JBJS | Article

The Journal of Bone & Joint Surgery, Volume 83, Issue 6

Articles | June 01, 2001

Dega Osteotomy for the Treatment of Congenital Dysplasia of the Hip

Jan S. Grudziak, MD, PhD; W. Timothy Ward, MD

Investigation performed at Children’s Hospital of Pittsburgh and the Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
Jan S. Grudziak, MD, PhD
W. Timothy Ward, MD
Children’s Hospital of Pittsburgh, 3705 Fifth Avenue at DeSoto Street, Pittsburgh, PA 15213. E-mail address for J.S. Grudziak: grudzij@chplink.chp.edu. E-mail address for W.T. Ward: wardt@chplink.chp.edu
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.

The Journal of Bone & Joint Surgery. 2001; 83:845-854

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Abstract

Background: In 1969 Dega described a transiliac osteotomy to treat residual acetabular dysplasia secondary to congenital hip dysplasia or dislocation. We were unable to find a thorough description of the technique in the English-language orthopaedic literature, and the number of clinical follow-up series is small.

Methods: Twenty-two children (twenty-four hips) with an average age of five years and ten months and varying degrees of congenital hip dysplasia, subluxation, or dislocation were treated with a Dega osteotomy. Twenty hips (83%) had a concomitant femoral osteotomy and thirteen (54%) had an anterior open reduction of the hip in addition to the Dega osteotomy. To be included in the study group, each patient had to have complete clinical documentation of the range of motion, presence or absence of a limp, limb-length discrepancy, hip pain, and limitation of activity. Radiographs were reviewed to determine the acetabular index, the center-edge angle, whether the Shenton line was intact or broken, and any change in the projection of the obturator foramen.

Results: At an average of fifty-five months postoperatively, all patients demonstrated unlimited physical activity and no limp. The average acetabular index changed from 33° preoperatively to 12° at the time of follow-up. The center-edge angle ranged from less than —30° to 18° preoperatively and from 18° to 40° (average, 31°) at the time of follow-up. A change in the obturator foramen was observed in fourteen hips (58%). The Shenton line was broken in seventeen hips preoperatively but in none postoperatively. One Dega osteotomy was revised immediately after the index operation, and three hips underwent late repeat correction of the proximal part of the femur; one of the repeat corrections was performed together with a repeat Dega osteotomy.

Conclusions: Our initial experience with the Dega osteotomy demonstrated it to be a valuable surgical treatment of congenital dysplasia of the hip in a child of walking age. Our experience is comparable with that of many European authors, including those reporting studies from Dega’s own institution.

Figures in this Article

Introduction

Various pelvic innominate osteotomies have been described for the treatment of residual acetabular dysplasia secondary to congenital hip dysplasia or dislocation. These osteotomies may be performed as an isolated procedure or along with an open reduction of the hip and a proximal femoral osteotomy. Innominate osteotomies can be divided into two types: complete and incomplete transiliac osteotomies. The osteotomies described by Salter¹, Steel², and Sutherland and Greenfield³ are examples of complete transiliac osteotomies. The first English-language description of an incomplete transiliac osteotomy for the treatment of acetabular dysplasia secondary to congenital dysplasia of the hip appears to be that written by Albee⁴ in 1915. Albee described a semicircular osteotomy of the lateral part of the acetabular rim that was directed obliquely from lateral to medial just cephalad to the attachment of the hip capsule into the ilium.

The most widely known incomplete transiliac osteotomy is that described by Pemberton⁵. This osteotomy starts approximately 10 to 15 mm above the anterior inferior iliac spine, curves gently posteriorly, and ends at the level of the ilioischial limb of the triradiate cartilage halfway between the sciatic notch and the posterior part of the acetabular rim. The osteotomy is believed to hinge at the triradiate cartilage, but theoretically it may also hinge at the symphysis pubis⁵.

The Pembersal osteotomy described by Perlik et al.⁶ originated from a serendipitous variation on the Pemberton osteotomy. A Pembersal osteotomy is similar to a Pemberton osteotomy, except that the posterior extent continues more caudally to cross the ilioischial limb of the triradiate cartilage, extending into the body of the ischium. Theoretically, this osteotomy hinges at the triradiate cartilage, symphysis pubis, and ischial osteotomy site, providing both acetabular redirection and reshaping. Because of an inadequate exposure of the ischial region caudal to the sciatic notch, it is difficult for the surgeon to know whether, or where, the osteotomy actually crosses the ilioischial triradiate limb, thereby raising a question as to whether a Pemberton or a Pembersal procedure is actually being performed. Furthermore, since the caudal extension of the Pembersal osteotomy crosses the triradiate growth cartilage, there is a potential for growth arrest of the triradiate cartilage.

