Selected Instructional Course Lectures The American Academy of Orthopaedic Surgeons

Transcription

1 748 Selecte Instructional Course Lectures The American Acaemy of Orthopaeic Surgeons ROBERT A. HART EDITOR, VOL. 63 COMMITTEE ROBERT A. HART CHAIR CRAIG J. DELLA VALLE MARK W. PAGNANO THOMAS W. THROCKMORTON PAUL TORNETTA III EX-OFFICIO DEMPSEY S. SPRINGFIELD DEPUTY EDITOR OF THE JOURNAL OF BONE AND JOINT SURGERY FOR INSTRUCTIONAL COURSE LECTURES Printe with permission of the American Acaemy of Orthopaeic Surgeons. This article, as well as other lectures presente at the Acaemy s Annual Meeting, will be available in March 2014 in Instructional Course Lectures, Volume 63. The complete volume can be orere online at or by calling (8 A.M.-5 P.M., Central time).

2 749 Diagnosis an Management of Developmental Dysplasia of the Hip from Triraiate Closure Through Young Aulthoo Klaus A. Siebenrock, MD, Simon D. Steppacher, MD, Christoph E. Albers, MD, Pascal C. Haefeli, MD, an Moritz Tannast, MD An Instructional Course Lecture, American Acaemy of Orthopaeic Surgeons Management of the Acetabular Sie Closure of the triraiate cartilage may occur as early as eight to ten years of age 1. Thus, typically the pelvis of a very young teenager alreay is amenable to ifferent kins of juxta-acetabular osteotomies for the treatment of hip isorers. Treatment options for the ysplastic acetabulum can be ivie into (1) augmentation an (2) reorientation proceures. Augmentation proceures inclue a Chiari osteotomy 2 or ifferent techniques of shelf proceures 3,baseon the principle of loa reuction by istributing loa through a larger surface area. However, the potentially amage labrum an articular cartilage at the abnormally loae acetabular rim 4 remain within the main weight-bearing zone with both of these surgical proceures. This may be one main cause of inferior results reporte with Chiari osteotomies in aolescents who are more than fourteen years ol 5 or in patients with a torn labrum 6. Augmentation proceures are not commonly inicate in aolescents an young aults currently, but may be consiere in acetabula with a very short roof or in hips in which the acetabular raius is smaller than the raius of the femoral hea. Three types of juxta-acetabular osteotomies for acetabular reorientation are currently in wier use. These osteotomies inclue (1) a spherical or rotational osteotomy, (2) a triple osteotomy, an (3) the Bernese periacetabular osteotomy. The principle of the spherical or rotational osteotomy was escribe by Wagner 7 in Europe an by Ninomiya an Tagawa 8 in Japan. The osteotomy is performe with a curve chisel close to the subchonral bone. The avantage is that it provies a mobile fragment. However, this osteotomy lacks the potential for meialization of the hip center 9 an may become intra-articular in the caual portion of the acetabulum 10.Tönnis et al. 11 popularize a triple osteotomy with complete osteotomies of the iliac, ischial, an pubic bone. Initial fixation inclue osteosynthesis of the iliac an pubic bone. The recommene postoperative treatment was immobilization in a spica cast for several weeks. With the current technique, the ischial spine with the attache sacrospinal ligament remains attache to the pelvic segment, an fixation of the acetabular fragment has become easier without the nee for postoperative cast immobilization. The Bernese periacetabular osteotomy was popularize in 1988 by Ganz et al. 12 an was first performe in This osteotomy has the avantage of creating a polygonal acetabular fragment while leaving the posterior column intact, by an incomplete osteotomy of the ischium. There is immeiate postoperative stability since the pelvic ring is not isrupte. There is no eformity of the true pelvis in young female patients, allowing for chilbirth through vaginal elivery after surgical correction 13. The mobile acetabular fragment allows aequate corrections, even for severe eformities, an has the potential for an optimal meialization of the acetabular center of rotation. Fixation of the Disclosure: None 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. None of the authors, or their institution(s), have ha any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomeical arena that coul be perceive to influence or have the potential to influence what is written in this work. Also, 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 Disclosures of Potential Conflicts of Interest submitte by authors are always provie with the online version of the article. J Bone Joint Surg Am. 2013;95:749-55

