JBJS | Congenital Hip Disease in Adults. Classification of Acetabular Deficiencies and Operative Treatment with Acetabuloplasty Combined with Total Hip Arthroplasty*

The Journal of Bone & Joint Surgery, Volume 78, Issue 5

Articles | May 01, 1996

Congenital Hip Disease in Adults. Classification of Acetabular Deficiencies and Operative Treatment with Acetabuloplasty Combined with Total Hip Arthroplasty*

GEORGE HARTOFILAKIDIS, M.D.†; KONSTANTINOS STAMOS, M.D.‡; THEOFILOS KARACHALIOS, M.D.‡; THEOLOGOS T. IOANNIDIS, M.D.‡; NIKOLAOS ZACHARAKIS, M.D.‡, ATHENS, GREECE

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Investigation performed at the Orthopaedic Department, Athens University, K.A.T. Hospital, Athens.

The Journal of Bone & Joint Surgery. 1996; 78:683-92

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Abstract

We describe three distinct types of congenital hip disease in adults. The first type is dysplasia, in which the femoral head is contained within the original true acetabulum. The second type is low dislocation, in which the femoral head articulates with a false acetabulum, the inferior lip of which contacts or overlaps the superior lip of the true acetabulum, giving the appearance of two overlapping acetabula. The third type is high dislocation, in which the femoral head has migrated superoposteriorly and there is no contact between the true and the false acetabulum. We describe and classify the acetabular abnormalities and deficiencies found with these three types.If the anterior, posterior, and superior aspects of the acetabular component cannot be covered during a total hip arthroplasty because of a deficient acetabulum in an adult who has congenital hip disease, we advocate an acetabuloplasty technique (which we have named a cotyloplasty) that involves medial advancement of the acetabular floor by the creation of a controlled comminuted fracture of its medial wall, autogenous bone-grafting, and the implantation of a small acetabular component with cement.This procedure was performed in sixty-six patients (eighty-six hips). Forty-nine of the hips had a high dislocation, thirty-one had a low dislocation, and six were dysplastic. Two to fifteen years (mean, seven years) after the operation, the clinical and radiographic results were satisfactory. Only two acetabular components needed to be revised for aseptic loosening, at 5.3 and 7.5 years postoperatively. Moreover, the cumulative success rate for the acetabular components was 100 per cent at five years and 93.2 per cent at ten years.

Figures in this Article

Introduction

Our early attempts to treat congenital hip disease in adults with use of total hip arthroplasty were frustrated by our lack of knowledge regarding the local anatomical abnormality in these hips. The frequent failure to identify the true acetabulum at the time of the operation led to placement of the acetabular component in an incorrect anatomical position, resulting in inadequate coverage and containment of the component. This failure led to our study of the pathoanatomy of the acetabulum associated with congenital hip disease in adults, the development of a classification system for these hips, and the development of specific reconstruction techniques for the acetabulum^13,30 as an adjunct to treatment with total hip arthroplasty.

We discuss our terminology for the different types of congenital hip disease in adults, and we present the results for sixty-six adults (eighty-six hips) who had such disease that was treated with the acetabuloplasty technique, which we have termed a cotyloplasty, in combination with total hip arthroplasty.

*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.

†21 Photiou Patriarchou Street, Athens 11471, Greece. Please address requests for reprints to Professor Hartofilakidis.

‡Othopaedic Department, Athens University, K.A.T. Hospital, 10 Athinas Street, Athens 14561, Greece.

*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.

†21 Photiou Patriarchou Street, Athens 11471, Greece. Please address requests for reprints to Professor Hartofilakidis.

‡Othopaedic Department, Athens University, K.A.T. Hospital, 10 Athinas Street, Athens 14561, Greece.

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Figs. 1-A and 1-B: A twenty-eight-year-old woman who had a dysplastic hip on the right. The left hip was normal. Fig. 1-A: Anteroposterior radiograph of the pelvis.

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Fig. 1-B Line drawing of the same hips. The right femoral head was contained within the original acetabulum. There was some degree of subluxation due to the mechanical effect of the osteophyte covering the fossa and of the capital drop.

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Figs. 2-A and 2-B: A forty-two-year-old woman who had a high dislocation of the hip on the right and a low dislocation on the left. Fig. 2-A: Anteroposterior radiograph of the pelvis.

