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The Journal of Bone & Joint Surgery, Volume 84, Issue 3

Scientific Article | March 01, 2002

Eccentric Rotational Acetabular Osteotomy for Acetabular Dysplasia : Follow-up of One Hundred and Thirty-two Hips for Five to Ten Years

Yukiharu Hasegawa, MD; Toshiki Iwase, MD; Shinji Kitamura, MD; Ken-ichi Yamauchi, MD; Shinji Sakano, MD; Hisashi Iwata, MD

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Investigation performed at the Department of Orthopaedics, Nagoya University School of Medicine, Nagoya, Japan

Yukiharu Hasegawa, MD
Toshiki Iwase, MD
Shinji Kitamura, MD
Ken-ichi Yamauchi, MD
Shinji Sakano, MD
Hisashi Iwata, MD
Department of Orthopaedics, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan. E-mail address for Y. Hasegawa: hassey@med.nagoya-u.ac.jp

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. 2002; 84:404-410

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Abstract

Background: Eccentric rotational acetabular osteotomy for the operative treatment of acetabular dysplasia consists of a spherical but eccentric osteotomy and rotation of the acetabulum that moves the center of rotation of the head of the femur medially and distally. No bone graft is needed. The reorientation of the acetabular fragment not only improves acetabular coverage but also restores the center of rotation of the subluxated hip. The purpose of this paper was to describe eccentric rotational acetabular osteotomy for the treatment of acetabular dysplasia and to evaluate its clinical and radiographic outcomes.

Methods: We performed this procedure consecutively in 132 hips in 126 patients with dysplasia of the hip. Eighteen hips had no osteoarthritis, fifty-three had early osteoarthritis, and sixty-one had advanced osteoarthritis. Seven patients were male, and 119 were female. The average age was 36.5 years at the time of the index operation, and the average duration of follow-up was 7.5 years. Twenty-three hips in twenty-two patients were also treated with intertrochanteric valgus osteotomy to further improve joint congruency at the time of the acetabular osteotomy.

Results: The average preoperative Harris hip score of 71 points improved to an average score of 89 points at the time of the latest follow-up. The average center-edge angle improved from 0Â° to 36Â°. An apparent change in the stage of the arthritis was observed in seven hips (5%), one of which had had early-stage disease and six of which had had advanced disease preoperatively.

Conclusions: Eccentric rotational acetabular osteotomy appears to be a good treatment option for young patients with either early or advanced hip osteoarthritis secondary to dysplasia.

Figures in this Article

Introduction

Various surgical procedures for the treatment of osteoarthritis due to acetabular dysplasia have been reported^1-5. In order to obtain better femoral head coverage, various three-dimensional osteotomies of the pelvis have been developed^4,6-8. When these techniques are used, it is difficult to calculate or predict the degree of pelvic movement, distally and medially. In theory, a femoral or pelvic reconstructive osteotomy normalizes joint contact pressure by correcting the abnormal anatomy. Reorientation of the dysplastic acetabulum into a more horizontal position produces a more normal load transfer and stress distribution on the hip joint^4,9.

Since 1985, we have performed an acetabular osteotomy for residual dysplasia of the hip with use of the technique of Ninomiya and Tagawa⁸. This osteotomy effectively provides coverage of the femoral head with acetabular cartilage. However, if the gluteus medius muscle is widely detached to obtain sufficient operative exposure, the resulting weakness of this muscle creates a serious problem¹⁰. In order to obtain sufficient exposure without weakening the gluteus muscles, we modified the technique of exposure by using a transtrochanteric approach.

According to the original technique of rotational acetabular osteotomy described by Ninomiya and Tagawa⁸, the osteotomized acetabular fragment is moved laterally and anteriorly. It is not easy to obtain substantial medial or distal displacement of the head of the femur. It also takes a long time for the bone graft to consolidate, which delays the rehabilitation program. To eliminate these problems, we modified the procedure by making the osteotomy eccentric around the center of rotation of the head of the femur. A curved osteotomy chisel is introduced from a position closer to the joint space, and the acetabulum is osteotomized eccentrically. Rotation of the acetabular fragment allows medial and distal displacement of the femoral head to be obtained simultaneously.