In 1969, Dega⁷ reported on what he called a transiliac osteotomy, which was actually an incomplete transiliac osteotomy in which the cut penetrated the anterior and middle portions of the inner cortex of the ilium, leaving an intact hinge posteriorly consisting of the intact posteromedial iliac cortex and sciatic notch. Several authors working in Dega’s institution have reported their results with use of a Dega osteotomy for the treatment of acetabular dysplasia secondary to congenital dislocation or subluxation of the hip. In certain instances, the procedure was combined with an open reduction and/or proximal femoral osteotomy^8-16. Unfortunately, none of these publications, nor Dega’s seminal reports, provide a detailed description of the operative technique.

The aim of the present paper is twofold. One of us (J.S.G.) had, at the time of writing, an eight-year experience with this osteotomy at Dega’s institution. Thus, we are able to provide an accurate description of the procedure as devised by Dega and as it has been performed at Dega’s institution in Poznan, Poland, since 1968. We also report the initial experience of one of us (W.T.W.) with this osteotomy, either as an isolated procedure or combined with proximal femoral osteotomy and/or open reduction of the hip, for the treatment of acetabular dysplasia secondary to congenital dysplasia of the hip.

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Fig. 1:: The anterolateral incision is made starting 1 cm inferior and posterior to the anterior superior iliac spine and extending distally over the proximal part of the femur, centered over the greater trochanter.

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Fig. 2:: The Dega incomplete transiliac osteotomy line is marked on the lateral cortex of the ilium, and a guide-wire is inserted under fluoroscopic control to exit just above the horizontal limb of the triradiate cartilage.

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Fig. 3-A:: The osteotome penetrating the inner cortex, viewed from the lateral aspect of the ilium.

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Fig. 3-B:: View from the inner side of the pelvis, showing an intact posteromedial cortical hinge. The length of the intact inner cortex depends on the amount of anterior or lateral coverage desired.

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Fig. 4:: The osteotomy site is levered open with either an osteotome or a small laminar spreader.

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Fig. 5-A:: Two grafts that are large enough to keep the osteotomy site open at the premeasured height are inserted.

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Fig. 5-B:: A larger graft is inserted anteriorly. The posterior graft should be smaller in order not to loosen the anterior graft.

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Fig. 6-A:: Figs. 6-A, 6-B, and 6-C Case 5. Fig. 6-A Preoperative anteroposterior radiograph of a two-year and five-month-old girl who had not had prior treatment. The acetabular index measures 31°.

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Fig. 6-B:: Anteroposterior radiograph made immediately following an anterior open reduction, femoral shortening, and a Dega osteotomy.

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Fig. 6-C:: Thirty-six months after the operation, an anteroposterior radiograph demonstrated excellent coverage of the femoral head, with the acetabular index measuring 9° and the center-edge angle measuring 38°.

Materials and Methods

We retrospectively reviewed the results of one surgeon’s (W.T.W.) operative experience with the Dega osteotomy for the treatment of congenital dysplasia of the hip in children of walking age. For this study, we defined congenital dysplasia of the hip as different degrees of congenital underdevelopment of the acetabulum or the proximal part of the femur, or both, with or without concomitant subluxation or dislocation of the femoral head. For a patient to be included in the study, preoperative and postoperative clinical and radiographic information had to be available and the duration of follow-up after the index operation had to have been at least two years. We excluded patients in whom the hip dislocation or dysplasia was secondary to underlying neurological disease. The study population (see Appendix) consisted of twenty-two patients, nineteen girls and three boys, with a total of twenty-four involved hips. (Two patients [Cases 15 and 16] had bilateral involvement.) The average age at the time of the operation was five years and ten months, with a range of one year and eleven months to fifteen years and ten months. The duration of follow-up averaged fifty-five months, with a range of twenty-eight to ninety-one months. Thirteen of the twenty-four hips had had no prior treatment, whereas eight had undergone a previous attempted closed reduction and three had undergone various combinations of open reduction and femoral and/or pelvic osteotomy.

