Improved fit by asymmetric tibial prosthesis for total knee arthroplasty

The relationship of the medially-offset stem of the tibial component to the medial tibial cortex in total knee replacements in Korean patients

“…While most of the current TKR systems have a tibial component with a symmetrically-shaped and centrally-positioned stem, some have a stem with a medial offset on an asymmetrical baseplate. 7,13,14 These modified designs have been based on anatomical studies in Caucasian subjects in whom the medullary canal of the tibia is biased medially from the centre of the tibial plateau. 7,13,14 However, several studies have suggested that in Asian subjects, the anatomical features of the proximal tibia may be different from those of Caucasians.…”

“…7,13,14 These modified designs have been based on anatomical studies in Caucasian subjects in whom the medullary canal of the tibia is biased medially from the centre of the tibial plateau. 7,13,14 However, several studies have suggested that in Asian subjects, the anatomical features of the proximal tibia may be different from those of Caucasians. 10,[15][16][17] In our practice for Korean patients undergoing TKR, we have noticed during pre-operative radiological planning that the mechanical axis was located medially to the axis of the shaft in many patients.…”

Can tibial coverage in total knee replacement be reliably evaluated with three-dimensional image-based digital templating?

“…7,16-18 Moreover, there are several disadvantages to previously reported methods, being time consuming and labour intensive, often requiring cadavers or surgical resection specimens and being prone to magnification or other measurement errors. 2,7,16-18 A previous study compared eight different tibial tray designs, including six symmetric and two asymmetric designs. 17 However, limited details were given regarding the criteria for choosing the template size and position to calculate tibial coverage.…”

“…15 The controversy could be related to differences in methods, but importantly the reliability of the templating and measurement method employed is consistently not reported. 7,16-18 …”

“…7,16-18 Two-dimensional (2D) tibial models created from photographed resection specimens obtained during TKR, from cadavers 17 or digitised unmagnified radiographs of retrieved surgical specimens, have been described. 2,16,19 However, the reliability of these 2D methods has never been reported, and could be questioned due to the lack of perspective and the obstruction of key anatomical landmarks when fitting the component template.…”