A new approach to implant alignment and ligament balancing in total knee arthroplasty focussing on joint loads

Abstract

Preservation and recovery of the mechanical leg axis as well as good rotational alignment of the prosthesis components and well-balanced ligaments are essential for the longevity of total knee arthroplasty (TKA). In the framework of the OrthoMIT project, the genALIGN system, a new navigated implantation approach based on intra-operative force-torque measurements, has been developed. With this system, optical or magnetic position tracking as well as any fi xation of invasive rigid bodies are no longer necessary. For the alignment of the femoral component along the mechanical axis, a sensorintegrated instrument measures the torques resulting from the deviation between the instrument ' s axis and the mechanical axis under manually applied axial compression load. When both axes are coaxial, the resulting torques equal zero, and the tool axis can be fi xed with respect to the bone. For ligament balancing and rotational alignment of the femoral component, the genALIGN system comprises a sensor-integrated tibial trial inlay measuring the amplitude and application points of the forces transferred between femur and tibia. Hereby, the impact of ligament tensions on knee joint loads can be determined over the whole range of motion. First studies with the genALIGN system, including a comparison with an imageless navigation system, show the feasibility of the concept.

How to improve femoral component rotational alignment in computer-assisted TKA

“…Although computer-assisted surgery has been demonstrated to improve TKA components alignment on the coronal and sagittal plane [8][9][10]12], there is still no consensus regarding navigation systems' accuracy in the improvement of navigated TKA alignment on the horizontal plane. Zimmerman et al [28] recently introduced a new device based on force-torque measurements to improve ligament balancing and axial and rotational alignment in TKA; however, their encouraging results have not been demonstrated in clinical practice. It is for these reasons that a more reliable and accurate rotational anatomical landmark should be addressed to in TKA.…”

Optimal designs and surgical technique for hip and knee joint replacement: The best is yet to come!

“…There are already multiple sensor types under development. [75][76][77] Biomimetic surfaces and biological resurfacing will help mimic the motion of a native knee. 78,79 This will require new materials, geometries, and additive manufacturing (3D printing) techniques.…”

Intraoperative analysis of patellofemoral joint morphology before and after total knee arthroplasty

“…Despite this expected increase in operations, patellofemoral joint disorders, e.g. patellar subluxation and dislocation, implant wear or anterior knee pain, remain present and constitute a major factor of insufficiency after TKA [ 10 , 22 , 28 , 35 , 37 ].…”