A New Augmentation Method for Improved Screw Fixation in Fragile Bone

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Osteoporosis Research

Background:

• Pertrochanteric fractures (TF) are common in osteoporotic patients, often leading to fixation failure due to poor bone quality.
• Current augmentation methods for bone-implant anchorage in TF lack strong evidence and standardized delivery techniques.
• Reinforcing the bone-implant interface is crucial for successful TF fixation in osteoporotic bone.

Purpose of the Study:

• To develop and evaluate a novel method for delivering a calcium sulphate/hydroxyapatite (CaS/HA) biomaterial for lag-screw augmentation in TF.
• To assess the immediate mechanical anchorage of augmented lag-screws in an osteoporotic bone model.
• To demonstrate the feasibility and efficacy of the CaS/HA delivery technique in clinical and ex-vivo settings.

Main Methods:

• A novel delivery method for CaS/HA biomaterial at the lag-screw bone-implant interface was developed.
• Mechanical testing was performed using an osteoporotic Sawbones model to evaluate lag-screw pull-out strength.
• Proof-of-concept studies included in-vivo delivery in TF patients and ex-vivo analysis on donated femoral heads using micro-CT.

Main Results:

• CaS/HA augmentation increased lag-screw peak extraction force by fourfold compared to un-augmented screws, comparable to PMMA.
• Clinical X-rays confirmed successful, low-pressure injection and spreading of CaS/HA at the bone-implant interface.
• Micro-CT imaging of femoral heads showed complete coverage of lag-screw threads by CaS/HA biomaterial.

Conclusions:

• A novel and effective method for augmenting lag-screws with CaS/HA biomaterial in pertrochanteric fractures has been presented.
• This technique shows potential for significantly improving lag-screw anchorage in osteoporotic bone.
• The findings suggest a possible reduction in fracture fixation failure and reoperation rates for fragile patients.