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Fig. 2-B Line drawing of the same hips. The right femoral head articulates with the iliac wing proximal to the true acetabulum. The true acetabulum on the left was partially covered by the false one, producing an image of two overlapping acetabula. The use of the term subluxation to describe the left hip would be misleading.

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Figs. 3-A and 3-B: Three-dimensional computerized tomography scans. Fig. 3-A: A high dislocation. The triangular appearance of the true acetabulum, the segmental deficiency of the entire periphery, the narrow opening, and the inadequate depth of the acetabulum are apparent.

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Fig. 3-B A low dislocation. The visible part of the true acetabulum is hypoplastic with anterior and posterior segmental deficiency, a narrow opening, and inadequate depth.

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Fig. 4 Bar graphs of the preoperative clinical scores for the eighty-six hips treated with a cotyloplasty in addition to a total hip arthroplasty (above the line), compared with the postoperative scores for the eighty-one hips that had a good or excellent result (below the line).

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Figs. 5-A and 5-B: Anteroposterior radiographs of the pelvis of a fifty-seven-year-old woman who had bilateral high dislocation that had not been treated previously. Fig. 5-A: Preoperatively, there was a false acetabulum on the left with severe osteoarthrotic changes. The high dislocation, as evaluated with the method of Crowe et al.³, measured 9.2 centimeters on the right and 7.0 centimeters on the left.

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Fig. 5-B Ten years after a bilateral total hip arthroplasty performed with use of offset-bore acetabular components, combined with a cotyloplasty, the clinical and radiographic results were satisfactory.

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Figs. 6-A and 6-B: A forty-four-year-old woman who had bilateral congenital hip disease. Fig. 6-A: Anteroposterior radiograph of the pelvis. Although there was only a small difference in the degree of subluxation between the two hips, the local anatomical abnormalities were different. The right femoral head articulated with the false acetabulum, while the true acetabulum was partly covered by the false one (a low dislocation). The left femoral head, although subluxated, was contained in the original acetabulum (a dysplastic hip).

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Fig. 6-B Line drawing of the same hips, showing the differences between a low dislocation and a dysplastic hip with approximately the same degree of subluxation.

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Fig. 7 Illustration showing three alternative techniques that have been used for acetabular reconstruction during total hip arthroplasty in hips with a low dislocation. A, Superior placement of the cup. The cup is placed in the false acetabulum, and the superior location of the center of rotation of the artificial joint is accepted. B, The superolateral augmentation technique with the use of a structural graft. C, The cotyloplasty technique. Complete coverage and anatomical placement of the cup are obtained with controlled medialization.

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Fig. 8 Anteroposterior and lateral radiographs of a deficient acetabulum on the right that was reconstructed with the cotyloplasty technique. Complete incorporation of the graft was observed at five months postoperatively.

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TABLE I CLINICAL GRADING OF THE HIP

*For the postoperative results, a grade of 6 was considered excellent and a grade of 5, good or satisfactory.†The range of motion is the sum total of all of the ranges of movement (flexion, abduction-adduction, and rotation).

Points*	Description
Pain
1	Severe and spontaneous
2	Severe on attempting to walk
3	Tolerable, permits limited activity
4	Only after some activty, disappears quickly with rest
5	Slight or intermittent on starting to walk but decreases with normal activity
6	None

Range of motion†
1	0—30 degrees
2	>30—60 degrees
3	>60—10 degrees
4	>100—160 degrees
5	>160—210 degrees
6	>210 degrees

Walking
1	Few meters or bedridden, uses two canes or crutches
2	Time and distance very limited with or without a cane
3	Limited with one cane, difficult without a cane, able to stand for long periods
4	Long distances with one cane, limited without a cane
5	Does not need a cane but has a limp
6	Normal

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TABLE I CLINICAL GRADING OF THE HIP

Points*	Description
Pain
1	Severe and spontaneous
2	Severe on attempting to walk
3	Tolerable, permits limited activity
4	Only after some activty, disappears quickly with rest
5	Slight or intermittent on starting to walk but decreases with normal activity
6	None

Range of motion†
1	0—30 degrees
2	>30—60 degrees
3	>60—10 degrees
4	>100—160 degrees
5	>160—210 degrees
6	>210 degrees

