Patient-reported outcomes of periacetabular osteotomy from the prospective ANCHOR cohort study

Transcription

1 Washington University School of Meicine Digital Open Access Publications 2017 Patient-reporte outcomes of periacetabular osteotomy from the prospective ANCHOR cohort stuy John C. Clohisy Washington University School of Meicine in St. Louis Jeffrey Ackerman Washington University School of Meicine in St. Louis Geneva Baca Washington University School of Meicine in St. Louis Jack Baty Washington University School of Meicine in St. Louis Paul E. Beaule Washington University School of Meicine in St. Louis See next page for aitional authors Follow this an aitional works at: Recommene Citation Clohisy, John C.; Ackerman, Jeffrey; Baca, Geneva; Baty, Jack; Beaule, Paul E.; Kim, Young-Jo; Millis, Michael B.; Poeszwa, Davi A.; Schoenecker, Perry L.; Sierra, Rafael J.; Sink, Ernest L.; Sucato, Daniel J.; Trousale, Robert T.; an Zaltz, Ira,,"Patient-reporte outcomes of periacetabular osteotomy from the prospective ANCHOR cohort stuy." The Journal of Bone an Joint Surgery.99, (2017). This Open Access Publication is brought to you for free an open access by Digital It has been accepte for inclusion in Open Access Publications by an authorize aministrator of Digital For more information, please contact

2 Authors John C. Clohisy, Jeffrey Ackerman, Geneva Baca, Jack Baty, Paul E. Beaule, Young-Jo Kim, Michael B. Millis, Davi A. Poeszwa, Perry L. Schoenecker, Rafael J. Sierra, Ernest L. Sink, Daniel J. Sucato, Robert T. Trousale, an Ira Zaltz This open access publication is available at Digital

3 33 COPYRIGHT Ó 2017 BY THE JOURNAL OF BONE AND JOINT SURGERY, INCORPORATED Patient-Reporte Outcomes of Periacetabular Osteotomy from the Prospective ANCHOR Cohort Stuy John C. Clohisy, MD, Jeffrey Ackerman, MD, Geneva Baca, BA, Jack Baty, MS, Paul E. Beaulé, MD, FRCSC, Young-Jo Kim, MD, PhD, Michael B. Millis, MD, Davi A. Poeszwa, MD, Perry L. Schoenecker, MD, Rafael J. Sierra, MD, Ernest L. Sink, MD, Daniel J. Sucato, MD, Robert T. Trousale, MD, an Ira Zaltz, MD, on behalf of the ANCHOR Stuy Group Investigation performe at Washington University, St. Louis, Missouri Backgroun: Current literature escribing the periacetabular osteotomy (PAO) is mostly limite to retrospective case series. Larger, prospective cohort stuies are neee to provie better clinical evience regaring this proceure. The goals of the current stuy were to (1) report minimum 2-year patient-reporte outcomes (pain, hip function, activity, overall health, an quality of life), (2) investigate preoperative clinical anisease characteristics as preictors of clinical outcomes, an (3) report the rate of early failures an reoperations in patients unergoing contemporary PAO surgery. Methos: A large, prospective, multicenter cohort of PAO proceures was establishe, an outcomes at a minimum of 2 years were analyze. A total of 391 hips were inclue for analysis (79% of the patients were female, an the average patient age was 25.4 years). Patient-reporte outcomes, conversion to total hip replacement, reoperations, an major complications were ocumente. Variables with a p value of 0.10 in the univariate linear regressions were inclue in the multivariate linear regression. The backwar stepwise selection metho was use to etermine the final risk factors of clinical outcomes. Results: Clinical outcome analysis emonstrate major clinically important improvements in pain, function, quality of life, overall health, an activity level. Increasing age an a boy mass inex status of overweight or obese were preictive of improve results for certain outcome metrics. Male sex an mil acetabular ysplasia were preictive of lesser improvements in certain outcome measures. Three (0.8%) of the hips unerwent early conversion to total hip arthroplasty, 12 (3%) require reoperation, an 26 (7%) experience a major complication. Conclusions: This large, prospective cohort stuy emonstrate the clinical success of contemporary PAO surgery for the treatment of symptomatic acetabular ysplasia. Patient anisease characteristics emonstrate preictive value that shoul be consiere in surgical ecision-making. Level of Evience: Therapeutic Level IV. See Instructions for Authors for a complete escription of levels of evience. Peer review: This article was reviewe by the Eitor-in-Chief an one Deputy Eitor, an it unerwent bline review by two or more outsie experts. It was also reviewe by an expert in methoology an statistics. The Deputy Eitor reviewe each revision of the article, an it unerwent a final review by the Eitor-in-Chief prior to publication. Final corrections an clarifications occurreuring one or more exchanges between the author(s) an copyeitors. Avariety of hip-preservation proceures have been evelope an propose for the treatment of symptomatic acetabular ysplasia 1-6. In 