JBJS | One-Stage Treatment of Congenital Dislocation of the Hip in Children Three to Ten Years Old. Functional and Radiographic Results*

The Journal of Bone & Joint Surgery, Volume 80, Issue 3

Articles | March 01, 1998

One-Stage Treatment of Congenital Dislocation of the Hip in Children Three to Ten Years Old. Functional and Radiographic Results*

MICHAEL G. RYAN, M.D.†; LYLE O. JOHNSON, M.D.‡; DEBORAH S. QUANBECK, M.D.‡; BARBARA MINKOWITZ, M.D.§, MINNEAPOLIS, MINNESOTA

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Investigation performed at the Shriners Hospital for Children, Twin Cities, Minneapolis

The Journal of Bone & Joint Surgery. 1998; 80:336-44

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Abstract

We reviewed the results of operative treatment of congenital dislocation of the hip in eighteen children (twenty-five hips) whose average age at the time of the index operation was six years and four months (range, three years to nine years and eleven months). None of the patients had had previous treatment of the dislocation. Preliminary traction was used for five patients (six hips), and open reduction and femoral shortening was performed in all hips.The functional result was assessed, according to the Iowa hip-rating system, after an average duration of follow-up of ten years and six months (range, six years and two months to sixteen years and ten months). Sixteen hips had an excellent result; seven, a good result; and two, a fair result. The average limb-length discrepancy was 0.8 centimeter (range, zero to four centimeters), and the average foot-progression angle was 11 degrees (range, 0 to 30 degrees) of external rotation.According to Severin's classification of the radiographic appearance, seven hips had an excellent result; eleven, a good result; four, a fair result; and three, a poor result. Four of eleven hips that had evidence of osteonecrosis of the proximal part of the femur had a severe deformity, and one patient had radiographic evidence of moderate degenerative osteoarthrosis when she was sixteen years old.On the basis of this review, we suggest that a one-stage operative procedure consisting of open reduction, femoral shortening, and pelvic osteotomy (if necessary) for previously untreated congenital dislocation of the hip in children who are three to ten years old can result in remodeling of the acetabulum and a functional hip.

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Introduction

Introduction | Materials and Methods | Results | Discussion | References

Despite neonatal screening and early treatment of congenital dislocation of the hip in newborns and infants, it is not uncommon to see an older child who has untreated congenital dislocation of the hip^1,4,9,20. This condition can result in soft-tissue contractures and persistent dysplastic changes in the hip, leading to osteoarthrosis in early adulthood^29,30. It is not known whether there is a specific age when treatment produces a worse result than does no treatment, and there is no consensus regarding the best management for an older child who has untreated congenital dislocation of the hip^{7,19,21,23,32}.

The principles of treatment of congenital dislocation of the hip for an older child are different than those for a newborn^1,2,6. In an older child, contractures of the muscles, tendons, and capsule around the hip prevent reduction and can produce pressure on the developing femoral head during or after reduction, leading to ischemia^5,10,23,26. Traction has been used before reduction of a dislocated hip to decrease the prevalence of ischemia of the femoral head, but there are insufficient data to support the consistent use of this treatment. Closed or open reduction without osseous realignment has been associated with residual dysplasia^17,18. Femoral shortening has been shown to facilitate reduction and does not appear to increase the prevalence of osteonecrosis of the femoral head^4,8,23. In a study of twenty-five children (thirty-three hips) who had congenital dislocation of the hip, Galpin et al.⁸ concluded that a one-stage procedure without preoperative traction did not increase the risk of osteonecrosis. Schoenecker and Strecker²³ compared the results in eight children (thirteen hips) who had femoral shortening at the time of open reduction with those in seventeen children (twenty-six hips) who had traction before open reduction; osteonecrosis developed in fourteen hips (54 per cent) that had traction and in none of the hips that had femoral shortening. Klisic and Jankovic¹², in a study of forty-seven children (sixty hips) who had an open reduction and femoral shortening, reported the development of osteonecrosis in seventeen hips. Some authors have recommended a one-stage procedure consisting of open reduction, capsulorrhaphy, femoral shortening, and (if necessary) pelvic osteotomy^8,11,12. However, the results of those studies were not assessed with use of standard measurable clinical and radiographic criteria. There are few long-term studies of the functional and radiographic outcomes of this approach.

We evaluated the radiographic and functional results of a one-stage operative procedure for previously untreated congenital dislocation of the hip in eighteen children (twenty-five hips) who were three to ten years old.

*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.

†St. Charles Medical Center, 2500 N.E. Neff Road, Bend, Oregon 97701.

‡Shriners Hospital for Children, 2025 River Road, Minneapolis, Minnesota 55414.

§Staten Island University, 475 Seaview Avenue, Staten Island, New York 10305.

*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.

†St. Charles Medical Center, 2500 N.E. Neff Road, Bend, Oregon 97701.

‡Shriners Hospital for Children, 2025 River Road, Minneapolis, Minnesota 55414.

§Staten Island University, 475 Seaview Avenue, Staten Island, New York 10305.

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TABLE I DATA ON THE PATIENTS

*A reduction was considered adequate when the center-edge angle was more than 15 degrees, the acetabular index was less than 28 degrees, and the Shenton line was intact. †A score of 90 to 100 points indicated an excellent result; 80 to 89 points, a good result; 70 to 79 points, a fair result; and less than 70 points, a poor result. ‡The patient had bilateral congenital dislocation.

