Efficiency of Zoledronic Acid in Inhibiting Accelerated Periprosthetic Bone Loss After Cementless Total Hip Arthroplasty in Osteoporotic Patients: A Prospective, Cohort Study.

Objective: To investigate the influence of preoperative osteopenia/osteoporosis on periprosthetic bone loss after total hip arthroplasty (THA) and the efficiency of zoledronate (ZOL) treatment in periprosthetic bone preservation.

Methods: This multicenter, prospective cohort study was conducted in four centers between April 2015 and October 2017. Patients were assigned to Normal BMD, Osteopenia, and Osteoporosis+ZOL groups. Patients with osteopenia received daily oral calcium (600 mg/d) and vitamin D (0.5 μg/d), while patients in the Osteoporosis+ZOL group received additional ZOL annually (5 mg/year). Periprosthetic bone mineral density (BMD) in seven Gruen zones, radiographic parameters, Harris hip score, EuroQol 5-Dimensions (EQ-5D) score, and BMD in hip and spine were measured within 7 days, 3 months, 12 months postoperation and annually thereafter.

Results: A total of 266 patients were enrolled, while 81 patients that completed the first year follow-up were involved in the statistical analysis. The mean follow-up time was 1.3 years. There were significant decreases of mean BMD in total Gruen zones (-4.55%, P < 0.05) and Gruen zone 1 (-10.22%, P < 0.01) in patients with osteopenia during the first postoperative year. Patients in the Osteoporosis+ZOL group experienced a marked increase in BMD in Gruen zone 1 (+16%) at the first postoperative year, which had a significant difference when compared with the Normal BMD group (P < 0.05) and the Osteopenia Group (P < 0.001). Low preoperative BMD in hip and spine was predictive of bone loss in Gruen zone 1 at 12 months after THA in patients with normal BMD (R = 0.40, P < 0.05).

Conclusions: Patients with osteopenia are prone to higher bone loss in the proximal femur after cementless total hip arthroplasty (THA). ZOL, not solely calcium and vitamin D, could prevent the accelerated periprosthetic bone loss after THA in patients with osteopenia and osteoporosis.