1988, Ganz an colleagues introuce the Bernese periacetabular osteotomy (PAO) for acetabular reorientation 2. This proceure is performe through 1 incision, maintains posterior column integrity, preserves the acetabular bloo supply, enables powerful multiplanar acetabular reorientation, an provies reliable Disclosure: This work was supporte in part by Awar UL1RR from the National Center for Research Resources (J.C.C.). It was also supporte in part by the Curing Hip Disease Fun (J.C.C.), the ANCHOR Fun, Smith & Nephew (J.C.C.), an the NFL Charities (J.C.C.). On the Disclosure of Potential Conflicts of Interest forms, which are provie with the online version of the article, one or more of the authors checke yes to inicate that the author ha a relevant financial relationship in the biomeical arena outsie the submitte work. Disclaimer: The content of this article is solely the responsibility of the authors anoes not necessarily represent the official views of the National Center for Research Resources or the National Institutes of Health. J Bone Joint Surg Am. 2017;99:

4 34 Fig. 1 Summary of the ANCHOR PAO cohort stuy. healing 1,2,7-16. Nevertheless, the publishe clinical evience regaring this proceure is mostly limite to single-surgeon or single-institution retrospective case series 17. Controversy remains relative to surgical inications, consistency of clinical outcomes, preictors of treatment results, survivorship, an generalizability of the proceure. Therefore, there exists a major nee for large, prospective patient cohorts in investigations of PAO surgery. Given the major nee for better clinical evience to guie surgeon an patient ecision-making, we evelope a multicenter hip preservation stuy group, name ANCHOR (Acaemic Network of Conservational Hip Outcomes Research). Patient enrollment an comprehensive ata collection began in , an to ate, we have enrolle 1,393 PAO patients. We recently complete minimum 2-year follow-up on our first 478 hips (the PAO-1 cohort). This ata set is the source for the current report (Fig. 1). The purposes of the current stuy were to (1) report minimum 2-year patient-reporte outcomes (pain, hip function, activity, overall health, an quality of life), (2) investigate preoperative clinical anisease characteristics as preictors of clinical outcomes, an (3) report the rate of early failures an reoperations among patients unergoing contemporary PAO surgery. Methos Patient Selection This multicenter, prospective, observational cohort stuy was approve by each participating institution s institutional review boar. From January 1, 2008, to December 31, 2010, 11 surgeons at 8 North American meical centers prospectively enrolle 478 consecutive hips (445 patients) treate with PAO (the PAO-1 cohort). All participating surgeons have experience in PAO surgery 19. All patients were offere stuy participation. Patients were inclue if they unerwent a PAO for the treatment of symptomatic acetabular ysplasia. Fifty-four hips (53 patients) that unerwent a PAO for other iagnoses were exclue, as was 1 hip (1 patient) that unerwent revision PAO (Fig. 1). After exclusions, there were 423 hips (391 patients) available for inclusion. For multivariate analysis, 32 aitional hips were exclue to avoi bias because they unerwent stage bilateral proceures. For these patients, ata regaring the first hip treate were use in statistical analyses. This create our stuy cohort of 391 hips (391 patients). Sixteen of the patients (16 hips) were lost to follow-up an 4 patients (4 hips) withrew. Therefore, 371 (95%) of the 391 eligible patients (hips) were available for the minimum 2-year follow-up (mean follow-up, 2.6 years; range, 2.0 to 5.4 years) (Fig. 1). Stuy Population Of the inclue 391 patients (391 hips), 308 (79%) were female an 83 (21%) were male. The average age at surgery was 25.4 years (range, 10.2 to 53.6 years). The average boy mass inex (BMI) was 24.9 kg/m 2 (range, to kg/ m 2 ); 113 (29%) of the patients were overweight (BMI of 25 to <30 kg/m 2 ), an 54 (14%) of the patients were obese (BMI of 30 kg/m 2 ). Fifty-nine (15%) of the hips ha previously unergone ipsilateral hip surgery (Tables I an II). At the time of PAO, 70 hips unerwent concomitant hip arthroscopy an 233 ha TABLE I PAO Cohort Patient Characteristics* Variable Summary Statistics Age at surgery (yr) 25.4 ± 9.5 ( ) Male 83 (21%) Right hip 230 (59%) Caucasian 343 (88%) BMI (kg/m 2 ) 24.9 Normal (<25 kg/m 2 ) 224 (57%) Overweight (25 to <30 kg/m 2 ) 113 (29%) Obese ( 30 kg/m 2 ) 54 (14%) Comorbiities Depression 50 (13%) Back pain 89 (23%) Diabetes 2 (0.5%) Previous ipsilateral hip surgery 59 (15%) *Stuy cohort of 391 patients (391 hips). The values are presente as the mean an, for age, the stanareviation with the range in parentheses. The values are presente as the number, with the percentage in parentheses.