The purpose of this study was to report the surgical technique and the clinical and radiographic results of eccentric rotational acetabular osteotomy in the treatment of a group of patients with hip dysplasia, most of whom had osteoarthritis of the hip.

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Fig. 1:: Schematic illustration of eccentric acetabular rotational osteotomy, performed with use of a 45-mm-radius chisel. A: The curved skin incision is made about 5 cm proximal to the greater trochanter. A Y-shaped fascial incision allows complete anterior-posterior exposure of the gluteus medius muscle. B: Transtrochanteric approach. The short rotator muscles are tagged and cut. C: The gluteal muscles and the greater trochanter are retracted with a Charnley pin retractor. The osteotomy site (broken line), chosen with use of an image intensifier, is approximately 15 mm from the joint line. D: The planned eccentric acetabular osteotomy line. E and F: After rotation of the eccentric acetabular fragment, the femoral head is simultaneously displaced medially and distally; no bone graft is used. The acetabular fragment is fixed with Kirschner wires.

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Fig. 2:: Eccentric rotational acetabular osteotomy performed under image-intensifier control in a forty-five-year-old woman with advanced osteoarthritis. A: Before the osteotomy. B: Determination of the osteotomy position above the joint line with a straight chisel. C: Osteotomy performed with a curved chisel according to the preoperative plan. D: The rotated acetabular fragment was temporarily fixed with a Kirschner wire in order to evaluate the coverage and position of the femoral head.

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Fig. 3:: Radiographic parameters. a: Center-edge angle according to Wiberg¹⁵. b: Sharp angle. c: Acetabulum-head index. d: Vertical and horizontal distance from the teardrop.

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Fig. 4-A:: Fig. 4-A A fifty-four-year-old woman presented with pain in the left hip. Joint-space narrowing and sclerotic changes of the acetabulum were observed. In maximum hip abduction, the joint space was wider, with improved congruence.

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Fig. 4-B:: Fig. 4-B An eccentric rotational acetabular osteotomy was performed. The center-edge angle improved from -4Â° preoperatively to 35Â° at the time of follow-up (at six years), and the acetabulum-head index improved from 48% to 96%. The center of the femoral head was moved 7 mm medially and 5 mm distally. The Harris hip score improved from 80 points to 100 points at one year after the surgery and was maintained at 100 points six years after the surgery. This radiograph was made six years after the surgery.

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TABLE I: Type of Surgical Procedure According to the Stage of Osteoarthritis

*The values indicate the number of hips.

Stage	Eccentric Rotational Acetabular Osteotomy*	Eccentric Rotational Acetabular Osteotomy and Concomitant Intertrochanteric Valgus Femoral Osteotomy*	Total*
1	?18	?0	?18
2	?51	?2	?53
3	?40	19	?59
4	??0	?2	??2
Total	109	23	132

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TABLE I: Type of Surgical Procedure According to the Stage of Osteoarthritis

*The values indicate the number of hips.

Stage	Eccentric Rotational Acetabular Osteotomy*	Eccentric Rotational Acetabular Osteotomy and Concomitant Intertrochanteric Valgus Femoral Osteotomy*	Total*
1	?18	?0	?18
2	?51	?2	?53
3	?40	19	?59
4	??0	?2	??2
Total	109	23	132

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TABLE II: Patient Demographics According to the Stage of Osteoarthritis for Patients Treated with Eccentric Rotational Acetabular Osteotomy Only

	Stage 1	Stage 2	Stage 3	Total
No. of patients (hips)	16 (18)	48 (51)	40 (40)	104 (109)
Mean age (range) (yr)	19.7 (15-43)	33.7 (20-55)	45.2 (19-59)	36.5 (15-59)
No. of hips in females; males	18; 0	49; 2	37; 3	104; 5
Mean duration of follow-up (range) (yr)	7.6 (5-10)	7.4 (5-10)	7.5 (5-10)	7.5 (5-10)

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TABLE II: Patient Demographics According to the Stage of Osteoarthritis for Patients Treated with Eccentric Rotational Acetabular Osteotomy Only