Walking
1	Few meters or bedridden, uses two canes or crutches
2	Time and distance very limited with or without a cane
3	Limited with one cane, difficult without a cane, able to stand for long periods
4	Long distances with one cane, limited without a cane
5	Does not need a cane but has a limp
6	Normal

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TABLE II CLASSIFICATION OF THE THREE TYPES OF CONGENITAL HIP DISEASE IN ADULTS

Type	Acetabular Deficency	No. of Hips in Present Study
Dysplasia		325
	1. Superior segmental deficiency	325 (100%)
	2. Secondary shallowing due to fossa-covering osteophyte	325 (100%)

Low dislocation (visualized part)		43
	1. Anterior and posterior segmental deficiency	43 (100%)
	2. Narrow opening	43 (100%)
	3. Inadequate depth	43 (100%)
	4. Increased anteversion	32 (74%)
	5. Lack of posterior bone stock	4 (9%)

High dislocation		62
	1. Segmental deficiency of the entire acetabular rim	62 (100%)
	2. Narrow opening	62 (100%)
	3. Inadequate depth	62 (100%)
	4. Excessive anteversion	62 (100%)
	5. Abnormal distribution of bone stock, mainly superoposteriorly	56 (90%)

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TABLE II CLASSIFICATION OF THE THREE TYPES OF CONGENITAL HIP DISEASE IN ADULTS

Type	Acetabular Deficency	No. of Hips in Present Study
Dysplasia		325
	1. Superior segmental deficiency	325 (100%)
	2. Secondary shallowing due to fossa-covering osteophyte	325 (100%)

Low dislocation (visualized part)		43
	1. Anterior and posterior segmental deficiency	43 (100%)
	2. Narrow opening	43 (100%)
	3. Inadequate depth	43 (100%)
	4. Increased anteversion	32 (74%)
	5. Lack of posterior bone stock	4 (9%)

High dislocation		62
	1. Segmental deficiency of the entire acetabular rim	62 (100%)
	2. Narrow opening	62 (100%)
	3. Inadequate depth	62 (100%)
	4. Excessive anteversion	62 (100%)
	5. Abnormal distribution of bone stock, mainly superoposteriorly	56 (90%)

Types of Congenital Hip Disease

We previously described ¹³ three distinct types of congenital hip disease in adults, on the basis of the relationship between the femoral head and the true or false acetabulum. With dysplasia, the femoral head, despite some degree of subluxation, is still contained within the original acetabulum (Figs. 1-A and 1-B). With low dislocation, the femoral head articulates with a false acetabulum that partially covers the true acetabulum. Radiographically, there appear to be two overlapping acetabula; the inferior part of the false acetabulum is an osteophyte that begins at the level of the superior rim of the true acetabulum. The visible part of the true acetabulum can easily be missed during the operation. With high dislocation, the femoral head has migrated superiorly and posteriorly. The true acetabulum is inferior and anterior to the hollow in the iliac wing, with which the femoral head articulates, and may have the appearance of a false acetabulum (Figs 2-A and 2-B).

Materials and Methods

The intraoperative records of anatomical abnormalities of the acetabulum and radiographic data were obtained for 430 hips in adults with congenital hip disease who had been managed operatively between 1973 and 1991. Three hundred and twenty-five of the hips were dysplastic, forty-three had a low dislocation, and sixty-two had a high dislocation.

Three-dimensional computerized tomography scans were made for forty hips (twenty-two patients) and confirmed the local anatomical abnormalities that were found (Figs 3-A and 3-B).

Four parameters were investigated: (1) segmental deficiencies of the acetabular rim (superiorly, anteriorly, and posteriorly); (2) the amount of anteversion and the depth and opening (the distance between the anterior and the posterior rim) of the true acetabulum; (3) the amount of acetabular bone stock (superiorly, anteriorly, and posteriorly); and (4) the presence of osteophytes in the area of the true and false acetabula.

Sixty-six patients (eighty-six hips) who had a total hip arthroplasty as treatment for congenital hip disease between March 1978 and December 1990 and who also had an acetabular deficiency that necessitated an acetabuloplasty (cotyloplasty) were included in this study. All but one of these patients were women. The mean age at the time of the operation was forty-seven years (range, twenty-three to seventy years). The mean duration of follow-up was seven years (range, two to fifteen years). Forty-nine of the treated hips had had a high dislocation, thirty-one had had a low dislocation, and six had been dysplastic. All of the operations were performed with Charnley implants and the Charnley technique, which involves an osteotomy of the greater trochanter. A Charnley offset-bore cup was used in forty-eight hips and a small Charnley cup, in thirty-eight. The offset-bore cup, which is thirty-six millimeters in diameter, has an eccentric socket to provide a thicker (ten-millimeter) superior wall and has no peripheral flange.

