测量。术前，术后1年和2年还评估了腰椎BMD。结果术后两年，开关组1区的BMD（％）显着高于对照组（P = 0.02）。开关组和ALD组的7区BMD（％）显着高于对照组（P = 0.01，P = 0.03）。术后2年，转换组的腰椎BMD（％）侧明显高于ALD和对照组。另一方面，术后2年，开关组和ALD组的腰椎BMD（％）侧明显高于对照组。结论术后2年，转换治疗对腰椎以及1区和7区的BMD有显着影响。特别是在1区，它比单独使用ALD更有效。试用注册UMIN，注册号UMIN000016158。2015年1月8日注册。