Effects of differences in the rotational position of the ligament balancer on the intraoperative medial and lateral soft tissue balance in total knee arthroplasty

Abstract

OBJECTIVES: To examine the effects of differences in the rotational position of the ligament balancer on the intraoperative medial and lateral soft tissue balance in total knee arthroplasty (TKA), and to determine the proper rotational alignment of the tibial implant.

METHODS: The study involved 27 knees measured using a new balancer that can be fixed to the tibial resection surface and that allows placement of femoral and rotational trial inserts. The GENUS CS rotational mobile insert (Adler Ortho, Milan, Italy) was used.

RESULTS: Excessive internal rotational alignment of the balancer caused significant medial tightness, while excessive external rotational alignment caused significant lateral tightness. There was no significant correlation between the intraoperative insert rotation angle and the postoperative rotational alignment of the tibial implant.

DISCUSSION: In mobile inserts, a self-alignment mechanism is considered to allow compensation for the acceptable range of differences in the rotational alignment of the tibial implant.

CONCLUSION: Excessive internal or external rotational alignment of the balancer significantly changed the intraoperative medial and lateral soft tissue balance.