Clinical and radiographic data obtained preoperatively and at yearly intervals postoperatively were available for all sixty-six patients. One patient was lost to follow-up after three years, and one patient died seven years postoperatively for reasons unrelated to the operation.

The conventional system of Merle d'Aubigné and Postel, as modified by Charnley ² (Table I), was used for the clinical evaluation. Survivorship analysis was also done ^1,6,18. Revision (planned or performed) of the acetabular component or removal of the component as part of a Girdlestone procedure was considered as a failure. Standard anteroposterior radiographs of the pelvis made postoperatively were studied for each patient. Measurements were made separately by two observers with use of magnifying lenses and vernier calipers with a precision of 0.02 millimeter ¹⁷. Migration of the cup, relative to the teardrop, and wear of the cup were recorded ^16,17. In addition, radiolucent lines at the host-graft, host-cement, and graft-cement interfaces were evaluated. Union of the bone graft was indicated by the absence of sclerosis and radiolucent lines at the host-graft interface as well as by the presence of trabecular bridging at that interface on the postoperative anteroposterior radiographs.

Operative Technique

The cotyloplasty technique ^13,30 was developed by one of us (K. S.) and has been used in our department since 1978. It was developed for hips in which the remaining osseous cavity, after preparation of the true acetabulum, cannot accommodate even a specially designed, small acetabular component inserted with or without cement.

In hips with a high dislocation, the true acetabulum is identified by using the thickened and elongated joint capsule as a guide, while in hips with a low dislocation the true acetabulum has to be excavated from underneath the inferior part of the false acetabulum. The existing hypoplastic true acetabulum is enlarged and deepened with the use of Lexer chisels and small reamers (forty to forty-four millimeters in diameter). Care must be taken to direct the reamers in a superoposterior direction, where adequate bone stock can be found, in order to avoid fracture of the thin and hypoplastic anterior acetabular wall. The deepening is continued until the outer surface of the internal pelvic cortex is reached. If, on completion of the reaming, it is found that the acetabular cavity that was created will not accommodate a small or an offset-bore cup at an angle of 40 to 45 degrees to the horizontal and with 10 degrees of anteversion, a controlled comminuted fracture of the entire paper-thin medial wall of the acetabulum is created with use of a Charnley deepening reamer or a Lexer chisel, or both. The reamer is struck lightly with a hammer until the entire floor of the acetabulum fractures. Care must be taken not to perforate the internal layer of the periosteum. A blind anchorage hole is then made with a Charnley starting drill in the roof of the acetabulum and, if possible, in the ischium. A large amount of autogenous cancellous morselized graft (cut into small pieces) obtained from the femoral head and neck is placed between the fragments of the acetabular floor and on the periosteum of the fractured medial wall. The graft and the fragments of the acetabular floor are then molded and pushed slightly inward with a hemispherical pusher or wrapped gauze, or both. The acetabular component is then cemented at an angle of 40 to 45 degrees to the horizontal and with 10 degrees of anteversion, with minimum inward pressure applied to avoid excessive medialization.

Although the fixation of the cup can be considered adequate to withstand vertical compressive vectors, this is not the case for the horizontal compressive vectors applied by the muscles of the hip. Therefore, three to four weeks of bed rest is recommended postoperatively, and full weight-bearing is not allowed until the graft is incorporated radiographically, usually at three to four months postoperatively.

Results

All 325 dysplastic hips had a deficiency of the superior segment of the acetabulum and a shallow acetabulum due to an osteophyte covering the acetabular fossa. All forty-three hips with a low dislocation had a deficiency of the anterior and posterior segments of the acetabulum, a narrow opening of the acetabulum, and an inadequate depth of the acetabulum. Thirty-two of the forty-three hips had increased anteversion, and four had a lack of posterior bone stock. All sixty-two hips with a high dislocation had a segmental deficiency of the entire acetabular rim, a narrow opening of the acetabulum, an inadequate depth of the acetabulum, and excessive anteversion. Fifty-six of these hips had abnormal distribution of the bone stock, mainly located superoposteriorly (Table II). These constant and occasional findings in the three distinct types of congenital hip disease in adults were present in varying degrees of severity, depending on the stage of the disease.

