Anteverting Periacetabular Osteotomy for Symptomatic Acetabular Retroversion. Results at Ten Years

Transcription

1 1785 COPYRIGHT Ó 2014 BY THE JOURAL OF BOE AD JOIT SURGERY, ICORPORATED Anteverting Periacetabular Osteotomy for Symptomatic Acetabular Retroversion Results at Ten Years Klaus A. Siebenrock, MD, Clauio Schaller, MD, Moritz Tannast, MD, Marius Keel, MD, an Lorenz Büchler, MD Investigation performe at the Department of Orthopeic Surgery, Inselspital Bern, University of Bern, Bern, Switzerlan Backgroun: Acetabular retroversion is associate with pincer-type femoroacetabular impingement an can lea to hip osteoarthritis. We report the ten-year results of a previously escribe patient cohort that ha corrective periacetabular osteotomy for the treatment of symptomatic acetabular retroversion. Methos: Clinical an raiographic parameters were assesse preoperatively an at two an ten years postoperatively. A Kaplan-Meier survivorship analysis of the twenty-two patients (twenty-nine hips) with a mean follow-up (an stanar eviation) of 11 ± 1 years (range, nine to twelve years) was performe. In aition, a univariate Cox regression analysis was one with conversion to total hip arthroplasty as the primary en point an progression of the osteoarthritis, a fair or poor result accoring to the Merle Aubigné score, or the nee for revision surgery as the seconary en points. Results: The mean Merle Aubigné score improve significantly from 14 ± 1.4 points (range, 12 to 17 points) preoperatively to 16.9 ± 0.9 points (range, 15 to 18 points) at ten years (p < 0.001). There were also significant improvements with regar to hip flexion (p = 0.003), internal rotation (p = 0.003), an auction (p = 0.002) compare with the preoperative status. o significant increase of the mean Tönnis osteoarthritis score was seen at ten years (p = 0.06). The cumulative ten-year survivorship, with conversion to a total hip arthroplasty as the primary en point, was. The cumulative ten-year survivorship in achievement of one of the seconary en points was 71% (95% confience interval, 54% to 88%). Preictors for poor outcome were the lack of femoral offset creation an overcorrection of the acetabular version resulting in excessive anteversion. Conclusions: Anteverting periacetabular osteotomy for acetabular retroversion leas to favorable long-term results with preservation of the native hip at a mean of ten years. Overcorrection resulting in excessive anteversion of the hip an omitting concomitant offset creation of the femoral hea-neck junction are associate with an unfavorable outcome. 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 byan expert in methoologyan statistics. The Deputy Eitor reviewe each revision of the article, an it unerwent a final reviewbythe Eitor-in-Chief prior to publication. Final corrections an clarifications occurreuring one or more exchanges between the author(s) an copyeitors. Pincer-type femoroacetabular impingement, efine as acetabular overcoverage of the femoral hea that leas to an early pathological contact between the prominent acetabular rim an the femoral neck, is an establishe cause of hip pain an osteoarthritis 1-3. Acetabular retroversion is an acetabular morphology that leas to pincer-type femoroacetabular impingement 2-5. It is efine on raiographs by positive crossover 4-6, posterior wall 4, an ischial spine signs 7,8 (see Appenix). There is increasing evience that acetabular retroversion is the result of an externally rotate hemipelvis rather than a local osseous protuberance of the acetabulum The logical surgical treatment of a retroverte acetabulum shoul consist of an anteverting reorientation of the acetabulum by a periacetabular osteotomy (see Appenix). A previous report of the early Disclosure: one of the authors receive payments or services, either irectly or inirectly (i.e., via his or her institution), from a thir party in support of any aspect of this work. One or more of the authors, or his or her institution, has ha a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomeical arena that coul be perceive to influence or have the potential to influence what is written in this work. o author has ha any other relationships, or has engage in any other activities, that coul be perceive to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitte by authors are always provie with the online version of the article. J Bone Joint Surg Am. 2014;96:

