Complications associated with the periacetabular osteotomy

Transcription

1 Washington University School of Meicine igital Open Access Publications 2014 Complications associate with the periacetabular osteotomy Ira Zaltz William Beaumont Hospital Geneva Baca Washington University School of Meicine in St. Louis Young-Jo Kim Boston Chilren's Hospital Perry Schoenecker Shriner's Hospital, St. Louis Robert Trousale Mayo Clinic See next page for aitional authors Follow this an aitional works at: Recommene Citation Zaltz, Ira; Baca, Geneva; Kim, Young-Jo; Schoenecker, Perry; Trousale, Robert; Sierra, Rafael; Sucato, aniel; Sink, Ernie; Beaulé, Paul; Millis, Michael B.; Poeszwa, avi; an Clohisy, John C.,,"Complications associate with the periacetabular osteotomy." The journal of bone an joint surgery.96, (2014). This Open Access Publication is brought to you for free an open access by igital It has been accepte for inclusion in Open Access Publications by an authorize aministrator of igital For more information, please contact

2 Authors Ira Zaltz, Geneva Baca, Young-Jo Kim, Perry Schoenecker, Robert Trousale, Rafael Sierra, aniel Sucato, Ernie Sink, Paul Beaulé, Michael B. Millis, avi Poeszwa, an John C. Clohisy This open access publication is available at igital

3 1967 COPYRIGHT Ó 2014 BY THE JOURNAL OF BONE AN JOINT SURGERY, INCORPORATE Complications Associate with the Periacetabular Osteotomy A Prospective Multicenter Stuy Ira Zaltz, M, Geneva Baca, BA, Young-Jo Kim, M, Perry Schoenecker, M, Robert Trousale, M, Rafael Sierra, M, aniel Sucato, M, Ernie Sink, M, Paul Beaulé, M, Michael B. Millis, M, avi Poeszwa, M, an John C. Clohisy, M Investigation performe at the Washington University School of Meicine, St. Louis, Missouri, an William Beaumont Hospital, Royal Oak, Michigan Backgroun: The purpose of this prospective multicenter stuy was to etermine an categorize all complications associate with the periacetabular osteotomy performe by experience surgeons. Methos: We prospectively analyze perioperative complications in 205 consecutive unilateral periacetabular osteotomies performe at seven institutions by ten surgeons. All perioperative complications were recore at an average of ten weeks an one year after surgery in stanarize fashion using a valiate complication graing scheme applie to hip preservation proceures. The mean patient age was 25.4 years. There were 143 female an sixty-two male patients. The most common iagnosis was evelopmental acetabular ysplasia, an concomitant proceures most commonly inclue femoral osteochonroplasty (58%) or hip arthroscopy (20%), which coul inclue labral repair or resection. Results: Major complications (grae III or IV) occurre in twelve patients (5.9%). Seven complications were evient at the ten-week visit an five at the one-year visit. Nine of the complications require a secon surgical intervention, incluing repair for acetabular migration or implant ajustment (four patients), incision anrainage for a eep infection (two patients), an heterotopic bone resection, contralateral peroneal nerve ecompression, an posterior column fixation (one patient each). Three thromboembolic complications were manage meically. There were no vascular injuries, permanent nerve palsies, intra-articular osteotomies an/or fractures, or acetabular osteonecrosis. The most common grae-i or II complication was asymptomatic heterotopic. Conclusions: For surgeons experience with the periacetabular osteotomy, it is a safe proceure but is associate with a 5.9% risk of grae-iii or IV complications beyon the learning curve. The majority of these complications are resolve without permanent isability. 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 eputy Eitor, an it unerwent bline review by two or more outsie experts. The eputy 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. Acetabular ysplasia is a skeletal isorer that is associate with the evelopment of osteoarthritis of the hip 1-3. Malalignment of the acetabulum contributes to the evelopment of pathomechanical stress along the rim of the acetabulum that eventually results in labrochonral failure 4-7. Multiple osteotomies have been esigne to enable surgical reorientation of the acetabulum, improve femoral hea coverage, an reistribute weight-bearing forces more evenly across the acetabulum 8,9. The Bernese periacetabular osteotomy escribe by Ganz et al. enables reorientation of the acetabulum while preserving posterior column pelvic continuity 10. Multiple surgical approaches have been utilize to perform the isclosure: One or more 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 an aspect of this work. In aition, 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. No 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 isclosures 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:

4 1968 osteotomy Clinical outcome stuies have inicate that the majority of patients experience major pain reuction an improve function after periacetabular osteotomy 14. A therapeutic intervention that is esigne to alter the natural history of a symptomatic yet variably progressive isorer such as acetabular ysplasia is require to be safe, efficacious, reproucible, an associate with few an tolerable complications. It is accepte that the Bernese periacetabular osteotomy is a complex proceure with a steep learning curve that can be associate with a substantial number of variably morbi perioperative complications 11, The prevalence of severe complications seems to iminish with more surgical experience, on the basis of retrospective reports 16,19,21. Previous reports have escribe subjective categories of minor, moerate, an major complications with little attention to subsequent meical, surgical, or raiographic interventions require or to long-term consequences of the complications. Complication reporting for the periacetabular osteotomy has been inconsistent, an the finings regaring complication rates have been variable, with small patient cohorts an without a stanarize graing scheme 14. Currently, there are no available prospective ata regaring the prevalence of surgical complications following the Bernese periacetabular osteotomy performe in centers by surgeons experience with the proceure. The purpose of this prospective multicenter stuy was to use a stanarize complication graing scheme to etermine an categorize all complications associate with the Bernese periacetabular osteotomy performe by experience surgeons for the correction of symptomatic acetabular eformities. Materials an Methos Patient Selection Following iniviual institutional review boar approval at seven North American centers, prospective ata were collecte on 205 consecutive patients who unerwent periacetabular osteotomy from August 15, 2007, to August 31, There were 143 female an sixty-two male patients with a mean age of 25.4 years (range, eleven to fifty-four years). The mean boy mass inex (BMI) was 25.3 kg/m 2 (range, 11.7 to 46.6 kg/m 2 ) (Table I). All patients with a periacetabular osteotomy were inclue regarless of preoperative iagnosis, comorbiities, prior surgical proceures, or simultaneous associate proceures. The preoperative iagnoses were evelopmental ysplasia (179 patients; 87%), femoroacetabular impingement (twelve patients; 6%), Legg- Calvé-Perthes isease (nine patients; 4%), cerebral palsy (three patients; 1%), Charcot-Marie-Tooth isease (two patients; 1%), proximal femoral focal eficiency (one patient; 0.5%), an multiple epiphyseal ysplasia (one patient; 0.5%). (Two patients ha more than one iagnosis.) TABLE I Preoperative emographic ata an Patient-Reporte Comorbiities of 205 Treate with the Periacetabular Osteotomy Characteristic Value Sex (no. [%]) F 143 (69.8) M 62 (30.2) Age* (yr) 25.4 ( ) Height* (cm) 167 ( ) Weight* (kg) 71.3 ( ) BMI* (kg/m 2 ) 25.3 ( ) Patient-reporte comorbiities (no. [%]) Heart isease 2 (1) Hypertension 5 (2.4) Asthma 25 (12.2) Liver isease 1 (0.5) Overweight 20 (9.8) Cancer 1 (0.5) Osteoarthritis 25 (12.2) Back pain 47 (23) Tobacco use 17 (8.3) rug use 2 (1) *The values are given as the mean, with the range in parentheses. BMI = boy mass inex. Surgical Proceure The ten surgeons performing periacetabular osteotomies within the seven selecte centers were consiere experience with the proceure. All except one surgeon were certifie by the American Boar of Orthopaeic Surgery an ha subspecialty concentration in either peiatric orthopaeic surgery or ault reconstruction surgery. They ha been in practice for an average of thirteen years (range, one to thirty-seven years). Prior to the commencement of ata acquisition, they ha performe the periacetabular