5 35 TABLE II Prior Ipsilateral Proceures in the PAO Cohort* Total no. of patients with prior ipsilateral hip surgery Proceure Pelvic osteotomy 22 (37%) Hip arthroscopy 18 (31%) Other 17 (29%) Proximal femoral osteotomy 13 (22%) Open reuction 13 (22%) Close reuction 6 (10%) Acetabuloplasty 3 (5%) Shelf proceure 2 (3%) Limite open osteochonroplasty 2 (3%) Capsulorrhaphy 2 (3%) Surgical islocation 1 (1.7%) Acetabular osteochonroplasty 1 (1.7%) PAO 1 (1.7%) Open reuction/capsulorrhaphy 1 (1.7%) Labral repair/refixation 1 (1.7%) *Stuy cohort of 391 patients (391 hips). Inclues patients with prior bilateral surgery. The values are given as the number of patients, with the percentage of patients who unerwent the prior ipsilateral hip surgery in parentheses. aitional proceures other than arthroscopy (not incluing isolate open arthrotomy) (Table III). Data Collection After proviing informe consent for participation in this stuy, patients were given a comprehensive series of questionnaires (see Appenix) 18. Patient emographics, meical comorbiities, social history, an previous hip surgery were ocumente (Table I). The patient-reporte outcome measures inclue the moifie Harris hip score (mhhs) 20 to assess pain an function; the Hip Disability an Osteoarthritis Outcome Score (HOOS), with 5 subscores 21,22 to evaluate lower-extremity function, activity, an quality of life; the University of California, Los Angeles (UCLA) score 23 to assess activity level; an the Short Form (SF)-12 Health Survey to measure overall health (version 2, SF-12v2) 24. Patients also self-reporte their overall satisfaction with surgery, by answering the question, What is your satisfaction level with your surgery? Response options inclue extremely satisfie, very satisfie, satisfie, somewhat satisfie, an unsatisfie. Telephone interviews were attempte for all patients who ha not been seen in the clinic. Three-hunre an twenty (82%) of the patients ha complete clinical an raiographic follow-up, while 51 (13%) of the patients ha telephone follow-up. Surgeons also ocumente preoperative iagnoses, finings of a physical examination, raiographic parameters, surgical proceure etails, operative finings, an postoperative treatments for each patient (see Appenix) 18. Preoperative an follow-up raiographs inclue, at minimum, staning or supine anteroposterior pelvic, frog, or Dunn lateral an false profile raiographs 18. In this report, we focus on the ifference between preoperative an postoperative acetabular inclination 25, anterior center-ege angle (A-CEA) 26, lateral center-ege angle (L-CEA) 27,Tönnis grae 25, an joint congruity 28 (Table IV). The severity of acetabular ysplasia was categorize as mil (L-CEA of 15 or acetabular inclination [AI] of <10 ), moerate (L-CEA of 5 to <15 or AI of 10 to <20 ), or severe (L-CEA of <5 or AI of 20 ) accoring to the consensus of the authors 29,30. Intraoperative isease classification was recore prospectively Surgical Treatment All patients unerwent a PAO using the basic technique escribe by Ganz et al. 2, but etails of the surgical technique were left to the iscretion of the surgeon. Acetabular reuction was assesse with intraoperative raiography. Aitional ipsilateral proceures were performe if the surgeon ecie it was necessary to optimize the hip reconstruction (Table III). All failures, efine as conversion to total hip arthroplasty, reoperations, an major complications, were ocumente prospectively. We previously reporte on complications associate with PAO surgery 19. Major complications were efine as grae III (requiring intervention) or IV (life-threatening or with the potential for permanent isability) accoring to the Dino-Clavien graing scheme 32,33 as moifie an valiate by our group 34,35. Statistical Analysis Continuous variables, with the exception of BMI, Tönnis grae, an some of the intra-articular variables, are reporte as the mean an the stanareviation with the p value an 95% confience interval (CI). BMI, Tönnis grae, an the continuous intra-articular variables were ivie into categories an treate as categorical variables. Categorical variables are reporte as percentages. Changes between preoperative an postoperative values were teste with paire-sample t tests. The relationship between each risk factor an the preoperative to postoperative ifference in each outcome variable was evaluate with simple linear regression. When an outcome ha >1 risk factor with a p value of 0.10, a multiple regression analysis was performe. All risk factors with a p value of 0.10 were initially inclue in the moel. A backwar stepwise metho was then use, removing risk factors with a p value of >0.05 TABLE III Concomitant Proceures at the Time of PAO* Proceure No. Open arthrotomy 300 Arthroscopy 70 Surgical hip islocation 10 Acetabular chonroplasty 14 Acetabular rim osteoplasty 4 Acetabular microfracture 3 Femoral hea/neck osteochonroplasty 230 Femoral hea chonroplasty 7 Femoral hea microfracture 2 Femoral intertrochanteric osteotomy 13 Femoral relative neck lengthening 4 Partial labral resection 27 Labral refixation/repair 22 Ligamentum teres ebriement 8 Trochanteric avancement 3 Proximal femoral osteotomy 2 Psoas lengthening/release 2 Synovectomy 1 Capsuloplasty 1 Capsulorrhaphy 1 Other 8 *Stuy cohort of 391 patients (391 hips). Patients may have ha >1 aitional concomitant proceure to optimize hip reconstruction.

