Precision soft tissue balancing: grid-assisted pie-crusting in total knee arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering

Background:

• Varus and valgus knee deformities stem from medial and lateral soft tissue imbalances.
• Correcting these deformities during total knee arthroplasty (TKA) is crucial but lacks standardized techniques.
• Optimal soft-tissue release methods for TKA in deformed knees remain debated.

Purpose of the Study:

• To assess the efficacy of a novel grid-based pie-crusting technique for soft-tissue release in TKA.
• To evaluate the impact of this technique on medial collateral ligament (MCL) and lateral collateral ligament (LCL) lengthening and stiffness.

Main Methods:

• Cadaver knees underwent dissection, isolating the MCL or LCL.
• A 3D-printed grid guided pie-crusting perforations on the ligaments.
• Mechanical testing measured ligament deformation and stiffness changes after incremental perforations.

Main Results:

• Grid-based pie-crusting significantly increased the medial femorotibial space (MCL group) and femur-fibula gap (LCL group).
• Ligament stiffness decreased proportionally with the number of perforations in both MCL and LCL.
• The technique demonstrated gradual lengthening without sacrificing structural integrity, evidenced by high R-squared values in regression analyses.

Conclusions:

• The novel grid-based pie-crusting technique allows for controlled, gradual lengthening of knee ligaments.
• This method preserves the structural integrity of the MCL and LCL during soft-tissue release.
• The technique offers a valuable addition to the surgical toolkit for TKA in patients with varus and valgus knee deformities.