	Stage 1	Stage 2	Stage 3	Total
No. of patients (hips)	16 (18)	48 (51)	40 (40)	104 (109)
Mean age (range) (yr)	19.7 (15-43)	33.7 (20-55)	45.2 (19-59)	36.5 (15-59)
No. of hips in females; males	18; 0	49; 2	37; 3	104; 5
Mean duration of follow-up (range) (yr)	7.6 (5-10)	7.4 (5-10)	7.5 (5-10)	7.5 (5-10)

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TABLE III: Demographics of Patients Who Underwent Combined Eccentric Rotational Acetabular Osteotomy and Intertrochanteric Valgus Femoral Osteotomy

*The number of hips with 20Â°, 25Â°, and 30Â° of valgus osteotomy.

No. of patients (hips)	22 (23)
Mean age (range) (yr)	41.5 (31-56)
No. of hips in females; males	21; 2
Valgus osteotomy*	15; 6; 2
Mean duration of follow-up (range) (yr)	7.4 (5-10)

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TABLE III: Demographics of Patients Who Underwent Combined Eccentric Rotational Acetabular Osteotomy and Intertrochanteric Valgus Femoral Osteotomy

*The number of hips with 20Â°, 25Â°, and 30Â° of valgus osteotomy.

No. of patients (hips)	22 (23)
Mean age (range) (yr)	41.5 (31-56)
No. of hips in females; males	21; 2
Valgus osteotomy*	15; 6; 2
Mean duration of follow-up (range) (yr)	7.4 (5-10)

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TABLE IV: Clinical and Radiographic Data According to the Stage of Osteoarthritis and the Addition of an Intertrochanteric Valgus Femoral Osteotomy

*The values are given as the mean and standard deviation.

Clinical and Radiographic Data	Stage 1	Stage 2	Stage 3	Intertrochanteric Valgus Femoral Osteotomy	Total
Harris hip score* (points)
Preoperative	79.8 ± 7.4	73.3 ± 6.8	68.6 ± 6.9	65.2 ± 5.9	71.3 ± 8.1
Final follow-up	98.3 ± 3.4	89.3 ± 14.1	87.5 ± 5.7	83.4 ± 6.2	?89.0 ± 10.6
Center-edge angle* (deg)
Preoperative	?—0.4 ± 10.0	—0.7 ± 8.9	2.7 ± 9.3	—4.4 ± 8.9	—0.2 ± 9.4
Final follow-up	38.2 ± 8.0	36.9 ± 7.3	38.0 ± 7.4	33.1 ± 8.4	36.3 ± 7.7
Acetabulum-head index* (%)
Preoperative	?50 ± 12	?49 ± 12	?51 ± 11	?51 ± 13	?50 ± 12
Final follow-up	?95 ± 10	?94 ± 11	?95 ± 12	?94 ± 13	?95 ± 12
Medial displacement* (mm)	?4.9 ± 2.7	?4.9 ± 3.2	?2.5 ± 4.4	?3.9 ± 3.9	?4.1 ± 3.8
Distal displacement*(mm)	?3.9 ± 4.1	?4.1 ± 5.1	?2.8 ± 4.0	?3.4 ± 2.8	?3.5 ± 4.3
Deterioration in stage of osteoarthritis (no. of hips)	?0	?1	?5	?1	?7

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TABLE IV: Clinical and Radiographic Data According to the Stage of Osteoarthritis and the Addition of an Intertrochanteric Valgus Femoral Osteotomy

*The values are given as the mean and standard deviation.

