2017 ISAKOS Biennial Congress ePoster #1212

 

The Influence of Intra-Operative Soft Tissue Balance on Postoperative Knee Stability and Flexion Angle in Posterior-Stabilized Total Knee Arthroplasty

Takao Inokuchi, MD, Kobe, Hyogo JAPAN
Tomoyuki Matsumoto, MD, PhD, Kobe, Hyogo JAPAN
Koji Takayama, MD, PhD, Kobe, Hyogo JAPAN
Hirotsugu Muratsu, MD, PhD, Himeji, Hyogo JAPAN
Kazunari Ishida, MD, PhD, Kobe, Hyogo JAPAN
Shinsuke Kirizuki, MD, Kobe, Hyogo JAPAN
Yuichi Kuroda, MD, Kobe JAPAN
Ryosuke Kuroda, MD, PhD, Kobe, Hyogo JAPAN

Kobe University, Kobe, Hyogo, JAPAN

FDA Status Not Applicable

Summary

The intra-operative condition of the soft tissue balance reflected the post-operative values in posterior-stabilized total knee arthroplasty, and appropriate flexion gap and lateral laxity in flexion might be important for the acquisition of post-operative high flexion angle.

Abstract

Background

Clinical values of intra-operative assessment of soft tissue balance has been reported in total knee arthroplasty (TKA). Our recent cruciate-retaining (CR)-TKA study using offset-type tensor showed postoperative flexion angle was positively correlated with intraoperative joint component gap, and postoperative knee flexion angle is affected by lateral laxity in CR-TKA. The purpose of this study was to investigate the effect of intra-operative soft tissue balance on post-operative knee stability and range of motion in posterior-stabilized (PS) TKA.

Material And Methods

We retrospectively analyzed Thirty-three knees in 33 patients (7 males and 26 females) with varus knee osteoarthritis who underwent TKA using e.motion-PS (B. Braun Aesculap, Germany) whose knee flexion angle could be measured at 1 years after operation. The mean age was 75.2 years old. The mean follow-up was 15.4 months. Intra-operative soft tissue balance including the joint component gap (CG) (joint center gap and joint gaps of the medial and lateral compartments at 0° and 90° of flexion) and ligament balance (varus angle: VA) were assessed under 40lbs. of distraction force at extension and 90° of flexion. Post-operative CG and VA evaluation assessed at one-year follow-up by stress radiographs at extension and flexion were assessed and compared with intra-operative values. Correlations between intra-operative soft tissue parameters and post-operative soft tissue parameters, and that between the soft tissue parameters and postoperative knee flexion angle were analyzed using simple linear regression models.
Result: Post-operative CG at extenson and flexion (90°) angles were significantly correlated with the intra-operative CG values (extenson; R = 0.41, P < 0.05, flexion; R = 0.60, P < 0.05). The post-operative VA at extension was significantly correlated with the intra-operative values (R = 0.37, P < 0.05). There were no correlations between the post-operative VA at flexion angle. Post-operative knee flexion angle showed a positive correlation with postoperative center gap difference (flexion - extension) (R = 0.48, P < 0.05), lateral compartment gap difference (R = 0.48, P < 0.05) and post-operative VA in flexion (R = 0.38, P < 0.05). There were no correlations between the medial compartment gap difference and postoperative knee flexion angle.

Conclusion

The intra-operative condition of the soft tissue balance reflected the post-operative values in PS TKA at one-year follow-up. In the PS TKA, appropriate flexion gap and lateral laxity in flexion might be important for the acquisition of post-operative high flexion angle. Based on these findings, we suggest that surgeons should try not to make lateral joint too tight to achieve high flexion angle after PS-TKA.