Precooling an acetabular liner makes its insertion into a metal shell easier.

Area of Science:

• Orthopedic Surgery
• Biomaterials Engineering
• Medical Device Design

Background:

• Acetabular liners are critical components in hip replacement surgery.
• Current methods for seating polyethylene liners can require significant force.
• Precooling liners may offer a method to reduce the force needed for insertion.

Purpose of the Study:

• To investigate the effect of precooling on the force required to seat acetabular polyethylene liners.
• To document the cooling and heating rates of liners with a specific locking mechanism.
• To compare insertion forces at different temperatures with the force exerted by surgeons.

Main Methods:

• Documented cooling and heating rates of 58- and 70-mm acetabular liners in an ice-water bath.
• Measured the force required to seat liners into their metal shells at various temperatures (0°C, room, body).
• Quantified the maximum thumb force exerted by surgeons during liner seating.

Main Results:

• Cooling liners to near 0°C took up to 8 minutes; subsequent warming to body temperature took up to 24 minutes.
• Insertion forces were significantly lower at 0°C compared to room and body temperatures.
• Precooled liners (at 0°C) required insertion forces achievable by manual surgeon force.

Conclusions:

• Temporary shrinkage of polyethylene liners via precooling effectively reduces seating forces.
• Precooling acetabular liners to 0°C facilitates manual insertion by surgeons.
• This technique has the potential to improve the ease and safety of hip implant procedures.