No difference in mid-term survival and clinical outcome between patient-specific and conventional instrumented total knee arthroplasty: a randomized controlled trial
The purpose of this multicentre prospective randomized controlled trial was to compare the survival rate and clinical outcome in total knee arthroplasty (TKA) after MRI-based patient-specific instruments (PSI) and conventional instruments 5 years after initial surgery.
At a mean follow-up of 5.1 years (0.4), 163 patients (90.6%) with a mean age of 71.8 years (8.7) were analysed. A survival analysis with revision of the TKA as endpoint was performed. The Knee Society Score (KSS), evaluations on plain radiographs and patient-reported outcome measures (PROMs) were obtained preoperatively and at each FU.
At final follow-up, one TKA in the PSI- (1.2%) and 3 TKAs in the conventional group (3.8%) had undergone revision surgery (n.s.). No radiological abnormalities were noted at any time point. Postoperatively, the KSS and PROMs significantly improved within each group compared with the preoperative values. There were no clinically relevant differences for the KSS [PSI: 77.4, 9.8 (95% CI 75.0–79.7) vs. conventional: 77.3 10.5 (95% CI 74.9–79.8)] and the PROMs between both groups (n.s.) at 5 years follow-up.
There is still a lack of reliable data on the survival of TKA and clinical evidence, when using PSI for TKA. Longer follow-up studies are, therefore, needed.
Level of evidence
KeywordsPatient-specific instruments Conventional instruments Total knee arthroplasty Mid-term Survival Randomized controlled trial PROMS TKA RCT PSI
MGMS: Designed the study, gathered and analysed all the data, wrote the initial draft of the manuscript and managed the study. BB: Ensured the accuracy of the data and the analysis, wrote and revised the manuscript. WW: Gathered and ensured the accuracy of the data and revised the manuscript. HH: Designed the study and revised the manuscript. RD: Designed the study and revised the manuscript. RB: Ensured the accuracy of the data and the analysis, wrote and revised the manuscript. RV: Ensured the accuracy of the data and analysis and revised the manuscript. LR: Ensured the accuracy of the data and revised the manuscript. NPK: Conceived the study and revised the manuscript.
No financial support was received for this study.
Compliance with ethical standards
Conflict of interest
One author (NK) is a paid consultant on the PSI surgical technique for Zimmer-Biomet, Europe. The other authors certify that they have no commercial associations (e.g., consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted manuscript.
The study was approved by the ethics committee of Zuyderland-Zuyd, Number 10-T-21.
For this type of study formal informed consent was obtained from each included patient.
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