Effect of shape on bone cement polymerization time in knee joint replacement surgery

Area of Science:

• Orthopedic surgery
• Biomaterials science
• Polymer chemistry

Background:

• Bone cement polymerization time is influenced by various factors, but the predictive value of cement shape remains unclear.
• Understanding these factors is crucial for optimizing surgical outcomes in total joint arthroplasty.

Purpose of the Study:

• To investigate whether different bone cement shapes (lump vs. pan) affect polymerization time.
• To determine the relationship between cement shape, ambient operating theater conditions (temperature, humidity), and equilibration time.

Main Methods:

• Prospective study of 237 patients undergoing primary total knee arthroplasty.
• Bone cement samples were prepared in lump and pan shapes.
• Polymerization time was defined as the point of no macroscopic indentation.

Main Results:

• Polymerization time was significantly longer for the pan shape compared to the lump shape (P < .001).
• Antibiotic Simplex bone cement exhibited a shorter polymerization time than Palacos R+G (P < .001).
• Polymerization time decreased with increasing temperature, humidity, and equilibration time, irrespective of cement shape.

Conclusions:

• Bone cement shape significantly impacts polymerization time, with the pan shape providing a more clinically relevant measure.
• Temperature, humidity, and equilibration time affect polymerization time similarly across both lump and pan shapes.
• Applying constant pressure with the knee in <45° flexion until pan-shaped cement is fully polymerized is recommended clinically.