Case	Gender, Age at Op. (Yrs. + Mos.)	Traction	Type of Pelvic Osteot.	Adequate Reduction on Immed. Postop. Radiograph*	Duration of Follow-up (Yrs. + Mos.)	Results at Latest Follow-up Examination
Age at Follow-up (Yrs. + Mos.)	Iowa Hip Score¹⁴† (Points)	Severin Grade²⁴	Grade of Degenerative Changes³	Type of Osteo- necrosis^5,22
1	F, 3 + 0	N	Pemberton	N	9 + 4	12 + 4	95	II	I	II
2	F, 3 + 10	N	Salter	N	7 + 8	11 + 6	84	I	I
3‡	M, 4 + 0	N	Salter	N	10 + 6	14 + 6	97	II	I	I
	M, 4 + 2	N	Pemberton	Y	10 + 4	14 + 6	97	II	II
4	F, 4 + 2	N	Pemberton	Y	10 + 8	14 + 10	99	I	0
5	F, 4 + 2	N	Salter	Y	7 + 4	11 + 6	99	I	0
6	F, 4 + 4	Y	None	Y	12 + 11	17 + 3	94	II	0	II
7	M, 5 + 3	Y	None	N	12 + 3	17 + 6	77	II	II
8	F, 5 + 7	N	Pemberton	N	9 + 3	15 + 9	84	III	I
9	F, 5 + 10	N	Pemberton	Y	6 + 2	12 + 0	76	I	0
10‡	F, 6 + 0	N	None	N	15 + 2	21 + 2	97	I	0
	F, 6 + 3	N	None	N	14 + 11	21 + 2	97	II	I
11	F, 6 + 4	N	None	N	13 + 10	20 + 2	92	I	0
12	F, 6 + 6	Y	Pemberton	Y	11 + 6	18 + 0	84	I	II
13	F, 6 + 8	Y	Salter	Y	12 + 2	18 + 10	97	II	I	I
14‡	F, 7 + 2	N	Salter	Y	9 + 7	16 + 9	89	II	0
	F, 7 + 3	N	Salter	Y	9 + 6	16 + 9	89	II	II	III
15‡	F, 7 + 9	Y	Shelf	Y	6 + 3	14 + 0	96	IV	II	III
	F, 7 + 10	Y	None	N	6 + 2	14 + 0	97	III	II	I
16‡	M, 7 + 11	N	None	N	16 + 10	24 + 9	88	IV	II	III
	M, 8 + 2	N	None	N	16 + 7	24 + 9	88	IV	II	II
17‡	F, 8 + 0	N	Salter	Y	8 + 9	16 + 9	93	II	0
	F, 8 + 2	N	Pemberton	Y	8 + 7	16 + 9	91	II	III	II
18‡	M, 9 + 8	N	Salter	Y	8 + 6	18 + 2	91	III	II
	M, 9 + 11	N	Salter	Y	8 + 3	18 + 2	91	III	II	III

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TABLE I DATA ON THE PATIENTS

Case	Gender, Age at Op. (Yrs. + Mos.)	Traction	Type of Pelvic Osteot.	Adequate Reduction on Immed. Postop. Radiograph*	Duration of Follow-up (Yrs. + Mos.)	Results at Latest Follow-up Examination
Age at Follow-up (Yrs. + Mos.)	Iowa Hip Score¹⁴† (Points)	Severin Grade²⁴	Grade of Degenerative Changes³	Type of Osteo- necrosis^5,22
1	F, 3 + 0	N	Pemberton	N	9 + 4	12 + 4	95	II	I	II
2	F, 3 + 10	N	Salter	N	7 + 8	11 + 6	84	I	I
3‡	M, 4 + 0	N	Salter	N	10 + 6	14 + 6	97	II	I	I
	M, 4 + 2	N	Pemberton	Y	10 + 4	14 + 6	97	II	II
4	F, 4 + 2	N	Pemberton	Y	10 + 8	14 + 10	99	I	0
5	F, 4 + 2	N	Salter	Y	7 + 4	11 + 6	99	I	0
6	F, 4 + 4	Y	None	Y	12 + 11	17 + 3	94	II	0	II
7	M, 5 + 3	Y	None	N	12 + 3	17 + 6	77	II	II
8	F, 5 + 7	N	Pemberton	N	9 + 3	15 + 9	84	III	I
9	F, 5 + 10	N	Pemberton	Y	6 + 2	12 + 0	76	I	0
10‡	F, 6 + 0	N	None	N	15 + 2	21 + 2	97	I	0
	F, 6 + 3	N	None	N	14 + 11	21 + 2	97	II	I
11	F, 6 + 4	N	None	N	13 + 10	20 + 2	92	I	0
12	F, 6 + 6	Y	Pemberton	Y	11 + 6	18 + 0	84	I	II
13	F, 6 + 8	Y	Salter	Y	12 + 2	18 + 10	97	II	I	I
14‡	F, 7 + 2	N	Salter	Y	9 + 7	16 + 9	89	II	0
	F, 7 + 3	N	Salter	Y	9 + 6	16 + 9	89	II	II	III
15‡	F, 7 + 9	Y	Shelf	Y	6 + 3	14 + 0	96	IV	II	III
	F, 7 + 10	Y	None	N	6 + 2	14 + 0	97	III	II	I
16‡	M, 7 + 11	N	None	N	16 + 10	24 + 9	88	IV	II	III
	M, 8 + 2	N	None	N	16 + 7	24 + 9	88	IV	II	II
17‡	F, 8 + 0	N	Salter	Y	8 + 9	16 + 9	93	II	0
	F, 8 + 2	N	Pemberton	Y	8 + 7	16 + 9	91	II	III	II
18‡	M, 9 + 8	N	Salter	Y	8 + 6	18 + 2	91	III	II
	M, 9 + 11	N	Salter	Y	8 + 3	18 + 2	91	III	II	III

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Table II SECONDARY PROCEDURES FOR INSTABILITY OF THE HIP

*The patient had bilateral congenital dislocation.

Case	Type of Instability	Type of Second Procedure	Duration between Initial Reduction and Second Procedure (Mos.)	Before Second Procedure			After Second Procedure			At Most Recent Examination
Ace- tabular Index (Degrees)	Center- Edge Angle (Degrees)	Shenton Line	Ace- tabular Index (Degrees)	Center -Edge Angle (Degrees)	Shenton Line	Ace- tabular Index (Degrees)	Center- Edge Angle (Degrees)	Shenton Line
2	Dysplasia	Pemberton	36	31	-1	Broken	8	30	Intact	14	44	Broken
3	Subluxation	Open reduction, Pemberton	17	60	-38	Broken	19	40	Intact	22	35	Intact
7	Dislocation	Open reduction, Salter	3	45	-90	Broken	6	38	Intact	15	43	Intact
8	Dysplasia	Varus femoral osteot.	3	42	0	Intact	38	13	Intact	17	13	Intact
14*	Subluxation	Open reduction, derotat. osteot.	4	31	17	Broken	26	22	Intact	34	23	Intact
15*	Subluxation	Varus derotat. osteot., shelf proc.	6	40	12	Broken	26	18	Intact	27	8	Intact
18*	Excess varus	Valgus femoral osteot.	5	24	30	Broken	26	28	Intact	50	3	Broken
	Osteonecrosis	Varus femoral osteot.	24	36	12	Broken	36	8	Intact	40	18	Intact

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Table II SECONDARY PROCEDURES FOR INSTABILITY OF THE HIP

*The patient had bilateral congenital dislocation.

