JBJS | Total Hip Arthroplasty with Cement for Juvenile Rheumatoid Arthritis. Results at a Minimum of Ten Years in Patients Less Than Thirty Years Old*

The Journal of Bone & Joint Surgery, Volume 79, Issue 1

Articles | January 01, 1997

Total Hip Arthroplasty with Cement for Juvenile Rheumatoid Arthritis. Results at a Minimum of Ten Years in Patients Less Than Thirty Years Old*

MICHAEL J. CHMELL, M.D.†; RICHARD D. SCOTT, M.D.‡; WILLIAM H. THOMAS, M.D.§; CLEMENT B. SLEDGE, M.D.§, BOSTON, MASSACHUSETTS

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Investigation performed at Brigham and Women's Hospital, Boston

The Journal of Bone & Joint Surgery. 1997; 79:44-52

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Abstract

We retrospectively reviewed the clinical and radiographic results of total hip arthroplasty with cement in patients with juvenile rheumatoid arthritis who were less than thirty years old at the time of the index procedure. Thirty-nine patients (sixty-six hips) were managed with this procedure at our institution between 1971 and 1983. Six patients (eleven hips) died before a minimum of ten years of follow-up; the remaining thirty-three patients (fifty-five hips) were followed for at least eleven years. Twenty-eight patients (forty-six hips) had at least one original component in situ after an average duration of clinical follow-up of 15.1 years, and twenty-three of these patients (thirty-eight hips) were followed radiographically for an average of 14.7 years. At the time of the latest follow-up examination, all twenty-eight patients were able to walk outside the home; twenty of these patients (thirty-five hips; 76 per cent) had no pain with activity, and eight patients (eleven hips; 24 per cent) had mild-to-moderate pain with activity.Over-all, twelve (18 per cent) of the sixty-six femoral components and twenty-three (35 per cent) of the sixty-six acetabular components were revised after an average of 12.8 and 11.8 years, respectively. The fifteen-year survival rate for the femoral components was 85 per cent with revision or radiographic loosening as the end point. The fifteen-year survival rate for the acetabular components was 70 per cent with revision as the end point and 61 per cent with revision or radiographic loosening as the end point.The benefits of total hip arthroplasty were maintained over the long term in most of our patients who had juvenile rheumatoid arthritis. However, the durability of the components in these young patients remains a concern.

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Introduction

Introduction | Materials and Methods | Results | Discussion | References

Juvenile rheumatoid arthritis affects approximately 100,000 children per year in the United States. The hip may be involved in as many as 30 to 60 per cent of these patients^{10,11,17,24,26}, but only a small fraction ultimately have total hip arthroplasty because of destruction of the joint. Nevertheless, the effects of juvenile rheumatoid arthritis may be devastating in terms of physical, social, and emotional development because of their impact on function. The goal of treatment, therefore, is to restore as much function as possible.

Rheumatoid arthritis affecting the hip often produces the primary functional impairment in an individual who has involvement of multiple joints^10,11,21. This is because of the importance of the hip joint itself, as well as the concurrent effects on the pelvis and the entire lower extremity during walking. Loss of the ability to walk may foster psychosocial problems in a child, adolescent, or young adult because of resultant isolation and dependency.

The utility of total hip arthroplasty for the relief of pain and the restoration of function in appropriately selected patients who have juvenile rheumatoid arthritis has been documented previously^{2,4,15,17,22,24,29}. The unique technical aspects of total hip arthroplasty in such patients, resulting from variations in skeletal size as well as the presence of deficiencies of pelvic bone stock, torsional deformities, and contractures, also have been described^11,15,22,24. By reviewing the records of a large population of patients who had been followed for a minimum of ten years, we sought to determine the long-term durability of total hip arthroplasty with cement in adolescents and young adults who had juvenile rheumatoid arthritis.

*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.

†Rockford Orthopedic Associates, 5668 East State Street, Rockford, Illinois 61108.

‡New England Baptist Hospital, 125 Parker Hill Avenue, Boston, Massachusetts 02120.

§Brigham and Women's Hospital, 75 Francis Street, Boston, Massachusetts 02120.

*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.

†Rockford Orthopedic Associates, 5668 East State Street, Rockford, Illinois 61108.

‡New England Baptist Hospital, 125 Parker Hill Avenue, Boston, Massachusetts 02120.

§Brigham and Women's Hospital, 75 Francis Street, Boston, Massachusetts 02120.

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Figs. 1-A and 1-B: Radiographs of a twenty-two-year-old man who was managed with a bilateral total hip arthroplasty with cement because of juvenile rheumatoid arthritis. Fig. 1-A: Preoperative radiograph demonstrating bilateral destruction of the hip joint.

