Proximal tibial resection in varus-deformed tibiae during total knee arthroplasty: an in vitro study using sawbone...

This study was designed to investigate accuracy of the tibial component in the coronal plane when the lateral condylar eminence was determined as the proximal reference of proximal tibial cutting in varus-deformed knees.

Varus-deformed tibiae were designed using the entire tibia sawbone models of four categories (varus 0°, 5°, 10° and 15°). Each of ten sawbones was allocated into four in each group. All sawbones were osteotomised with the proximal reference of proximal tibial cutting as the lateral intercondylar eminence. The thickness of the cut tibial medial and lateral condyles were measured. After implantation of the tibial component, anteroposterior (AP) radiographs were obtained. An independent examiner evaluated angles between the perpendicular line to the tibial tray and the shaft/mechanical axes of the tibia.

The mean angular difference between the axis perpendicular to the prosthesis and the mechanical/shaft axes of the tibia were not significant in any group. When the tibial component coronal alignment was measured based on the tibial mechanical axis, no significant difference was observed in any group, but when based on the shaft axis of the tibia, it was significantly different between Group A and Group D.

Accuracy of the tibial component alignment was acceptable in varus-deformed knees when the lateral intercondylar eminence was used as a reference for tibial osteotomy, although any prolonged clinical benefits will require long-term in vivo study.