A double-blind randomized controlled trial of total knee replacement using patient-specific cutting block instrumentation versus standard instrumentation

Abstract

Background: Patient-specific cutting blocks in total knee arthroplasty have been promoted to improve mechanical alignment, reduce alignment outliers and improve patient outcomes. The aim of this study was to compare the efficacy of patient-specific instrumentation (PSI) and conventional instrumentation (CI) in achieving neutral alignment and accurate component positioning in total knee arthroplasty.

Methods: We conducted a double-blinded randomized controlled trial in which patients were randomly assigned to treatment with either PSI or CI.

Results: Fifty-four patients were included in the study. No relevant improvement in coronal alignment was found between the PSI and CI groups with post-hoc power of 0.91. Tibial slope was found to be more accurately reproduced to the preoperative target of 3° with PSI than with CI (3.8°± 3.1° v. 7.7°± 3.6°, respectively, p < 0.001). There were no differences found in patient-reported outcome measures, surgical time or length of hospital stay.

Conclusion: Given the added cost of the PSI technique, its use is difficult to justify given the small improvement in only a single alignment parameter.

Clinical trial registration: Clinicaltrials.gov, no. NCT03416946

Conflict of interest statement

T. Turgeon and D. Hedden are consultants with Smith & Nephew. Smith & Nephew supplied the cutting blocks used in the study. No other competing interests were declared.

© 2019 Joule Inc. or its licensors

Figures

Fig. 1

Coronal hip–knee–ankle (HKA) angle and coronal implant alignment. Black lines show the width and centre points of the hip, femoral condyles, tibial plateau and ankle. Dark grey lines demarcate the tibial mechanical axis and base-plate alignment. Light grey lines demarcate the femoral mechanical axis and femoral component alignment. The intersection of the femoral and tibial mechanical axes is the HKA angle.

Fig. 2

Sagittal femoral and tibial component alignment. The femoral component alignment is the angle subtended in light grey. The tibial component alignment is the intersection of the black and white lines.