Documentation of the range of motion, presence or absence of a limp, limb-length discrepancy, hip pain, and limitation of activity was obtained from the medical records both preoperatively and at the last follow-up visit. Radiographs were used to measure the acetabular index¹⁷ and the center-edge angle¹⁸, to look for any change in the appearance of the obturator foramen postoperatively, and to determine whether the Shenton line was intact or broken. The height-to-width ratio of the obturator foramen, as seen on the anteroposterior pelvic radiograph, was used to assess change in the position of the obturator foramen relative to the appearance on the preoperative radiograph; such change indirectly indicates motion through the symphysis pubis.

Preoperatively, eleven hips were classified radiographically as having only acetabular dysplasia, with a concentrically reduced femoral head; six, as being subluxated; and seven, as being completely dislocated. Hips with a concentrically positioned femoral head and an acetabular index of 20° were classified as dysplastic. A subluxated hip was defined as one in which there was only partial contact between the acetabulum and the femoral head. In a subluxated hip, the femoral head is not concentrically reduced and the Shenton line is broken. Dislocation meant a total lack of contact between the femoral head and the acetabulum. Open reduction was performed for all hips with subluxation or dislocation of the femoral head. Femoral osteotomy was performed when there was a need for femoral shortening or for correction of excessive femoral valgus or anteversion. Femoral valgus was considered to be excessive when the true neck-shaft angle exceeded 135° on an abduction-internal rotation radiograph of the hip, and anteversion of the proximal part of the femur was considered to be excessive when the hip had to be internally rotated >45° on the abduction-internal rotation radiograph to demonstrate the true neck-shaft angle. Femoral shortening was generally used in the treatment of completely dislocated hips to avoid creating excessive forces across the hip joint following open reduction. Femoral osteotomy was performed in all hips with dislocation or subluxation and in seven of the eleven hips classified as having acetabular dysplasia.

Surgical Technique

The patient is positioned supine with the involved hip tilted up approximately 30° to 40° by a bump placed at the midlumbar level. An extended anterolateral incision is made starting 1 cm inferior and posterior to the anterior superior iliac spine and extending distally over the proximal part of the femur, centered over the greater trochanter (Fig. 1). The interval between the tensor fasciae latae muscle posteriorly and the sartorius muscle anteriorly is developed, and the sartorius is released from its origin on the anterior superior iliac spine. The abductor muscles are sharply reflected off of the lateral wall of the ilium just distal to the iliac apophysis. The apophysis itself is not split. The abductor muscles and the periosteum are completely separated from the ilium and the hip capsule back to the sciatic notch, which is fully exposed, and an adult-size blunt Hohmann retractor is then inserted into the notch. Neither the muscles nor the periosteum are dissected off of the inner wall of the ilium. The reflected head of the rectus femoris muscle is separated from the hip capsule and is incised. The tendon of the straight head of the rectus femoris muscle is detached from the anterior inferior iliac spine only when necessary for proper visualization of the capsule. The tendinous portion of the iliopsoas muscle is isolated from the capsule and is transected either over the anteromedial aspect of the capsule just distal to the pelvic brim or more distally, near its insertion. Open reduction of the hip and/or concomitant femoral osteotomy with shortening and rotation to correct excessive anteversion are performed at this time if required.

The vastus lateralis fascia and muscle are split, exposing the proximal part of the femur. If valgus correction was planned preoperatively, we use a 90° AO infant blade-plate for fixation and reduce the true neck-shaft angle to 110° to 120°. If shortening and rotation without valgus correction was planned, then a straight one-third tubular AO plate is utilized. Two small Kirschner wires are inserted into the femur, one above the osteotomy plane and the other below the level of the desired shortening, to aid in determining the amount of anteversion correction. The femur is osteotomized in the subtrochanteric or intertrochanteric region, and the fragments are allowed to overlap as the femoral head is reduced deeply into the acetabulum. A femoral shortening equivalent to the amount of overlap is then performed. Preliminary fixation of the straight plate or 90° blade-plate is achieved with a bone clamp. The hip is flexed to 90°, and the clamp is loosened so that enough external rotation of the distal fragment is added to make internal and external rotation of the hip symmetrical. Observation of the guide-wires at this point reveals an estimated anteversion correction ranging from 10° to 40°. At this point, the femoral head will rest deeply in the still steep acetabulum and have a diminished tendency to dislocate with the lower limb in neutral position.

