Patient-specific Guides Do Not Improve Accuracy in Total Knee Arthroplasty: A Prospective Randomized Controlled Trial

Abstract

Background Recently, patient-specific guides (PSGs) have been introduced, claiming a significant improvement in accuracy and reproducibility of component positioning in TKA. Despite intensive marketing by the manufacturers, this claim has not yet been confirmed in a controlled prospective trial. Questions/purposes We (1) compared three-planar component alignment and overall coronal mechanical alignment between PSG and conventional instrumentation and (2) logged the need for applying changes in the suggested position of the PSG. Methods In this randomized controlled trial, we enrolled 128 patients. In the PSG cohort, surgical navigation was used as an intraoperative control. When the suggested cut deviated more than 3°from target, the use of PSG was abandoned and marked as an outlier. When cranial-caudal position or size was adapted, the PSG was marked as modified. All patients underwent long-leg standing radiography and CT scan. Deviation of more than 3°from the target in any plane was defined as an outlier. Results The PSG and conventional cohorts showed similar numbers of outliers in overall coronal alignment (25% versus 28%; p = 0.69), femoral coronal alignment (7% versus 14%) (p = 0.24), and femoral axial alignment (23% versus 17%; p = 0.50). There were more outliers in tibial coronal (15% versus 3%; p = 0.03) and sagittal 21% versus 3%; p = 0.002) alignment in the PSG group than in the conventional group. PSGs were abandoned in 14 patients (22%) and modified in 18 (28%). Conclusions PSGs do not improve accuracy in TKA and, in our experience, were somewhat impractical in that the procedure needed to be either modified or abandoned with some frequency. Level of Evidence Level I, therapeutic study. See instructions for authors for a complete description of levels of evidence.

Handheld Navigation Device and Patient-Specific Cutting Guides Result in Similar Coronal Alignment for Primary Total Knee Arthroplasty: a Retrospective Matched Cohort Study

“…Pfitzner et al reported similar findings, with tibial component alignment of 1.0°, with a 3% outlier (±3°from neutral) rate, and femoral component alignment of 1.0°, with a 3% outlier (±3°from [32,42]. Some of the variability in results may relate to particular surgical methods or to the reference standard used to assess error.…”

“…For example, in the present study, the entire femoral preparation was completed first in order to optimize placement of the tibial cutting guide. Further, some studies used postoperative imaging as the reference standard [34], while others used intra-operative assessments based on computer-assisted navigation instruments [21,32,42]. In the sagittal plane, the KA2 group achieved an average slope closer to 3°of posterior slope (2.7°) compared to the VISIONAIRE group (4.4°).…”

“…Compared to computed tomography (CT)-based PSI, MRI-based PSI accounts for residual articular cartilage, which may allow more accurate fit of the PSI cutting guides on the femur and tibia intra-operatively [20]. Yet, studies specific to VISIONAIRE PSI report conflicting results [9,10,21,32,33,42].…”

Patient-specific computed tomography based instrumentation in total knee arthroplasty: a prospective randomized controlled study

“…Our study was designed to verify the utility of CT-based Signature™ PSI for precise implant positioning. In general, results of studies on PSI are equivocal [8,15,[25][26][27][28]. We believe that results obtained with one particular PSI system are not automatically applicable to other systems and should not be generalised [14,23].…”

“…Particular systems differ in terms of shape and contact areas between the guide and bone. Finally, there are magnetic resonance imaging (MRI)-and CT-based custom guides available [17], and in some systems, pre-operative standing AP X-ray of the entire leg is required to fabricate PSI [26]. In the Signature™ system, which was the subject of this paper, pinning guides are used to restore mechanical axis, and both MRI and CT scans may be used.…”