3 750 weight-bearing area of the acetabular cartilage (Figs. 1-A an 1-B). A fovea alta further reuces the weight-bearing zone between the cartilaginous joint surfaces of the femoral hea an the acetabulum, aggravating the unerlying ysplastic pathomorphology 18. Fig. 1 Fig. 1-A In a normal hip, the fovea capitis femoris is caual to the weight-bearing area of the acetabulum. Fig. 1-B In ysplastic hips, because of the extreme valgus, the fovea can exten into the weight-bearing area, reucing the loae articular cartilage surface. The fovea-acetabular angle is efine as the angle forme by a line from the femoral hea center to the meial ege of the weight-bearing zone of the acetabulum (reference line) an a line from the femoral hea center to the superior ege of the fovea capitis femoris. The value of the fovea-acetabular angle is positive if the superior ege of the fovea capitis femoris lies caual to the meial ege of the weight-bearing zone of the acetabulum (Fig. 1-A). It becomes negative if the superior ege of the fovea capitis femoris lies cranial to the meial ege of the weight-bearing zone of the acetabulum (Fig. 1-B). osteotomize fragment can be one typically with screws only in the acetabular fragment, an postoperative care requires only partial weight-bearing on crutches without the nee for a cast. Thus, the Bernese periacetabular osteotomy has become our preferre treatment for correction of acetabular ysplasia in hips with a close triraiate growth plate. Treatment of the Abnormal Femoral Sie Developmental ysplasia of the hip also affects the femoral hea sie. There is a wie range of eformities of the proximal part of the femur from a subtle ovalshape eformity of the femoral hea to aberrant torsion or orientation of the femoral neck, to more severe abnormalities of the entire proximal part of the femur femoral hea eformities), an (3) restoration of a normal femoral neck-shaft angle after a previous varus osteotomy of the proximal part of the femur. Extreme Valgus with Fovea Alta In ysplastic hips, an abnormal valgus femoral neck configuration may be associate with a fovea alta 18, with the fovea capitis femoris more cranial than in a normal hip joint an the ligamentum capitis femoris articulating with the Joint Incongruency After Periacetabular Osteotomy Primary or seconary eformity of the femoral hea leas to numerous instantaneous centers of rotation that epen on the actual surface uner stress, which varies with the relative position of the acetabulum an femur 17. This can be seen on an abuction raiograph mae either preoperatively or intraoperatively after periacetabular osteotomy. If the abuction raiograph shows improve hip congruency, a varus osteotomy shoul be consiere (Figs. 2-A, 2-B, an 2-C) 17. Femoral Neck-Shaft Realignment After a Previous Proximal Femoral Varus Osteotomy If resiual hip ysplasia after a previous proximal femoral varus osteotomy nees acetabular correction, a periacetabular osteotomy may lea to restricte hip abuction, flexion, an internal rotation. A corrective rotational valgus intertrochanteric osteotomy can then minimize anterolateral Aitional Intertrochanteric Osteotomy Generally, a concomitant intertrochanteric osteotomy is only inicate in approximately 10% of all patients unergoing periacetabular osteotomy 17.The most common inications for an aitional intertrochanteric osteotomy are (1) an extreme valgus angulation of the femoral neck with a fovea alta, (2) joint incongruency following acetabular reorientation (typically seen with more severe Fig. 2 Figs. 2-A, 2-B, an 2-C A nineteen-year-ol woman who presente with acetabular ysplasia, coxa valga, an a high fovea capitis femoris in the right hip. Fig. 2-A Anteroposterior raiograph mae at the time of presentation. Fig. 2-B The preoperative raiograph showe slight incongruence of the joint that resolve in the abuction view. Fig. 2-C Raiograph mae after a periacetabular osteotomy with an intertrochanteric varus femoral osteotomy.

