Abstract
Soft tissue balancing, while accepted as crucial to total knee arthroplasty (TKA)
outcomes, is incompletely defined as the subject of broad recommendations. We analyzed
120 computer-assisted, posterior stabilized TKA undertaken for osteoarthritis. Coronal
plane laxity was measured, in the 91 varus and 29 valgus knees, prior to any bone
resection or soft tissue release, and again after implant insertion. Soft tissue laxity
parameters were correlated to the American Knee Society Score (2011) at a minimum
follow-up of 12 months with a focus on patient function and satisfaction. Thirteen
specific laxity parameters showed a significant correlation to satisfaction, one parameter
correlated to function, and another to both functional and satisfaction outcomes.
Most correlations were weak, the strongest related to postoperative decreases in coronal
plane laxity. Greater preoperative varus but not valgus deformity was associated with
higher satisfaction scores. Additionally, 30 patients who reported 40 of 40 satisfaction
and that their TKA knee felt normal at all times did not have soft tissue balancing
parameters distinguishing them from other subjects. Patient satisfaction and function
outcomes demonstrated limited correlation to coronal plane soft tissue parameters.
It appears that optimizing TKA satisfaction and function is not as simple as producing
a narrow range of coronal laxity parameters. The ongoing debate around optimal coronal
plane alignment and its subsequent effect on coronal plane soft tissues may not be
as independently important as currently argued. Soft tissue balance may need to be
considered as a more complex global envelope.
Keywords
total knee arthroplasty - ligament balance - posterior stabilized - satisfaction -
function