Case	Type of Instability	Type of Second Procedure	Duration between Initial Reduction and Second Procedure (Mos.)	Before Second Procedure			After Second Procedure			At Most Recent Examination
Ace- tabular Index (Degrees)	Center- Edge Angle (Degrees)	Shenton Line	Ace- tabular Index (Degrees)	Center -Edge Angle (Degrees)	Shenton Line	Ace- tabular Index (Degrees)	Center- Edge Angle (Degrees)	Shenton Line
2	Dysplasia	Pemberton	36	31	-1	Broken	8	30	Intact	14	44	Broken
3	Subluxation	Open reduction, Pemberton	17	60	-38	Broken	19	40	Intact	22	35	Intact
7	Dislocation	Open reduction, Salter	3	45	-90	Broken	6	38	Intact	15	43	Intact
8	Dysplasia	Varus femoral osteot.	3	42	0	Intact	38	13	Intact	17	13	Intact
14*	Subluxation	Open reduction, derotat. osteot.	4	31	17	Broken	26	22	Intact	34	23	Intact
15*	Subluxation	Varus derotat. osteot., shelf proc.	6	40	12	Broken	26	18	Intact	27	8	Intact
18*	Excess varus	Valgus femoral osteot.	5	24	30	Broken	26	28	Intact	50	3	Broken
	Osteonecrosis	Varus femoral osteot.	24	36	12	Broken	36	8	Intact	40	18	Intact

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Figs. 1-A, 1-B, and 1-C: Case 13. Radiographs of a girl who was six years and eight months old when she was managed with the index operation because of congenital dislocation of the right hip. Fig. 1-A: Anteroposterior radiograph of the pelvis, made at the time of the initial examination, showing unilateral dislocation of the hip.

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Fig. 1-B Radiograph made two months after an open reduction, capsulorrhaphy, femoral shortening, and Salter innominate osteotomy, showing adequate reduction.

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Fig. 1-C Radiograph made twelve years and two months postoperatively, showing the femoral head within the remodeled acetabulum. The Iowa hip score¹⁴ was excellent (97 points), the radiographic result was graded Severin²⁴ class II (good), and the degenerative changes were rated grade I (minimum changes).

Materials and Methods

Introduction | Materials and Methods | Results | Discussion | References

We reviewed the medical records of eighteen children (twenty-five hips) who had the index operation, between the ages of three and ten years, for the treatment of congenital dislocation of the hip at the Shriners Hospital for Children, Minneapolis, or the Gillette Children's Hospital, St. Paul, Minnesota, between 1968 and 1990. Patients who had an associated muscular or chromosomal disorder were excluded.

There were fourteen girls (eighteen hips) and four boys (seven hips) (Table I). Seven patients had dislocation of the left hip, four had dislocation of the right, and seven had bilateral dislocation. Four patients had a family history of congenital dysplasia of the hip. The average age was six years and four months (range, three years to nine years and eleven months) at the time of the operation and sixteen years and ten months (range, eleven years and six months to twenty-four years and nine months) at the most recent follow-up examination. The average duration of follow-up was ten years and six months (range, six years and two months to sixteen years and ten months). At the initial visit, evidence of pain, a Trendelenburg sign, and any alteration in the range of motion were recorded.

Five patients (six hips) were managed with skeletal traction for an average of nineteen days (range, four to forty-three days) before the operative procedure. Traction was used, according to the preference of the surgeon, in the early years of the study. No specific criteria were used to determine when to discontinue the traction. None of the hips were reduced with traction.

Open reduction of the hip and capsulorrhaphy was performed through a Smith-Petersen or ilioinguinal approach. Shortening and derotation of the femur was accomplished at the level of the intertrochanteric region; a varus component was added to the derotation in eleven hips (nine patients). A pelvic osteotomy was performed if indicated, and the type of osteotomy was chosen according to the preference of the surgeon. A Pemberton acetabuloplasty was performed in seven hips; a Salter osteotomy, in nine; and a shelf procedure, in one. Soft-tissue structures that appeared to be impeding reduction were released or excised at the time of open reduction. Partial capsular excision was performed in twenty-four hips; capsular plication, in twenty-five; iliopsoas release, in twenty-five; excision of the pulvinar, in twenty-two; release of the ligamentum teres, in fifteen; incision of the transverse acetabular ligament, in twelve; incision of the labrum in a radial fashion, in eleven; partial labral excision, in one; and an adductor tenotomy, in five.

After the operation, each patient wore a hip-spica cast with the hip in more than 90 degrees of flexion and in less than 90 degrees of abduction; extreme rotation was avoided. The cast was changed six weeks postoperatively for fifteen patients (twenty-two hips), and it was removed from three patients (three hips) who then wore a polyethylene orthosis for an additional six weeks. Thirteen patients (twenty hips) had general anesthesia for the procedure, and five patients (five hips) had the cast changed in the inpatient unit. Eleven patients (thirteen hips) had removal of the pin during the same anesthesia session. Thirteen patients (seventeen hips) had removal of the plate and screws. The cast was removed at an average of eleven weeks (range, six to fourteen weeks).

Radiographs were made immediately after the operation, when the cast was changed, at six months and one year postoperatively, and then at yearly intervals until skeletal maturity. The preoperative radiographs were reviewed to determine the degree of displacement of the femoral head²⁷ (the Tönnis²⁸ grade), the station of the hip⁷, the acetabular index¹⁵, and the continuity of the Shenton line¹⁶. The immediate postoperative and latest follow-up radiographs were used to measure the acetabular index, the acetabular angle of Sharp²⁵, the center-edge angle of Wiberg³¹, the articulotrochanteric distance, the Shenton line, and the femoral neck-shaft angle. The latest imaging studies included an anteroposterior radiograph with the patient standing as well as cross-table lateral and frog-leg lateral radiographs with the patient supine; a scanogram or radiographs of the lower extremities with the patient standing were used to evaluate the limb-length discrepancy, if there was one.

Severin's classification system²⁴ was used to grade the hips (Table I). Class I was assigned if the hip was considered to be normal, with a center-edge angle of Wiberg³¹ of more than 20 degrees in adults (fourteen years old or more) and more than 15 degrees in children (six to thirteen years old). Class-II hips had a mild deformity of the femoral head or neck, but the hip was concentrically reduced. The center-edge angle was the same as that in class I. Class-III hips were dysplastic without subluxation. The center-edge angle was less than 20 degrees in adults and less than 15 degrees in children. Class-IV hips were subluxated, and the center-edge angle was 0 degrees or less. In class-V hips, the femoral head articulated within a secondary acetabulum. Class-VI hips were dislocated.

Osteonecrosis was identified with use of the criteria of Salter et al.²², which included the failure of the ossific nucleus to appear or the failure of an existing ossific nucleus to grow within one year after the reduction, broadening of the femoral neck during the year after the reduction, increased radiographic density of the femoral head followed by the radiographic appearance of fragmentation, and residual deformity of the femoral head when reossification was complete. Salter et al.²² reported osteonecrosis in thirty-five of 163 hips that had been treated for congenital dislocation. The osteonecrosis was classified with the use of the system of Bucholz and Ogden⁵.

