Abstract
Summary
Alignment results did not differ between PSG and conventional instrumentation. A small reduction in operation time and blood loss was found with the PSG system, but is unlikely of clinical significance. Length of hospital stay was identical for both groups.
Introduction
Several techniques for aligning a TKA exist nowadays. Patient-specific guiding (PSG) has relatively recently been introduced to try to resolve the shortcomings of existing techniques while optimising the operative procedure. Still few reports have been published on the clinical outcome and on the peroperative results of this new technique. This prospective, double-blind, randomised controlled trial was designed to address the following research questions: 1. Is there a significant difference in outliers in alignment in the frontal and sagittal plane between PSG TKA and conventional TKA. 2. Is there a significant difference in operation time, blood loss and length of hospital stay between the 2 techniques.
Patients & Methods
180 patients were randomised for PSG TKA (group 1) or conventional TKA (group 2) in 2 centres. Patients were stratified per hospital. Alignment of the mechanical axis of the leg and flexion/extension and varus/valgus of the individual prosthesis components were measured on digital, standing, long-leg and standard lateral radiographs by 2 independent outcome assessors in both centres. Percentages of outliers, > 3°, were determined. We compared blood loss, operation time and length of hospital stay.
Results
There was no statistically significant difference in mean mechanical axis or outliers in mechanical axis between groups. No statistically significant difference was found for the alignment of the individual components in the frontal plane, nor for the percentages of outliers. There was a statistically significant difference in outliers for the femoral component in the sagittal plane, with a higher percentage of outliers in the group 1 (p = 0.017). No such significant result was found for the tibial component in that plane. All interclass correlation coefficients were good. Blood loss was 100 mL less in group 1 (p = 0.000). Operation time was 5 minutes shorter in group 1 (p = 0.000). Length of hospital stay was almost identical with a mean of 3.6 days (p = 0.657).
Discussion/Conclusions
The results in terms of obtaining a neutral mechanical axis and a correct position of the prosthesis components did not differ between groups. A small reduction in operation time and blood loss was found with the PSG system, but is unlikely of any clinical significance. Future research should especially focus on cost-effectiveness analysis and functional outcome of PSG TKA.