Clinical and Radiographic Data	Stage 1	Stage 2	Stage 3	Intertrochanteric Valgus Femoral Osteotomy	Total
Harris hip score* (points)
Preoperative	79.8 ± 7.4	73.3 ± 6.8	68.6 ± 6.9	65.2 ± 5.9	71.3 ± 8.1
Final follow-up	98.3 ± 3.4	89.3 ± 14.1	87.5 ± 5.7	83.4 ± 6.2	?89.0 ± 10.6
Center-edge angle* (deg)
Preoperative	?—0.4 ± 10.0	—0.7 ± 8.9	2.7 ± 9.3	—4.4 ± 8.9	—0.2 ± 9.4
Final follow-up	38.2 ± 8.0	36.9 ± 7.3	38.0 ± 7.4	33.1 ± 8.4	36.3 ± 7.7
Acetabulum-head index* (%)
Preoperative	?50 ± 12	?49 ± 12	?51 ± 11	?51 ± 13	?50 ± 12
Final follow-up	?95 ± 10	?94 ± 11	?95 ± 12	?94 ± 13	?95 ± 12
Medial displacement* (mm)	?4.9 ± 2.7	?4.9 ± 3.2	?2.5 ± 4.4	?3.9 ± 3.9	?4.1 ± 3.8
Distal displacement*(mm)	?3.9 ± 4.1	?4.1 ± 5.1	?2.8 ± 4.0	?3.4 ± 2.8	?3.5 ± 4.3
Deterioration in stage of osteoarthritis (no. of hips)	?0	?1	?5	?1	?7

Materials and Methods

Patients

Eccentric rotational acetabular osteotomy was performed in 126 consecutive patients (132 hips) with acetabular dysplasia at Nagoya University Hospital from January 1989 to December 1994. All 132 hips were followed for at least five years. Seven patients (seven hips) were male and 119 (125 hips) were female. The average age at the time of the osteotomy was 36.5 years (range, fifteen to fifty-nine years). In twenty-two patients (twenty-three hips), the eccentric rotational acetabular osteotomy was combined with a Sugioka intertrochanteric valgus osteotomy¹¹ (Tables I, II, and III).

Clinical and radiographic evaluations were performed preoperatively and postoperatively. All patients were followed annually for at least five years. The average duration of follow-up was 7.5 years (range, five to ten years). Osteoarthritis of the hip was classified according to the radiographic appearance with the system of Ninomiya and Tagawa⁸. Stage 1 indicated no osteoarthritic change (eighteen hips); Stage 2, slight narrowing of the joint space associated with sclerosis of the subchondral bone (fifty-three hips); Stage 3, marked narrowing of the joint space associated with cystic lucencies and small osteophytes in the femoral head and acetabulum (fifty-nine hips); and Stage 4, no joint space with marked osteophyte formation at the margins (two hips). We defined stage 2 as an early stage and stages 3 and 4 as advanced stages.

Prerequisites for Eccentric Rotational Acetabular Osteotomy

The prerequisites for the eccentric rotational acetabular osteotomy were (1) acetabular dysplasia with a center-edge angle of <10Â° and discontinuity of Shenton’s line, (2) unsuccessful nonoperative treatment for six months, (3) an age between fifteen and sixty years, (4) joint congruity and femoral head coverage in maximum abduction, and (5) no pain on flexion and extension of the hip with the extremity held in abduction. The prerequisite for a concomitant intertrochanteric valgus femoral osteotomy¹¹ was a femoral head deformity causing joint space narrowing in maximum abduction.

Surgical Instruments and Preoperative Planning

The center of rotation of the femoral head is independent of the radius of the chisel (see Appendix). We developed curved chisels that minimize the risk of damaging the iliac vessels or other intrapelvic structures. All eccentric rotational acetabular osteotomies were performed with a curved 45-mm-radius chisel (Mizuho Ikakogyo, Tokyo, Japan).

Before surgery, the osteotomy was planned with use of drawings based on an anteroposterior radiograph of the pelvis made with the hip held in maximum abduction.

Surgical Technique

(Fig. 1)

The patient is positioned in the lateral decubitus position. A 25-cm curved incision is made 5 cm proximal to the greater trochanter, convex in the proximal direction. A Y-shaped incision in the tensor fasciae latae allows complete anterior-posterior exposure of the gluteus medius muscle (Fig. 1, A). The greater trochanter is detached with a 4-cm-wide chisel and is reflected proximally. The short rotator muscles are tagged and divided (Fig. 1, B). The rectus femoris muscle is not released. The gluteus medius and minimus muscles are reflected proximally 30 mm from the acetabular rim and are held with a Charnley pin retractor fixed in the ilium (Fig. 1, C).

