Does the modelling of the pectus bar affect its stability? Rationale for using a short flat bar

Area of Science:

• Thoracic surgery
• Biomechanical engineering
• Medical device design

Background:

• The Nuss procedure for pectus excavatum carries a risk of postoperative bar displacement.
• The influence of pectus bar geometry on corrective stability is not well understood.

Purpose of the Study:

• To investigate how pectus bar modeling affects implant stability.
• To determine if alternative implant configurations can enhance clinical success in pectus excavatum repair.

Main Methods:

• Computational modeling simulated bar implantation with varying shapes and sizes.
• A 250 N sternal force was applied to assess reaction forces and moments.
• A clinical trial compared conventional U-shaped bars with computationally designed implants.

Main Results:

• U-shaped bars generated destabilizing forces and moments, leading to sliding and rotation.
• Flat bars exhibited no lateral or rotational destabilizing forces.
• Clinical groups showed similar cosmetic results, postoperative times, and hospital stays, but 2 conventional bars flipped.

Conclusions:

• Pectus bar shape is a critical factor in surgical stability.
• A flat, shorter pectus bar offers adequate deformity correction with reduced displacement risk.