Background <p>The PAtellar Resurfacing compared to selective patellar resurfacing Trial (PART) is a randomised controlled trial (RCT) to evaluate the clinical and cost-effectiveness of selective patellar resurfacing (intraoperative decision by surgeon) compared to always patellar resurfacing in patients undergoing elective primary total knee replacement (TKR). This paper presents the PART statistical analysis plan, detailing the trial analysis and presentation plan. The proposed analysis follows recommendations from the International Council for Harmonisation guideline on Good Clinical Practice and “Guidelines for the Content of Statistical Analysis Plans in Clinical trials” and are in line with the Consolidated Standards of Reporting Trials.</p> Methods/design <p>PART is a multi-centre, randomised, blinded, pragmatic parallel two-group superiority RCT aiming to recruit 990 patients undergoing primary TKR. The primary outcome is the Oxford Knee Score (OKS) 12 months after TKR surgery. The planned statistical analyses of the trial primary and secondary outcomes are described in detail, including approaches to deal with the following: missing data, multiple testing, violation of model assumptions, withdrawals from the trial, non-adherence with the treatment and other protocol deviations.</p> Discussion <p>This manuscript prospectively describes, prior to the completion of data collection and database lock, the analyses to be undertaken for the PART trial to reduce the risk of reporting bias and data-driven analyses.</p> Trial registration <p>The trial was registered as ISRCTN33276681 on 27 Feb 2023, before recruitment began.</p>