Simulation of total knee arthroplasty in 5° or 7° valgus: A study of gap imbalances and changes in limb and knee alignments from native

Abstract

This study calculated the frequency of occurrence of gap imbalances between medial and lateral compartments at 0° flexion and within a compartment between 0° and 90° flexion, and changes in limb and knee alignment from native after computer simulation of total knee arthroplasty (TKA) with the knee set in 5° or 7° valgus at 0° flexion. TKA was simulated on 49 3D bone models of native limbs. At 0° flexion, the femoral component was set in 5° or 7° valgus from the anatomic axis of the femur, and the tibial component was set 0° to the tibial anatomic axis. At 90° flexion, internal-external rotation of the femoral component was set perpendicular to the anteroposterior axis of the trochlear groove (Method 1), parallel to the transepicondylar axis (Method 2), 3° externally rotated to the posterior condylar axis (Method 3), and gap-balanced to the tibial resection at 0° flexion (Method 4). For 5° and 7° valgus knees, the frequency of occurrence of TKAs (1) with ≥2 mm gap imbalance between compartments at 0° flexion was ≥49%, (2) with ≥2 mm gap imbalance within a compartment between 0° and 90° flexion ranged from 43-69% for Methods 1, 2, and 3, and (3) with ≥2° change in limb and knee alignment from native was ≥47%. Achieving balanced gaps between compartments at 0° flexion may often require soft tissue release. Unbalanced gaps within a compartment between 0° and 90° flexion represent a potential instability which is difficult to surgically correct. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2031-2039, 2017.

Differences in Trochlear Morphology from Native Using a Femoral Component Interfaced with an Anatomical Patellar Prosthesis in Kinematic Alignment and Mechanical Alignment

“…Finally, a single method for setting the rotation of the femoral component was studied with MA whereas multiple methods are used clinically. 12,27…”

Analysis of differences in laxities and neutral positions from native after kinematically aligned TKA using cruciate retaining implants

“…Related to the second key finding, the result that only 6 of 20 neutral positions were statistically different from native after KA TKA has several clinical implications. No statistical differences of the V‐V neutral positions indicate that KA TKA likely achieved the goal of aligning the femoral and tibial components to restore the native joint lines and thus the native alignments of the limb and knee because malalignments would cause differences in the V‐V neutral position . No statistical differences of the C‐D neutral position indicate that the correct tibial insert thickness was selected, and that the posterior tibial slope was correctly set using the intraoperative quality assurance checks .…”

Kinematic Alignment in Cruciate Retaining Implants Improves the Biomechanical Function in Total Knee Arthroplasty during Gait and Deep Knee Bend

“…In a previous study, it was reported that TKA using MA required the management of complex and uncorrectable collateral ligament imbalance, and it led to a wide range of changes in tibiofemoral alignment from normal knee conditions. 43,44 KA TKA has the advantage of preventing imbalance of the collateral ligaments, which have a wide variety of complex mechanisms that are not correctable through collateral ligament release, as well as a wide range of changes in the natural alignment of the lower extremity resulting from MA TKA. KA TKA restores the normal alignment of the lower extremity and the joint line of the knee, thus providing more physiological forces exerted on the collateral ligaments than MA TKA, which is unnaturally aligned to a neutral MA.…”