Clinical Results

Eighty-one (94 per cent) of the eighty-six hips that had an acetabuloplasty combined with a total hip arthroplasty had a good or excellent clinical result (Fig. 4). Two hips were considered to be failures since both the acetabular component and the femoral stem needed to be revised because of aseptic loosening at 5.3 and 7.5 years. Two more femoral components also needed to be revised because of aseptic loosening, but the acetabular components remained intact. One patient was not available for the clinical follow-up.

The score for pain on the modified scale of Merle d'Aubigné and Postel improved from a mean of 2.6 points (range, 1 to 5 points) preoperatively to a mean of 5.6 points (5 or 6 points) postoperatively. Similarly, the score for function improved from a preoperative mean of 2.6 points (range, 1 to 4 points) to a postoperative mean of 5.5 points (4, 5, or 6 points), and the score for range of motion improved from a mean of 3 points (range, 1 to 6 points) to a mean of 4.6 points (range, 3 to 6 points). The differences between the preoperative and postoperative scores were all significant (p < 0.05). There was no radiographic deterioration of the grafted area in the acetabular floor (Figs. 5-A and 5-B).

Survivorship analysis of the acetabular components showed a cumulative rate of success of 100 per cent (standard error, 0.0 per cent; 95 per cent confidence interval, 100 to 100 per cent) at five years and 93.2 per cent (standard error, 8.4 per cent; 95 per cent confidence interval, 76.8 to 100 per cent) at ten years.

Radiographic Results

Two (2 per cent) of the eighty-six acetabular components had migrated (displaced more than two millimeters). Although radiolucent lines that were more than one millimeter wide were present around twelve acetabular components (14 per cent), the lines were progressive (indicating aseptic loosening) around only two of them. Five of the twelve acetabular components had radiolucent lines predominantly in zones 2 and 3 of DeLee and Charnley⁵ (the cement-graft interface). Fourteen acetabular components (16 per cent) had more than 0.15 millimeter of wear a year. There was radiographic incorporation (union) of all of the bone grafts, as determined by trabecular bridging and the lack of sclerosis at the host-graft interface.

Marked formation of trabecular bone within the graft mass, indicative of remodeling, was seen in seventy hips (81 per cent). This was in combination with a loss of thickness of the graft mass in twenty-six hips (30 per cent). Partial resorption of the central part of the graft was found in only eleven (13 per cent) of the hips.

Discussion

While trying to understand the underlying pathology of congenital hip disease, especially that of the acetabular site, in adults, we realized that the existing terminology and classification were inadequate to guide decisions regarding reconstruction. There is some controversy in the literature regarding the terms used to describe the different types of congenital hip disease in adults. This results in problems with communication, the planning of treatment, and the evaluation of results. The main reason for this controversy is the indiscriminate use of the terms dysplasia, subluxation, and dislocation for the comparison of dissimilar disorders. The term subluxation is especially misleading because it refers to the degree of displacement of the femoral head but does not define the acetabular abnormality^3,8 (Figs. 6-A and 6-B). Moreover, the existing classification of acetabular deficiencies⁴ is more relevant to the revision of a total hip arthroplasty. It is difficult to include the acetabular deficiencies encountered in hips with congenital hip disease in adults in such a classification.

To reconstruct the acetabulum successfully during total hip arthroplasty for congenital hip disease in an adult, certain information is necessary: the position of the true acetabulum (because anatomical placement of the acetabular component is highly desirable)^17,32, the degree of anteversion of the true acetabulum, the adequacy of the bone stock for proper placement and fixation of the component, and the existence of segmental defects that may result in inadequate coverage of the component^25,31. Taking all of these factors into consideration, we verified our previously proposed terminology regarding congenital hip disease in adults. We present a working classification of acetabular deficiencies that offers guidelines for operative treatment and is based on information found on simple anteroposterior radiographs of the pelvis and on operative anatomy.

From our description of anatomical abnormalities, it is obvious that during the operation, especially in dislocated hips, a surgeon often faces an anteverted shallow true acetabulum with superior, anterior, or posterior segmental defects and poor bone stock. The question arises as to how such acetabula can be reconstructed¹⁹ (Fig. 7).

