The objective of this article was to evaluate the effect of the change of posterior condylar offset to range of motion (ROM) and clinical results after computer-assisted cruciate-retaining mobile-bearing total knee arthroplasty (TKA). A total of 111 knees underwent cruciate-retaining mobile-bearing TKAs under computer-assisted navigation from January 2005 to September 2007. All cases were primary osteoarthritis and had <15 degrees of valgus or varus deformity. We divided patients into 4 groups according to change of posterior condylar offset, which was measured by postoperative minus preoperative posterior condylar offset (group 1: <-2 mm; group 2: -2-0 mm; group 3: 0-+2 mm; group 4: >2 mm). Preoperative age, thigh girth, body mass index, flexion contracture, further flexion, Hospital for Special Surgery (HSS) score, Knee Society (KS) knee score, and KS functional score did not show significant difference between groups. The measured change of posterior condylar offset ranged from +3.70 to -3.95 mm with a mean value of -1.67 mm. Postoperatively, there were no statistical differences between each group on flexion contracture (P=.522), further flexion (P=.442), HSS score (P=.116), KS knee score (P=.479), or KS functional score (P=.578). We could find no significant difference between ROM or clinical results with computer-assisted cruciate-retaining mobile-bearing TKAs in the comparison of groups according to changes of posterior condylar offset.
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