4 751 Fig. 3 Figs. 3-A, 3-B, an 3-C A twenty-four-year-ol man with resiual ysplasia after previous shelf acetabuloplasty an varus femoral osteotomy of the right hip. Fig. 3-A Preoperative anteroposterior raiograph. Fig. 3-B Anteroposterior raiograph mae after a periacetabular osteotomy was performe with resection of the shelf acetabuloplasty an a concomitant intertrochanteric valgus femoral osteotomy. Fig. 3-C Raiograph of the hip mae ten years postoperatively showing an excellent clinical result. impingement an improve clinical abuction by avancing the greater trochanter istally an laterally (Figs. 3-A, 3-B, an 3-C). Substantial (Perthes-Like) Femoral Hea Deformities Surgical correction of acetabular abnormalities associate with major femoral hea eformities is complex. It is conceivable that hips with major femoral hea eformities, such as Legg-Calvé- Perthes isease or slippe capital femoral epiphysis, shoul be treate with aitional correction of the eformity of the proximal part of the femur. In severely eforme femoral heas, the femoral sie nees to be aresse prior to the periacetabular osteotomy, at times with the technique of a surgical hip islocation with or without an extene retinacular soft-tissue flap 19. Surgical correction inclues osteoplasty of the severely eforme femoral hea, trimming of the greater trochanter, an relative lengthening of the femoral neck with istalization of the greater trochanter (see Appenix). In some patients, intertrochanteric flexion or extension osteotomies can be performe. Prevention of Femoroacetabular Impingement Hips with evelopmental ysplasia often have a ecrease femoral hea-neck offset 14. With the acetabular reorientation typically anterosuperior, hea coverage will be increase, which potentially initiates painful femoroacetabular impingement against the proximal part of the femur with reuce femoral hea-neck offset (Fig. 4). Therefore, in hips with limite internal rotation (<30 ), the joint shoul be opene, visually inspecte, an analyze for impingement with the hip flexe an internally rotate 20. The arthrotomy allows for inspection of the acetabular labrum as well as the assessment of the anatomy of the femoral hea-neck junction. An osteochonroplasty with removal of the aspherical portion of the femoral hea-neck junction shoul be one (Fig. 4 an Appenix). To provie a rough guieline for the amount of bone to be resecte, the goal of internal rotation of 30 in 90 of flexion seems appropriate 21. Optionally, major unstable labral tears can be ebrie or repaire with suture anchors 15. Surgical Consierations an Our Preferre Technique The patient is place in a supine position with the hemipelvis an leg of the affecte sie sterilely prepare an rape. The skin incision is a shortene ilioinguinal incision. The incision starts laterally at the intersection between the meial an mile thir of the iliac wing an extens about 5 cm meial to the anterior superior iliac spine. The incision is place about 2 cm istal to the iliac crest (Fig. 5-A). This type of incision is cosmetically superior to the moifie Smith-Petersen incision. The sartorius muscle (meial) is separate from the tensor fascia lata muscle (lateral), exposing the irect origin of the rectus femoris muscle from the anterior inferior iliac spine. The abominal wall muscles are sharply issecte off the iliac crest, an the iliac muscle is mobilize from the iliac wing. The origin of the sartorius muscle together with the inguinal ligament is sharply issecte, mobilize, an meially retracte from the anterior superior iliac spine with the Fig. 4 The current technique of periacetabular osteotomy is shown. Typically, ysplastic hips present with an aspherical femoral hea (asterisk) (left). Before periacetabular osteotomy, this ecrease hea-neck offset is compensate for by the iminishe anterior acetabular coverage. After proper reorientation, femoroacetabular impingement may become apparent in eep flexion an internal rotation (arrow) (center). Iatrogenic acetabular overcoverage can worsen this impingement. Through an intraoperative arthrotomy, the femoroacetabular impingement can be assesse (right). If necessary, a concomitant osteochonroplasty of the femoral neck can be performe (arrows). (Reprouce, with moification, from Springer Science1Business Meia: 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 Jan 25. [Epub ahea of print]. Reprouce with permission.)