6 36 TABLE IV Preoperative an Postoperative Raiographic Parameters Associate with PAO Preop. (N = 391) Postop. (N = 320) Change (Mean an St. Dev.)* P Value L-CEA Mean (eg) ± 12.4 <0.001 <5 35% 5 to <15 30% 15 35% A-CEA Mean (eg) ± 17.0 <0.001 <5 41% 5 to <15 32% 15 28% Acetabular inclination Mean (eg) ± 10.7 <0.001 <10 5% 10 to <20 36% 20 59% Tönnis classification Grae % 93% Grae 2 8% 6% Grae 3-4 2% 1% Joint congruity Excellent 34% 55% Goo 54% 38% Fair 11% 7% Poor 1% 0% *The change is base on patients with preoperative an postoperative measures. in the multivariate moel, starting with the least significant an rerunning the moel with the remaining risk factors until all remaining inepenent variables ha a p value of The effect of hospital site on the moel was then examine using an inicator variable for each site. Possible interactions between hospital site an the risk factors in the moel were evaluate. The relationship of raiographic parameters an intra-articular variables with outcomes were evaluate in analyses of covariance, with the postoperative outcome variable as the epenent variable, the raiographic parameters an intra-articular measurement as the inepenent variables, an the preoperative scores as the covariate. Results At an average of 2.6 years of follow-up (range, 2.0 to 5.4 years), there were clinically important improvements in all mean patient-reporte outcome measures when compare with preoperative baseline scores (Table V). Three hunre an sixtyfour (93%) of the patients were satisfie with their outcome (55% extremely satisfie, 26% very satisfie, an 12% satisfie). There was a major ecrease in the overall level of pain, which was reflecte by a mean increase (less pain) of 28.3 (95% CI, 25.3 to 30.1) for the HOOS pain subscore (p < 0.001). Hip an lowerextremity function improve markely, as inicate by a mean increase of 23.6 (95% CI, 21.5 to 25.5) for the mhhs an an increase of 21.4 (95% CI, 18.9 to 23.6) for the HOOS activities of aily living subscore (p < for both). The improvement in mhhs was also reflective of patient improvement in mean activity level, which was inicate by mean increases of 0.4 (95% CI, 0.23 to 0.77) for the UCLA score an 30.8 (95% CI, 27.5 to 34.1) for the HOOS sports an recreation subscore. Patients overall quality of life an overall health improve, as reflecte by mean increases of 34.6 (95% CI, 31.4 to 37.0) for the HOOS quality of life score (p < 0.001), 9.2 for the SF-12 physical component summary score (p < 0.001), an 2.2 for the SF-12 mental component summary score (p <0.001). Clinically important changes have been reporte to be 6 to 11 points for the HOOS subscales (0 to 100 points) 22 an 3 to 5 points for the SF-12 subscales (0 to 100 points) 24. Inepenent preictors of patient-reporte outcomes were ientifie with multivariate regression analysis an inclue age, sex, BMI, concomitant ipsilateral proceures, an hospital site (Table VI). Increasing age was preictive of improve postoperative HOOS pain scores. Each aitional year of age was correlate with 0.29 points (95% CI, 0.20 to 0.56 points) of improvement in postoperative pain score (p = 0.04). Male sex was a negative preictor of the ability to perform activities of aily living; male sex was associate with a clinically important ecrease of 9.16 points (95% CI, to 23.18

7 37 TABLE V Preoperative an Postoperative Patient-Reporte Outcomes Associate with PAO* Mean Score Change Preop. Postop. Mean an St. Dev. 95% CI N P Value MCID mhhs ± <0.001 NA UCLA ± NA HOOS Total symptoms ± < Pain ± < Activities of aily living ± < Sports an recreation ± < Quality of life ± < SF-12 Physical component ± < Mental component ± < *Stuy cohort of 371 hips in 371 patients available for minimum 2-year clinical follow-up. The change is base on patients with preoperative an postoperative measures. MCID = minimal clinically important ifference, an NA = not applicable. points) in the HOOS activities of aily living score (p = 0.003). Compare with normal BMI (<25 kg/m 2 ), being overweight (BMI of 25 to <30 kg/m 2 ) was correlate with an improvement of 6.05 (95% CI, 0.08 to 12.03) in the postoperative HOOS pain score (p <0.05), a clinically important improvement of 8.36 (95% CI, 2.73 to 13.99) in the HOOS activities of aily living score (p = 0.004), an an improvement of 8.11 (95% CI, 1.14 to 15.08) in the HOOS quality of life score (p = 0.02). Compare with normal BMI, obesity (BMI of 30 kg/m 2 ) was correlate with a clinically important improvement of 8.81 (95% CI, 1.43 to 16.19) in the HOOS activities of aily living score (p = 0.02) an 3.58 (95% CI, 0.01 to 7.14) in the