The hip was considered to be adequately reduced when the radiographs showed an intact Shenton line, a center-edge angle of more than 15 degrees, and an acetabular index of less than 28 degrees. We compared the initial and latest radiographs of the patients who had an adequate reduction with those of the patients who had an inadequate reduction. The adequacy of acetabular remodeling was evaluated by comparing the immediate postoperative radiograph with the latest radiograph. Improvement of the acetabular index by at least 8 degrees and to 20 degrees or less on the most recent radiographs was considered to be adequate correction.

Degenerative changes were rated, according to the system of Boyer et al.³, as grade 0 (no degenerative changes), grade I (no more than one cyst or osteophyte, no bone sclerosis, and a normal joint space), grade II (one or a few subchondral cysts as well as osteophytes, minimum subchondral sclerosis, and slight narrowing of the joint space), or grade III (multiple subchondral cysts and osteophytes, marked subchondral sclerosis, and moderate-to-severe narrowing of the joint space).

The preoperative variables included the age at the time of the reduction, unilateral or bilateral involvement, the initial acetabular index, and the use of preoperative traction. Intraoperative variables included the type of pelvic osteotomy (none, a Salter innominate osteotomy, a Pemberton acetabuloplasty, or a shelf procedure) and the adequacy of the initial reduction. The postoperative radiographic variables included the immediate postoperative and the latest center-edge angle of Wiberg³¹, the acetabular angle of Sharp²⁵, the acetabular index, the articulotrochanteric distance, the Shenton line, the shape of the femoral head, and the femoral neck-shaft angle. The parameters used to determine the outcome at the latest follow-up evaluation were the score according to the Iowa hip-rating system¹⁴, the Severin classification, the presence of degenerative joint disease, and evidence of osteonecrosis of the proximal part of the femur. The presence of a limp, Trendelenburg sign, or limb-length discrepancy and the foot-progression angle were assessed.

Statistical analysis was done to determine the relationship of preoperative, intraoperative, and immediate postoperative variables to the final outcome variables. Pairwise univariate analysis of the outcome variables was performed to reduce the set of measured variables for later multivariate analysis, which consisted of linear regression, logistic regression, and log-linear analysis. Multivariate analysis was performed, where appropriate, with a statistical software program (Statistix; NH Analytical Software, Roseville, Minnesota, and NCSS, Kaysville, Utah).

Results

Introduction | Materials and Methods | Results | Discussion | References

Preoperatively, six patients had pain in the hip and eight had fatigue with activity. The records of four patients contained no information about pain or fatigue. Preoperatively, flexion averaged 109 degrees (range, 45 to 130 degrees); the flexion contracture, 6 degrees (range, 0 to 3 degrees); abduction, 33 degrees (range, 10 to 70 degrees); internal rotation, 60 degrees (range, 0 to 110 degrees); and external rotation, 38 degrees (range, 10 to 70 degrees). All patients walked with a limp and had a positive Trendelenburg sign.

At the time of follow-up, the average Iowa hip-rating score was 91 points (range, 76 to 99 points). No patient had pain at rest, used crutches or a cane, or needed analgesics for relief of pain. Flexion averaged 104 degrees (range, 75 to 135 degrees); the flexion contracture, 3 degrees (range, 0 to 10 degrees); abduction, 29 degrees (range, 0 to 55 degrees); internal rotation, 24 degrees (range, 0 to 50 degrees); and external rotation, 36 degrees (range, 15 to 50 degrees). The average foot-progression angle was 11 degrees (range, 0 to 30 degrees) of external rotation. The Trendelenburg sign was positive in nine of the twenty-five hips and was negative in sixteen. The average limb-length discrepancy was 0.8 centimeter (range, zero to four centimeters). Only one patient (Case 8) had a four-centimeter limb-length discrepancy.

Skeletal maturity was assessed on the basis of the appearance of the proximal femoral physis and the triradiate cartilage. At the latest follow-up evaluation, fourteen patients (twenty-one hips) were skeletally mature. Four patients who were less than thirteen years old and had unilateral dislocation of the hip were not skeletally mature. Preoperative radiographs revealed an average acetabular index of 43 degrees (range, 31 to 50 degrees). The acetabular index at the latest follow-up evaluation averaged 23 degrees (range, 8 to 50 degrees). Preoperatively, four hips were classified as grade 3 and twenty-one were classifed as grade 4 according to the criteria of Tönnis. Six hips that had been treated with traction remained dislocated (0 station of Gage and Winter⁷) before the operation.

Immediate postoperative radiographs showed adequate reduction of fourteen hips and inadequate reduction of eleven. At the time of the latest follow-up, the Shenton line was intact in seventeen hips. The center-edge angle averaged 21 degrees (range, -25 to 44 degrees). According to Severin's classification²⁴, seven hips (28 per cent) were class I; eleven (44 per cent), class II; four (16 per cent), class III; and three (12 per cent), class IV. The degenerative changes, according to the system of Boyer et al.³, were grade 0 in eight hips (32 per cent), grade I in six (24 per cent), grade II in ten (40 per cent), and grade III in one (4 per cent). On the basis of the criteria of Salter et al.²², osteonecrosis was present in the proximal part of the femur in eleven hips. According to the system of Bucholz and Ogden⁵, the osteonecrosis was type I in three hips, type II in four, and type III in four. Osteonecrosis developed in four of the six hips treated with traction.

Eleven of the fourteen hips that had an adequate reduction (an acetabular index of less than 28 degrees, a center-edge angle of more than 15 degrees, and an intact Shenton line) had a satisfactory radiographic outcome (Severin class I or class II) (Figs. 1-A, 1-B, and 1-C). Osteonecrosis developed in two of the remaining three hips that initially had been believed to be adequately reduced, and the outcome was unsatisfactory (Severin class III or IV). The third hip had evidence of moderate (grade-II) degenerative joint disease when the patient was sixteen years old.

Four of the eleven hips that initially had an inadequate reduction (an acetabular index of 28 degrees or more and a center-edge angle of 15 degrees or less) had a fair or poor result (Severin class III or IV) on the radiographs made at the most recent follow-up examination. The remaining seven hips were graded Severin class I or class II; three of these hips had had a second operation, and the other four had adequate remodeling, to an acetabular index of 20 degrees or less on the most recent follow-up radiograph. Three hips that showed signs of remodeling had not had a pelvic osteotomy. The acetabular index changed at least 8 degrees in five of the twenty-five hips, and one of those five hips had had an adequate initial reduction.

