Abstract
BackgroundStress 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 methodsPatients 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.ResultsTwo 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.ConclusionsSwitching 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 registrationUMIN, registry number UMIN000016158. Registered 8 January 2015
Highlights
Total hip arthroplasty (THA) is a promising surgical treatment, providing pain relief, functional recovery, and long-term stable clinical results, with 20-year implant survival rates higher than 90% [1, 2]
Switching therapy had a significant effect on bone mineral density (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
Summary
Total hip arthroplasty (THA) is a promising surgical treatment, providing pain relief, functional recovery, and long-term stable clinical results, with 20-year implant survival rates higher than 90% [1, 2]. Stress shielding can induce bone mineral density (BMD) loss around the femoral implant [3,4,5]. BMD loss around the implant has not been found to result in poorer clinical outcomes after THA, a large retrospective cohort study suggested that the use of bisphosphonate decreased the risk of revision after THA [6]. BMD loss around the implant may be associated with an increased risk of periprosthetic fractures [7]. 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. 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
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