postoperative SF-12 physical component summary score (p <0.05). Prior ipsilateral surgery was correlate with an improvement of 0.9 (95% CI, 0.1 to 1.7) in the postoperative UCLA score (p = 0.02). An ipsilateral proceure performe at the time of PAO was preictive of an improvement of 5.35 (95% CI, 0.1 to 10.29) in the HOOS total symptoms score (p <0.05) an a clinically important increase of 4.64 (95% CI, 1.8 to 7.49) in the SF-12 physical component summary score (p = 0.001). There was a significant effect of site on the outcomes of the UCLA score an HOOS total symptoms an total pain. Two sites ha significantly lower ifferences between preoperative an postoperative UCLA scores than i the other sites. Aing an inicator variable for the 2 sites to the moel cause the covariate of ipsilateral proceures to become nonsignificant. Although there were significant site effects for the 2 HOOS outcomes, they i not interact with the other variables in the moel an i not affect the interpretation of their effect on outcomes. Baseline ysplasia severity was teste by categorizing the severity of eformity as mil (L-CEA of 15 or AI of <10 ), moerate (L-CEA of 5 to <15 or AI of 10 to <20 ), or severe (L-CEA of <5 or AI of 20 ) (Fig. 2). A strong correlation was ientifie with postoperative mhhs an HOOS pain an sports an recreation scores. While all ysplasia severity categories ha improvements in patient-reporte outcome scores, analyses of covariance emonstrate that patients with severe ysplasia ha greater improvements in the mhhs an HOOS pain an sports an recreation scores when compare with those with milysplasia (p < 0.02). Those with moerate ysplasia also ha a greater improvement in mhhs relative to the mil group (p < 0.02) (Fig. 2). No pairwise ifferences were emonstrate between the ifferent categories of ysplasia severity as categorize by AI. The severity of the preoperative Tönnis grae of osteoarthritis i not correlate with patient-reporte outcome scores. Intraoperative isease classification (labrum an acetabular an femoral hea articular cartilage) showe no correlation with patient-reporte outcomes (ata not shown). At the most recent follow-up, 3 (0.8%) of the hips ha unergone conversion to total hip arthroplasty an 12 (3%) of the hips require reoperation, excluing harware removal. The average age, at the time of surgery, of the patients requiring subsequent total hip replacement was 28.3 years (range, 18 to 35 years), an 2 of the 3 each ha unergone >2 previous ipsilateral hip proceures. Reoperations inclue 8 hip arthroscopies for persistent pain after the PAO. Major complications, classifie as moifie Dino-Clavien grae III or IV were note for 26 (7%) of the hips. Transient nerve palsy was note in 9 (2%) of the cases, 6 with complete resolution. There were 2 cases (0.5%) of pulmonary emboli an 1 (0.3%) eep venous thrombosis (DVT), all treate successfully with anticoagulation. There were 2 cases (0.5%) of eep infection requiring operative ebriement. There were 6 fractures (1.5%). There was 1 islocation requiring close reuction. Four (1%) of the patients experience heterotopic ossification requiring excision. One patient fell, causing loss of fixation that require a return to the operating room for refixation of the mobilize acetabulum.

8 38 TABLE VI Summary of Inepenent Preictors for PAO Outcome Measures* ä Inepenent Preictors of Patient-Reporte Outcomes Age Male Sex Overweight (BMI of 25 to <30 kg/m 2 ) Patient Self-Reporte Outcome Measure HOOS Total symptoms Total pain 0.29 (0.20 to 0.56) (0.08 to 12.03) <0.05 Total activities of ( to 23.18) (2.73 to 13.99) aily living Total quality of life 8.11 (1.14 to 15.08) 0.02 SF-12 physical component *Multivariate analysis base on patient-reporte outcome measures for 371 hips in 371 patients available for minimum 2-year clinical follow-up. UCLA, mhhs, an SF-12 mental component summary scores were not inepenently associate with patient-reporte outcomes. Site 12. Sites 6 an 12. Fig. 2 Baseline ysplasia severity was teste by categorizing the severity of eformity severity as mil (L-CEA of 15 or AI of <10 ) (n = 137 hips), moerate (L-CEA of 5 to <15 or AI of 10 to <20 ) (n= 117 hips), or severe (L-CEA of <5 or AI of 20 ) (n= 137 hips). While all patients ha significant improvement in their patient-reporte outcome scores, analyses of covariance emonstrate that patients with severe ysplasia ha greater improvements in the mhhs, HOOS pain, an HOOS sports an recreation scores when compare with those with milysplasia (p<0.02). Those with moerate ysplasia also ha a greater improvement in mhhs relative to the mil group (p<0.02).