2 1786 TABLE I Demographic Data on the Patients Parameter Value Total no. of patients (hips) 22 (29) Bilateral involvement (% of hips) 24 Male patients (% of hips) 66 Age* (yr) 23 ± 8 (14-41) Height* (cm) 174 ± 6 ( ) Weight* (kg) 66 ± 7 (54-74) Boy mass inex* (kg/m 2 ) 22 ± 2 (18-24) Previous surgery (% of hips) 7 Duration of symptoms* (mo) 17 ± 7 (6-24) Concomitant offset correction (% of hips) 83 Os acetabuli (% of hips) 7 Signal alteration of labrum on preop. MRA scan (% of hips) 86 Signal alteration of joint cartilage on preop. MRA scan (% of hips) 24 *The values of continuous parameters are expresse as the mean an the stanareviation, with the 95% confience interval in parentheses. One hip ha ha an intertrochanteric varus osteotomy, an one ha ha surgical hip with offset creation. results of this technique showe a significant improvement of symptoms an hip function 15. However, to ate, no long-term follow-up exists as far as we know. We aske the following questions: (1) Will the clinical measurements (Merle Aubigné score, range of motion, an impingement test) improve in the long-term follow-up? (2) Will the raiographic measures (Tönnis grae of osteoarthritis an morphological hip parameters) be maintaine over time? (3) What is the cumulative mean ten-year survivorship of the hip after anteverting periacetabular osteotomy for symptomatic acetabular retroversion? (4) What are the preictors for a poor outcome or revision surgery? Materials an Methos Aretrospective follow-up stuy of twenty-two consecutive patients (twentynine hips) who ha an anteverting periacetabular osteotomy from April 1997 to August 1999 was performe. This report is a follow-up of a previous report on the two-year results of the same patient cohort publishe in this journal 15. The inications for surgery were (1) clinical finings of femoroacetabular impingement (i.e., hip pain), (2) reproucibility of these symptoms with the impingement test ( ha a positive test), (3) raiographic evience of acetabular retroversion, an (4) chonrolabral amage seen on a magnetic resonance arthrography (MRA) scan (twenty-four of twenty-nine hips). We evaluate the patients clinically an raiographically ten years postoperatively. These results were then compare with the preoperative an two-year follow-up status, an the initial ata were teste for negative preictive factors. This stuy was approve by the local institutional review boar. Patients The proceure was performe in twenty-nine hips in twenty-two consecutive patients (Table I). There were no exclusion criteria. The mean age (an stanar eviation) of the patients at the time of surgery was 23 ± 8 years (range, fourteen to forty-one years). There were thirteen male (nineteen hips; 66%) an nine female patients (ten hips; 34%). Two hips (7%) ha previous surgery. One hip ha unergone an intertrochanteric varus osteotomy, an one hip ha a surgical hip with femoral hea-neck osteochonroplasty. One patient (one hip; 3%) ha Sprengel eformity with macrocephaly. All other patients were otherwise healthy. The iagnosis of femoroacetabular impingement an the inication for surgical treatment were base on a positive correlation among symptoms (typically groin pain), physical finings on examination (in particular, reproucible pain in flexion an internal rotation of the hip), finings of acetabular retroversion on raiographs, an evience of chonrolabral lesions on MRA scans in twenty-four hips. In the remaining five hips, the patients ha a previous MRA scan an corrective periacetabular osteotomy on the contralateral sie for acetabular retroversion. Follow-up Evaluation o patient was lost to follow-up. The mean uration of follow-up was 11 ± 1 years (range, nine to twelve years). Eighteen patients (twenty-five hips; 86%) were evaluate both clinically an raiographically. Two patients (two hips; 7%) were evaluate on a clinical basis only. They ecline a follow-up raiograph because they were pain-free (each ha a Merle Aubigné score of 18 points). Two patients (two hips; 7%) ecline both a clinical an raiographic follow-up an were evaluate by means of a telephone interview only. Since their last follow-up examination two years postoperatively, both ha been entirely asymptomatic an neither ha further hip surgery. Clinical Evaluation The twenty patients (twenty-seven hips) were assesse at the last follow-up evaluation with use of the Merle Aubigné an Postel scoring system 16.Accoring to the Merle Aubigné system, a result was consiere poor when the score was <12 points; fair when it was 12 to 14 points; goo when it was 15, 16, or 17 points; an excellent when it was 18 points. The anterior impingement test (painful flexion an internal rotation of the hip) was assesse. In aition, the full goniometric range of motion an gait were analyze. All parameters were ocumente preoperatively an at two an ten years postoperatively (Table II). Raiographic Evaluation Routine raiographic evaluation consiste of a preoperative anteroposterior pelvic raiograph an a false-profile view. The anteroposterior pelvic raiograph was mae with the patient in the supine position with a stanarize technique escribe earlier 5,6. All but five hips ha a preoperative MRA scan of the hip with intra-articular injection of gaolinium for evaluation of lesions of