5 752 Figs. 5 Figs. 5-A through 5-D Our preferre technique of periacetabular osteotomy is shown. Fig. 5-A An ilioinguinal incision is performe. Fig. 5-B Intraoperative view after mobilization of the iliopsoas an the sartorius muscles. The first cut of the ischium is performe through the interval between the joint capsule an the rectus femoris muscle. Fig. 5-C The four periacetabular osteotomies are shown. Fig. 5-D Offset creation is performe with the rectus femoris muscle retracte meially through an H-shape capsulotomy. iliacus an psoas muscles (Fig. 5-B). As a further moification from the previously use technique, the two origins of the rectus femoris muscle are left intact an the interval between the rectus muscle (lateral) an the iliopsoas muscle (meial) is issecte an bluntly opene with scissors. The iliocapsularis muscle 22 is sharply separate from the capsule laterally an mobilize meially, together with the iliopsoas muscle. A Hohmann retractor is place into the superior pubic ramus 2 to 3 cm meial to the pubic eminence. With use of scissors, the infra-articular space is sprea open strictly following the contour of the calcar irectly on the intact capsule (Fig. 5-B). With the tip of the scissors, the ischial bone can be palpate beneath the posterior horn. With a specially esigne curve chisel, the first ischial osteotomy is one. The osteotomy of approximately 4 to 5 cm is an incomplete cut of the ischium. Next, two blunt retractors are place aroun the superior aspect of the pubic bone to protect the soft tissues an perform the pubic osteotomy (Fig. 5-C). At the level of the anterior superior iliac spine, partial elevation of the abuctor muscles from the outsie of the iliac wing is one to place a blunt retractor for protection of the abuctor muscles. The periosteum an obturator internus muscles are bluntly issecte off the quarilateral plate, an another blunt curve retractor is place on the quarilateral surface close to the ischial spine to further retract the soft tissues meially. With use of an oscillating saw, an oblique iliac osteotomy is performe at the level of the anterior superior iliac spine (Fig. 5-C). This osteotomy ens 1 to 2 cm lateral to the pelvic rim. From there, an osteotomy angle approximately 110 istally in regar to the previous horizontal cut of the ilium. This osteotomy is performe with a

6 753 TABLE I Minimum Ten-Year Survivorship of the Hip After Surgical Treatment of Developmental Dysplasia with Conversion to Total Hip Arthroplasty as the En Point Stuy Technique Duration of Follow-up* (yr) No. of Hips Age* (yr) Survival Rate (%) Siebenrock et al. 10 (1999) Periacetabular 11.3 (10-14) (13-56) 82 Kralj et al. 27 (2005) Periacetabular 12 (7-15) (18-50) 85 Flecher et al. 28 (2008) Periacetabular 12 (2-19) (18-47) 74 Steppacher et al. 26 (2008) Periacetabular 20.4 (19-23) (13-56) 61 Matheney et al. 40 (2009) Periacetabular 9 ± (10-44) 84 Ito et al. 46 (2011) Periacetabular 11 (5-20) (12-56) 96 Nakamura et al. 34 (1998) Rotational 13 (10-23) (11-52) 95 Takatori et al. 47 (2000) Rotational 13 (10-18) (19-40) 96 Takatori et al. 30 (2001) Rotational 19.8 (15-22) (20-28) 100 Nozawa et al. 48 (2002) Rotational 11.4 (10-15) (13-53) 98 Yasunaga et al. 39 (2004) Rotational 11 (8-15) (13-58) 100 Guille et al. 31 (1992) Triple 12 (10-16) (11-16) 91 van Hellemont et al. 35 (2005) Triple 15 (13-20) (14-46) 88 Janssen et al. 36 (2009) Triple 12 (11-12) (24-57) 85 Schramm et al. 9 (2003) Wagner spherical 23.9 (20-29) ± Zagra et al. 29 (2007) Wagner spherical 23.1 (21-27) (17-27) 100 *Continuous ata are expresse as the mean, with the range in parentheses if available, or the stanar eviation. straight an a curve chisel an is irecte to the ischial spine. A Schanz screw is inserte at the level of the anterior inferior iliac spine to o a controlle fracture of the remaining bone (Fig. 5-C). A spreaer inserte in the osteotomy gap of the iliac bone assists this maneuver. The controlle fracture can be aie by an aitional cut with the specially esigne curve chisel from the insie