Missingness map. x-axis: outcome variables: gender, age, Visual Analogue Scale (VAS) for pain, Oxford Knee Score (OKS) for function, and EQ5D for quality of life at preoperative baseline and three, six, and twelve months follow-up. y-axis: data points missing at random (12%) due to patients lost-to-follow-up: missing data have been estimated probabilistically with uncertainty using the statistical software package Amelia v1.7.6 or higher. The estimation procedure is replicable and reproducible with Open Access statistical software R (4.0.0 or higher). The missingness map shows the missing data fields in our dataset. All patients have a preprocedure and 1 year VAS for pain as seen on the right-hand column of the plot. The left-hand column then the missing OKS and EQ5D.