3 1787 TABLE II Clinical Results Parameter Preop. Two-Year Postop. Ten-Year Postop. Merle Aubigné score 16 * (points) 14.0 ± 1.4 (12-17) 16.9 ± 0.9 (15-18) 16.6 ± 1.2 (14-18) Positive anterior impingement test (% of hips) Range of motion* (eg) Flexion 99 ± 9 (90-110) 106 ± 8 (90-120) 106 ± 9 (90-124) Internal rotation in 90 of flexion 11 ± 9 (0-26) 21 ± 10 (5-40) 20 ± 10 (0-34) External rotation in 90 of flexion 33 ± 17 (14-70) 35 ± 15 (15-61) 31 ± 10 (12-47) Abuction 35 ± 10 (14-47) 34 ± 7 (20-40) 27 ± 8 (18-42) Auction 22 ± 9 (10-37) 30 ± 4 (24-36) 22 ± 10 (1-45) *The values are expresse as the mean an the stanareviation, with the 95% confience interval in parentheses. Compare with the preoperative status, the ifference was significant (p < 0.05). The ifference between the two an ten-year results was significant (p < 0.05). the cartilage an labrum. The preoperative MRA scan showe labral alterations in all but one patient. Thirteen hips showeegeneration of the labrum, incluing ganglion formation in two an a labral tear in ten hips. In aition, twelve hips showe thinning or signal alterations of the ajacent articular cartilage. In one hip, no specific labral or chonral abnormalities were etecte. At each follow-up evaluation, an anteroposterior pelvic raiograph an a crosstable lateral raiograph of the proximal part of the femur were mae. In orer to escribe the preoperative an postoperative morphologic features of the acetabulum an the femoral hea, thirteen stanar raiographic parameters (see Appenix) were assesse by one observer using previously evelope an valiate computer software (Hip2orm; University of Bern, Bern, Switzerlan) Postoperative raiographic parameters were compare with previously efine normal raiographic values of the acetabulum 20. Evience of osteoarthritis of the hip prior to surgery an progression uring follow-up were grae accoring to the classification system of Tönnis et al. 21. Heterotopic ossifications were grae accoring to the system of Brooker et al. 22. Statistical Analysis We teste normal istribution of all continuous parameters with the Kolmogorov- Smirnov test. The paire Stuent t test was use for comparison of normally istributeata. The Wilcoxon rank-sum test was use to compare ata without normal istribution. Differences between categorical variables were analyze with the Fisher exact test. A survivorship analysis was performe accoring to the Kaplan-Meier metho 23. The primary en point was efine as conversion to total hip arthroplasty. The seconary en points were (1) raiographic progression of the osteoarthritis, (2) a fair or poor score ( 14 points) accoring to the Merle Aubigné system at the latest follow-up evaluation, or (3) any reoperation relate to correction of acetabular coverage or persistent impingement. The univariate Cox proportional-hazars moel was use to etect factors preicting primary an seconary en points an to calculate the corresponing hazar ratios. Hazar ratios were calculate with the 95% confience interval (CI). Source of Funing One author (M.T.) receive funing from the Swiss ational Science Founation. This funing source playe no role in stuy esign, ata collection, analysis, interpretation, writing, or submission of the manuscript. Results Clinical Outcome At a mean of ten years, the Merle Aubigné scorehaimprove significantly compare with the preoperative value Fig. 1 Figs. 1-A, 1-B, an 1-C A sixteen-year-ol female patient with acetabular retroversion. Fig. 1-A The preoperative anteroposterior raiograph showing positive crossover 4, posterior wall 4, an ischial spine signs 7,8. Fig. 1-B The postoperative raiograph mae after the anteverting periacetabular osteotomy. Fig. 1-C At the ten-year follow-up, the Merle Aubigné score was 18 points (excellent) without evience of osteoarthritis.

4 1788 (p < 0.001; Table II). There was no significant ifference in the Merle Aubigné score at two or ten years postoperatively (p = 0.093). Of the twenty-seven hips in twenty patients available for clinical follow-up, six (22%) ha an excellent result accoring to the Merle Aubigné score (Fig. 1); nineteen (70%), a goo result; an two (7%), a fair result. The prevalence of a positive anterior impingement test ecrease significantly at the ten-year follow-up compare with the preoperative status (p < 0.001; Table II). A significant increase in flexion (p = 0.003), internal rotation (p = 0.003), an auction (p = 0.002) was seen at the ten-year follow-up compare with the preoperative status. Comparison of the two an ten-year follow-up