The baseline assessment appointments will occur within one month of the initial approach. At the baseline appointment patients will meet with the research coordinator and the independent research assistant/tester (physical therapist) who will be the blinded tester. Patients will return their signed informed consent form and baseline questions completed. Those who are not willing to participate in the RCT (HIPARTI Study), will be asked if interested in being included in a prospective longitudinal cohort study including similar baseline and follow-up tests as those in the RCT (this will be the HARP Study with separate papers published). All patients in the HARP Study will undergo hip arthroscopy surgery. The Australian site will include most of their patients in the HARP Study, since the majority of orthopedic surgeons working privately will not participate in the HIPARTI Study. Data collection will be performed electronically for both the HIPARTI and the HARP Studies entering all data in the approved Checkware system (www.checkware.no).