osteotomy for an average of nine years (range, one to eighteen years) an each surgeon ha performe an average of 231 periacetabular proceures (range, eighteen to 715 proceures). The one surgeon with more limite experience (one year in practice an eighteen periacetabular osteotomies) who was inclue in the stuy was consiere to have aequate experience because this surgeon ha major exposure to the proceure as a resient, ha specific fellowship training in the proceure, an worke with an experience mentor in practice before the stuy commence. Surgical eucation an training in the periacetabular osteotomy varie among the ten surgeons: five reporte aitional fellowship training, seven reporte visiting another experience surgeon, six reporte inepenent learning, an six performe practice caaveric issections. All surgeons were involve in at least two of these eucational activities. The periacetabular osteotomy was performe accoring to the technique escribe by Ganz et al. 10 using the Smith-Petersen interval to preserve the hip abuctor origin 13. The periacetabular cuts are mae as previously escribe, an the mobilize acetabulum is then appropriately reoriente; assesse using fluoroscopy or raiographs, or both, epening on the institution; an stabilize using screws primarily irecte from proximal to istal. Postoperatively, patients were prescribe intravenous antibiotics for twenty-four hours. The use of prophylaxis for venous thromboembolism epene on the iniviual surgeon. All patients were prescribe toe-touch weight-bearing until visible raiographic union was evient. ata Collection ata regaring surgeon experience, training, years in practice, metho of learning the periacetabular osteotomy, an previously performe proceures were obtaine by a questionnaire complete by all participating surgeons. Regarless of iagnosis, patients unergoing periacetabular osteotomy were entere in the stuy an were followe prospectively for meical an surgical complications associate with the proceure. Preoperatively acquireata inclue height, weight, sex, race, preoperative iagnosis, Tönnis grae, meical comorbiities, an prior hip operations. All perioperative an postoperative complications or events associate with a eviation from routine postoperative recovery were recore in a prospective fashion at scheule follow-up visits.

5 1969 The primary outcome measure was the presence or absence of perioperative complications. Complications were grae accoring to the moifie Clavien-ino graing scheme 22-25, a valiate scheme applicable across cultures an surgical isciplines that focuses on treatments require to manage complications an on the long-term impact of surgical complications. This graing scheme was recently moifie, valiate for hip preservation surgery, an applie to hip preservation proceures 24,25 (see Appenix). A grae-i complication require no treatment an no eviation from a normal postoperative course. A grae-ii complication eviate from the normal postoperative course by requiring either pharmacological treatment or close monitoring as an outpatient. A grae-iii complication require surgical, enoscopic, or raiographic intervention an may require an unplanne hospital amission. A grae-iv complication was life-threatening or was not treatable, with potential for permanent isability. A grae-v complication resulte in eath. All perioperative complications within one year of surgery were recore prospectively in a stanarize fashion. ecrease sensation in the istribution of the lateral femoral cutaneous nerve, a known sequela of the surgical approach an retraction with periacetabular osteotomy, was not consiere a complication. However, ysesthesia relate to the lateral femoral cutaneous nerve was consiere a complication because of the potential for long-term pain. In aition, persistent pain, consiere a treatment failure in some cases, was not consiere a complication as the etiology of pain following hip-preserving surgery is multifactorial. A complication form (see Appenix) was complete by one of the treating surgeons an/or research assistants uner the irection of the treating surgeon at each patient s first postoperative visit an again at the one-year postoperative visit. Each complication was consiere iniviually; thus, a single patient coul have more than one complication. eientifie forms were sent to the