The osteotomy site is approximately 15 mm from the joint space, and the angle and direction of the osteotomy are determined with an image intensifier (Fig. 1, D). The osteotomy is started with a straight chisel, 15 mm in width, to a depth of 5 to 10 mm, and is completed with the curved chisel. The direction of the chisel is angled a few degrees proximally according to the preoperative plan and is completed step by step by tilting the chisel anteriorly and posteriorly. Each successive cut is made by carefully aiming the chisel next to the previously osteotomized portion of the ilium at a distance of approximately half of the width of the chisel, thereby achieving a spherical osteotomy. It is important that the anterior and superior part of the ilium is osteotomized in a spherical fashion so that the femoral head can be shifted distally. To prevent osteonecrosis, care should be taken not to make the acetabular fragment too thin^7,12,13.

The osteotomy of the pubic bone is technically demanding. Detaching the underside of the reflected head of the rectus femoris muscle along the joint capsule with an elevator enables the chisel to reach the pubic bone. With a deep muscle retractor, the iliopsoas muscle can be retracted anteriorly and the osteotomy of the pubic bone can be visualized. The ilium, ischium, and pubis are osteotomized spherically with this technique. After residual bone and fibrous tissue are resected, the acetabular fragment can be easily rotated into the intended position.

The coverage of the femoral head by the rotated acetabular fragment should be verified with an image intensifier before fixation of the acetabular fragment with two or three Kirschner wires (Fig. 1, E and F, and 2). The operative field is irrigated with saline solution, and the greater trochanter is repositioned and is fixed with a soft wire. A suction drain is inserted below the fascia.

Postoperatively, the patient remains at bed rest for two weeks and then uses a wheelchair for five weeks, with active range-of-motion exercises encouraged. After five weeks, 10-kg partial weight-bearing is permitted with two crutches. After nine weeks, a one-crutch gait is permitted and is used for six months. The Kirschner wires are removed, with the patient under local anesthesia, after six weeks.

Clinical and Radiographic Assessment

The evaluated parameters of the surgical procedure included operative time, blood loss, and complications. A clinical evaluation with use of the Harris hip rating¹⁴ and a radiographic evaluation (Fig. 3) were performed. The stage of the osteoarthritis at the latest follow-up evaluation was compared with the preoperative stage. The center-edge angle¹⁵, the Sharp angle, the acetabulum-head index, and the vertical and horizontal distances of the center of the femoral head from the teardrop were measured with a digitizer (model 4500; Graftek, Tokyo, Japan) and a personal computer 98 (NEC, Tokyo, Japan).

For statistical analysis, the Student t test and the chi-square test, the Kruskal-Wallis test, and the Wilcoxon signed-rank test were performed. A p value of <0.05 was considered significant.

Results

Clinical Evaluation

The average operative time was 144 minutes (range, ninety to 198 minutes), and the average total intraoperative and postoperative blood loss was 636 mL (range, 190 to 1250 mL). The average preoperative Harris hip score was 71 points (range, 52 to 98 points), which improved to 90 points (range, 65 to 100 points) at three years postoperatively and 89 points (range, 65 to 100 points) at the time of final follow-up (Table IV). The patients with Stage-1, 2, or 3 osteoarthritis and the patients treated with concomitant intertrochanteric valgus femoral osteotomy had significant improvement of the Harris hip score after the osteotomy (p < 0.001). The patients with Stage-1 disease had a significantly better mean Harris hip score at the time of follow-up than did the patients with Stage-3 disease (p < 0.0001), and the patients with no osteoarthritis or early-stage osteoarthritis (Stage 1 or 2) had a significantly better mean Harris hip score than did those with an advanced stage of osteoarthritis (Stage 3) (p = 0.02) (Figs. 4-A and 4-B). No patient required additional surgery during the follow-up period.

A positive Trendelenburg sign was found in fourteen patients before the operation and in six patients at the time of follow-up.