Next, the Dega osteotomy is performed to decrease acetabular dysplasia and to enhance containment of the femoral head. The orientation of the osteotomy is first marked on the lateral cortex of the ilium (Fig. 2). The direction of the osteotomy is curvilinear when viewed from the lateral cortex, starting just above the anterior inferior iliac spine, curving gently cephalad and posteriorly to reach a point superior to the midpoint of the acetabulum, and then continuing posteriorly to end approximately 1 to 1.5 cm in front of the sciatic notch. The most cephalad extent of the osteotomy is in the middle of the acetabulum, at a point on the ilium determined by the steepness of the acetabulum. Very steep acetabular inclinations require a correspondingly higher midpoint. A guide-wire is inserted under fluoroscopic control at the most cephalad point of the curvilinear marking line, directed caudally and medially to ensure that the osteotomy will exit at the appropriate level just above the horizontal limb of the triradiate cartilage. A straight 0.25 or 0.5-in (0.64 or 1.3-cm) osteotome is used to perform the bone cut, which extends obliquely medially and inferiorly, paralleling the guide-wire to exit through the inner cortex just above the iliopubic and ilioischial limbs of the triradiate cartilage (Fig. 3-A), leaving the posterior one-third of the inner cortex intact (Fig. 3-B). If predominantly anterior coverage is desired, the medial (inner) cortex is cut over the anterior and middle portion, leaving only the posterior sciatic notch hinge intact. If more lateral coverage is desired, more of the medial cortex is left intact, resulting in a posteromedial hinge based on the posteromedial inner cortex and the entire sciatic notch. In most cases, approximately one-quarter to one-third of the inner pelvic cortex is left intact posteriorly. With experience, the osteotomy cut might be performed safely without fluoroscopic guidance, as per Dega’s original description; however, we prefer to use fluoroscopy.

A 0.5-in (1.27-cm) osteotome is then used to gently lever open the osteotomy site either anteriorly or laterally in a controlled manner (Fig. 4). A small laminar spreader is also useful for this maneuver. Quite often, while the osteotomy site is being opened, the osteotomy cut on the outer cortex of the ilium propagates toward the sciatic notch as a greenstick fracture. However, since the posterior portion of the inner cortex is still intact, the outer cortical greenstick fracture does not weaken the recoil and stability at the osteotomy site.

The osteotomy site is kept open by inserting two correctly sized bone grafts (Figs. 5-A and 5-B). The grafts are fashioned from a bicortical segment of iliac crest bone or, alternatively, if femoral shortening had been performed, the segment of the femur that was removed is utilized as a graft. In cases in which there is a substantial gap at the osteotomy site, an autogenous femoral or iliac crest graft may not be sufficient. Under these circumstances, the height of the graft can be increased by utilizing freeze-dried fibular allograft cut into trapezoidal sections. The correct graft height is determined by simply noting the opening of the osteotomy gap created by the laminar spreader or the levering osteotome. In congenital dysplasia, acetabular deficiency is most pronounced anteriorly, mandating placement of the larger graft more anteriorly. A smaller graft is then wedged more posteriorly, just in front of the intact sciatic notch. Care is taken to ensure that both grafts are of an appropriate height and that the amount of correction of the dysplastic acetabulum provides enough coverage of the femoral head.

Once the grafts have been inserted, they are stable because of the inherent recoil at the osteotomy site produced by the intact sciatic notch¹⁹. Metallic internal fixation is not necessary. Variations in the graft size and placement, extent of the outer and inner cortical cuts, and thickness of the acetabular fragment make it possible to both reorient and reshape the acetabulum. The more posterior the extent of the outer cortical cut, and the greater the amount of the inner cortex left intact, the more lateral the tilt of the acetabulum. A more cephalad starting point and a steeper osteotomy angle allow for more lateral coverage. A more extensive cut through the inner cortex allows for more anterior coverage of the hip. Finally, the closer the osteotomy is to the acetabulum, the thinner and more pliable will be the acetabular fragment, theoretically allowing for more reshaping and less redirection to occur. These three-dimensional changes in the osteotomy are admittedly difficult to quantify, as is the true anatomical nature of a dysplastic hip. However, an experienced orthopaedic surgeon who is familiar with the spectrum of dysplastic hip pathology, and who applies the principles described above, should be able to perform an osteotomy that is precisely suited to the unique pathology of a given dysplastic hip. Once the osteotomy is performed, satisfactory femoral head coverage can be appreciated and the hip should be stable during flexion and rotation.

After closure, a one and one-half spica cast is applied with the hip in neutral extension, approximately 20° of internal rotation, and 20° to 30° of abduction. The cast is worn for eight to twelve weeks depending on the healing of the osteotomy site. After the cast is removed, progressive walking and range of motion are begun, but no formal physical therapy is prescribed.

