***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background Valid , reliable and responsive Patient-Reported Outcome ( PRO ) question naires for young to middle-aged , physically active individuals with hip and groin pain are lacking . Objective To develop and vali date a new PRO in accordance with the COnsensus-based St and ards for the selection of health Measurement INstruments ( COSMIN ) recommendations for use in young to middle-aged , physically active patients with long-st and ing hip and /or groin pain . Methods Preliminary patient interviews ( content validity ) included 25 patients .  Validity , reliability and responsiveness were evaluated in a clinical study including 101 physically active patients ( 50 women ) ; mean age 36 years , range 18–63 years . Results The Copenhagen Hip and Groin Outcome Score ( HAGOS ) consists of six separate subscales assessing Pain , Symptoms , Physical function in daily living , Physical function in Sport and Recreation , Participation in Physical Activities and hip and /or groin-related Quality of Life ( QOL ) . Test – retest reliability was substantial , with intraclass correlation coefficients ranging from 0.82 to 0.91 for the six subscales . The smallest detectable change ranged from 17.7 to 33.8 points at the individual level and from 2.7 to 5.2 points at the group level for the different subscales . Construct validity and responsiveness were confirmed with statistically significant correlation coefficients ( 0.37–0.73 , p < 0.01 ) for convergent construct validity and for responsiveness from 0.56 to 0.69 , p < 0.01 . Conclusion HAGOS has adequate measurement qualities for the assessment of symptoms , activity limitations , participation restrictions and QOL in physically active , young to middle-aged patients with long-st and ing hip and /or groin pain and is recommended for use in interventions where the patient 's perspective and health-related QOL are of primary interest . Trial registration Clinical Trials.gov Femoroacetabular impingement has been established as an important cause of groin pain and limitation of range of motion in young , active patients and a possible cause for early osteoarthritis of the hip .  Open surgery is a well-recognized approach for treatment and probably the st and ard for most surgeons , but recent reports regarding arthroscopic treatment procedures suggest comparable results . We present a technique that provides a way to securely penetrate the joint capsule and evaluate the clinical results of this technique in patients with femoroacetabular impingement . Between 2004 and 2007 , we prospect ively followed a cohort of 105 hips ( 88 patients ; 60 males , 28 females ) who underwent surgery for symptomatic cam or mixed femoroacetabular impingement . All patients were evaluated for the Nonarthritic Hip Score , clinical parameters , visual analog scale pain score , initial radiographic degenerative changes , and alpha angle .  At a minimum followup of 1.3 years ( average , 2.3 years ; range , 1.3–4.1 years ) , all clinical outcome measures improved . The Nonarthritic Hip Score improved from 56.7 points ( range , 15–92.5 points ) to 84.6 points ( range , 47.5–100 points ) . Nine patients ( 8.6 % ) underwent THA during followup . The outcome measures after arthroscopic therapy for femoroacetabular impingement seem comparable to those reported after open procedures .Level of Evidence : Level IV , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence Objective To determine the association between cam impingement , which is hip incongruity by a non-spherical femoral head and development of osteoarthritis . Methods A nationwide prospect i ve cohort study of 1002 early symptomatic osteoarthritis patients ( CHECK ) , of which st and ardised anteroposterior pelvic radiographs were obtained at baseline and at 2 and 5 years follow-up . Asphericity of the femoral head was measured by the α angle . Clinical ly , decreased internal hip rotation ( ≤20 ° ) is suggestive of cam impingement . The strength of association between those parameters at baseline and development of incident osteoarthritis ( K&L grade 2 ) or end-stage osteoarthritis ( K&L grade s 3 , 4 , or total hip replacement ) within 5 years was expressed in OR using generalised estimating