Radiographic Evaluation

The mean center-edge angle improved from 0Â° preoperatively to 36Â° at the time of final follow-up (Table IV). The mean acetabulum-head index improved from 50% preoperatively to 95% at the time of final follow-up. The mean Sharp angle improved from 49Â° preoperatively to 34Â° at the time of final follow-up.

On the average, the femoral head was moved 4.1 mm (range, -4 to 12 mm) medially and 3.5 mm (range, -8 to 20 mm) distally.

Bone unionæi.e., the appearance of continuous trabeculae between the acetabulum and the osteotomized fragmentæwas observed within three months in all hips.

Postoperative widening of the joint space of >1 mm was noted in five hips. Deterioration of the stage of the arthritis as evidenced by apparent narrowing or disappearance of the joint space was noted in seven hips (5%): one (2%) with Stage-2 disease and six (10%) with Stage-3 disease preoperatively (p = 0.033). Six of these hips had been treated with the eccentric rotational acetabular osteotomy only, and one had been treated with intertrochanteric valgus femoral osteotomy as well. One hip with Stage-2 arthritis and three hips with Stage-3 arthritis deteriorated within five years after the surgery. The hip with Stage-3 arthritis treated with eccentric rotational acetabular osteotomy and intertrochanteric valgus femoral osteotomy deteriorated five years after the procedure. Two hips with Stage-3 disease deteriorated after seven and eight years.

Complications

There were no serious complications, such as deep infection or deep venous thrombosis. A major hematoma was noted in five hips. Heterotopic bone occurred in three hips; it was grade 1 in two and grade 2 in one, according to the system of Brooker et al.¹⁶. Injury of the lateral femoral cutaneous nerve occurred in one hip, and reflex sympathetic dystrophy developed in another hip. Mild pain on joint motion caused by the Kirschner wires anterior to the hip joint was noted in ten hips; the pain disappeared after the wires were removed. There were no nonunions of the greater trochanter, but delayed union occurred in five hips (4%).

Discussion

Total hip arthroplasty is an excellent, cost-effective method of treatment for severe osteoarthritis in elderly patients. However, in younger, active, and vigorous patients, its role is still controversial^13,17,18. A number of surgical methods for the treatment of osteoarthritis of the hip secondary to dysplasia have been reported^19-22; they include varus intertrochanteric osteotomy², valgus intertrochanteric osteotomy²³, and pelvic osteotomy^24-29. Because of the potential for development of osteoarthritis in patients with notable acetabular dysplasia^30-33, we believe that acetabular osteotomy has a role in the management of this condition.

One aim when performing an acetabular osteotomy is to cover the femoral head with hyaline cartilage, thereby enlarging the weight-bearing surface and distributing the load over a greater area. Another aim is to achieve a more horizontal weight-bearing surface, thus decreasing the resultant force across the joint and improving joint congruency⁹.

It is crucial to avoid lateral translation of the acetabular fragment when a rotational acetabular osteotomy is performed. The center of rotation of the acetabular fragment should not be distal to the center of rotation of the femoral head.

Wagner described three modifications of acetabular osteotomy to obtain limb-lengthening and medial translation of the head of the femur^4,34. Ganz et al.⁷ reported the effect of the location of the center of adduction-rotation following mediolateral displacement of the acetabular fragment. It is difficult to adequately plan those acetabular osteotomies preoperatively^4,7,8, since optimal position can only be obtained during surgery with bulk bone graft and/or trimming of the acetabular fragment. In contrast, with the eccentric rotational acetabular osteotomy, we were able to consistently achieve the predicted and desired degree of medial and distal displacement when the goal in either direction was £20 mm. If greater amounts of displacement are required, bone graft from the ilium should be used.

Our modification of the procedure by making the osteotomy eccentric and not using bone graft eliminates some of the problems associated with rotational acetabular osteotomy. However, the surgical technique is complex. Care must be taken to choose the correct starting point, with the osteotomy begun in a proximal direction, and to avoid making the acetabular fragment too thin, since this can cause osteonecrosis of the fragment^13,35. The transtrochanteric approach is advantageous. It provides a better surgical field and causes less trauma to the muscles around the hip joint, facilitating earlier rehabilitation¹⁰. However, union of the greater trochanter was delayed in five hips in our series.