Results

Twenty (83%) of the twenty-four hips had a concomitant femoral osteotomy, and thirteen (54%) had an anterior open reduction prior to the Dega osteotomy; all procedures were performed during the same operation. The duration of follow-up averaged fifty-five months, with a range of twenty-eight to ninety-one months. Preoperatively, no patient complained of hip pain or limitation of activity, except for a fifteen-year and ten-month-old boy who limited his activity secondary to groin pain (Case 8). All patients with subluxation or dislocation had had a limp and limitation of abduction preoperatively. At the time of follow-up, no patient had a limitation of activity, hip pain, or a limp. The range of motion was equal to that of the contralateral, normal hip in all patients with unilateral involvement, and it was considered to be normal in the two patients who had bilateral involvement. No patient had persistent limb-length inequality of >1 cm. Since the clinical results were satisfactory in all twenty-four hips, no association was observed between the clinical results and the preoperative radiographic classification.

The acetabular index improved in all hips. Preoperatively it averaged 33°, with a range of 20° to 46°, and postoperatively it averaged 12°, with a range of 6° to 23° (see Appendix). In patients in whom the triradiate cartilage was closed, we used the Sharp angle²⁰ to assess reorientation and/or reshaping of the acetabulum. In one patient (Case 8), the Sharp angle decreased from 45° preoperatively to 37° at the time of the last follow-up. In two patients (Cases 10 and 17), the Sharp angle at the time of the last follow-up was 44° and 38°, respectively. The center-edge angle improved in all hips. The preoperative angle (range, less than —30° to 18°) was negative in nine hips preoperatively; however, the angle was positive in all hips at the time of follow-up. In the seven dislocated hips with a preoperative center-edge angle of less than —30°, the angle improved to an average of 32° at the time of follow-up. In the fifteen dysplastic and subluxated hips with an average preoperative center-edge angle of 8°, the angle improved to an average of 31° at the time of follow-up. A change in the appearance of the obturator foramen, as seen on the anteroposterior radiograph, was observed in fourteen (58%) of the twenty-four hips immediately postoperatively. This change most likely reflects a reorientation of the component as a result of motion at the symphysis pubis. The Shenton line was broken in seventeen hips preoperatively but in none postoperatively; this indicated that subluxation and dislocation had been corrected in all hips. Preoperative classification of the hips as dysplastic, subluxated, or dislocated did not correlate with the radiographic appearance of the hips postoperatively (see Appendix).

A clinical example of a hip treated with the Dega osteotomy is shown in Figures 6-A, 6-B, and 6-C.

Complications

Only one patient (Case 19) had early failure directly attributable to the performance of the Dega osteotomy. A five and one-half-year-old girl had undergone an open reduction, a femoral shortening rotation osteotomy, and a Dega osteotomy for subluxation of the hip. In the immediate postoperative period, she was found to have inadequate coverage of the femoral head due to an inadequate open reduction and insufficient displacement at the Dega osteotomy gap. During the same hospitalization, a repeat open reduction and a revision Dega osteotomy were performed. At the revision surgery, the autogenous femoral graft used for the initial Dega osteotomy was replaced by a larger, cadaveric fibular strut graft, resulting in excellent coverage of the femoral head. The final result was very satisfactory.

Three patients (Cases 11, 12, and 20) had complications related to the execution of a proper femoral osteotomy. In one (Case 11), three years after a Dega osteotomy and a femoral varus rotation osteotomy for the treatment of hip dysplasia, another femoral varus shortening osteotomy was necessary to correct recurrent valgus overgrowth of the proximal part of the femur. In the second patient (Case 12), the fixation of the femoral osteotomy site failed in the early postoperative period. This was addressed by early repeat fixation of the femur. Unfortunately, during the follow-up period, an increasing valgus overgrowth of the femur with resultant recurrent acetabular dysplasia occurred. Four years following the index surgery, this recurrent problem was addressed by a repeat femoral varus shortening osteotomy and a repeat Dega osteotomy. Finally, in the third patient (Case 20), who had been treated initially with an open reduction, a Dega osteotomy, and a femoral shortening rotation osteotomy for hip subluxation, excessive external rotation of the femur resulted in an unsightly external-rotation gait with an inability to achieve any internal rotation of the hip. One year after the initial operation, this patient underwent an internal rotation osteotomy of the proximal part of the femur, resulting in excellent correction of the gait abnormality. All three of the hips with complications had a very satisfactory result at the time of the final follow-up.