of the quarilateral surface. Once the fragment is completely free, the acetabulum is oriente with the Schanz screw an Hohmann retractors. Preliminary fixation of the bone is one with use of 2.5-mm partially threae pins. An intraoperative raiograph is mae with a raiographic plate sli unerneath the patient, using a specially esigne sanwich table, which eliminates the nee to move the patient or the rapes. The evaluation criteria for an optimal correction are escribe in more etail in the following section. The intraoperative ecision for the nee of an aitional osteotomy on the femoral sie may require aitional abuction or auction raiographs. Three 3.5-mm cortical screws are typically use to efinitively fix the acetabular fragment. Internal rotation is evaluate with the hip flexe 90. If there is <30 of internal rotation in the presence of ecrease femoral hea-neck offset on a lateral raiograph, an H-shape capsulotomy is performe (Fig. 5-D). The rectus femoris muscle is retracte meially for the capsulotomy. The osseous contour of the anterosuperior femoral hea-neck contour 20 is trimme (a so-calle offset correction) with a curve chisel an/or a high-spee burr (Fig. 5-D) 20. This is best performe with the lower limb in 10 of flexion an various positions of rotation. The incision is close with absorbable sutures, an a running suture is place along the iliac crest to reattach the muscle sleeve an the inguinal ligament to the outer fascia of the pelvis an thigh. Postoperatively, a continuous passive motion machine is use an partial weightbearingof15to20kgisrecommene for six to eight weeks after surgery. Intraoperative Evaluation Intraoperative evaluation can most accurately an efficiently be one by examining an anteroposterior pelvic raiograph. The tube-to-film istance is approximately 1.2 m in our epartment. Recommenations for efining the so-calle ieal correction parameters can only be given in ranges an not to the exact egree. The parameters an recommene goals are (1) a lateral center-ege angle between 20 an 35, preferably between 25 an 30 ; (2)an anterior center-ege angle between 0 an 10, preferably in the upper range; (3) hea meialization with a istance between the meial aspect of the femoral hea an the ilioischial line of <10 mm; (4) restoration of the Shenton line; (5) a weight-bearing ome centere over the hea; (6) anteversion of the acetabulum as efine by the absence of a cross-over sign an the outlines of the anterior an posterior rim meeting at the lateral acetabular ege; an (7) restoration of hip joint congruency 23. Persistent joint incongruity after acetabular reorientation requires intraoperative functional raiographs mae with the hip in abuction or auction to ecie whether an intertrochanteric osteotomy is necessary. After obtaining a satisfactory correction, we juge the hip

7 754 motion, especially flexion an internal rotation. Although there is no agreement regaring the efinition of ecrease internal rotation, internal rotation that is only between 15 an 30 shoul lea one to further search for its cause. Exclusion of intra-articular femoroacetabular impingement or extra-articular impingement against the anterior inferior iliac spine is recommene 24.In a recent series of ninety patients, a femoral hea-neck offset correction was performe in 57% of the hips after acetabular reorientation through a periacetabular osteotomy Trousale RT, Ganz R. Posttraumatic acetabular ysplasia. Clin Orthop Relat Res Aug;(305): Chiari K. [Pelvic osteotomy in hip arthroplasty]. Wien Me Wochenschr Sep 19;103(38): German. Review of the Literature There is evience that acetabular reorientation can ecelerate joint egeneration 26. The long-term results (ten to almost thirty years) for all three types of juxta-acetabular osteotomies are summarize in Table I. The survivorship of the hip has been reproucibly shown to be approximately 90% after ten years an 60% to 70% after twenty years, inepenent of the reorientation technique. The long-term reports of the early series typically involve heterogeneous patient