coorinating center (Washington University) for entry into the prospective multicenter atabase. The first postoperative appointment occurre at an average of ten weeks (range, two to fifty-six weeks) following surgery an the secon postoperative visit at an average of fourteen months (range, eight to thirty-five months). Four patients (four hips) i not return for short-term follow-up. Twenty-eight patients (twenty-eight hips) i not return for the one-year follow-up visit espite efforts to contact patients via telephone. Therefore, complications were ocumente on 98% of the patients at the time of the short-term follow-up an 86% at the one-year follow-up. Statistics The incience of complications was presente using escriptive statistics. To compare patient comorbiities, BMI, intraoperative bloo loss, an previous surgery by the level of complication, we use linear an logistic regression as appropriate. Multivariable-ajuste moels inclue number of visits an any variables foun to be associate with the level of complication in univariate analyses at an alpha level of Two-sie p values of <0.05 were consiere significant. All analyses were performe using SAS software (version 9.3; SAS Institute, Cary, North Carolina). Source of Funing Resources from the Curing Hip isease Fun an the Acaemic Network for Conservational Hip Outcomes Research (ANCHOR) Fun were use for research personnel salary support an biostatistical consultation fees. Results Stuy Group Characteristics, Surgical Proceures, an Total Complications Two hunre an five consecutive patients who unerwent a periacetabular osteotomy at one of the stuy sites are the focus of this report (Table I). The most common patientreporte comorbiities inclue back pain (23%), asthma (12.2%), an osteoarthritis (12.2%). Twenty patients (9.8%) self-reporte being overweight. The preoperative iagnosis was evelopmental ysplasia of the hip for 87% of hips. The Tönnis TABLE II Concomitant Proceures Performe in Conjunction with the Periacetabular Osteotomy in 205 Concomitant Proceures No. (%) Hea an/or neck osteochonroplasty 118 (58) Arthroscopy 42 (20) Labral resection 16 (8) Surgical islocation 18 (9) Labral repair 14 (7) Femoral neck lengthening 13 (6) Chonroplasty 13 (6) Trochanteric avancement 12 (6) Femoral intertrochanteric osteotomy 3 (1) Microfracture 2 (1) Capsulorrhaphy 1 (0.5) Acetabular rim osteoplasty 1 (0.5) Psoas lengthening 1 (0.5) osteoarthritis grae inicate no raiographic changes (grae 0) or mil (grae 1) osteoarthritic changes in 89% of the hips. Twenty-nine patients (14%) ha prior hip surgery. The mean operative time measure from skin incision until the completion of skin closure was 171 minutes (range, fifty-seven to 510 minutes). The mean estimate bloo loss was 714 ml (range, 100 to 3900 ml), an no patient ha a bloo loss-relate complication. Concomitant proceures were commonly performe with the periacetabular osteotomy (Table II). The most frequently combine proceures were femoral hea-neck osteochonroplasty (58%) an hip arthroscopy (20%). Hip arthroscopy was performe for cartilage staging, labral ebriement, labral refixation, removal of a loose boy, or ligamentum teres ebriement. Combining the first an secon follow-up evaluations, seventy-one patients (34.6%) haocumente complications. Fifty-nine patients (28.8%) ha grae-i or II complications, an twelve (5.9%) ha grae-iii or IV complications. Nine of the twelve grae-iii or IV complications require aitional surgery. Early Postoperative Complications At the first postoperative appointment (at an average of ten weeks), a total of thirty (15%) of 201 hips ha complication events. Four patients (four hips) i not return for the first postoperative follow-up visit, but these patients ha no known complications. There were thirteen grae-i, ten grae-ii, four grae-iii, an three grae-iv complications (Table III). There were no permanent nerve injuries, intra-articular fractures, vascular injuries, acetabular osteonecrosis, or eaths. For the twenty-three patients (77%) with grae-i an II complications, the complication either resolve without treatment or require minor alterations in treatment uring follow-up visits. There were seven grae-iii or grae-iv complications in six patients (2.9%). Four complications require operative management an three require pharmacologic management.