equations . Results At baseline , 76 % of the included hips had no radiographic signs of osteoarthritis and 24 % doubtful osteoarthritis . Within 5 years , 2.76 % developed end-stage osteoarthritis . A moderate ( α angle > 60 ° ) and severe ( α angle > 83 ° ) cam-type deformity result ed in adjusted OR of 3.67 ( 95 % CI 1.68 to 8.01 ) and 9.66 ( 95 % CI 4.72 to 19.78 ) , respectively , for end-stage osteoarthritis . The combination of severe cam-type deformity and decreased internal rotation at baseline result ed in an even more pronounced adjusted OR , and in a positive predictive value of 52.6 % for end-stage osteoarthritis . For incident osteoarthritis , only a moderate cam-type deformity was predictive OR=2.42 ( 95 % CI 1.15 to 5.06 ) . Conclusions Individuals with both severe cam-type deformity and reduced internal rotation are strongly predisposed to fast progression to end-stage osteoarthritis . As cam impingement might be a modifiable risk factor , early recognition of this condition is important Purpose In the diagnosis of femoroacetabular impingement ( FAI ) , magnetic resonance imaging ( MRI ) and X-ray are widely accepted methods for detection . When evaluating the hip head-neck junction using MRI , oblique axial sequences are required . However , the construction and analysis of these images are restricted to specialist radiologists and surgeons in the field of hip joint MRI . This study sought to investigate whether ultrasound , a simple and inexpensive method , can be used as a reliable tool for diagnosing Cam-type FAI . Methods Forty patients , with a mean age of 39 years ( range , 18–61 years ) , were consecutively included in this prospect i ve study , following a diagnosis of Cam-type FAI on an oblique axial MRI .  All patients underwent ultrasound examination in the ventral longitudinal section at 20 ° external rotation , neutral position and 20 ° internal rotation . The alpha angle , anterior offset , offset-ratio , and anterior femoral distance ( AFD ) were measured using MRI and ultrasound . Results No significant differences were detected between the alpha angle on MRI and that using ultrasound in the neutral position or in 20 ° internal rotation , with strong correlations observed between these parameters ( r = 0.67 for neutral position , r = 0.77 for 20 ° internal rotation ) . The Pearson ’s correlation coefficient for the alpha angle on MRI and the ratio of AFD/anterior offset on ultrasound in internal rotation was 0.76 ( p < 0.0001 ) . Conclusions The results show strong correlations between MRI and ultrasound measurements in patients with Cam-type FAI . Consequently , ultrasound may provide a useful tool for the early diagnosis of Cam-type FAI in daily practice Abstract Purpose The purpose of this study was to examine the progression of clinical outcomes 3 , 6 and 12 months after  hip arthroscopy with labral repair for femoroacetabular impingement ( FAI ) . Methods From May 2009 to December 2011 , 87 consecutive patients [ 55 females ( median age 38 , range 17–63 ) and 32 males ( median age 38 , range 15–59 ) ] underwent hip arthroscopy and labral repair , by the same experienced surgeon . St and ardised , but unstructured , post-operative rehabilitation instructions were provided . Function and pain were evaluated using modified Harris Hip Score ( mHHS ) and visual analogue scale ( VAS ) pre-operatively and post-operatively at 3 , 6 , and 12 months . Results A main effect of time was seen for mHHS and pain ( VAS ) at 3 , 6 , and 12 months ( p < 0.001 ) . Mean ( SE ) mHHS improved significantly from 59.9 ( 1.9 ) pre-operatively to 74.5 ( 1.9 ) after 3 months ( p < 0.001 ) , and again from 3 to 6 months from 74.5 ( 1.9 ) to 80.1 ( 1.9 ) ( p = 0.004 ) , with no additional changes from 6 to 12 months [ 80.1 (1.9)–78.7 ( 1.9 ) , ( n.s . ) ] . Also , the mean ( SE ) VAS improved significantly from pre-operative 57.9 ( 2.6 ) to 30.0 ( 2.6 ) after 3 months ( p < 0.001 ) , and from 30.0 ( 2.6 ) to 22.6 ( 2.6 ) ( p = 0.017 ) , after 6 months with no additional changes from 6 to 12 months [ 22.6 (2.6)–27.9 ( 2.6 ) , ( n.s . ) ] . Conclusions Improvements in function ( mHHS ) and pain ( VAS ) were seen in patients after hip arthroscopy with labral repair for FAI at 3 , 6 , and 12 months . While significant