9 39 TABLE VI (continue) Inepenent Preictors of Patient-Reporte Outcomes Obese (BMI of 30 kg/m 2 ) Concomitant Proceures Site Effect 8.81 (1.43 to 16.19) (0.1 to 10.29) < ( to 21.29) (215.8 to 21.81) (0.01 to 7.14) < (1.8 to 7.49) Discussion While several surgical treatment options have been escribe for the treatment of acetabular ysplasia 1,2,7-16, these reports were mostly limite to retrospective single-surgeon or single-institution series 17. In this multicenter, prospective stuy, we report on our first 391 cases followe for a minimum of 2 years. The proceure has been associate with marke improvements in pain, hip/lower-extremity function, an quality of life. Patient activity increase after the PAO, an patient satisfaction with the surgery was very high (93%). The strongest preictors of successful outcomes were female sex, increase age, an the patient being overweight or obese. Our ata introuce several interesting finings relative to clinical preictors of PAO surgical outcomes. Specifically, increasing age was preictive of improve HOOS pain scores (0.29 points per year), an BMI status as overweight an as obese were positive preictors for multiple outcome measures, incluing HOOS pain, activities of aily living, an quality of life scores for the former an activities of aily living an the SF-12 physical component summary score for the latter. These observations were unexpecte, yet they may reflect patient expectations with surgery. It is possible that oler an overweight or obese patients place less eman on the hip an have lower functional expectations. Aitionally, male sex was a preictor of a lower HOOS activities of aily living score, suggesting sex-epenent ifferences in PAO outcomes. Previous stuies have highlighte the morphologic ifferences an potential for poorer outcomes for male patients 36. Current information suggests that male patients are at heightene risk for seconary femoroacetabular impingement (FAI) after PAO 36,37, an this coul negatively impact activities of aily living. Another preictor of suboptimal outcomes was preoperative milysplasia compare with severe ysplasia. While the patients with milysplasia emonstrate major improvements in all patient-reporte outcomes, the improvements were less than those of patients with moerate eformity (mhhs) an those with severe eformity (mhhs, HOOS pain, an HOOS sports an recreation). This fining highlights a very important an unresolve issue in hip-preservation surgery. Patients with milysplasia pose substantial challenges relative to iagnosis, treatment, an surgical ecisionmaking. Symptomatic milysplasia can be associate with other factors that may impact treatment results, incluing excessive femoral torsion an soft-tissue laxity. Precise acetabular reorientation is also challenging in the milly eforme hip, as overcorrection is possible an may lea to post-pao FAI. It is also known that a high percentage of ysplastic hips (incluing milly ysplastic ones) have concurrent femoral eformities associate with FAI an may be at risk for seconary FAI after PAO. Our stuy ha limitations. While all patients were iagnose an treate in a similar fashion, there may have been ifferences among surgeons iagnostic algorithms, treatment inications, an surgical proceure etails. From our analysis of the impact of site on PAO outcomes, 2 sites were emonstrate to have lower outcomes in terms of the UCLA an HOOS symptoms an pain scores. Although there were site effects with these HOOS subscores, they i not interact with other variables in the moel ani not affect their interpretation. Site i have an impact on the UCLA outcome. The aition of an inicator variable for the sites with lower outcomes cause the previously significant covariate of ipsilateral proceures to become nonsignificant, leaving only the site variable in the moel. Aitionally, these were short-term follow-up ata. As this cohort is followe over time, aitional observations will likely assist in the refinement of PAO surgery. The ANCHOR atabase is also primarily focuse on acetabular ysplasia, an measurements of femoral morphology was not reporte an how it contributestohipmechanicsispoorlyunerstoo. Mi-term to long-term outcomes of retrospective PAO cohorts have been reporte. Steppacher et al. reporte on 68 hips followe for an average of 20 years an foun a 60% survivorship rate 15. Poor clinical outcomes as measure by the Merle Aubigné an Postel score were associate with more avance

