Patient-Specific Instrumentation Combined With A New Tool for Gap Balancing Is Useful in Total Knee Replacement: 3-Year Follow-Up of A Retrospective Study

Abstract

Objective：The purpose of this study was to prove that knee function is well recovered using gap balancing technique with patient-specific instrumentation（PSI）combined a new balancer device in total knee arthroplasty (TKA) compared with the measured resection technique.Materials and methods：Data of 152 patients received TKA from August 2014 to June 2016 were studied retrospectively. Gap balancing technique assisted by PSI combined a new balance device was used in 80 patients (82 knees) and the measured resection technique was used in the surgery in 70 patients (70 knees). The data of surgery, imaging and knee function were compared. Results：The gap balancing technique assisted by PSI and a new balancer device was feasible in all operated knees and found to be reliable. In total, 152 patients (150 knees) with ages ranging from 52 to 78 years (mean 67 years) underwent TKA during the study period. The follow-up ranged from 35 to 52 months (mean 45 months). Only one patient underwent revision surgery in gap balance group at 2 years postoperatively due to infection. There was no difference in the incidence of anterior knee pain between the two groups. 2 patients received or required revisions. Until the latest follow-up, the mean flexion degree、KSS scores、VAS scores were not significantly different between the measured resection group and gap-balancing group at 12 weeks and 36 weeks. The average joint line displacement in GB group was 1.3 ± 1.1 mm (range 0-3) proximal and 1.2±1.4 mm in MR group. No outliers＞5 mm in each group were recorded. The mean leg axis was 1.8°±1.5°varus (range 0°-3°varus) versus the neutral mechanical axis in GB group and 1.4°±1.2°(range 0°-3°)in MR group. No outliers with＞ 3° deviation in each group were recorded.Conclusions：The gap balancing technique assisted by the new balancer device and PSI can be used to achieve accurate femoral component alignment as well as measured resection in 3 years outcomes. The new balancer device can be taken into account by surgeons who prefer the gap-balancing technique together with the PSI.