BACKGROUND: The Copenhagen Hip and Groin Outcome Score (HAGOS) was recently found valid, reliable, and responsive for patients undergoing hip arthroscopy. However, it is currently unknown to what degree patients undergoing hip arthroscopy improve and/or normalize their HAGOS result within the first year after surgery.

PURPOSE: First, to use HAGOS to evaluate clinical outcomes at 3, 6, and 12 months after hip arthroscopy for femoroacetabular impingement (FAI) and/or labral injury and compare the HAGOS results with the modified Harris Hip Score (mHHS). Second, to explore how many patients would (a) improve to a degree of minimal clinical importance (MIC) and (b) obtain scores within the reference intervals of healthy controls.

STUDY DESIGN: Cohort study; Level of evidence, 2.

METHODS: From September 2011 to March 2014, 97 consecutive patients [56 females (mean age, 38 years; range, 17-60 years) and 41 males (mean age, 37 years; range, 19-59 years)] underwent first-time hip arthroscopy for FAI and/or labral injury. Standardized postoperative rehabilitation instructions were provided. HAGOS (0-100 points) and mHHS (0-100 points) values were obtained preoperatively and again postoperatively at 3, 6, and 12 months. Furthermore, 158 healthy controls, matched on age and sex, were included to obtain HAGOS and mHHS reference values for comparison. Minimal important change was determined by using the 0.5 SD of the baseline values for HAGOS and mHHS.

RESULTS: Improvements for all HAGOS subscales and mHHS results were seen at 3 months ( P < .001). Further improvements were seen only for HAGOS Sport and Recreation (Sport/Rec) and Participation in Physical Activities (PA) subscales between 3 and 12 months ( P < .05) but not for HAGOS Pain, Symptoms, Activities of Daily Living (ADL), or Hip-Related Quality of Life (QOL) subscales or the mHHS. Furthermore, on HAGOS Sport/Rec, PA, and QOL subscales, patients reached scores of only 54 to 70 points 1 year after surgery. At the individual level, up to 70% of the patients experienced minimal important improvements during the first year after surgery, but only up to 38% and 36% of patients reached a score within the reference interval of HAGOS and mHHS, respectively.

CONCLUSION: Statistically and clinically relevant improvements in HAGOS and mHHS results after hip arthroscopy and rehabilitation can be seen at 3 months and up to 1 year. However, specific HAGOS subscales suggest that a patient's ability to function and participate in sport and physical activity is still markedly reduced 1 year after surgery. Furthermore, the majority of patients undergoing hip arthroscopy cannot expect to reach the level of the healthy population on self-reported pain and function within the first year after surgery.