Abstract Objectives: The purpose of this study is to analyze the trajectory of PROMs following hip preservation surgery using the UK’s Non-Arthroplasty Hip Registry, as well as assess the influence of any potential confounders on this trajectory. Design: Nationwide registry-based cohort study Setting: The UK’s Non-Arthroplasty Hip Registry Participants: Patients who underwent hip preservation surgery with iHOT-12 scores of pre-operative and at least two of the following three timepoints: 6 months, 1 year, and 2 years were included in the study. Main outcome measures: Patient-reported outcome measures (PROMs) trajectory after hip preservation surgery. To analyze the features and the predictors of the trajectory, Latent Growth Curve Modeling (LGCM) was performed. All the values are presented as mean. Results: Overall, 9,845 patients were included in this study. 7,081 patients underwent a hip arthroscopy (HA), and 1,327 patients underwent a periacetabular osteotomy (PAO). For HA, there were significant improvements in iHOT-12 scores from baseline to 6 months [32.2 to 58.2], but no significant change from 6 months to 1 year [mean: 58.0]. There was a significant decrease from 1 year to 2 years [mean: 51.7]. For PAO, there were significant improvements in iHOT-12 scores from baseline to 6 months [31.7 to 56.0], but no significant change from 6 months to 1 year [55.4], and from 1 year to 2 years [51.3]. LGCM showed that BMI and gender had a significant impact on pre-operative PROMs, while age and gender significantly influenced the recovery slope. Moreover, the trajectory of HA and PAO patients demonstrated contrasting changes between males and females in the iHOT-12 scores from 1 year to 2 years after surgery. Conclusions: The trajectory of HA patients does not reach a plateau after 1 year until 2 years, with a decrease in iHOT-12 scores observed from 1 year to 2 years, albeit within the MCID range. BMI, age and gender influenced the trajectory of both HA and PA.