cohorts 26-28, incluing patients with avance age an/or joint egeneration. In a follow-up stuy with a more homogeneous patient cohort at our institution, a goo clinical result without progression of osteoarthritis was achieve in 90% of the patients at a minimum ten-year follow-up interval 25. Follow-up stuies that have shown survivorship of up to 100% typically have involve a nonconsecutive series of patients 29, exclusive of patients with previous surgical proceures on the hip 30, low numbers of patients 29-31,ora substantial percentage of patients lost to follow-up 30. The natural history of hip ysplasia is not as goo 32. Several common negative preictors influencing the long-term outcome after acetabular reorientation for evelopmental ysplasia of the hip were ientifie. These inclue mainly emographic or inepenent preoperative factors such as avance age 27,33,34, low preoperative functional hip scores 26,35, a boy mass inex of >25 (kg/m 2 ) 36, preexisting early osteoarthritis 26,37-41,a preoperative limp 26, evience of a labral tear 42 with pain in flexion an internal rotation 26, an preoperative femoral hea subluxation 25,41. Postoperative lateral acetabular unercoverage 25,43 an excessive acetabular anteversion 25 can lea to persistent static overloa of the lateral an/or the anterior acetabular rim with subsequent egeneration. Postoperative lateral overcoverage 20,25 an acetabular retroversion 25,44 have been associate with ecrease hip survivorship because of iatrogenic postoperative femoroacetabular impingement between the overcorrecte acetabulum an the proximal part of the femur. A previous femoral hea-neck offset correction or, if necessary, an intraoperative offset correction in hips with an aspherical hea-neck junction improves the ten-year survivorship 25,45. In conclusion, improper acetabular reorientation, specifically incorrect acetabular version an a concomitant persistence of an aspherical femoral hea-neck junction, nees to be inclue as a risk factor for a less favorable outcome 25. Overview The appropriate surgical treatment of hip ysplasia after closure of the triraiate cartilage is a reorientation of the entire acetabulum. Among the ifferent surgical techniques for acetabular reorientation, periacetabular osteotomy has become the gol stanar. It provies the largest reorientation potential with inherent stability because of its polygonal shape without changing the imensions of the birth canal. There is increasing evience that the natural References 3. Lance M. Consitution une butrée ostéoplastique ans les luxationes subluxations congénitales e la hanche. Presse Me. 1925;33: French. 4. Klaue K, Durnin CW, Ganz R. The acetabular rim synrome. A clinical presentation of ysplasia of the hip. J Bone Joint Surg Br May;73(3): egeneration in ysplastic hips can be ecelerate by periacetabular osteotomy. The survival rate of the hip after acetabular reorientation is approximately 90% after ten years an 60% to 70% after twenty years. Careful patient selection, an optimal acetabular reorientation, an a concomitant osteochonroplasty of an aspherical femoral hea-neck junction may lea to improve long-term results. Appenix Figures showing raiographs of a twenty-five-year-ol woman with resiual eformity from Legg-Calvé- Perthes isease who ha an excellent result after a periacetabular osteotomy, surgical hip islocation with trimming of the femoral hea-neck junction, an lengthening of the femoral neck as well as raiographs of a female patient with evelopmental ysplasia of the hip who ha correction of a ecrease femoral hea-neck offset with an arthrotomy are available with the online version of this article as a ata supplement at jbjs.org. NOTE: The authors thank Joseph M. Schwab, MD, for assistance in the preparation of this manuscript. Klaus A. Siebenrock, MD Simon D. Steppacher, MD Christoph E. Albers, MD Pascal C. Haefeli, MD Moritz Tannast, MD Department of Orthopaeic Surgery, Inselspital, Bern University Hospital, Freiburgstrasse, Bern 3010, Switzerlan Printe with permission of the American Acaemy of Orthopaeic Surgeons. This article, as well as other lectures presente at the Acaemy s Annual Meeting, will be available in March 2014 in Instructional Course Lectures, Volume 63. The complete volume can be orere online at or by calling (8 a.m.-5 p.m., Central time). 5. Winhager R, Pongracz N, Schönecker W, Kotz R. Chiari osteotomy for congenital islocation an subluxation of the hip. Results after 20 to 34 years follow-up. J Bone Joint Surg Br Nov;73(6): Nishina T, Saito S, Ohzono K, Shimizu N, Hosoya T, Ono K. Chiari pelvic osteotomy for osteoarthritis. The

