Soft tissue balance changes depending on joint distraction force in total knee arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Arthroplasty Research

Background:

• Achieving optimal soft tissue balance is crucial for successful total knee arthroplasty (TKA).
• The relationship between joint distraction force and intraoperative soft tissue balance requires further elucidation.
• Posterior-stabilized TKA relies on precise ligamentous balancing for optimal function.

Purpose of the Study:

• To evaluate the influence of varying joint distraction forces on intraoperative soft tissue balance in primary posterior-stabilized TKA.
• To quantify the effect of joint distraction force on joint center gap and varus ligament balance.
• To investigate the role of differential soft tissue stiffness in TKA gap balancing.

Main Methods:

• A prospective study involving 78 knees undergoing primary posterior-stabilized TKA.
• Utilized the Offset Repo-Tensor® device to apply joint distraction forces of 20, 40, and 60 lbs.
• Measured joint center gap and varus ligament balance at extension and flexion under each distraction force.

Main Results:

• Joint center gap and varus ligament balance significantly increased with higher joint distraction forces.
• Lateral compartment stiffness was consistently lower than medial compartment stiffness.
• Increased distraction force led to greater varus laxity and joint gap due to differential soft tissue properties.

Conclusions:

• The magnitude of joint distraction force directly influences intraoperative soft tissue balance measurements in TKA.
• Differential soft tissue stiffness between knee compartments affects joint gap and ligament balance.
• Careful consideration of joint distraction force is essential for accurate soft tissue assessment, particularly with gap-balancing techniques.