Discussion

There has been a lot of confusion regarding what represents a Dega osteotomy. Much of it can be attributed to Dega himself and to his coworkers. Dega^7,21,22 described two different types of incomplete transiliac osteotomy. However, he never highlighted the important differences between them, thereby adding to the confusion of readers unfamiliar with the exact evolutionary history of this procedure. His initial osteotomy was first briefly mentioned in a 1964 German publication²¹, but it was not until 1969, in a Polish publication⁷, that he first referred to this initial osteotomy as a supraacetabular semicircular osteotomy. In his 1964 German publication, Dega²¹ did not provide a detailed written description of the supraacetabular semicircular osteotomy, but he did emphasize that the medial iliac cortex was not to be cut in any area, to guard against the possibility of the acetabular fragment displacing medially in a "manner consistent with a Chiari osteotomy."²¹ The supraacetabular semicircular osteotomy starts 1 to 1.5 cm cephalad to the acetabular rim and extends obliquely medially toward the triradiate cartilage, but it does not penetrate the inner cortex of the ilium^7,21. This osteotomy was described, and schematically represented, as a semicircular cut through the lateral wall of the ilium directed toward but not through the medial cortex of the ilium. This earlier supraacetabular osteotomy unequivocally did not transect the inner cortex of the ilium. It did, however, establish a basis for the subsequent development of what Dega termed a transiliac osteotomy⁷ but what we believe should be more accurately referred to in English as Dega’s incomplete transiliac osteotomy.

In 1974, Dega²² provided an extensive written description of his incomplete transiliac osteotomy in the Polish literature. This description emphasized the importance of maintaining an intact sciatic notch hinge while simultaneously cutting the inner iliac cortex over both its anterior and its middle extent. By 1974, Dega had stopped performing his supraacetabular semicircular osteotomy, and he did not even mention this variant in the 1974 publication. Unfortunately, the accompanying schematic illustrations in the 1974 publication do not accurately match the written description of the incomplete transiliac osteotomy. The frontal plane schematic incorrectly depicts a supraacetabular semicircular osteotomy with the entire inner cortex of the ilium left intact. In addition, the lateral postosteotomy schematic depicts the osteotomy as extending into the sciatic notch. This representation is not consistent with the written text, which describes an incomplete transiliac osteotomy; instead, it is more consistent with a supraacetabular semicircular osteotomy. This 1974 Polish publication by Dega was the last report from the Institute of Orthopedics and Rehabilitation in Poznan, Poland, that included a written description of the operative technique. Subsequent publications from this institution^8-14 were focused exclusively on the results of the treatment of various forms of acetabular dysplasia secondary to congenital dysplasia of the hip, and in different age-groups, with use of the incomplete transiliac osteotomy; they did not include even brief descriptions of the operative technique.

The theoretical location of the hinge in the Dega osteotomy can involve, to varying degrees, the sciatic notch, the posterior portion of the inner pelvic cortex, the horizontal limb of the triradiate cartilage, and the symphysis pubis. Since the hinge point is variable and not confined solely to the triradiate cartilage, we believe that the risk of damage to this structure is lower than it is with other incomplete transiliac osteotomies, such as those of Pemberton⁵, Trevor et al.²³, and Perlik et al.⁶.

The sciatic notch remains intact if the Dega osteotomy is done properly. As the osteotomy site is opened, there is an intrinsic recoil of the acetabular fragment that ensures stability of the graft without the need for internal fixation. After properly sized grafts are placed into the osteotomy site, they are so stable that one can shake the whole pelvis of the patient by grasping the grafts with a Kocher clamp¹⁹. Since the sciatic notch remains intact, iatrogenic limb-lengthening, which can occur with complete transiliac osteotomies, is less of a problem.

We believe that the Dega osteotomy can both reorient and reshape the acetabulum. Our radiographic results show that, in most cases, there is a change in the obturator foramen, the acetabular index, and the center-edge angle, signifying that the acetabulum was reoriented. Reshaping of the acetabulum is a more difficult phenomenon to quantitate, and we admit that this study does not settle this issue. We have observed that, in a younger child with a wide-open triradiate cartilage, most of the hinging occurs at the sciatic notch and the triradiate cartilage. As the child gets closer to skeletal maturity, more hinging probably occurs at the sciatic notch and the symphysis pubis. As a consequence of the variable hinge location, the Dega osteotomy can be performed with either an open or a closed triradiate cartilage, although we recommend that it be performed before closure of the triradiate cartilage. A similar opinion has been expressed by several European authors^8-10,12-14.