Statistical analysis showed that unilateral involvement and an age of seven years old or less at the time of the operation (p < 0.05) as well as a higher center-edge angle (p < 0.05) and an intact Shenton line on the immediate postoperative radiograph (p = 0.0056) were all significantly associated with a better Severin class at the most recent follow-up examination. An intact Shenton line was also associated with a lower rate of osteonecrosis (p = 0.05), whereas older children had a significantly higher rate of osteonecrosis (p = 0.06). In addition, dysplasia (the angle of Sharp²⁵) at the most recent follow-up evaluation was significantly associated with degenerative changes in the hip joint (p = 0.0056). With the numbers available, we could not detect a significant association between the measured variables and the most recent Iowa hip score.

Eight hips (seven patients) needed an additional procedure because of instability or persistent deformity of the hip (Table II). One hip (Case 7) needed a second open reduction, which was performed with a Salter innominate osteotomy, for a redislocation that occurred immediately after removal of the hip-spica cast. The result at the most recent follow-up evaluation was rated as Severin class II. Three hips in three patients (Cases 3, 14, and 15) had persistent subluxation; this necessitated a second open reduction in two hips (Cases 3 and 14) and a pelvic procedure in two (Cases 3 and 15). Two (Cases 3 and 14) of these three hips had a good result (Severin class II) at the most recent follow-up examination; the other one (Case 15) had persistent acetabular dysplasia and subluxation. Two hips (two patients) had a second procedure for acetabular dysplasia; one (Case 2) had a Pemberton acetabuloplasty and had an excellent result (Severin class I), and the other (Case 8) had a varus osteotomy of the femur and had a fair result (Severin class III). Osteonecrosis developed in one hip (Case 18), necessitating a varus femoral osteotomy because of subluxation, and the result at the most recent follow-up examination was graded Severin class III. A valgus osteotomy of the femur was performed in the other hip of the same patient because of excess varus alignment, and the result was graded Severin class III.

Trochanteric apophyseal arrest was performed in two hips in two patients (Cases 8 and 16 [right]). A four-centimeter limb-length discrepancy developed in one patient (Case 8) who had a second varus osteotomy for treatment of dysplasia three months after the index procedure. The family refused any intervention to equalize the limb lengths.

Additional complications included a supracondylar fracture of the femur in two patients (Cases 6 and 16). One fracture occurred when the cast was removed ten weeks postoperatively from a patient (Case 6) who had been managed with skeletal traction for six weeks. The other, a non-displaced fracture sustained four months after the index procedure, occurred in a patient (Case 16) who had not had preoperative traction. Both femoral fractures were treated with immobilization in a cast. One patient (Case 6) had stiffness after the index procedure, and manipulation of the hip was performed with the patient under general anesthesia. The range of motion at the most recent follow-up examination consisted of 130 degrees of flexion, 40 degrees of abduction, 20 degrees of internal rotation, and 40 degrees of external rotation.

Discussion

Introduction | Materials and Methods | Results | Discussion | References

The primary goal of treatment of congenital dislocation of the hip in a child is concentric reduction^2,6,18,32,33. A dislocated hip that is not reduced can lead to gait abnormalities, limitation of motion of the hip, pain in the joint, and arthrosis at an early age^29,30. The age at which open reduction is no longer feasible in a child is unknown, although the indications for operative intervention appear to broaden every few years. Femoral shortening has been shown to facilitate reduction in children who are more than three years old^4,23. In addition, it was concluded that a one-stage operation consisting of open reduction, femoral shortening, and correction of an acetabular deficiency with the appropriate pelvic osteotomy does not increase the risk of osteonecrosis in older children⁸.

A few investigators have evaluated the long-term functional and radiographic outcome of a one-stage operation for the treatment of congenital dislocation of the hip in a child who is more than three years old^11,13,19. Salter and Dubos²¹ performed open reduction and innominate osteotomy in thirty hips in children who were four to ten years old. Thirteen (43 per cent) of the thirty hips remained subluxated or dislocated (Severin class III or class IV) at the time of follow-up. After an average duration of follow-up of seven years, Klisic and Jankovic¹² found that forty-one (68 per cent) of sixty hips in forty-seven patients had a good or excellent radiographic result and thirty-eight (63 per cent) had a good or excellent overall result. The authors did not comment on the method used to evaluate osteonecrosis or on its effect on the outcome. Karakas et al.¹¹ reported the results of a primary one-stage combined operation in forty-seven children (fifty-five hips) who were at least four years old. Forty-two patients (forty-seven hips) had been managed with preoperative traction. They reported that thirty-seven hips (67 per cent) had a good or excellent clinical result and thirty-six (65 per cent) had a good or excellent radiographic result at an average of eight years after the operation. They found avascular necrosis in only four hips (7 per cent), but they did not classify the extent of the necrosis or the end results. Those authors believed that preoperative traction decreased the technical difficulties during the operation. However, they did not identify these difficulties or provide objective data to support their conclusions about the use of traction.

In the present study, eighteen children (twenty-five hips) with previously untreated congenital dislocation of the hip had a one-stage combined open reduction and femoral shortening between the ages of three and ten years. Thirteen patients (seventeen hips) had a concomitant pelvic osteotomy. Twenty-three hips (92 per cent) had a good or excellent Iowa hip score at an average of ten years and six months (range, six years and two months to sixteen years and ten months) after the procedure. Pain, if it was present, was usually mild, and the patients were not limited in activities related to the function of the hip. Fourteen patients (twenty-one hips) who were skeletally mature retained satisfactory function through adolescence and early adulthood. We found that hips that had an adequate initial reduction, as defined by our described criteria, maintained a satisfactory radiographic appearance unless osteonecrosis developed in the femoral head. If the initial reduction was inadequate in a child who was more than three years old, the potential for the acetabulum to remodel and to attain a satisfactory radiographic appearance at the time of the latest follow-up was low^3,11, even if a pelvic osteotomy had been performed.

The criteria described by Severin²⁴ commonly are used to assess the radiographic end results after treatment of congenital dislocation of the hip^{8,13,18,19,32}. We found that eighteen hips (72 per cent) had a good or excellent Severin rating (class I or class II). Our analysis showed that the age of the child at the time of treatment influenced the radiographic outcome at the latest follow-up examination. Children who were more than seven years old at the time of the initial treatment were significantly more likely to have residual dysplasia (Severin class III or class IV) and a higher rate of growth disturbance (p = 0.01). In a study of fifty-eight patients who had been followed for eighteen years, Massie and Howorth¹⁹ did not find any relationship between the age at the time of treatment and the outcome at the latest follow-up examination. Williamson et al.³³ reported the same finding in their study of forty-five hips that had been followed an average of seventeen years, but only one patient had been more than six years old. Other investigators have found results similar to ours^13,18,21. Karakas et al.¹¹ found few good clinical and radiographic results in patients who were more than eight years old at the time of the initial operation.

