No differences in patient-reported outcomes between medial pivot insert and symmetrical insert in total knee arthroplasty: A randomized analysis

Background

Although total knee arthroplasty (TKA) using a medial pivot insert reportedly improves kinematics compared with a symmetrical insert, improvements in patient-reported outcomes have not yet been reported. The aim of this study was to determine whether insert designs influenced patient-reported outcomes.

Methods

Seventy TKAs for osteoarthritis were randomly allocated to a symmetrical dish insert (SD group: 35 knees) or medial pivot insert (MP group: 35 knees). Thirty-two of the SD group (74.4?±?6.6?years old) and 33 of the MP group (73.8?±?6.0?years old) completed the two-year follow-up. The knee range of motion (ROM) and 2011 Knee Society score (2011KSS) were analyzed pre-operatively and postoperatively.

Results

There was no difference in pre-operative ROM or 2011KSS (Symptom: 7.3?±?5.9 in SD group, 8.4?±?5.4 in MP group, P?=?0.432; Satisfaction: 12.6?±?6.9 in SD group, 11.8?±?5.9 in MP group, P?=?0.581; Activity: 35.8?±?18.1 in SD group, 35.2?±?18.6 in MP group, P?=?0.883). At two years, although both group showed good improvement, there were no differences in ROM or 2011KSS (Symptom: 19.3?±?5.0 in SD group, 18.3?±?4.1 in MP group, P?=?0.351; Satisfaction: 24.0?±?7.6 in SD group, 22.9?±?7.9 in MP group, P?=?0.548; Activity: 60.3?±?14.8 in SD group, 54.3?±?17.3 in MP group, P?=?0.137).

Conclusions

The medial pivot insert was not superior to the symmetrical insert in patient-reported outcomes at two years after TKA.