Mobile-bearing total knee arthroplasty: More rotation is evident during more demanding tasks.
BACKGROUND
Some reports showed few but significant more axial femorotibial rotation in favor of mobile-bearing (MB) versus fixed-bearing (FB) total knee arthroplasty (TKA), mostly during knee bend fluoroscopic studies. The goal of the current study was to submit MB and FB groups of TKA patients to a turning activity, in which additional rotation was to be expected.


METHODS
Two consecutive cohorts of patients after TKA (10 FB and 11 MB knees in a total of 18 patients) were assessed using motion analysis five year postoperatively, while performing gait and sit-to-walk (STW) movements with and without turning steps.


RESULTS
Mean range of rotation in the FB group increased from 9.7° during gait, to 11.7° during STW straight, and to 14.3° during STW turning. Mean range of rotation in the MB group increased from 13.4° during gait to 21.0° during STW straight, and stayed at 21.1° during STW turning.


CONCLUSIONS
Too many uncontrolled variables in the current study hinder a meaningful discrimination of MB from FB TKA rotation. However, the study does illustrate how more demanding task loads could be helpful in exploring the geometric constraints of TKA variants.


LEVEL OF EVIDENCE
Level III, therapeutic study.
['Zürcher|Arthur W|AW|', 'van Hutten|Kim|K|', 'Harlaar|Jaap|J|', 'Terwee|Caroline B|CB|', 'Rob Albers|G H|GH|', 'Pöll|Ruud G|RG|']
D000328:Adult D019645:Arthroplasty, Replacement, Knee D015331:Cohort Studies D005260:Female D005684:Gait D006801:Humans D007720:Knee Prosthesis D008297:Male D008875:Middle Aged D020370:Osteoarthritis, Knee D016059:Range of Motion, Articular D012399:Rotation D016474:Weight-Bearing D055815:Young Adult
Mobile-bearing Rotation TKA Sit-to-walk