Alendronate does not inhibit early bone apposition to hydroxyapatite-coated total joint implants: a preliminary study

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Pharmacology

Background:

• Alendronate inhibits osteoclastic bone resorption, a process crucial for bone remodeling.
• Bone formation and remodeling are essential for the fixation of uncemented implants, particularly those with bioactive coatings like hydroxyapatite.
• Investigating the effect of osteoclast-inhibiting drugs on bone apposition to coated implants is therefore warranted.

Purpose of the Study:

• To evaluate the influence of alendronate on bone apposition to hydroxyapatite-coated femoral implants.
• To assess the effect of alendronate on short-term bone remodeling around these implants.

Main Methods:

• Twelve dogs received staged bilateral total hip arthroplasty with hydroxyapatite-coated stems.
• Six dogs were treated with oral alendronate, while six served as untreated controls.
• Histological analysis of implant sites was performed four weeks after the second surgery to measure bone apposition and coating characteristics.

Main Results:

• No significant differences were observed in radiographic or histologic findings between alendronate-treated and control groups.
• Alendronate did not significantly influence bone apposition, hydroxyapatite coating extent or thickness, or surrounding bone area.
• The hydroxyapatite coating significantly decreased over time in both groups.

Conclusions:

• Alendronate demonstrated no discernible effect on the initial fixation or short-term bone remodeling around hydroxyapatite-coated femoral implants.
• These findings are relevant for patients on alendronate therapy considering cementless total joint arthroplasty.
• The study suggests that bone formation may not be solely dependent on osteoclastic resorption for initial implant integration.