6 1970 TABLE III Complications Recore at First Follow-up Evaluation Grae I Grae II Grae III Grae IV Complication* Complication Complication Complication* Stitch abscess 2 Wounrainage 1 Acetabular migration 1 VTE 3 Superficial ehiscence 1 ehiscence 3 eep infection 2 Posterior column 1 Hematoma 1 Peroneal palsy 1 fracture Spinal heaache 1 Bent screw 1 Brooker grae-ii heterotopic Brooker grae-iii heterotopic 2 Femoral nerve ysfunction 1 Cariac arrhythmia 1 2 elaye union 1 Suture abscess 1 of pubis LFCN ysesthesia 4 Total *LFCN = lateral femoral cutaneous nerve, an VTE = venous thromboembolism. Specifically, in one patient, the acetabular fragment migrate following surgery, an a secon surgery for reuction an repeat fixation of the acetabulum was neee, with a proximal femoral osteotomy ae to enhance hip stability. In a secon patient, a postoperative compressive peroneal palsy that evelope in the contralateral limb from a sequential pneumatic compressive boot require peroneal neurolysis. This patient ha motor function return four months after surgery an, at the twenty-two-month follow-up evaluation, ha intact motor function an a resiual mil sensory eficit. Two patients with eep infections require incision anrainage proceures at three an eight weeks. Although both infections resolve, TABLE IV Complications Recore at Secon Follow-up Evaluation Grae I Grae II Grae III Grae IV Complication Complication* Complication* Complication Brooker grae-i heterotopic Brooker grae-ii heterotopic Brooker grae-iii heterotopic Brooker grae-iv heterotopic 21 LFCN ysesthesia 1 Brooker grae-iii heterotopic 7 Intra-articular screw 2 3 Acetabular migration 1 2 Posterior column nonunion require ORIF Snapping psoas 1 Ischial stress fracture 1 Inferior pubic ramus fracture 1 Total *LFCN = lateral femoral cutaneous nerve, an ORIF = open reuction an internal fixation. 1 1

7 1971 TABLE V Patient emographics, Comorbiities, an Intraoperative ata Compare with the Level of Complication Complications Characteristic or Comorbiity* P Value patients Mean age (yr) Female (%) Mean BMI (kg/m 2 ) BMI of 30 (%) Previous surgery (%) Neuromuscular complications (%) Migraines (%) Spinal proceure (%) Smoking (%) Cariovascular complications (%) Asthma (%) Back pain (%) epression (%) Anemia (%) Geometric mean estimate bloo loss (ml) *BMI = boy mass inex. P Values for tren were calculate by linear or logistic regression, as appropriate. one patient require total hip arthroplasty three years after the periacetabular osteotomy. Three venous thromboembolic complications (grae IV) in patients receiving chemoprophylaxis, one accompanie by a nonfatal pulmonary embolus, were reporte. All thromboembolic complications were successfully treate with anticoagulation therapy with no long-term averse sequelae. elaye Postoperative Complications For the secon follow-up visit, 177 patients (177 hips; 86%) presente for evaluation at an average of fourteen months. Forty-two new complications were reporte at the secon visit (Table IV). There were thirty-six grae-i complications, one grae-ii complication, an five grae-iii complications. There were no grae-iv complications. Thirty-three of thirty-six grae-i complications were asymptomatic heterotopic. Of the patients with heterotopic, twentyone ha Brooker grae-i, seven ha Brooker grae-ii, three ha Brooker grae-iii, an two ha Brooker grae-iv s primarily locate anteriorly an anterolaterally within the gluteus minimus an iliocapsularis. The five grae-iii complications inclue symptomatic heterotopic requiring excision in one hip, intra-articular migration of a screw in two hips, a posterior column fracture requiring operative fixation in one hip, an acetabular migration in one hip that ha been precipitate by a fall in the early postoperative perio that require revision surgery. TABLE VI Ajuste Means Calculate by Linear Regression an P Values for Tren Calculate by Linear or Logistic Regression, as Appropriate* Complications Characteristic P Value patients Female (%) Mean BMI (kg/m 2 ) Neuromuscular complications (%) epression (%) Geometric mean estimate bloo loss (ml) *Moels inclue all variables, as well as number of visits. BMI = boy mass inex.