results showe a significant ecrease in abuction (p = 0.015) an auction (p < 0.001) (Table II). Raiographic Outcome In comparison with the preoperative status, there was a significant increase in the lateral center-ege angle (p = 0.023), the superior coverage (p < 0.001), an the posterior coverage (p < 0.001) (see Appenix). A significant ecrease was observe for the postoperative extrusion inex (p = 0.016), the presence of the crossover sign (p < 0.001), the retroversion inex (p < 0.001), the posterior wall sign (p < 0.001), the Sharp angle (p = 0.001), an the total anterior coverage (p < 0.001). Although four hips progresse from a Tönnis osteoarthritis score of 0 to 1 at ten years, the overall progression of osteoarthritis was not significant (p = 0.06; see Appenix). Heterotopic ossifications were seen in fourteen hips in thirteen patients (six hips ha grae-1; four, grae-2; an four, grae-3 ossifications). Of those, four hips were rate as having reache an en point. One of the four ha grae-1 ossifications, a fair result accoring to the Merle Aubigné system, an progression of arthritis. Two hips with grae-2 ossifications ha either evience of raiographic progression of osteoarthritis or a fair result in the Merle Aubigné system. One patient with grae-3 heterotopic ossification unerwent excision of the ossifications uring revision surgical of the hip for treatment of a persistent camtype femoroacetabular impingement. Survivorship Analysis o hip ha a conversion to total hip arthroplasty. Eight hips (28%) reache at least one seconary en point. Two of the eight hips ha raiographic progression of osteoarthritis. Two ha raiographic osteoarthritis an a fair or poor Merle Aubigné score. Four patients (four hips; 14%) unerwent a reoperation relate to newly evelope posterior impingement (two hips), persistent anterior impingement (one hip), or loss of correction (one hip). The cumulative ten-year survivorship for the primary an seconary en points was an 71% (95% CI, 54% to 88%), respectively. Among the four reoperations, one patient presente with recurrent symptoms of anterior femoroacetabular impingement at 2.5 years postoperatively. Despite an arthrotomy an offset correction at the time of periacetabular osteotomy, this patient neee subsequent surgical hip with osteochonroplasty of the femoral hea-neck junction (the Merle Aubigné score was 18 points at ten years; see Appenix). One patient with excessive acetabular anteversion an clinical signs of posteroinferior femoroacetabular impingement unerwent trimming of the posterior acetabular wall through a surgical hip 1.6 years postoperatively (a Merle Aubigné score of 17 points at ten years; Fig. 2). The thir patient ha both persistent cam-type femoroacetabular impingement an acetabular overcorrection with resulting posterior femoroacetabular Fig. 2 Figs. 2-A through 2-D An eighteen-year-ol female patient with symptomatic acetabular retroversion. Fig. 2-A Preoperative raiograph. Fig. 2-B Raiograph mae after the anteverting periacetabular osteotomy. Fig. 2-C Four years postoperatively, the patient reporte posterior hip pain. Raiograph mae at that time shows a relatively prominent posterior wall with evelopment of a ouble contour (arrows) as a sign of posterior impingement. Fig. 2-D Raiograph showing the final result after the patient subsequently unerwent surgical hip with trimming of the posterior wall an partial screw removal one year later.

5 1789 TABLE III Comparison of Clinical Results at a Mean Follow-up of at Least Two Years After Different Treatments for Femoroacetabular Impingement Stuy Mean Follow-up Perio (Range) (yr) Type of Impingement o. of Patients (Hips) Type of Surgery Scoring Systems* Results Survivorship Rate ) Siebenrock et al. 15 (2003) 2.5 (2-4) Retroversion 22 (29) Periacetabular osteotomy Merle Aubigné 26 hips (90%) were grae goo to excellent; 3 hips ha subsequent surgery Tannast an Siebenrock 31 (2010) 5.1 (2-7.1) Mixe 100 (108) Surgical hip Merle Aubigné 91% ha goo to excellent results, epening on preop. osteoarthritis 91% Steppacher et al. 30 (2014) Beck et al. 1 (2004) Murphy et al. 32 (2004) Peters et al. 38 (2010) aal et al. 39 (2011) aal et al. 33 (2012) Chiron et al. 40 (2012) Lincoln et al. 41 (2009) Laue et al. 42 (2009) Ilizaliturri et al. 43 (2008) Brunner et al. 44 (2009) 6.0 (5-7) Mixe 75 (97) Surgical hip 4.7 (4-5.2) Mixe 19 (19) Surgical hip 5.2 ( ) Mixe 23 (23) Surgical hip 2.2 ( ) Mixe 94 (96) Surgical hip 3.8 ( ) Mixe 22 (30) Surgical hip 5.0 ( ) Mixe 185 (233) Surgical hip Merle Aubigné Merle Aubigné Merle Aubigné Harris hip score Hip outcome score, SF-12, an UCLA WOMAC, hip outcome score, SF-12, an UCLA 2.2 ( ) Mixe 106 (118) Mini-open onarthritic hip score an Harris hip score 2.0 ( ) Cam 14 (16) Mini-open with hip 2.5 ( ) Mixe 97 (100) Mini-open with hip 2.4 ( ) Cam 19 (19) Hip 2.4 ( ) Mixe 53 (53) Hip Harris hip score onarthritic hip score WOMAC onarthritic hip score an sports frequency score 91% ha goo to excellent clinical results without progression of osteoarthritis 9 hips (47%) were grae goo to excellent; mean osteoarthritis grae remaine unchange Hips at risk for failure showe avance preop. osteoarthritis 1 hip ha a worse score at the time of follow-up; failures showe avance preop. osteoarthritis At time of follow-up, 96% were still competing professionally 83% showe goo to excellent clinical result at time of follow-up; major revisions in 6% 18 hips (15%) showe progression of osteoarthritis by 1 point accoring to Tönnis Improve mean score; no raiographic progression of osteoarthritis Best results in patients <40 yr ol without preop. signs of osteoarthritis 16 hips (84%) showe an improve score; 3 hips (16%) eteriorate 58% returne to their full accustome level of activity 92% 74% 70% 94% 97% 97% 89% 95% continue

6 1790 TABLE III (continue) Stuy Mean Follow-up Perio (Range) (yr) Type of Impingement o. of Patients (Hips) Type of Surgery Scoring Systems* Results Survivorship Rate ) Philippon et al. 45 (2009) Philippon et al. 46 (2010) Byr an Jones 47 (2011) Palmer et al. 48 (2012) 2.3 (2-2.9) Mixe 112 (112) Hip 2.0 ( ) Cam 28 (28) Hip 2 Mixe 100 (100) Hip 3.8 Cam 185 (201) Hip Harris hip score Moifie Harris hip score Harris hip score onarthritic hip score Preictors for better outcome were the preop. score, signs of osteoarthritis, an labral repair Arthroscopic treatment of femoroacetabular impingement with labral repair allowe professional hockey players a prompt return to sport; 2 patients (7%) ha reinjury an aitional hip 79% showe goo to excellent results Clinical score, pain score, an satisfaction level significantly improve; risk for conversion to total hip arthroplasty was avance preop. osteoarthritis 92% 94% *SF-12 = Short Form-12, WOMAC = Western Ontario an McMaster Universities Osteoarthritis Inex, an UCLA = University of California Los Angeles activity score. Conversion to total hip arthroplasty was the en point. impingement. The cam-type femoroacetabular impingement was not recognize at the time of the initial surgery because no intraoperative arthrotomy was performe. This was correcte 4.4 years after the inex operation with a surgical of the hip. After subsequent arthroscopic resection of intra-articular ahesions an implant removal three years later, a posterior impingement evelope because of the relative posterior acetabular overcoverage. Eventually, a trimming of the posterior wall was necessary 10.5 years after the inex operation (the Merle Aubigné score was 13 points at twelve years). The fourth patient presente with partial loss of correction at the first follow-up visit, neeing revision periacetabular osteotomy eight weeks postoperatively. Fifteen patients ha been operatively treate on one sie only, an the asymptomatic, contralateral sie was not inclue in the systematic analysis of this stuy. However, follow-up information reveale that the asymptomatic, contralateral hip in one patient ha progresse to Tönnis grae-1 osteoarthritis an the contralateral hip in two patients ha a total hip arthroplasty. Preictive Factors A Cox regression analysis was performe on the basis of the following en points: (1) conversion to total hip arthroplasty, (2) raiographic progression of the osteoarthritis, (3) a fair or poor Merle Aubigné score ( 14 points), or (4) any reoperation relate to correction of acetabular coverage or persistent impingement. Three univariate preictors for the above-efine en points were ientifie: (1) the lack of offset correction at the time of periacetabular osteotomy (hazar ratio [HR], 11.0; 95% CI, 10.0 to 12.1; p = 0.021), (2) eficient anterior coverage of the acetabulum postoperatively (HR, 4.5; 95% CI, 3.7 to 5.2; p = 0.045), an (3) excessive posterior acetabular coverage (>55%) 19 of the acetabulum postoperatively (HR, 4.2; 95% CI, 3.5 to 5.0; p = 0.048). Discussion The goal of this stuy was to report the mean ten-year outcome of the first twenty-nine hips treate with an anteverting periacetabular osteotomy for symptomatic acetabular retroversion at our institute. After a mean of eleven years, the rate of conversion to a total hip arthroplasty, the clinical an raiographic outcome, an the nee for further revision surgery were analyze. The previously reporte goo clinical outcome after two years was maintaine at ten years. There was a tren towar raiographic progression of osteoarthritis. Overcorrection of the acetabulum an lack of femoral heaneck offset correction were associate with a less favorable outcome.