10 40 age at surgery, the preoperative hip score, a positive anterior impingement test, a limp, the osteoarthrosis grae, an the postoperative extrusion inex. Matheney et al. reporte on 135 hips anocumente a 76% survivorship rate at 9 years 9. Those authors ientifie 2 preictors of failure (efine as total hip replacement or a high pain score) incluing an age of >35 years at the time of surgery or poor/fair preoperative joint congruency. Clohisy et al. performe a systematic review of the literature that encompasse 626 hips followe for an average of 5 years 17. Seventy-nine percent ha a goo or excellent clinical result, 7.3% wereconvertetototalhipreplacement,anthemajorcomplication rate varie from 6% to 37%. Moerate to avance preoperative osteoarthritis was a preictor of poor outcome. It is important to note that these stuies represent the initial experiences with the PAO. Patient selection criteria an surgical technique have evolve substantially over the past 2 ecaes. To our knowlege this prospective, multicenter cohort stuy represents the largest an most comprehensive ata set for contemporary PAO surgery. Our results emonstrate marke improvements in patient-reporte outcomes, spanning pain, function, activity, quality of life, an overall health. Among wellselecte patients treate with soun surgical technique, favorable clinical outcomes can be expecte; the early failure/reoperation rates were low. Continue expansion an follow-up of the ANCHOR PAO cohort will provie high-level clinical evience to further refine an optimize this powerful hip-preservation proceure. Appenix The patient an surgeon questionnaires use in the stuy are available with the online version of this article as a ata supplement at jbjs.org (reprouce from: Clohisy JC, Baca G, Beaulé PE, Kim YJ, Larson CM, Millis MB, Poeszwa DA, Schoenecker PL, Sierra RJ, Sink EL, Sucato DJ, Trousale RT, Zaltz I; ANCHOR Stuy Group. Descriptive epiemiology of femoroacetabular impingement: a North American cohort of patients unergoing surgery. Am J Sports Me Jun;41(6): Epub 2013 May 13). n John C. Clohisy, MD 1 Jeffrey Ackerman, MD 2 Geneva Baca, BA 1 Jack Baty, MS 1 Paul E. Beaulé, MD, FRCSC 3 Young-Jo Kim, MD, PhD 4 Michael B. Millis, MD 4 Davi A. Poeszwa, MD 5 Perry L. Schoenecker, MD 6 Rafael J. Sierra, MD 7 Ernest L. Sink, MD 8 Daniel J. Sucato, MD 5 Robert T. Trousale, MD 7 Ira Zaltz, MD 9 1 Departments of Orthopaeic Surgery (J.C.C. an G.B.) an Biostatistics (J.B.), Washington University School of Meicine, St. Louis, Missouri 2 Illinois Bone & Joint Institute, Chicago, Illinois 3 Ottawa General Hospital, Ottawa, Ontario, Canaa 4 Department of Orthopaeic Surgery, Boston Chilren s Hospital, Boston, Massachusetts 5 Texas Scottish Rite Hospital, Dallas, Texas 6 Shriners Hospitals for Chilren, St. Louis, Missouri 7 Mayo Clinic, Rochester, Minnesota 8 Hospital for Special Surgery, New York, NY 9 Beaumont Hospital, Royal Oak, Michigan aress for J.C. Clohisy: clohisyj@wuosis.wustl.eu aress for J. Ackerman: jackerman@ibji.com aress for G. Baca: bacag@wuosis.wustl.eu aress for J. Baty: jbaty@wubios.wustl.eu aress for P.E. Beaule: pbeaule@toh.on.ca aress for Y.-J. Kim: Young-jo.kim@chilrens.harvar.eu aress for M.B. Millis: Michael.millis@tch.harvar.eu aress for D.A. Poeszwa: Davi.poeszwa@tsrh.org aress for P.L. Schoenecker: pschoenecker@shrinenet.org aress for R.J. Sierra: Sierra.rafael@mayo.eu aress for E.L. Sink: sinke@hss.eu aress for D.J. Sucato: Dan.sucato@tsrh.org aress for R.T. Trousale: Trousale.robert@mayo.eu aress for I. Zaltz: zaltzira@gmail.com References 1. Clohisy JC, St John LC, Nunley RM, Schutz AL, Schoenecker PL. Combine periacetabular an femoral osteotomies for severe hip eformities. Clin Orthop Relat Res Sep;467(9): Epub 2009 Mar Ganz R, Klaue K, Vinh TS, Mast JW. A new periacetabular osteotomy for the treatment of hip ysplasias. Technique an preliminary results. Clin Orthop Relat Res Jul;232: Ninomiya S, Tagawa H. Rotational acetabular osteotomy for the ysplastic hip. J Bone Joint Surg Am Mar;66(3): Salter RB. The classic. Innominate osteotomy in the treatment of congenital islocation an subluxation of the hip by Robert B. Salter, J. Bone Joint Surg. (Brit) 43B:3:518, Clin Orthop Relat Res Nov-Dec;137: Steel HH. Triple osteotomy of the innominate bone. J Bone Joint Surg Am Mar;55(2): Tönnis D. Surgical treatment of congenital islocation of the hip. Clin Orthop Relat Res Sep;258: Bieermann R, Donnan L, Gabriel A, Wachter R, Krismer M, Behensky H. Complications an patient satisfaction after periacetabular pelvic osteotomy. Int Orthop Oct;32(5): Epub 2007 Jun Hartig-Anreasen C, Troelsen A, Thillemann TM, Søballe K. What factors preict failure 4 to 12 years after periacetabular osteotomy? Clin Orthop Relat Res Nov;470(11): Matheney T, Kim YJ, Zurakowski D, Matero C, Millis M. Intermeiate to longterm results following the Bernese periacetabular osteotomy an preictors of clinical outcome: surgical technique. J Bone Joint Surg Am Sep;92(Suppl 1 Pt 2): Matta JM, Stover MD, Siebenrock K. Periacetabular osteotomy through the Smith-Petersen approach. Clin Orthop Relat Res Jun;363: McKinley TO. The Bernese periacetabular osteotomy: review of reporte outcomes an the early experience at the University of Iowa. Iowa Orthop J. 2003;23:23-8.

