Experimental investigation of threaded cup performance during insertion in total hip replacement

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Biomechanics

Background:

• Cementless threaded cups are common in European total hip arthroplasty (THA).
• Titanium and its alloys are preferred materials for hip implants.
• Optimal thread design for these cups remains undetermined.

Purpose of the Study:

• To compare insertion torques of various commercially available threaded cups.
• To validate experimental findings against surgeons' clinical experience.
• To determine the impact of cup size and thread design on insertion torque.

Main Methods:

• In vitro testing using a biaxial testing machine with polyurethane blocks.
• Recording insertion torque with a sensor during cup insertion.
• In vivo validation using human cadaver specimens for direct comparison.

Main Results:

• Significant differences in insertion torque were observed among four distinct cup designs.
• Both cup size (p=0.003) and thread design (p=0.0009) significantly influenced insertion torque.
• Cadaver study results corroborated in vitro torque data and aligned with clinical observations.

Conclusions:

• Cup size and thread design are critical factors affecting insertion torque in THA.
• Experimental data supports clinical experience regarding threaded cup performance.
• Further research into optimal thread design can enhance THA procedures.