Joint Line Modification in Kinematically Aligned Total Knee Arthroplasty Improves Functional Activity but Not Patient Satisfaction

Background: Joint line modification in kinematically aligned total knee arthroplasty (KA-TKA) is attracting attention in expectation of optimizing patient satisfaction after TKA. This study aimed to examine the effects of joint line modification on Pain Catastrophizing Scale (PCS), painDETECT score, and new Knee Society Score (KSS) 2011, all of which are robustly related to patient satisfaction. Methods: The study enrolled 45 knees of 45 patients undergoing KA-TKA and a matched group of 45 knees of 45 patients undergoing mechanically aligned (MA) TKA as controls. At a mean of 31.6 months after TKA, new KSS 2011, PCS, and painDETECT score were assessed and compared between KA- and MA-TKA. Data from all 90 patients were pooled into one group for secondary multiple regression analysis to identify postoperative variables affecting patient satisfaction. Results: Assessment with new KSS 2011 showed no significant differences between the 2 TKAs preoperatively, but functional activity score was significantly higher with KA-TKA than with MA-TKA postoperatively (P =.047). Among the 4 categories of functional activity score, advanced activity score was significantly higher with KA-TKA than with MA-TKA (P =.003). Of the 5 advanced activities, the score for climbing ladder/step stool was significantly greater with KA-TKA (P =.004). KA-TKA failed to influence patient satisfaction score. Multiple regression analysis revealed that standard activity score and PCS affected patient satisfaction positively and negatively, respectively. Conclusion: Joint line modification in KA-TKA improved functional activity but not patient satisfaction. PCS was a key element negatively affecting patient satisfaction.