improvements occurred from 3 to 6 months , no further improvements were seen from 6 to 12 months . Level of evidence Prospect i ve case series , Level IV Background : Excellent short-term results have been reported after  hip arthroscopic surgery to address femoroacetabular impingement ( FAI ) . Purpose /Hypothesis : The purpose of this study was to determine if patients with narrow joint spaces had inferior outcomes at a postoperative minimum of 5 years and if they had a higher conversion rate to total hip arthroplasty ( THA ) . The hypothesis was that patients with ≤2-mm joint spaces would report inferior outcomes and that patients with > 2-mm joint spaces would have improved survivorship ( no conversion to THA ) . Study Design : Cohort study ; Level of evidence , 3 . Methods : Between March 2005 and January 2008 , prospect ively collected data were analyzed for patients older than 18 years of age undergoing hip arthroscopic surgery for FAI . Radiographic measurements of joint space were collected , and hips were grouped as having preserved ( > 2 mm ) or limited ( ≤2 mm ) joint space . Outcome measures included the Western Ontario and McMaster Universities Arthritis Index ( WOMAC ) , modified Harris Hip Score ( MHHS ) , Hip Outcome Score ( HOS ) for activities of daily living and sports , and Short Form–12 ( SF-12 ) . Results : There were 559 patients included , 466 ( 83 % ) of whom were contacted . Fifty-four patients with limited joint spaces ( 86 % ) converted to THA , while only 63 patients with preserved joint spaces ( 16 % ) converted to THA . The mean survival time for patients with preserved joint spaces was 88 months ( 95 % CI , 85 - 91 months ) , and the mean survival time for patients with limited joint spaces was 40.0 months ( 95 % CI , 33.7 - 46.3 months ) ( P = .0001 ) . Complete follow-up outcome data were available on 323 patients , none of whom had THA , with a mean follow-up of 73 months . The mean postoperative HOS for activities of daily living and sports were significantly better in patients with preserved joint spaces ( 82 vs 62 [ P = .012 ] and 77 vs 47 [ P = .003 ] , respectively ) compared with those with limited joint spaces at a mean of 73 months postoperatively ( range , 60 - 97 months ) . Conclusion : Hip arthroscopic surgery for FAI result ed in significantly better outcomes and activity levels at minimum 5-year follow-up in patients with preserved joint spaces . Hips with limited joint spaces converted to THA earlier than did those with preserved joint spaces Over an eight-month period we prospect ively enrolled 122 patients who underwent arthroscopic surgery of the hip for femoroacetabular impingement and met the inclusion criteria for this study . Patients with bilateral hip arthroscopy , avascular necrosis and previous hip surgery were excluded . Ten patients refused to participate leaving 112 in the study . There were 62 women and 50 men . The mean age of the patients was 40.6 yrs ( 95 % confidence interval ( CI ) 37.7 to 43.5 ) . At arthroscopy , 23 patients underwent osteoplasty only for cam impingement , three underwent rim trimming only for pincer impingement , and 86 underwent both procedures for mixed-type impingement . The mean follow-up was 2.3 years ( 2.0 to 2.9 ) . The mean modified Harris hip score ( HHS ) improved from 58 to 84 ( mean difference = 24 ( 95 % CI 19 to 28 ) ) and the median patient satisfaction was 9 ( 1 to 10 ) . Ten patients underwent total hip replacement at a mean of 16 months ( 8 to 26 ) after arthroscopy . The predictors of a better outcome were the pre-operative modified HHS ( p = 0.018 ) , joint space narrowing > or= 2 mm ( p = 0.005 ) , and repair of labral pathology instead of debridement ( p = 0.032 ) . Hip arth 
    Output:
    
It is not clear when quality of life improvements were first achieved .
On average , residual mild pain and ADL and sport function scores lower than their healthy counterparts were reported by patients following surgery .
Conclusions On average , patients reported earlier pain and ADL function improvements , and slower sport function improvements after hip arthroscopy for FAI .
However , average scores from patients indicate residual mild hip pain and /or hip function lower than their healthy counterparts after surgery .