For patients with advanced stages of osteoarthritis, with moderate or marked narrowing of the joint space and many cysts and small osteophytes, the choice of treatment is still controversial. Yasunaga et al.³⁶ reported that postoperative joint congruence is the most important prognostic factor. Trousdale et al.³⁵ reported poor results of acetabular osteotomy in patients with advanced osteoarthritis. In our study, patients with advanced hip arthritis (Stage 3) had substantial improvement in their clinical scores. Acetabular osteotomy should still be considered as an alternative to total hip arthroplasty in younger patients with residual dysplasia and advanced osteoarthritis. However, early deterioration occurs in some cases, and patients who have more advanced osteoarthritis may benefit more from nonoperative treatment or a total hip arthroplasty, depending on their symptoms, level of activity, and age³⁵.

Appendix

Mathematical models describing the geometry of the osteotomies performed in this study are available with the electronic versions of this article, on our web site at www.jbjs.org (go to the article citation and click on "Supplementary Material") and on our quarterly CD-ROM (call our subscription department, at 781-449-9780, to order the CD-ROM).

Note: The authors thank Professor Hans Wingtrand and Dr. Uldis Kesteris for their instructions and assistance with the preparation of the manuscript.

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Fig. 3:: Radiographic parameters. a: Center-edge angle according to Wiberg¹⁵. b: Sharp angle. c: Acetabulum-head index. d: Vertical and horizontal distance from the teardrop.

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TABLE I: Type of Surgical Procedure According to the Stage of Osteoarthritis

*The values indicate the number of hips.

Stage	Eccentric Rotational Acetabular Osteotomy*	Eccentric Rotational Acetabular Osteotomy and Concomitant Intertrochanteric Valgus Femoral Osteotomy*	Total*
1	?18	?0	?18
2	?51	?2	?53
3	?40	19	?59
4	??0	?2	??2
Total	109	23	132

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TABLE I: Type of Surgical Procedure According to the Stage of Osteoarthritis

*The values indicate the number of hips.

Stage	Eccentric Rotational Acetabular Osteotomy*	Eccentric Rotational Acetabular Osteotomy and Concomitant Intertrochanteric Valgus Femoral Osteotomy*	Total*
1	?18	?0	?18
2	?51	?2	?53
3	?40	19	?59
4	??0	?2	??2
Total	109	23	132

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TABLE II: Patient Demographics According to the Stage of Osteoarthritis for Patients Treated with Eccentric Rotational Acetabular Osteotomy Only

	Stage 1	Stage 2	Stage 3	Total
No. of patients (hips)	16 (18)	48 (51)	40 (40)	104 (109)
Mean age (range) (yr)	19.7 (15-43)	33.7 (20-55)	45.2 (19-59)	36.5 (15-59)
No. of hips in females; males	18; 0	49; 2	37; 3	104; 5
Mean duration of follow-up (range) (yr)	7.6 (5-10)	7.4 (5-10)	7.5 (5-10)	7.5 (5-10)

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TABLE II: Patient Demographics According to the Stage of Osteoarthritis for Patients Treated with Eccentric Rotational Acetabular Osteotomy Only

	Stage 1	Stage 2	Stage 3	Total
No. of patients (hips)	16 (18)	48 (51)	40 (40)	104 (109)
Mean age (range) (yr)	19.7 (15-43)	33.7 (20-55)	45.2 (19-59)	36.5 (15-59)
No. of hips in females; males	18; 0	49; 2	37; 3	104; 5
Mean duration of follow-up (range) (yr)	7.6 (5-10)	7.4 (5-10)	7.5 (5-10)	7.5 (5-10)

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TABLE III: Demographics of Patients Who Underwent Combined Eccentric Rotational Acetabular Osteotomy and Intertrochanteric Valgus Femoral Osteotomy

*The number of hips with 20Â°, 25Â°, and 30Â° of valgus osteotomy.