8 755 influence of the torn an etache acetabular labrum. J Bone Joint Surg Br Sep;72(5): Wagner H. Osteotomies for congenital hip islocation. In: The hip. Proceeings of the fourth open scientific meeting of the hip society. St. Louis: CV Mosby; p Ninomiya S, Tagawa H. Rotational acetabular osteotomy for the ysplastic hip. J Bone Joint Surg Am Mar;66(3): Schramm M, Hohmann D, Raespiel-Troger M, Pitto RP. Treatment of the ysplastic acetabulum with Wagner spherical osteotomy. A stuy of patients followe for a minimum of twenty years. J Bone Joint Surg Am May;85(5): Siebenrock KA, Schöll E, Lottenbach M, Ganz R. Bernese periacetabular osteotomy. Clin Orthop Relat Res Jun;(363): Tönnis D, Behrens K, Tscharani F. A moifie technique of the triple pelvic osteotomy: early results. J Peiatr Orthop. 1981;1(3): 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): Leunig M, Siebenrock KA, Ganz R. Rationale of periacetabular osteotomy an backgroun work. Instr Course Lect. 2001;50: Steppacher SD, Tannast M, Werlen S, Siebenrock KA. Femoral morphology iffers between eficient an excessive acetabular coverage. Clin Orthop Relat Res Apr;466(4): Clohisy JC, Barrett SE, Goron JE, Delgao ED, Schoenecker PL. Periacetabular osteotomy in the treatment of severe acetabular ysplasia. Surgical technique. J Bone Joint Surg Am Mar;88(Suppl 1 Pt 1): Tannast M, Hanke M, Ecker TM, Murphy SB, Albers CE, Puls M. LCPD: reuce range of motion resulting from extra- an intraarticular impingement. Clin Orthop Relat Res Sep;470(9): Hersche O, Casillas M, Ganz R. Inications for intertrochanteric osteotomy after periacetabular osteotomy for ault hip ysplasia. Clin Orthop Relat Res Feb;(347): Nötzli HP, Müller SM, Ganz R. [The relationship between fovea capitis femoris an weight bearing area in the normal an ysplastic hip in aults: a raiologic stuy]. Z Orthop Ihre Grenzgeb Nov- Dec;139(6): German. 19. Ganz R, Huff TW, Leunig M. Extene retinacular soft-tissue flap for intra-articular hip surgery: surgical technique, inications, an results of application. Instr Course Lect. 2009;58: Myers SR, Eijer H, Ganz R. Anterior femoroacetabular impingement after 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): Babst D, Steppacher SD, Ganz R, Siebenrock KA, Tannast M. The iliocapsularis muscle: an important stabilizer in the ysplastic hip. Clin Orthop Relat Res Jun;469(6): Millis MB, Siebenrock KA; Session Participants. 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[Periacetabular osteotomy meium term survival in ault acetabular ysplasia]. Rev Chir Orthop Reparatrice Appar Mot Jun;94(4): French. 29. Zagra L, Corbella M, Giacometti Ceroni R. Wagner s spherical periacetabular osteotomy: long term results. Hip Int. 2007;17(Suppl 5):S Takatori Y, Ninomiya S, Nakamura S, Morimoto S, Moro T, Nagai I, Mabuchi A. Long-term results of rotational acetabular osteotomy in patients with slight narrowing of the joint space on preoperative raiographic finings. J Orthop Sci. 2001;6(2): Guille JT, Forlin E, Kumar SJ, MacEwen GD. Triple osteotomy of the innominate bone in treatment of evelopmental ysplasia of the hip. J Peiatr Orthop Nov-Dec;12(6): Murphy SB, Ganz R, Müller ME. The prognosis in untreate ysplasia of the hip. A stuy of raiographic factors that preict the outcome. J Bone Joint Surg Am Jul;77(7): Murphy S, Deshmukh R. Periacetabular osteotomy: preoperative raiographic preictors of outcome. 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