11 Murphy SB, Millis MB. Periacetabular osteotomy without abuctor issection using irect anterior exposure. Clin Orthop Relat Res Jul;364: Peters CL, Erickson JA, Hines JL. Early results of the Bernese periacetabular osteotomy: the learning curve at an acaemic meical center. J Bone Joint Surg Am Sep;88(9): Siebenrock KA, Leunig M, Ganz R. Periacetabular osteotomy: the Bernese experience. Instr Course Lect. 2001;50: Steppacher SD, Tannast M, Ganz R, Siebenrock KA. Mean 20-year followup of Bernese periacetabular osteotomy. Clin Orthop Relat Res Jul;466(7): Epub 2008 May Troelsen A, Elmengaar B, Søballe K. Meium-term outcome of periacetabular osteotomy an preictors of conversion to total hip replacement. J Bone Joint Surg Am Sep;91(9): Clohisy JC, Schutz AL, St John L, Schoenecker PL, Wright RW. Periacetabular osteotomy: a systematic literature review. Clin Orthop Relat Res Aug;467 (8): Epub 2009 Apr Clohisy JC, Baca G, Beaulé PE, Kim YJ, Larson CM, Millis MB, Poeszwa DA, Schoenecker PL, Sierra RJ, Sink EL, Sucato DJ, Trousale RT, Zaltz I; ANCHOR Stuy Group. Descriptive epiemiology of femoroacetabular impingement: a North American cohort of patients unergoing surgery. Am J Sports Me Jun;41(6): Epub 2013 May Zaltz I, Baca G, Kim YJ, Schoenecker P, Trousale R, Sierra R, Sucato D, Sink E, Beaulé P, Millis MB, Poeszwa D, Clohisy JC. Complications associate with the periacetabular osteotomy: a prospective multicenter stuy. J Bone Joint Surg Am Dec 3;96(23): Harris WH. Traumatic arthritis of the hip after islocation an acetabular fractures: treatment by mol arthroplasty. An en-result stuy using a new metho of result evaluation. J Bone Joint Surg Am Jun;51(4): Bellamy N, Buchanan WW, Golsmith CH, Campbell J, Stitt LW. Valiation stuy of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic rug therapy in patients with osteoarthritis of the hip or knee. J Rheumatol Dec;15(12): Nilsotter AK, Lohmaner LS, Klässbo M, Roos EM. Hip Disability an Osteoarthritis Outcome Score (HOOS) valiity an responsiveness in total hip replacement. BMC Musculoskelet Disor May 30;4:10. Epub 2003 May Amstutz HC, Thomas BJ, Jinnah R, Kim W, Grogan T, Yale C. Treatment of primary osteoarthritis of the hip. A comparison of total joint an surface replacement arthroplasty. J Bone Joint Surg Am Feb;66(2): Ware J, Jr., Kosinski M, Turner-Bowker D, Ganek B. How to score Version 2 of the SF-12 Health Survey (with a supplement ocumenting Version 1). Lincoln, RI: Quality Metric Incorporate; Tönnis D. Normal values of the hip joint for the evaluation of X-rays in chilren an aults. Clin Orthop Relat Res Sep;(119): Lequesne M, e Seze. [False profile of the pelvis. A new raiographic incience for the stuy of the hip. Its use in ysplasias anifferent coxopathies]. Rev Rhum Mal Osteoartic Dec;28: French. 27. Wiberg G. The anatomy an roentgenographic appearance of a normal hip joint. Acta Chir Scan. 1939(83): Yasunaga Y, Ochi M, Terayama H, Tanaka R, Yamasaki T, Ishii Y. Rotational acetabular osteotomy for avance osteoarthritis seconary to ysplasia of the hip. J Bone Joint Surg Am Sep;88(9): Clohisy JC, Barrett SE, Goron JE, Delgao ED, Schoenecker PL. Periacetabular osteotomy for the treatment of severe acetabular ysplasia. J Bone Joint Surg Am Feb;87(2): Nepple JJ, Martell JM, Kim YJ, Zaltz I, Millis MB, Poeszwa DA, Sucato DJ, Sink EL, Clohisy JC; ANCHOR Stuy Group. Interobserver an intraobserver reliability of the raiographic analysis of femoroacetabular impingement anysplasia using computer-assiste measurements. Am J Sports Me Oct;42(10): Epub 2014 Aug Beck M, Kalhor M, Leunig M, Ganz R. Hip morphology influences the pattern of amage to the acetabular cartilage: femoroacetabular impingement as a cause of early osteoarthritis of the hip. J Bone Joint Surg Br Jul;87 (7): Clavien PA, Sanabria JR, Strasberg SM. Propose classification of complications of surgery with examples of utility in cholecystectomy. Surgery May;111 (5): Dino D, Demartines N, Clavien PA. Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients an results of a survey. Ann Surg Aug;240(2): Sink EL, Beaulé PE, Sucato D, Kim YJ, Millis MB, Dayton M, Trousale RT, Sierra RJ, Zaltz I, Schoenecker P, Monreal A, Clohisy J. Multicenter stuy of complications following surgical islocation of the hip. J Bone Joint Surg Am Jun 15;93 (12): Sink EL, Leunig M, Zaltz I, Gilbert JC, Clohisy J; Acaemic Network for Conservational Hip Outcomes Research Group. Reliability of a complication classification system for orthopaeic surgery. Clin Orthop Relat Res Aug;470(8): Epub 2012 Apr Duncan ST, Bogunovic L, Baca G, Schoenecker PL, Clohisy JC. Are there sexepenent ifferences in acetabular ysplasia characteristics? Clin Orthop Relat Res Apr;473(4): Epub 2015 Jan Ziebarth K, Balakumar J, Domayer S, Kim YJ, Millis MB. Bernese periacetabular osteotomy in males: is there an increase risk of femoroacetabular impingement (FAI) after Bernese periacetabular osteotomy? Clin Orthop Relat Res Feb;469 (2): Clohisy JC, Nunley RM, Carlisle JC, Schoenecker PL. Incience an characteristics of femoral eformities in the ysplastic hip. Clin Orthop Relat Res Jan;467(1): Epub 2008 Nov Robertson DD, Essinger JR, Imura S, Kuroki Y, Sakamaki T, Shimizu T, Tanaka S. Femoral eformity in aults with evelopmental hip ysplasia. Clin Orthop Relat Res Jun;327: Steppacher SD, Tannast M, Werlen S, Siebenrock KA. Femoral morphology iffers between eficient an excessive acetabular coverage. Clin Orthop Relat Res Apr;466(4): Epub 2008 Feb Sugano N, Noble PC, Kamaric E, Salama JK, Ochi T, Tullos HS. The morphology of the femur in evelopmental ysplasia of the hip. J Bone Joint Surg Br Jul;80 (4):711-9.