The Hip Disability and Osteoarthritis Outcome Score (HOOS) questionnaire, developed in 2003 with the purpose of assessing the patients’ view about their hip limited functions, is reliable and validated in Italian. The HOOS is meant to be used over both short and long-time intervals; to assess treatment-induced changes (medication, surgery, physiotherapy) from week to week or over years due to the primary injury or post-traumatic hip osteoarthritis. It is a self-administered questionnaire consisting of 40 items divided into five subscales of assessment relevant to the patient: Pain (P), Symptoms (S), Activity of Daily Living (ADL), Sport and Recreation Function (Sport/Rec) and Hip-Related Quality of Life (QoL). Patients can express their opinion through standardized response options based on the five-point Likert scale (none, mild, moderate, severe, extreme); each answer is scored ranging from zero (no problem) to four (extreme problems). The overall score ranges from 0 (severe disability) to 100 (excellent condition).