Postoperative CAC can be in added value in patients following an outpatient surgery pathway for TKA, resulting in reduced experienced pain and consumption of opioids during the first postoperative days.

I.

Prospective cohort study, Level II.

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.