The clinical results in our patients, as evaluated with use of the Iowa hip score, were not matched by equally good radiographic results. Malvitz and Weinstein¹⁸ also noted this discrepancy, which is believed to be due to the fact that use of the functional scoring system for children does not adequately reflect their future clinical outcome. In addition, the clinical findings may not deteriorate until there are radiographic changes of osteoarthrosis. Our findings suggest that the clinical and radiographic outcomes remain satisfactory until early adulthood. However, a longer duration of follow-up would be necessary to determine whether the results of this treatment method eventually deteriorate. The presence of early degenerative changes in our patients is a cause for concern, as it suggests that even patients who have a good Severin grade may be predisposed to early osteoarthrosis. A longer duration of follow-up is needed to determine if the early degenerative changes will progress to advanced osteoarthrosis of the hip. Other factors, such as the development of osteonecrosis, may be more important than the Severin classification for determining the outcome in an adult.

The use of preoperative traction to facilitate reduction of congenital dislocation of the hip and possibly to lower the postoperative rate of osteonecrosis is controversial. Malvitz and Weinstein¹⁸, in a study of 119 patients (153 hips) who were one month to nine years old, showed that the prevalence of osteonecrosis was the same with or without the use of traction before management with closed reduction. As mentioned, Schoenecker and Strecker²³, in a study comparing the results in eight patients (thirteen hips) who had been managed with femoral diaphyseal shortening with those in seventeen patients (twenty-six hips) managed with traction, found a higher prevalence of osteonecrosis in the group managed with traction. They concluded that femoral shortening was preferable to traction in the reduction of congenital dislocation of the hip in children who are more than three years old. Galpin et al.⁸ reviewed the results of one-stage operative management without preoperative traction in twenty-five children (thirty-three hips) who were more than two years old. Femoral shortening and, in twenty-one hips, a pelvic osteotomy were performed at the time of the open reduction. At an average of three years and seven months (range, two years to six years and ten months), the prevalence of avascular necrosis in those patients was not higher than that found in historical controls. Bucholz and Ogden⁵ as well as Kalamchi and MacEwen¹⁰ showed that the effects of osteonecrosis may not be apparent until patients have been followed for twelve years or more. Although the prevalence of osteonecrosis (44 per cent; eleven of twenty-five hips) was high in the present study, it is comparable with that reported in studies with similar methods for the evaluation of osteonecrosis^10,18. The prevalence of severe deformity secondary to complete necrosis of the capital femoral epiphysis (16 per cent; four hips) was low in our study. It appears that skeletal traction does not decrease the risk of osteonecrosis. We agree with other authors^5,10,21,26 that patients must be followed to skeletal maturity to assess fully the final growth disturbance. It is possible that the radiographic changes of early osteoarthrosis of the hip only become apparent in the skeletally mature hip.

We found that a concentric reduction was more difficult to attain and to maintain in the five children (ten hips) who were more than seven years old. Our results suggest that the age at the time of the reduction, the quality of the initial reduction, and perhaps bilateral involvement affect the radiographic outcome at or near skeletal maturity and that the ability of the acetabulum to remodel is limited in children who are more than three years old. Adequate reduction at the initial operation offers the best chance for a good or excellent long-term radiographic appearance of the hip.

References

Introduction | Materials and Methods | Results | Discussion | References

Ashley, R. K.; Larsen, L. J.; and James, P. M.: Reduction of dislocation of the hip in older children. A preliminary report. J. Bone and Joint Surg.,54-A: 545-550, April 1972.54-A545 1972

Berkeley, M. E.; Dickson, J. H.; Cain, T. E.; and Donovan, M. M.: Surgical therapy for congenital dislocation of the hip in patients who are twelve to thirty-six months old. J. Bone and Joint Surg.,66-A: 412-420, March 1984.66-A412 1984

Boyer, D. W.; Mickelson, M. R.; and Ponseti, I. V.: Slipped capital femoral epiphysis. Long-term follow-up study of one hundred and twenty-one patients. J. Bone and Joint Surg.,63-A: 85-95, Jan. 1981.63-A85 1981

Browne, R. S.: The management of late diagnosed congenital dislocation and subluxation of the hip. With special reference to femoral shortening. J. Bone and Joint Surg.,61-B(1): 7-12, 1979.61-B(1)7 1979

Bucholz, R. W., and Ogden, J. A.: Patterns of ischemic necrosis of the proximal femur in nonoperatively treated congenital hip disease. In The Hip. Proceedings of the Sixth Open Scientific Meeting of The Hip Society, pp. 43-63. St. Louis, C. V. Mosby, 1978.

Coleman, S. S.: Congenital Dysplasia and Dislocation of the Hip, pp. 95-154. St. Louis, C. V. Mosby, 1978.

Gage, J. R., and Winter, R. B.: Avascular necrosis of the capital femoral epiphysis as a complication of closed reduction of congenital dislocation of the hip. A critical review of twenty years' experience at Gillette Children's Hospital. J. Bone and Joint Surg.,54-A: 373-388, March 1972.54-A373 1972

Galpin, R. D.; Roach, J. W.; Wenger, D. R.; Herring, J. A.; and Birch, J. G.: One-stage treatment of congenital dislocation of the hip in older children, including femoral shortening. J. Bone and Joint Surg.,71-A: 734-741, June 1989.71-A734 1989

Herold, H. Z., and Daniel, D.: Reduction of neglected congenital dislocation of the hip in children over the age of six years. J. Bone and Joint Surg.,61-B(1): 1-6, 1979.61-B(1)1 1979

Kalamchi, A., and MacEwen, G. D.: Avascular necrosis following treatment of congenital dislocation of the hip. J. Bone and Joint Surg.,62-A: 876-888, Sept. 1980.62-A876 1980

Karakas, E. S.; Baktir, A.; Argün, M.; and Türk, C. Y.: One-stage treatment of congenital dislocation of the hip in older children. J. Pediat. Orthop.,15: 330-336, 1995.15330 1995

Klisic, P., and Jankovic, L.: Combined procedure of open reduction and shortening of the femur in treatment of congenital dislocation of the hips in older children. Clin Orthop.,119: 60-69, 1976.11960 1976 [PubMed]

Klisic, P.; Jankovic, L.; and Basara, V.: Long-term results of combined operative reduction of the hip in older children. J. Pediat. Orthop.,8: 532-534, 1988.8532 1988

