The posterior tibial slope does not influence the flexion angle in posterior-stabilized mobile-bearing total knee arthroplasty
Susumu Takemura,1 Tessyu Ikawa,2 Yohei Ohyama,1 Mitsunari Kim,3 Kunio Takaoka,3 Yukihide Minoda,1 and Yoshinori Kadoya3Knee
Background
It remains uncertain whether an increase in the tibial slope leads to better flexion in posterior-stabilized (PS) total knee prostheses.
Purpose
To compare the intra-operative flexion angle between standard and an additional 10° posterior slope inserts.
Patients and methods
Between December 2014 and February 2015, 22 patients (25 knees) who underwent PS mobile-bearing primary total knee arthroplasty (TKA) were included. Flexion angles were measured using either standard or specially-made inserts. Differences in flexion angles between the two situations were analyzed to determine the relationship between changes in flexion angle and pre-operative flexion angle or body mass index (BMI), and between intra- and post-operative flexion angle.
Results
The difference between the average flexion angle of standard inserts and specially-made inserts was not statistically significant. Although the correlations between changes in flexion angle due to insert difference and flexion angle, pre-operative flexion angle or BMI were not significant, there was a positive correlation between intra-operative and post-operative flexion at 2 years.
Conclusion
The results showed an additional posterior tibial slope by 10° did not affect the intra-operative flexion angle. Surgeons performing PS mobile-bearing TKA do not need to excessively slope the tibial bone cutting to improve the post-operative flexion angle.
Level of evidence
I, Experimental study.
Supplementary Information
The online version contains supplementary material available at 10.1186/s42836-021-00085-5.
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