The experience with the Dega osteotomy has been discussed in many European publications^9-14,24-28. One of us (J.S.G.) and colleagues⁸ presented the first English-language report on the long-term results of the Poznan group’s experience with the Dega osteotomy for the treatment of congenital dislocation of the hip. In the present study, we documented excellent clinical and radiographic results, comparable with those reported by the European authors. Concentric reduction of the hip was achieved and maintained in all patients, and all had a decrease in the acetabular dysplasia, usually to normal values as measured by the acetabular index and the center-edge angle. Our reoperation rate was higher than those in the studies by one of us (J.S.G.) and colleagues⁸, Labaziewicz and Piskorski⁹, Pucher et al.^10,11, and Senger et al.^12-14. For example, Labaziewicz and Piskorski reported that only three of seventy-two hips needed a secondary operation. In that study, one hip redislocated immediately following an open reduction and a Dega osteotomy, one hip had dislodgment of the graft, and one hip required a secondary procedure to undo excessive correction of the neck-shaft angle. Senger et al.¹⁴ reported the results of treatment of 201 cases of congenital dislocation of the hip. There were four postoperative redislocations, one femoral fracture, and one case of coxa vara resulting from excessive correction of the neck-shaft angle. Pucher et al., in two publications^10,11, reported no redislocations. However, those reports disclosed two serious complications: in one patient, for whom fluoroscopic control was not used, the osteotomy extended into the hip joint, and in the other patient septic arthritis developed. Our problems have been largely confined to the technical aspects of performing femoral osteotomy, not to the execution of the Dega osteotomy itself.

The Dega osteotomy is just one component of the comprehensive, complicated surgery required to treat severe congenital dysplasia of the hip in children of walking age. It must be accompanied by a satisfactorily performed open reduction and an appropriate correction of the proximal femoral deformity when needed. Our study emphasized the necessity of performing the Dega osteotomy in a technically sound manner, with particular attention paid to obtaining stability at the osteotomy site and preserving the elastic recoil that results from an intact sciatic notch. In our limited experience with the Dega transiliac osteotomy, the procedure was satisfactory for the treatment of acetabular dysplasia in children of walking age.

Appendix

A table showing clinical and radiographic data (preoperative hip classification, gender, prior treatment, operations performed with the Dega osteotomy, age at the time of surgery and at the time of follow-up, duration of follow-up, acetabular index, center-edge angle, change in the appearance of the obturator foramen, status of the Shenton line, complications, and subseqent surgery) is available with the electronic versions of this article, on our web site (www.jbjs.org) and on our CD-ROM (call 781-449-9780, ext. 140, to order).

References

Salter RB: Innominate osteotomy in the treatment of congenital dislocation and subluxation of the hip. J Bone Joint Surg Br,1961.43: 518-39, 43518 1961

Steel HH: Triple osteotomy of the innominate bone. J Bone Joint Surg Am,1973.55: 343-50, 55343 1973 [PubMed]

Sutherland DH, and Greenfield R: Double innominate osteotomy. J Bone Joint Surg Am,1977.59: 1082-91, 591082 1977 [PubMed]

Albee FH: The bone graft wedge. Its use in the treatment of relapsing, acquired, and congenital dislocation of the hip. New York Med J,1915.102: 433-5, 102433 1915

Pemberton PA: Pericapsular osteotomy of the ilium for treatment of congenital subluxation and dislocation of the hip. J Bone Joint Surg Am,1965.47: 65-86, 4765 1965 [PubMed]

Perlik PC; Westin GW; and Marafioti RL: A combination pelvic osteotomy for acetabular dysplasia in children. J Bone Joint Surg Am,1985.67: 842-50, 67842 1985 [PubMed]

Dega W: Selection of surgical methods in the treatment of congenital dislocation of the hip in children. Chir Narzadow Ruchu Ortop Pol,1969.34: 357-66, Polish34357 1969 [PubMed]

Grudziak JS; Labaziewicz L; Kruczynski J; Nowakowski A; Wierusz-Kozlowska M; and Schwartz R: Combined one-staged open reduction, femoral osteotomy, and Dega pelvic osteotomy for developmental dysplasia of the hip. J Pediatr Orthop,1993.13: 680, 13680 1993

Labaziewicz L, and Piskorski Z: Early results of treatment of congenital hip disloction by means of a one-stage operation consisting in open reduction, transiliac osteotomy and detorsion-devalgization osteotomy with femur shortening. Chir Narzadow Ruchu Ortop Pol,1974.39: 615-20, Polish39615 1974 [PubMed]

