Cement restrictor function below the femoral isthmus

Area of Science:

• Orthopedic surgery
• Biomaterials engineering
• Medical device design

Background:

• Cement restrictors are crucial for achieving an interference fit within the medullary canal during orthopedic procedures.
• The distal flare of the femur can compromise the intramedullary fit of certain cement restrictor designs.
• Understanding cement restrictor performance is vital for preventing cement leakage and ensuring procedural success.

Purpose of the Study:

• To evaluate the pressure resistance and cement leakage performance of three distinct cement restrictor designs: universal, press-fit, and expandable.
• To determine which cement restrictor design is most effective in resisting high pressures in a closed cement column.
• To assess the impact of distal femoral anatomy on cement restrictor performance.

Main Methods:

• Synthetic femora were reamed to simulate the distal femoral flare.
• Three cement restrictor types (universal, press-fit, expandable) were inserted into the synthetic femora.
• Low-viscosity cement was pressurized using a pneumatic ram, with simultaneous recording of cement pressure and restrictor displacement.
• Cement leakage past the restrictors was quantified.

Main Results:

• Expandable cement restrictors demonstrated the highest pressure resistance.
• Resorbable expandable (REX Cement Stop) and press-fit restrictors effectively prevented cement leakage.
• Universal and press-fit restrictors showed failure at low pressures when positioned below the femoral isthmus.

Conclusions:

• Cement restrictor performance varies significantly based on design and placement relative to the femoral isthmus.
• Expandable designs offer superior pressure handling, while REX Cement Stop and press-fit designs excel in preventing leakage.
• Preoperative templating is essential to guide the selection of cement restrictors, particularly when placement below the femoral isthmus is anticipated.