Important Factors for Retrograde Nailing Through Total Knee Arthroplasty: A Cadaveric Study

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Implant Design

Background:

• Retrograde femoral nailing is a common procedure for treating femur fractures.
• Total knee arthroplasty (TKA) implants can alter the anatomy, potentially complicating retrograde nailing.
• Understanding the interaction between TKA designs and nailing is crucial for surgical success.

Purpose of the Study:

• To evaluate the influence of total knee arthroplasty (TKA) implant design and femoral component size on the range of motion required for retrograde femoral nailing.
• To determine the minimum knee flexion needed to safely perform retrograde nailing with different TKA components.

Main Methods:

• Cadaveric specimens with single radius (SR) and medial pivot (MP) TKA designs were used.
• Tests included cruciate retaining (CR), cruciate substituting (CS), and posterior stabilizing (PS) liners.
• Minimum knee flexion to avoid reamer impingement on TKA components was measured.

Main Results:

• At least 70 degrees of knee flexion is required for retrograde nailing with SR and MP TKA designs.
• Posterior stabilizing (PS) implants necessitated significantly greater flexion for both TKA designs.
• Femoral component size did not influence the required flexion; however, reamer deviation was noted.

Conclusions:

• Performing retrograde nailing through TKA implants requires substantial knee flexion, particularly with PS designs.
• Surgeons must consider implant design and achieve adequate flexion to prevent damage to TKA components.
• A consistent reamer path deviation necessitates careful surgical technique.