The acetabular component must be placed in the area of the true acetabulum²⁰ for purely mechanical reasons, although some authors have accepted superior, but not lateral, placement of the cup²⁴. With such anatomical placement, the superior, anterior, and posterior coverage of the cup becomes an important issue. It was recently shown that when the superolateral aspect of the acetabular rim is lacking, the load shifts to the posterosuperior aspect of the rim and stresses at the component-bone interface increase²⁷. It has also been shown that, in hips in which there is a superior segmental defect in combination with adequate anterior and posterior bone stock (such as with dysplasia), even 80 per cent coverage of the component is acceptable^25,31 and there is no need for acetabular augmentation.

Reconstruction of the acetabulum is more difficult when a circumferential segmental defect is combined with poor bone stock (such as with high and low dislocations). The use of a bulk structural autogenous graft from the femoral head to augment the superolateral aspect of the acetabular rim was proposed initially¹², and the short-term clinical results were excellent. However, the high rate of failure (46 per cent; twenty-one of forty-six hips) reported after approximately twelve years^11,22 raised doubt as to the efficacy of this technique, and those who recommend it now^19,23 rely considerably less on the bulk graft than on the host bone for support of the acetabular component. The reason for such a high rate of failure may be the complex pathoanatomy that we described previously and the abnormal distribution of stresses combined with the unfavorable long-term biological behavior of structural grafts.

Since 1978, we have used an acetabuloplasty technique (cotyloplasty) in which the main mechanical advantage is that the weight-bearing areas are allowed to shift to beneath the acetabular roof while adequate anterior and posterior coverage of the cup is achieved. We recommend that this technique be used mainly in hips with a high or low dislocation when, after preparation of the true acetabulum, the osseous cavity cannot accommodate even a specially designed, small acetabular component. Our 2 per cent rate of failure (two of eighty-six hips) after a mean of seven years, and the fact that the rate of failure did not increase after 7.5 years, raise the question as to why this technique has superior clinical results compared with others.

We believe that the morselized femoral autogenous graft that we used is superior to allogeneic bone for the reconstruction of osseous segments ⁰. Moreover, the host-graft interface (the broken acetabular floor and internal layer of the pelvic periosteum) in these relatively young patients is biologically active, which may ensure incorporation of the graft (Fig. 8). Additionally, the anatomical placement of the cup, combined with carefully controlled medialization, optimizes the mechanical environment and influences the long-term survival of the artificial hip. It must be stressed, however, that excessive medialization of the cup may adversely affect the outcome¹⁷ and must be avoided.

We also found a satisfactory radiographic appearance of the cement-graff interface, indicating the stability and sufficiency of cement-graft bonding. Although our early experimentation on the mechanical behavior of the cement-graft interface has not been published³⁰, recent important experimental and clinical work^9,21,26 has shown that the concept of coating cement with graft chips is promising and may have important applications in the field of hip reconstruction. Furthermore, early fears regarding thermally induced osteocyte necrosis and vascular damage¹⁵ seem to be unfounded, and the use of a metal mesh between the cement and the bone graft^28,29 is not currently advised.

Comparison of our clinical and radiographic results with those of Dunn and Hess⁷ and of Hess and Umber¹⁴ is not feasible. Those authors proposed limited fragmentation of the medial wall, for the same purpose as in our study, as well as reinforcement of the graft-cement interface with a wire mesh. However, to the best of our knowledge, the long-term results of their series have not been published.

Recently, Paavilainen et al., in a study of Lord cups inserted without cement as treatment for congenital hip disease, reported that fragmentation of the medial wall and cancellous bone-grafting with medialization could supplement the augmentation of the superolateral aspect of the rim with a bone graft from the removed femoral head²³.

In conclusion, for better communication, planning of treatment, and evaluation of results, a common terminology is needed to express the different types of congenital hip disease in adults. We advise the use of the terms dysplasia, low dislocation, and high dislocation.

The classification of The American Academy of Orthopaedic Surgeons⁴, which is designed to describe acetabular deficiencies after total hip arthroplasty, cannot be applied directly to acetabular deficiencies in adults who have untreated congenital hip disease. Thus, a separate classification is needed that takes into account the pathoanatomy seen in association with such disease.