8 1972 There were no significant associations between patient comorbiities, BMI, intraoperative bloo loss, previous surgery, an any type of complication recoreuring the followup perio (Tables V an VI). There was a tren towar an association between male sex an obesity an an increase risk of complications, but it was not significant. iscussion The Bernese periacetabular osteotomy an allie proceures 10,26,27 are commonly use for the treatment of symptomatic acetabular ysplasia. Although the so-calle learning curve for the periacetabular osteotomy has not been clearly efine, complications associate with this proceure have been reporte in a nonstanarize fashion uring learning-curve experiences (see Appenix). In their original escription, Ganz et al. reporte that all clinically important complications occurre within the first eighteen operative proceures 10.Subsequent authors have reporte similar associate complications uring the early phase of implementation. Trumble et al. reporte on the first 124 patients who unerwent a periacetabular osteotomy 17. The majority of the complications occurre in the so-calle early part of the series an were more prevalent in patients treate using the ilioinguinal approach. Crockarell et al. reporte the first twenty-one periacetabular osteotomies performe by a single surgeon at the Mayo Clinic, representing what was consiere the learning curve at that institution 15.Theyreporte three ischial fractures, two peroneal palsies that resolve, three asymptomatic pubic nonunions, five hips with heterotopic (two with type I, two with type II, an one with type III), an one peroneal neuralgia. avey an Santore reviewe the first seventy periacetabular osteotomies at their institution an note a substantial ecrease in the number of complications occurring within the secon group of thirty-five proceures compare with the first group of thirty-five proceures 16.Incluing what were previously terme trivial complications, now consiere Clavien-ino grae I an II, they reporte a total of fifty complications within the first seventy patients, with a substantial reuction in major an moerate complications from 46% to 14% in the secon cohort of patients. Matta et al. reporte the results for fifty-eight patients (sixty-six hips) at an average of four years after periacetabular osteotomy that was performe using a moifie Smith-Petersen approach 12.Fourteen percent ha moerate formation of heterotopic bone with two requiring excision, an 16% ha nonunion of the pubis. No vascular or neurologic complications were reporte. Clohisy et al. reporte the results following periacetabular osteotomy to treat both high-grae acetabular ysplasia an Legg-Calvé-Pertheslike hip eformities 28. Two complications were note among thirteen patients (sixteen hips) with severe ysplasia; one patient ha an ischial nonunion, an another, a heavy smoker, ha loss of fixation that require open reuction 28. For hips with major femoral heaeformities, those authors reporte three complications associate with twenty-four periacetabular osteotomies 29. Two patients with a previous hip reconstruction ha transient peroneal nerve palsies after combine periacetabular osteotomy an femoral proceures. One patient ha grae-ii heterotopic. Peters et al. reporte the results for seventy-three patients following periacetabular osteotomy at a mean follow-up of forty-three months, in which nine of ten major complications occurre within the first thirty hips 19. These inclue three femoral an one sciatic nerve palsy, four woun hematomas, two eep infections, an a broken osteotome tip that was left within the patient. Bieermann et al. reporte complications an patient satisfaction in sixty periacetabular osteotomies performe from 1988 to 1998 at a single institution by six ifferent surgeons utilizing the classic Smith- Petersen approach 20. There were twenty-five minor an twenty-two major complications. Bieermann et al. foun lower Western Ontario an McMaster Universities Osteoarthritis Inex (WOMAC) scores in patients with persistent lateral femoral cutaneous ysfunction compare with controls. Thawrani et al. reporte complications following periacetabular osteotomy in aolescents 21. In contrast to the stuy by avey an Santore, there was no change in complication rates when the initial surgical group of forty-two patients was compare with the secon group of forty-two patients. Following a mentorship arrangement, Howie et al. escribe only two complications in their first twenty-six periacetabular osteotomies, suggesting that this learning format may mitigate complications 30. In North America, periacetabular osteotomy has become the proceure of choice for the correction of symptomatic acetabular ysplasia. Evience supporting the surgical complexity inclues complication rates as high as 46% in some series 16,20. In the literature, the ocumentation of complications is primarily retrospective, obtaine with inconsistent methoology, an is neither comprehensively categorize nor stratifie. To our knowlege, there is no prior ocumentation of complications following periacetabular osteotomy performe in high-volume centers by surgeons with substantial experience using the proceure. The present stuy is important for several reasons. First, it is comprehensive an prospective an utilizes a valiate classification scheme to categorize all complications of the periacetabular osteotomy. As such, the stuy efines complications that are associate with this proceure when performe by experience surgeons. Secon, it serves as a benchmark to which surgeons can compare complication outcomes. Thir, it illustrates the complexity of the proceure an the persistence of some complications beyon the initial learning curve. Since there were no permanent neurologic or vascular injuries irectly attributable to the operative proceure, our ata suggest that serious complications occur at lower rates in the hans of experience surgeons. Although no complication resulte in permanent isability, there were nine complications over the stuy perio that require reoperations. Aitionally, major heterotopic, i.e., Brooker grae III an IV, is a potential complication that may require excision an prophylaxis shoul affecte patients require future prosthetic joint reconstruction. Although these patients are currently asymptomatic, the clinical importance of heterotopic will require long-term follow-up. At this point, we o not have ata to make specific recommenations for heterotopic prophylaxis. This is a subject of ongoing investigation.