Larson, C. B.: Rating scale for hip disabilities. Clin. Orthop.,31: 85-93, 1963.3185 1963 [PubMed]

Laurenson, R. D.: The acetabular index. A critical review. J. Bone and Joint Surg.,41-B(4): 702-710, 1959.41-B(4)702 1959

Lichtblau, S.: Early recognition of congenital dislocation and congenital subluxation of the hip. An evaluation of Shenton's line. Clin. Orthop.,48: 181-189, 1966.48181 1966 [PubMed]

Lindstrom, J. R.; Ponseti, I. V.; and Wenger, D. R.: Acetabular development after reduction in congenital dislocation of the hip. J. Bone and Joint Surg.,61-A: 112-118, Jan. 1979.61-A112 1979

Malvitz, T. A., and Weinstein, S. L.: Closed reduction for congenital dysplasia of the hip. Functional and radiographic results after an average of thirty years. J. Bone and Joint Surg.,76-A: 1777-1792, Dec. 1994.76-A1777 1994

Massie, W. K., and Howorth, M. B.: Congenital dislocation of the hip. Part II. Results of open reduction as seen in early adult period. J. Bone and Joint Surg.,33-A: 171-190, Jan. 1951.33-A171 1951

Morel, G.: The treatment of congenital dislocation and subluxation of the hip in the older child. Acta Orthop. Scandinavica,46: 364-399, 1975.46364 1975

Salter, R. B., and Dubos, J.-P.: The first fifteen years' personal experience with innominate osteotomy in the treatment of congenital dislocation and subluxation of the hip. Clin. Orthop.,98: 72-103, 1974.9872 1974 [PubMed]

Salter, R. B.; Kostuik, J.; and Dallas, S.: Avascular necrosis of the femoral head as a complication of treatment for congenital dislocation of the hip in young children: a clinical and experimental investigation. Canadian J. Surg.,12: 44-61, 1969.1244 1969

Schoenecker, P. L., and Strecker, W. B.: Congenital dislocation of the hip in children. Comparison of the effects of femoral shortening and of skeletal traction in treatment. J. Bone and Joint Surg.,66-A: 21-27, Jan. 1984.66-A21 1984

Severin, E.: Contribution to the knowledge of congenital dislocation of the hip joint. Late results of closed reduction and arthrographic studies of recent cases. Acta Chir. Scandinavica, Supplementum 63, 1941.

Sharp, I. K.: Acetabular dysplasia. The acetabular angle. J. Bone and Joint Surg.,43-B(2): 268-272, 1961.43-B(2)268 1961

Thomas, C. L.; Gage, J. R.; and Ogden, J. A.: Treatment concepts for proximal femoral ischemic necrosis complicating congenital hip disease. J. Bone and Joint Surg.,64-A: 817-828, July 1982.64-A817 1982

Tönnis, D.: Normal values of the hip joint for the evaluation of x-rays in children and adults. Clin. Orthop.,119: 39-47, 1976.11939 1976 [PubMed]

Tönnis, D. [editor]: Congenital Hip Dislocation—Avascular Necrosis. New York, Thieme-Stratton, 1982.

Walker, J. M.: Congenital hip disease in a Cree-Ojibwa population: a retrospective study. Canadian Med. Assn. J.,116: 501-504, 1977.116501 1977

Wedge, J. H., and Wasylenko, M. J.: The natural history of congenital disease of the hip. J. Bone and Joint Surg.,61-B(3): 334-338, 1979.61-B(3)334 1979

Wiberg, G.: Studies on dysplastic acetabula and congenital subluxation of the hip joint. With special reference to the complication of osteo-arthritis. Acta Chir. Scandinavica, Supplementum 58, 1939.

Wilkinson, J., and Carter, C.: Congenital dislocation of the hip. The results of conservative treatment. J. Bone and Joint Surg.,42-B(4): 669-688, 1960.42-B(4)669 1960

Williamson, D. M.; Glover, S. D.; and Benson, M. K. D'A.: Congenital dislocation of the hip presenting after the age of three years. A long-term review. J. Bone and Joint Surg.,71-B(5): 745-751, 1989.71-B(5)745 1989

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Fig. 1-B Radiograph made two months after an open reduction, capsulorrhaphy, femoral shortening, and Salter innominate osteotomy, showing adequate reduction.

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TABLE I DATA ON THE PATIENTS

Case	Gender, Age at Op. (Yrs. + Mos.)	Traction	Type of Pelvic Osteot.	Adequate Reduction on Immed. Postop. Radiograph*	Duration of Follow-up (Yrs. + Mos.)	Results at Latest Follow-up Examination
Age at Follow-up (Yrs. + Mos.)	Iowa Hip Score¹⁴† (Points)	Severin Grade²⁴	Grade of Degenerative Changes³	Type of Osteo- necrosis^5,22
1	F, 3 + 0	N	Pemberton	N	9 + 4	12 + 4	95	II	I	II
2	F, 3 + 10	N	Salter	N	7 + 8	11 + 6	84	I	I
3‡	M, 4 + 0	N	Salter	N	10 + 6	14 + 6	97	II	I	I
	M, 4 + 2	N	Pemberton	Y	10 + 4	14 + 6	97	II	II
4	F, 4 + 2	N	Pemberton	Y	10 + 8	14 + 10	99	I	0
5	F, 4 + 2	N	Salter	Y	7 + 4	11 + 6	99	I	0
6	F, 4 + 4	Y	None	Y	12 + 11	17 + 3	94	II	0	II
7	M, 5 + 3	Y	None	N	12 + 3	17 + 6	77	II	II
8	F, 5 + 7	N	Pemberton	N	9 + 3	15 + 9	84	III	I
9	F, 5 + 10	N	Pemberton	Y	6 + 2	12 + 0	76	I	0
10‡	F, 6 + 0	N	None	N	15 + 2	21 + 2	97	I	0
	F, 6 + 3	N	None	N	14 + 11	21 + 2	97	II	I
11	F, 6 + 4	N	None	N	13 + 10	20 + 2	92	I	0
12	F, 6 + 6	Y	Pemberton	Y	11 + 6	18 + 0	84	I	II
13	F, 6 + 8	Y	Salter	Y	12 + 2	18 + 10	97	II	I	I
14‡	F, 7 + 2	N	Salter	Y	9 + 7	16 + 9	89	II	0
	F, 7 + 3	N	Salter	Y	9 + 6	16 + 9	89	II	II	III
15‡	F, 7 + 9	Y	Shelf	Y	6 + 3	14 + 0	96	IV	II	III
	F, 7 + 10	Y	None	N	6 + 2	14 + 0	97	III	II	I
16‡	M, 7 + 11	N	None	N	16 + 10	24 + 9	88	IV	II	III
	M, 8 + 2	N	None	N	16 + 7	24 + 9	88	IV	II	II
17‡	F, 8 + 0	N	Salter	Y	8 + 9	16 + 9	93	II	0
	F, 8 + 2	N	Pemberton	Y	8 + 7	16 + 9	91	II	III	II
18‡	M, 9 + 8	N	Salter	Y	8 + 6	18 + 2	91	III	II
	M, 9 + 11	N	Salter	Y	8 + 3	18 + 2	91	III	II	III