With all three types of congenital hip disease, especially high and low dislocations, if the cup cannot be covered anteroposteriorly because of the aforementioned deficiencies, medial advancement of the floor of the acetabulum (cotyloplasty) combined with total hip arthroplasty may be an alternative treatment for this complex problem.

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Figs. 1-A and 1-B: A twenty-eight-year-old woman who had a dysplastic hip on the right. The left hip was normal. Fig. 1-A: Anteroposterior radiograph of the pelvis.

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Figs. 2-A and 2-B: A forty-two-year-old woman who had a high dislocation of the hip on the right and a low dislocation on the left. Fig. 2-A: Anteroposterior radiograph of the pelvis.

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Fig. 3-B A low dislocation. The visible part of the true acetabulum is hypoplastic with anterior and posterior segmental deficiency, a narrow opening, and inadequate depth.

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Fig. 6-B Line drawing of the same hips, showing the differences between a low dislocation and a dysplastic hip with approximately the same degree of subluxation.

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TABLE I CLINICAL GRADING OF THE HIP

Points*	Description
Pain
1	Severe and spontaneous
2	Severe on attempting to walk
3	Tolerable, permits limited activity
4	Only after some activty, disappears quickly with rest
5	Slight or intermittent on starting to walk but decreases with normal activity
6	None

Range of motion†
1	0—30 degrees
2	>30—60 degrees
3	>60—10 degrees
4	>100—160 degrees
5	>160—210 degrees
6	>210 degrees

Walking
1	Few meters or bedridden, uses two canes or crutches
2	Time and distance very limited with or without a cane
3	Limited with one cane, difficult without a cane, able to stand for long periods
4	Long distances with one cane, limited without a cane
5	Does not need a cane but has a limp
6	Normal

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TABLE I CLINICAL GRADING OF THE HIP

Points*	Description
Pain
1	Severe and spontaneous
2	Severe on attempting to walk
3	Tolerable, permits limited activity
4	Only after some activty, disappears quickly with rest
5	Slight or intermittent on starting to walk but decreases with normal activity
6	None

Range of motion†
1	0—30 degrees
2	>30—60 degrees
3	>60—10 degrees
4	>100—160 degrees
5	>160—210 degrees
6	>210 degrees

Walking
1	Few meters or bedridden, uses two canes or crutches
2	Time and distance very limited with or without a cane
3	Limited with one cane, difficult without a cane, able to stand for long periods
4	Long distances with one cane, limited without a cane
5	Does not need a cane but has a limp
6	Normal

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TABLE II CLASSIFICATION OF THE THREE TYPES OF CONGENITAL HIP DISEASE IN ADULTS

Type	Acetabular Deficency	No. of Hips in Present Study
Dysplasia		325
	1. Superior segmental deficiency	325 (100%)
	2. Secondary shallowing due to fossa-covering osteophyte	325 (100%)

Low dislocation (visualized part)		43
	1. Anterior and posterior segmental deficiency	43 (100%)
	2. Narrow opening	43 (100%)
	3. Inadequate depth	43 (100%)
	4. Increased anteversion	32 (74%)
	5. Lack of posterior bone stock	4 (9%)

High dislocation		62
	1. Segmental deficiency of the entire acetabular rim	62 (100%)
	2. Narrow opening	62 (100%)
	3. Inadequate depth	62 (100%)
	4. Excessive anteversion	62 (100%)
	5. Abnormal distribution of bone stock, mainly superoposteriorly	56 (90%)

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TABLE II CLASSIFICATION OF THE THREE TYPES OF CONGENITAL HIP DISEASE IN ADULTS

Type	Acetabular Deficency	No. of Hips in Present Study
Dysplasia		325
	1. Superior segmental deficiency	325 (100%)
	2. Secondary shallowing due to fossa-covering osteophyte	325 (100%)

Low dislocation (visualized part)		43
	1. Anterior and posterior segmental deficiency	43 (100%)
	2. Narrow opening	43 (100%)
	3. Inadequate depth	43 (100%)
	4. Increased anteversion	32 (74%)
	5. Lack of posterior bone stock	4 (9%)

High dislocation		62
	1. Segmental deficiency of the entire acetabular rim	62 (100%)
	2. Narrow opening	62 (100%)
	3. Inadequate depth	62 (100%)
	4. Excessive anteversion	62 (100%)
	5. Abnormal distribution of bone stock, mainly superoposteriorly	56 (90%)