Biomechanical comparison of two extensor mechanism reconstruction techniques.

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Biomechanical Analysis

Background:

• Extensor mechanism disruption is a common complication after total knee arthroplasty.
• High failure rates of primary repair necessitate reconstruction, often using synthetic mesh.
• Existing literature lacks biomechanical comparisons of different mesh reconstruction techniques.

Purpose of the Study:

• To biomechanically compare two synthetic mesh techniques for extensor mechanism reconstruction after total knee arthroplasty: the tuberosity technique and the intramedullary technique.
• To evaluate construct stiffness, yield force, and ultimate failure load.

Main Methods:

• Synthetic mesh constructs were implanted in cadaveric tibiae using either the tuberosity or intramedullary technique.
• Biomechanical testing involved applying joint reaction forces and axial tensile loads to the mesh constructs.
• Infrared motion analysis tracked displacements to measure construct properties.

Main Results:

• The intramedullary technique demonstrated significantly higher stiffness (3x) and ultimate failure load (54% greater) compared to the tuberosity technique.
• The intramedullary technique also showed increased yield strength.
• Failure modes differed, with the tuberosity technique failing at the insertion site and the intramedullary technique failing proximally.

Conclusions:

• The intramedullary technique offers a biomechanical advantage for total knee arthroplasty extensor mechanism reconstruction.
• Implanting mesh under the tibial base plate may enhance construct stability.
• Further research could explore the role of soft tissue ingrowth in long-term outcomes.