7 1791 The stuy has limitations. One limitation is the lack of a comparative group with no treatment. We are therefore not able to show that the natural history of symptomatic acetabular retroversion can be potentially change. However, an increasing number of recent publications have suggeste that acetabular retroversion is a risk factor for hip pain an osteoarthritis 2-4. Our results suggest that, in such patients, an anteverting periacetabular osteotomy improves the clinical scores at ten years of follow-up without significant progression of osteoarthritis. Another limitation is the lack of a comparative group with acetabular rim trimming instea of an acetabular reorientation proceure in patients with the same pathomorphology. Such a comparative group oes not exist in our atabase because of the unerstaning of the pathology at the time of surgery (more than ten years ago). The inication to perform a periacetabular osteotomy instea of acetabular rim trimming was consistently base on a substantially retroverte acetabulum as well as a eficient posterior wall in twenty-four of twenty-nine hips. Trimming of the anterior acetabular rim in those hips woul have reuce the lunate surface, potentially resulting in a ysplastic hip. Thirty-two percent of the patients in our series unerwent bilateral anteverting periacetabular osteotomy. Generally, this raises the question of whether a patient-base instea of a joint-base statistical approach woul be more appropriate 24,25. We chose a joint-base approach for statistical analysis for the following reasons. First, we analyze the iniviual morphology of each joint separately. This implies certain sie-specific variations. Secon, the postoperative surgical correction has to be juge iniviually for a hip. Thir, none of the negative preictive factors are general factors that simultaneously apply for both hips. There is increasing evience that acetabular retroversion represents a malorientation rather than excessive anterior an eficient posterior femoral hea coverage 4,7,12. As in hip ysplasia 9, a reirectional osteotomy of the acetabulum more reliably restores or approaches normal anatomy in hips with substantial retroversion. The cutoff between hips with a low retroversion inex, which coul be treate by a trimming of the anterosuperior portion of the rim, an hips with a higher retroversion inex requiring a periacetabular osteotomy still remains unclear. As a rough guieline, we propose that an acetabular retroversion inex 11,15,26 of 30% together with posterior wall an ischial spine signs in young patients are an inication for acetabular reorientation rather than trimming of the rim. To our knowlege, there are no comparable follow-up ata about anteverting pelvic osteotomies for acetabular retroversion. Comparing our results with reporteata about acetabular rim trimming in mixe or pincer-type femoroacetabular impingement is ifficult. There is a large heterogeneity in reporting ata, applie surgical techniques, an ientification of istinct impingement subtypes (Table III). Some stuies have note an excellent survivorship of the hip but with a substantially shorter follow-up perio For stuies with a mean follow-up of at least five years after rim trimming through a surgical hip, the survivorship of the hips was reporte to range from 70% to 97%. These numbers are consierably lower than our results. One possible explanation might be that the lunate surface with acetabular reorientation is preserve. With rim trimming, the joint contact area can be critically reuce, leaing to increase abnormal loaing of the remaining cartilage an potentially to earlier failures 30,34. The 14% revision rate in our series is relatively high. We attribute this to ifficulties an the learning curve in fining the optimal acetabular orientation similar to previous experiences for acetabular reorientation in hip ysplasia 35,36. Three of the four revisions were relate to a persistent femoroacetabular impingement. Of those three hips, two evelope a posterior impingement ue to a newly create posterior overcoverage an one ha persistent anterior impingement. The posterior impingement was successfully aresse with posterior rim trimming, while the anterior impingement was relieve with open femoral neck osteochonroplasty. Thus, in hips with normal-appearing posterior coverage inicate by a posterior rim outline lateral to the center of rotation (an absent posterior wall sign), we prefer to perform a rim trimming rather than a corrective periacetabular osteotomy. A recent stuy has shown that high femoral anteversion combine with a high neck-shaft angle promotes posterior hip impingement 37.Thus,femoral anteversion is routinely