Pucher A, and Piskorski Z: Early results of surgical treatment for congenital dislocation of the hip by the Degi method in young children. Chir Narzadow Ruchu Ortop Pol,1992.57: 199-203, Polish57199 1992 [PubMed]

Pucher A; Labaziewicz L; and Kaczmarczyk J: Early results of surgical treatment for congenital hip dislocation in children using Degi’s method in children under 18 months of age. Chir Narzadow Ruchu Ortop Pol,1994.59: 135-42, Polish59135 1994 [PubMed]

Senger A; Pucher A; and Piskorski Z: Isolated transiliac osteotomy in the surgical treatment of congenital hip dysplasia. Chir Narzadow Ruchu Ortop Pol,1988.53: 175-81, Polish53175 1988 [PubMed]

Senger A; Wlodarczyk R; Kesa P; and Grudziak J: Results of the surgical treatment of residual dysplasia of the hip joint with or without subluxation by transiliac osteotomy and corrective osteotomy of the proximal end of the femur. Chir Narzadow Ruchu Ortop Pol,1988.53: 182-9, Polish53182 1988 [PubMed]

Senger A; Labaziewicz L; Kruczynski J; Nowakowski A; and Schwartz R: Results of the surgical treatment of congenital dislocation of the hip joint by open reduction and transiliac and corrective osteotomies of the proximal end of the femur. Chir Narzadow Ruchu Ortop Pol,1988.53: 190-4, Polish53190 1988 [PubMed]

Swiderski G; Marciniak W; and Milanowski Z: Results of acetabulum reconstruction by transiliac osteotomy in treatment of children with congenital hip dislocation. Chir Narzadow Ruchu Ortop Pol,1969.34: 383-90, Polish34383 1969 [PubMed]

Swiderski G; Marciniak W; and Milanowski Z: Slope transiliac osteotomy in the treatment of congenital hip joint subluxation. Beitr Orthop Traumatol,1970.17: 152-60, German17152 1970 [PubMed]

Hilgenreiner H: Zur Frühdiagnose und Frühbehandlung der angeborenen Hüftgelenksverrenkung. Med Klin,1925.21: 1385-8, 211385 1925

Wiberg G: Studies on dysplastic acetabularand congenital subluxation of the hip joint. With special reference to the complication of osteo-arthritis. Acta Chir Scand,1939.Suppl: 58, Suppl58 1939

Ward WT, Grudziak JS, Moreland MS. Dega’s approach to developmental dysplasia of the hip instructional video program. Pittsburgh: Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, and Children’s Hospital of Pittsburgh; 1994.

Sharp IK: Acetabular dysplasia. The acetabular angle. J Bone Joint Surg Br,1961.43: 268-72, 43268 1961

Dega W: Schwierigkeiten in der chirurgischen reposition der veralteten kongenitalen subluxation des hüftgelenkes bei Kindern. Beitr Orthop Traumatol,1964.11: 642-7, 11642 1964

Dega W: Transiliac osteotomy in the treatment of congenital hip dysplasia. Chir Narzadow Ruchu Ortop Pol,1974.39: 601-13, Polish39601 1974 [PubMed]

Trevor D; Johns DL; and Fixsen JA: Acetabuloplasty in the treatment of congenital dislocation of the hip. J Bone Joint Surg Br,1975.57: 167-74, 57167 1975 [PubMed]

Franke J; Fengler F; Ackermann HJ; and Brauer G: Rehabilitation of so-called congenital hip dislocation with special reference to Dega’s transiliac pelvic osteotomy. Z Gesamte Hyg,1976.22: 919-26, German22919 1976 [PubMed]

Hein G, and Hein W: Our ideas for treatment of dislocated dysplastic hip in early childhood. Beitr Orthop Traumatol,1989.36: 313-7, German36313 1989 [PubMed]

Reichel H, and Hein W: Dega acetabuloplasty combined with intertrochanteric osteotomies. Clin Orthop,1996.323: 234-42, 323234 1996 [PubMed]

Reichel H; Hauschild M; and Hein W: Long-term outcome of acetabulum-plasty. Z Orthop Ihre Grenzeb,1996.134: 131-6, German134131 1996

Schulze KJ; Schmidt M; and Hillig M: Follow-up results of Dega’s acetabuloplasty (author’s transl). Z Orthop Ihre Grenzeb,1980.118: 905-14, German118905 1980