9 1973 This stuy has certain limitations. First, the prior experience of the surgeons varie consierably among the participating centers, with one surgeon participating after only one year of inepenent practice. This surgeon, however, ha substantial avance training in performing periacetabular osteotomy. Secon, we i not assess surgeon skill an so were not able to correlate skill with complications. At present, there is neither an objective measure of skill nor a metho of correlating skill with experience. Thir, many patients travele to the participating centers for surgery. These young an mobile patients are frequently lost to follow-up, an twenty-eight patients (14%) faile to return at one year. Fourth, the long-term consequence of certain complications is not known because of the length of follow-up in this stuy. Finally, the majority of grae-i complications have little if any clinical importance yet are reporte because of our rigorous ata collection methoology. Fifth, we were not able to correlate persistent pain with complications. Presently, persistent pain may occur following an uncomplicate periacetabular osteotomy, potentially inicating treatment failure in certain situations. How complications relate to persistent pain is a focus of ongoing stuies. Our ata inicate that the periacetabular osteotomy is a safe proceure for the correction of acetabular ysplasia in the hans of experience surgeons. Nevertheless, there remains a risk for perioperative complications, with grae-iii or IV complications occurring in 5.9% of our patients. Our ata suggest that most of these complications are manageable with no associate permanent isability. Appenix Complication forms an tables showing the moifie Clavien-ino classification scheme anata on selecte historically reporte complications following periacetabular osteotomy are available with the online version of this article as a ata supplement at jbjs.org. n NOTE: The authors thank the ANCHOR (Acaemic Network for Conservational Hip Outcomes Research) stuy coorinators (Patricia Connell, Sharmeen Alam, Kristy McCanlish, Amy Nguyen, Katie Hill, Ariana e La Rocha, Erin Magennis, Claire Gilbert, Barbara Foreman, ebbie Szymanski, an Gillian Parker) for ata collection an analysis. Ira Zaltz, M William Beaumont Hospital Royal Oak, References Woowar Avenue, Suite 100, Royal Oak, MI Geneva Baca, BA John C. Clohisy, M epartment of Orthopaeic Surgery, Washington University School of Meicine, One Barnes-Jewish Plaza, Suite 11300, West Pavilion, Campus Box 8233, St. Louis, MO aress for J.C. Clohisy: clohisyj@wuosis.wustl.eu Young-Jo Kim, M Michael B. Millis, M epartment of Orthopaeic Surgery, Boston Chilren s Hospital, Hunnewell-2, 300 Longwoo Avenue, Boston, MA Perry Schoenecker, M Shriner s Hospital, Meical Staff Office, 2001 South Linberg Boulevar, St. Louis, MO Robert Trousale, M Rafael Sierra, M Mayo Clinic, 200 1st Street SW E14B, Rochester, MN aniel Sucato, M avi Poeszwa, M Texas Scottish Rite Hospital, 2222 Welborn Street, allas, TX Ernie Sink, M Hospital for Special Surgery, 535 East 70th Street, New York, NY Paul Beaulé, M Ottawa General Hospital, 501 Smyth Roa, Suite 5004, Ottawa, ON K1H 8L6, Canaa 1. Cooperman R, Wallensten R, Stulberg S. Acetabular ysplasia in the ault. Clin Orthop Relat Res May;(175): Murphy SB, Ganz R, Müller ME. The prognosis in untreateysplasia of the hip. A stuy of raiographic factors that preict the outcome. J Bone Joint Surg Am Jul;77(7): Ganz R, Leunig M, Leunig-Ganz K, Harris WH. The etiology of osteoarthritis of the hip: an integrate mechanical concept. 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