**3. Age**

The incidence of hip arthroscopy for older adults has grown exponentially along the last 2 decades. An increase of 280% in incidence of hip arthroscopy has been observed in the United States from 2005 to 2014 in the Medicare population, with 8100 primary hip arthroscopies performed [10].

Two variables are considered when studying hip arthroscopy results in older patients: 1) Improvement on functional scores; 2) Conversion rate to THA. A randomized controlled trial by Martin et al. compared hip arthroscopy and physical therapy versus physical therapy alone for patients older than 40 years with limited osteoarthritis (Tönnis grades 0–2) [11]. Arthroscopic acetabular labral repair with postoperative physical therapy led to better outcomes than physical therapy alone [11]. Martin et al. also reported a cross-over rate of 64% for patients from the non-surgical group to the hip arthroscopy group after 14 weeks, i.e., 64% of patients needed surgery after unsuccessful physical therapy [11]. Horner et al., in a systematic review published in 2017, concluded that patients over 40 years-old undergoing hip arthroscopy including femoral osteochondroplasty and labral repair presented clinically significant improvements in most research studies, whereas labral debridement did not produce clinically significant improvements postoperatively [12]. In a clinical scenario, the clinician should consider the difference in "normal" values for functional hip scores according to the age when making treatment recommendations or comparing results. Sharfman et al. compared the patient-reported outcomes measures among 3 different age groups for non-symptomatic individuals: <40 years, 40 to 60 years, and > 60 years [13]. The iHOT, mHHS, HOS-ADL, and HOS-Sport of these asymptomatic respondents all decreased in an age-dependent manner: iHOT (<40, 94.1; 40–60, 92.4; >60, 87.0), mHHS (<40, 94.8; 40–60, 91.3; >60, 89.1), HOS-ADL (<40, 98.4; 40–60, 95.0; >60, 90.9), and HOS-Sport (<40, 95.7; 40–60, 82.9; >60, 72.9) [13]. The authors stressed the importance of comparing a patient's outcome scores with the age-normalized scores to establish an accurate reference frame with which to interpret outcomes [13]. In advancing age, the hip function grows in importance to maintain mental and general health.

The conversion rate to THA after hip arthroscopy is another factor to consider when recommending hip arthroscopy to older patients. According to Malik et al., the native hip was preserved at 2 years after surgery in 81.5% Medicare patients who underwent primary hip arthroscopy between 2005 and 2014 [10]. Patients >65 years had a 20% THA rate versus a 15% THA rate for below 65years of age at 2 years after

the hip arthroscopy [10]. Horner et al., in a systematic review, reported a rate of conversion to THA of 18.1% for patients 40 or older, 23.1% for patients over 50, and 25.2% for patients over 60 with a mean of 25.0 months to THA [12].

Age should not be used as an isolated criterium to recommend one or another hip treatment, since significant variability is observed among patients of same age in overall health status, comorbidities, physical activities, requirements, and patient's expectations.
