TITLE:
Additional Dose of Zolendronic Acid for Inadequate Response in Avascular Necrosis
AUTHORS:
Sanjay Agarwala, Mayank Vijayvargiya
KEYWORDS:
Avascular Necrosis, Bisphosphonate, Zolendronic Acid
JOURNAL NAME:
Open Journal of Orthopedics,
Vol.15 No.11,
November
28,
2025
ABSTRACT: Background: Bisphosphonates have demonstrated efficacy in management of Avascular necrosis of femoral head (AVNFH) and in delaying or obviating the need for surgical interventions. However, the delayed onset of pain relief following bisphosphonate therapy can reduce patient compliance, prompting some to opt for surgical alternatives. This study evaluates the clinico-radiological outcomes of an additional dose of zoledronic acid (ZA) in AVNFH. Methods: This retrospective observational study was conducted between January 2020 and December 2022. Patients diagnosed with AVNFH received a bisphosphonate regimen consisting of 5 mg intravenous zoledronic acid (ZA) annually, alongside 35 mg of oral alendronate twice weekly for three years. Patients who experienced less than 50% improvement in the Visual Analogue Scale (VAS) score at 6 weeks were administered an additional dose of ZA. The study assessed clinical outcomes through VAS and Harris Hip Scores (HHS), clinical failure rates, radiological progression and collapse rates. Results: Among 362 hips included in the study, 338 hips (93.4%) achieved a satisfactory clinical outcome, avoiding THR at a mean follow-up of 28 months (12-51 months). The clinical failure rates were as follows: 5% in Stage I (1/20 hips), 9.1% in Stage II (28/306 hips), and 13.9% in Stage III (5/36 hips). Radiological progression rates were 65% for Stage I, 31.7% for Stage II, and 13.9% for Stage III. An additional dose of zoledronic acid at 6 weeks significantly improved the VAS score from 7.9 to 2.7, and the HHS from 50.9 to 75.5 at 3 months. Conclusion: Our study demonstrates that combination bisphosphonate therapy is effective in managing AVNFH by reducing disease progression, collapse rates, and the need for THR. The addition of an extra dose of ZA at 6 weeks leads to significant improvements in both pain and function, likely due to the dose-dependent effect of bisphosphonates in AVNFH treatment.