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TABLE I DATA ON THE PATIENTS

Case	Gender, Age at Op. (Yrs. + Mos.)	Traction	Type of Pelvic Osteot.	Adequate Reduction on Immed. Postop. Radiograph*	Duration of Follow-up (Yrs. + Mos.)	Results at Latest Follow-up Examination
Age at Follow-up (Yrs. + Mos.)	Iowa Hip Score¹⁴† (Points)	Severin Grade²⁴	Grade of Degenerative Changes³	Type of Osteo- necrosis^5,22
1	F, 3 + 0	N	Pemberton	N	9 + 4	12 + 4	95	II	I	II
2	F, 3 + 10	N	Salter	N	7 + 8	11 + 6	84	I	I
3‡	M, 4 + 0	N	Salter	N	10 + 6	14 + 6	97	II	I	I
	M, 4 + 2	N	Pemberton	Y	10 + 4	14 + 6	97	II	II
4	F, 4 + 2	N	Pemberton	Y	10 + 8	14 + 10	99	I	0
5	F, 4 + 2	N	Salter	Y	7 + 4	11 + 6	99	I	0
6	F, 4 + 4	Y	None	Y	12 + 11	17 + 3	94	II	0	II
7	M, 5 + 3	Y	None	N	12 + 3	17 + 6	77	II	II
8	F, 5 + 7	N	Pemberton	N	9 + 3	15 + 9	84	III	I
9	F, 5 + 10	N	Pemberton	Y	6 + 2	12 + 0	76	I	0
10‡	F, 6 + 0	N	None	N	15 + 2	21 + 2	97	I	0
	F, 6 + 3	N	None	N	14 + 11	21 + 2	97	II	I
11	F, 6 + 4	N	None	N	13 + 10	20 + 2	92	I	0
12	F, 6 + 6	Y	Pemberton	Y	11 + 6	18 + 0	84	I	II
13	F, 6 + 8	Y	Salter	Y	12 + 2	18 + 10	97	II	I	I
14‡	F, 7 + 2	N	Salter	Y	9 + 7	16 + 9	89	II	0
	F, 7 + 3	N	Salter	Y	9 + 6	16 + 9	89	II	II	III
15‡	F, 7 + 9	Y	Shelf	Y	6 + 3	14 + 0	96	IV	II	III
	F, 7 + 10	Y	None	N	6 + 2	14 + 0	97	III	II	I
16‡	M, 7 + 11	N	None	N	16 + 10	24 + 9	88	IV	II	III
	M, 8 + 2	N	None	N	16 + 7	24 + 9	88	IV	II	II
17‡	F, 8 + 0	N	Salter	Y	8 + 9	16 + 9	93	II	0
	F, 8 + 2	N	Pemberton	Y	8 + 7	16 + 9	91	II	III	II
18‡	M, 9 + 8	N	Salter	Y	8 + 6	18 + 2	91	III	II
	M, 9 + 11	N	Salter	Y	8 + 3	18 + 2	91	III	II	III

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Table II SECONDARY PROCEDURES FOR INSTABILITY OF THE HIP

*The patient had bilateral congenital dislocation.

Case	Type of Instability	Type of Second Procedure	Duration between Initial Reduction and Second Procedure (Mos.)	Before Second Procedure			After Second Procedure			At Most Recent Examination
Ace- tabular Index (Degrees)	Center- Edge Angle (Degrees)	Shenton Line	Ace- tabular Index (Degrees)	Center -Edge Angle (Degrees)	Shenton Line	Ace- tabular Index (Degrees)	Center- Edge Angle (Degrees)	Shenton Line
2	Dysplasia	Pemberton	36	31	-1	Broken	8	30	Intact	14	44	Broken
3	Subluxation	Open reduction, Pemberton	17	60	-38	Broken	19	40	Intact	22	35	Intact
7	Dislocation	Open reduction, Salter	3	45	-90	Broken	6	38	Intact	15	43	Intact
8	Dysplasia	Varus femoral osteot.	3	42	0	Intact	38	13	Intact	17	13	Intact
14*	Subluxation	Open reduction, derotat. osteot.	4	31	17	Broken	26	22	Intact	34	23	Intact
15*	Subluxation	Varus derotat. osteot., shelf proc.	6	40	12	Broken	26	18	Intact	27	8	Intact
18*	Excess varus	Valgus femoral osteot.	5	24	30	Broken	26	28	Intact	50	3	Broken
	Osteonecrosis	Varus femoral osteot.	24	36	12	Broken	36	8	Intact	40	18	Intact

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Table II SECONDARY PROCEDURES FOR INSTABILITY OF THE HIP

*The patient had bilateral congenital dislocation.

Case	Type of Instability	Type of Second Procedure	Duration between Initial Reduction and Second Procedure (Mos.)	Before Second Procedure			After Second Procedure			At Most Recent Examination
Ace- tabular Index (Degrees)	Center- Edge Angle (Degrees)	Shenton Line	Ace- tabular Index (Degrees)	Center -Edge Angle (Degrees)	Shenton Line	Ace- tabular Index (Degrees)	Center- Edge Angle (Degrees)	Shenton Line
2	Dysplasia	Pemberton	36	31	-1	Broken	8	30	Intact	14	44	Broken
3	Subluxation	Open reduction, Pemberton	17	60	-38	Broken	19	40	Intact	22	35	Intact
7	Dislocation	Open reduction, Salter	3	45	-90	Broken	6	38	Intact	15	43	Intact
8	Dysplasia	Varus femoral osteot.	3	42	0	Intact	38	13	Intact	17	13	Intact
14*	Subluxation	Open reduction, derotat. osteot.	4	31	17	Broken	26	22	Intact	34	23	Intact
15*	Subluxation	Varus derotat. osteot., shelf proc.	6	40	12	Broken	26	18	Intact	27	8	Intact
18*	Excess varus	Valgus femoral osteot.	5	24	30	Broken	26	28	Intact	50	3	Broken
	Osteonecrosis	Varus femoral osteot.	24	36	12	Broken	36	8	Intact	40	18	Intact