No. of patients (hips)	22 (23)
Mean age (range) (yr)	41.5 (31-56)
No. of hips in females; males	21; 2
Valgus osteotomy*	15; 6; 2
Mean duration of follow-up (range) (yr)	7.4 (5-10)

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TABLE III: Demographics of Patients Who Underwent Combined Eccentric Rotational Acetabular Osteotomy and Intertrochanteric Valgus Femoral Osteotomy

*The number of hips with 20Â°, 25Â°, and 30Â° of valgus osteotomy.

No. of patients (hips)	22 (23)
Mean age (range) (yr)	41.5 (31-56)
No. of hips in females; males	21; 2
Valgus osteotomy*	15; 6; 2
Mean duration of follow-up (range) (yr)	7.4 (5-10)

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TABLE IV: Clinical and Radiographic Data According to the Stage of Osteoarthritis and the Addition of an Intertrochanteric Valgus Femoral Osteotomy

*The values are given as the mean and standard deviation.

Clinical and Radiographic Data	Stage 1	Stage 2	Stage 3	Intertrochanteric Valgus Femoral Osteotomy	Total
Harris hip score* (points)
Preoperative	79.8 ± 7.4	73.3 ± 6.8	68.6 ± 6.9	65.2 ± 5.9	71.3 ± 8.1
Final follow-up	98.3 ± 3.4	89.3 ± 14.1	87.5 ± 5.7	83.4 ± 6.2	?89.0 ± 10.6
Center-edge angle* (deg)
Preoperative	?—0.4 ± 10.0	—0.7 ± 8.9	2.7 ± 9.3	—4.4 ± 8.9	—0.2 ± 9.4
Final follow-up	38.2 ± 8.0	36.9 ± 7.3	38.0 ± 7.4	33.1 ± 8.4	36.3 ± 7.7
Acetabulum-head index* (%)
Preoperative	?50 ± 12	?49 ± 12	?51 ± 11	?51 ± 13	?50 ± 12
Final follow-up	?95 ± 10	?94 ± 11	?95 ± 12	?94 ± 13	?95 ± 12
Medial displacement* (mm)	?4.9 ± 2.7	?4.9 ± 3.2	?2.5 ± 4.4	?3.9 ± 3.9	?4.1 ± 3.8
Distal displacement*(mm)	?3.9 ± 4.1	?4.1 ± 5.1	?2.8 ± 4.0	?3.4 ± 2.8	?3.5 ± 4.3
Deterioration in stage of osteoarthritis (no. of hips)	?0	?1	?5	?1	?7

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TABLE IV: Clinical and Radiographic Data According to the Stage of Osteoarthritis and the Addition of an Intertrochanteric Valgus Femoral Osteotomy

*The values are given as the mean and standard deviation.

Clinical and Radiographic Data	Stage 1	Stage 2	Stage 3	Intertrochanteric Valgus Femoral Osteotomy	Total
Harris hip score* (points)
Preoperative	79.8 ± 7.4	73.3 ± 6.8	68.6 ± 6.9	65.2 ± 5.9	71.3 ± 8.1
Final follow-up	98.3 ± 3.4	89.3 ± 14.1	87.5 ± 5.7	83.4 ± 6.2	?89.0 ± 10.6
Center-edge angle* (deg)
Preoperative	?—0.4 ± 10.0	—0.7 ± 8.9	2.7 ± 9.3	—4.4 ± 8.9	—0.2 ± 9.4
Final follow-up	38.2 ± 8.0	36.9 ± 7.3	38.0 ± 7.4	33.1 ± 8.4	36.3 ± 7.7
Acetabulum-head index* (%)
Preoperative	?50 ± 12	?49 ± 12	?51 ± 11	?51 ± 13	?50 ± 12
Final follow-up	?95 ± 10	?94 ± 11	?95 ± 12	?94 ± 13	?95 ± 12
Medial displacement* (mm)	?4.9 ± 2.7	?4.9 ± 3.2	?2.5 ± 4.4	?3.9 ± 3.9	?4.1 ± 3.8
Distal displacement*(mm)	?3.9 ± 4.1	?4.1 ± 5.1	?2.8 ± 4.0	?3.4 ± 2.8	?3.5 ± 4.3
Deterioration in stage of osteoarthritis (no. of hips)	?0	?1	?5	?1	?7