Comparable clinical outcome and implant longevity after CT- or MRI-based patient-specific instruments for total knee arthroplasty: a 2-year follow-up of a RCT

Abstract

Purpose Patient‐specific instruments (PSI) are already widespread used in total knee arthroplasty (TKA). Either computed tomography (CT) scans or magnetic resonance imaging (MRI) scans are used pre‐operatively to create jigs to guide resection during surgery. This study is a sequel of previous work that showed significantly more radiological outliers for posterior slope when CT‐based guides were used. The aim of this study was to assess differences in revision rate and clinical outcome between the two groups at 2‐year follow‐up. Methods At the 2‐year follow‐up, 124 patients were analysed in this prospective, randomised single‐blind study. A survival analysis with revision of the TKA as endpoint was performed. Patients fulfilled four patient‐reported outcome measurements (PROMs). Scores on the questionnaires were compared between both groups at the different follow‐up visits. Results At final follow‐up, there was no significant difference in the survival rates of the CT‐ and MRI‐based PSI surgery. Postoperatively, the PROMs significantly improved within each group compared with the pre‐operative values. There were no significant differences for the PROMs between both groups at the 2‐years follow‐up. Conclusions Although previous results showed more outliers regarding posterior slope for CT‐based PSIs, no difference in revision rate or the outcome of PROMs was found at 2‐year follow‐up. Further research to determine what the influence is of radiological outliers on implant survival and clinical outcomes is necessary. Level of evidence I.

Patient-specific instrumentation in total knee arthroplasty: a review of the current literature

“…One patient in each group had to undergo revision surgery, due to progressive valgus instability and respectively a broken bearing. In both groups the patient reported outcome measures showed a significant improvement with the preoperative values, but no difference between the groups were found 32 .…”

“…However no significant differences were found in Patient Reported Outcome und Experience Measures (PROM: OKS, WOMAC, VAS, EQ-5D). The PROMs improved significantly within each group compared with preoperative values 32 .…”