Implant sizing of the P.F.C. sigma rotating-platform total knee system

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Implant Design and Sizing

Background:

• Total knee arthroplasty (TKA) is a common procedure to alleviate knee pain and restore function.
• Accurate sizing of prosthetic components is crucial for optimal surgical outcomes and implant longevity.
• Variations in implant sizing between sexes and within bilateral knees may impact TKA performance.

Purpose of the Study:

• To evaluate implant size discrepancies in P.F.C. Sigma rotating-platform total knee arthroplasties.
• To compare component sizing between male and female patients.
• To assess size consistency in bilateral knee replacements and compare P.F.C. Sigma femur dimensions to commercial templates.

Main Methods:

• Retrospective analysis of P.F.C. Sigma rotating-platform TKAs performed between 2004 and 2005.
• Assessment of implant size relationships between femoral and tibial components.
• Comparison of mediolateral (ML) and anteroposterior (AP) dimensions using commercial femoral radiograph templates.

Main Results:

• 64% of women received a tibial tray one size smaller than the femoral component.
• 63.5% of men had same-sized femoral and tibial components.
• Bilateral knee component sizes were consistent in 97% of women and 90% of men; P.F.C. Sigma femoral components exhibited smaller ML dimensions compared to other available knee replacements.

Conclusions:

• Significant size variations exist in P.F.C. Sigma TKA components, particularly a tendency for smaller tibial trays in women.
• While bilateral knee sizing is generally consistent, the P.F.C. Sigma femur's narrower ML dimension warrants consideration in implant selection.
• Further research into the clinical implications of these sizing variations and comparisons with other implant systems is recommended.