measure preoperatively in our institute. In combination with acetabular retroversion, it shoul lea to the consieration of ecreasing femoral anteversion by a femoral osteotomy or by choosing anterior rim trimming in hips with a rather normal-appearing posterior coverage. Restoration of a physiological femoral hea-neck offset an avoiance of an excessive acetabular anteversion were crucial factors for success when an anteverting periacetabular osteotomy was performe for acetabular retroversion. Appenix Figures emonstrating typical raiographic signs of acetabular retroversion, an illustration of an anteverting periacetabular osteotomy, an raiographs of a patient with symptomatic acetabular retroversion an a cam-type eformity that was treate with an anteverting periacetabular osteotomy; a table comparing preoperative an postoperative raiographic parameters; an a escription of the surgical technique use to perform an anteverting reorientation of the acetabulum with a periacetabular osteotomy are available with the online version of this article as a ata supplement at jbjs.org. n Klaus A. Siebenrock, MD Clauio Schaller, MD Moritz Tannast, MD Marius Keel, MD Lorenz Büchler, MD Department of Orthopeic Surgery, Inselspital Bern, University of Bern, 3010 Bern, Switzerlan. aress for K.A. Siebenrock: klaus.siebenrock@insel.ch

8 1792 References 1. Beck M, Leunig M, Parvizi J, Boutier V, Wyss D, Ganz R. Anterior femoroacetabular impingement: part II. Miterm results of surgical treatment. Clin Orthop Relat Res Jan;(418): Ganz R, Parvizi J, Beck M, Leunig M, ötzli H, Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res Dec;(417): Giori J, Trousale RT. Acetabular retroversion is associate with osteoarthritis of the hip. Clin Orthop Relat Res Dec;(417): Reynols D, Lucas J, Klaue K. Retroversion of the acetabulum. A cause of hip pain. J Bone Joint Surg Br Mar;81(2): Tannast M, Siebenrock KA, Anerson SE. Femoroacetabular impingement: raiographic iagnosis what the raiologist shoul know. AJR Am J Roentgenol Jun;188(6): Siebenrock KA, Kalbermatten DF, Ganz R. Effect of pelvic tilt on acetabular retroversion: a stuy of pelves from caavers. Clin Orthop Relat Res Feb;(407): Kalberer F, Sierra RJ, Maan SS, Ganz R, Leunig M. Ischial spine projection into the pelvis : a new sign for acetabular retroversion. Clin Orthop Relat Res Mar;466(3): Epub 2008 Feb Kakaty DK, Fischer AF, Hosalkar HS, Siebenrock KA, Tannast M. The ischial spine sign: oes pelvic tilt an rotation matter? Clin Orthop Relat Res Mar;468(3): Epub 2009 Aug Fujii M, akashima Y, Sato T, Akiyama M, Iwamoto Y. Pelvic eformity influences acetabular version an coverage in hip ysplasia. Clin Orthop Relat Res Jun;469(6): Epub 2011 Jan Jamali AA, Mlaenov K, Meyer DC, Martinez A, Beck M, Ganz R, Leunig M. Anteroposterior pelvic raiographs to assess acetabular retroversion: high valiity of the cross-over-sign. J Orthop Res Jun;25(6): Köhnlein W, Ganz R, Impellizzeri FM, Leunig M. Acetabular morphology: implications for joint-preserving surgery. Clin Orthop Relat Res Mar;467(3): Epub 2009 Jan Tannast M, Pfannebecker P, Schwab JM, Albers CE, Siebenrock KA, Büchler L. Pelvic morphology iffers in rotation an obliquity between evelopmental ysplasia of the hip an retroversion. Clin Orthop Relat Res Dec;470(12): 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): Siebenrock KA, Schöll E, Lottenbach M, Ganz R. Bernese periacetabular osteotomy. Clin Orthop Relat Res Jun;(363): Siebenrock KA, Schoeniger R, Ganz R. Anterior femoro-acetabular impingement ue to acetabular retroversion. Treatment with periacetabular osteotomy. J Bone Joint Surg Am Feb;85(2): Merle Aubigné R, Postel M. Functional results of hip arthroplasty with acrylic prosthesis. J Bone Joint Surg Am. 1954;35: Tannast M, Zheng G, Aneregg C, Burckhart K, Langlotz F, Ganz R, Siebenrock KA. Tilt an rotation correction of acetabular version on pelvic raiographs. Clin Orthop Relat Res Sep;438: Tannast M, Mistry S, Steppacher SD, Reichenbach S, Langlotz F, Siebenrock KA, Zheng G. Raiographic analysis of femoroacetabular impingement with Hip2orm-reliable an valiate. J Orthop Res Sep;26(9): Tannast M, Mistry S, Steppacher SD, Reichenbach S, Siebenroc KA, Zheng G. A comprehensive valiation of a new metho for correction of raiographic hip parameters for pelvic malpositioning. J Bone Joint Surg Br Sep 1;91 (SUPP III): Tannast M, Albers CE, Steppacher SD, Siebenrock KA. Hip pain in the young ault. In: Bentley G, eitor. European Instructional Lectures. Berlin, Germany: Springer; pp Tönnis D. General raiography of the hip joint. In: Tönnis D, eitor. Congenital ysplasia anislocations of the hip in chilren an aults. Heielberg: Springer; pp Brooker AF, Bowerman JW, Robinson RA, Riley LHJ Jr. Ectopic ossification following total hip replacement. Incience an a metho of classification. J Bone Joint Surg Am Dec;55(8): Kaplan EL, Meier P. onparametric estimation from incomplete observations. J Am Statist Assn. 1958;53: Park MS, Kim SJ, Chung CY, Choi IH, Lee SH, Lee KM. Statistical consieration for bilateral cases in orthopaeic research. J Bone Joint Surg Am Jul 21;92(8): Zhang Y, Glynn RJ, Felson DT. Musculoskeletal isease research: shoul we analyze the joint or the person? J Rheumatol Jul;23(7): ötzli HP, Wyss TF, Stoecklin CH, Schmi MR, Treiber K, Holer J. The contour of the femoral hea-neck junction as a preictor for the risk of anterior impingement. J Bone Joint Surg Br May;84(4): Barakos V, Vasconcelos JC, Villar R. Early outcome of hip for femoroacetabular impingement: the role of femoral osteoplasty in symptomatic improvement. J Bone Joint Surg Br Dec;90(12): Larson CM, Giveans MR. Arthroscopic management of femoroacetabular impingement: early outcomes measures. Arthroscopy May;24(5): Epub 2008 Jan Singh PJ, O Donnell JM. The outcome of hip in Australian football league players: a review of 27 hips. Arthroscopy Jun;26(6): Epub 2010 Mar Steppacher SD, Huemmer C, Schwab JM, Tannast M, Siebenrock KA. Surgical hip for treatment of femoroacetabular impingement: factors preicting 5-year survivorship. Clin Orthop Relat Res Jan;472(1): Epub 2013 Sep Tannast M, Siebenrock KA. [Open therapy of femoroacetabular impingement] [German]. Oper Orthop Traumatol Mar;22(1): Murphy S, Tannast M, Kim YJ, Buly R, Millis MB. Debriement of the ault hip for femoroacetabular impingement: inications an preliminary clinical results. Clin Orthop Relat Res Dec;(429): aal FD, Miozzari HH, SchärM, Hesper T, ötzli HP. Miterm results of surgical hip for the treatment of femoroacetabular impingement. Am J Sports Me Jul;40(7): Epub 2012 May Hipp JA, Sugano, Millis MB, Murphy SB. Planning acetabular reirection osteotomies base on joint contact pressures. Clin Orthop Relat Res Jul;(364): Albers CE, Steppacher SD, Ganz R, Tannast M, Siebenrock KA. Impingement aversely affects 10-year survivorship after periacetabular osteotomy for DDH. Clin Orthop Relat Res May;471(5): Epub 2013 Jan Leunig M, Siebenrock KA, Ganz R. Rationale of periacetabular osteotomy an backgroun work. Instr Courses Lect. 2001;50: Steppacher SD, Huemmer C, Schwab JM, Tannast M, Siebenrock KA. Surgical hip for treatment of femoroacetabular impingement: factors preicting 5-year survivorship. Clin Orthop Relat Res Jan;472(1): Epub 2013 Sep Peters CL, Schabel K, Anerson L, Erickson J. Open treatment of femoroacetabular impingement is associate with clinical improvement an low complication rate at short-term followup. Clin Orthop Relat Res Feb;468(2): aal FD, Miozzari HH, Wyss TF, ötzli HP. Surgical hip for the treatment of femoroacetabular impingement in high-level athletes. Am J Sports Me Mar;39(3): Epub 2010 Dec Chiron P, Espié A, Reina, Cavaignac E, Molinier F, Laffosse JM. Surgery for femoroacetabular impingement using a minimally invasive anterolateral approach: analysis of 118 cases at 2.2-year follow-up. Orthop Traumatol Surg Res Feb;98(1):30-8. Epub 2012 Jan Lincoln M, Johnston K, Muloon M, Santore R. Combine arthroscopic an moifie open approach for cam femoroacetabular impingement: a preliminary experience. Arthroscopy Apr;25(4): Laue F, Sariali E, ogier A. Femoroacetabular impingement treatment using an anterior approach. Clin Orthop Relat Res Mar;467(3): Epub 2008 Dec Ilizaliturri VMJ Jr, Orozco-Roriguez L, Acosta-Roríguez E, Camacho-Galino J. Arthroscopic treatment of cam-type femoroacetabular impingement: preliminary report at 2 years minimum follow-up. J Arthroplasty Feb;23(2): Epub 2007 Oct Brunner A, Horisberger M, Herzog RF. Sports an recreation activity of patients with femoroacetabular impingement before an after arthroscopic osteoplasty. Am J Sports Me May;37(5): Epub 2009 Feb Philippon MJ, Briggs KK, Yen YM, Kuppersmith DA. Outcomes following hip for femoroacetabular impingement with associate chonrolabral ysfunction: minimum two-year follow-up. J Bone Joint Surg Br Jan;91(1): Philippon MJ, Weiss DR, Kuppersmith DA, Briggs KK, Hay CJ. Arthroscopic labral repair an treatment of femoroacetabular impingement in professional hockey players. Am J Sports Me Jan;38(1): Epub 2009 Dec Byr JW, Jones KS. Arthroscopic management of femoroacetabular impingement: minimum 2-year follow-up. Arthroscopy Oct;27(10): Epub 2011 Aug Palmer DH, Ganesh V, Comfort T, Tatman P. Miterm outcomes in patients with cam femoroacetabular impingement treate arthroscopically. Arthroscopy ov;28(11): Epub 2012 Sep 6.