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Fig. 1-B Radiograph made fifteen years postoperatively, demonstrating a non-progressive radiolucent line about the acetabular component in zone III⁵ and no radiolucent lines about the femoral components. The components were well fixed and had not migrated from the position seen on the initial postoperative radiographs. The patient was pain-free and worked full-time at the time of the most recent examination.

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Figs. 2-A and 2-B: A twenty-six-year-old woman who was managed with a total hip arthroplasty with cement because of juvenile rheumatoid arthritis. Fig. 2-A: Radiograph, made fourteen years postoperatively, demonstrating loosening of the acetabular component; the loosening was clinically symptomatic.

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Fig. 2-B: Radiograph, made nineteen years after the index arthroplasty, demonstrating the maintenance of excellent fixation on the femoral side without substantial radiolucent lines. The acetabular component had been revised with a metal-backed cup without cement; the revision component was well fixed at five years.

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TABLE I LIFE-TABLE ANALYSIS OF ACETABULAR COMPONENTS, WITH FAILURE DEFINED AS REVISION

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	2	1	0	57.5	3.5	96.5	95	2.8
7 to 8	55	1	0	0	55	1.8	98.2	93	3.2
8 to 9	54	4	0	0	54	7.4	92.6	86	4.3
9 to 10	50	1	1	0	49.5	2	98	84.5	4.7
10 to 11	48	1	1	0	47.5	2.1	97.9	83	5.0
11 to 12	46	1	4	0	44	2.3	97.7	81	5.3
12 to 13	41	1	5	0	38.5	2.6	97.4	79	5.8
13 to 14	35	0	5	0	32.5	0	100	79	6.3
14 to 15	30	3	5	0	27.5	10.9	89.1	70	7.3
15 to 16	22	4	6	0	19	21	79	55	8.5
16 to 17	12	2	0	0	12	16.7	83.3	46	9.8
17 to 18	10	1	4	0	8	12.5	87.5	40	11.0
18 to 19	5	0	1	0	4.5	0	100	40	14.7
19 to 20	4	0	0	0	4	0	100	40	15.6
20 to 21	4	0	2	0	3	0	100	40	18.0
21 to 22	2	1	1	0	2	66.7	33.3	13.5	10.2

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TABLE I LIFE-TABLE ANALYSIS OF ACETABULAR COMPONENTS, WITH FAILURE DEFINED AS REVISION

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	2	1	0	57.5	3.5	96.5	95	2.8
7 to 8	55	1	0	0	55	1.8	98.2	93	3.2
8 to 9	54	4	0	0	54	7.4	92.6	86	4.3
9 to 10	50	1	1	0	49.5	2	98	84.5	4.7
10 to 11	48	1	1	0	47.5	2.1	97.9	83	5.0
11 to 12	46	1	4	0	44	2.3	97.7	81	5.3
12 to 13	41	1	5	0	38.5	2.6	97.4	79	5.8
13 to 14	35	0	5	0	32.5	0	100	79	6.3
14 to 15	30	3	5	0	27.5	10.9	89.1	70	7.3
15 to 16	22	4	6	0	19	21	79	55	8.5
16 to 17	12	2	0	0	12	16.7	83.3	46	9.8
17 to 18	10	1	4	0	8	12.5	87.5	40	11.0
18 to 19	5	0	1	0	4.5	0	100	40	14.7
19 to 20	4	0	0	0	4	0	100	40	15.6
20 to 21	4	0	2	0	3	0	100	40	18.0
21 to 22	2	1	1	0	2	66.7	33.3	13.5	10.2

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TABLE II LIFE-TABLE ANALYSIS OF ACETABULAR COMPONENTS, WITH FAILURE DEFINED AS REVISION OR RADIOGRAPHIC LOOSENING

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98.4	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	2	1	0	57.5	3.5	96.5	95	2.8
8 to 9	54	4	0	0	54	7.4	92.6	86	4.3
9 to 10	50	1	1	0	49.5	2	98	84.5	4.7
10 to l1	48	1	1	0	47.5	2.1	97.9	83	5.0
11 to 12	46	1	4	0	44	2.3	97.7	81	5.3
12 to 13	41	2	4	0	39	5.1	94.9	77	5.9
13 to 14	35	1	4	0	33	3	97	74.5	6.5
14 to 15	30	5	3	0	28.5	17.5	82.5	61	7.1
15 to 16	22	4	6	0	19	21	79	48.5	8.0
16 to 17	12	3	0	0	12	25	75	36	8.4
17 to 18	9	1	3	0	7.5	13.3	86.7	31.5	9.5
18 to 19	5	0	1	0	4.5	0	100	31.5	12.2
19 to 20	4	0	0	0	4	0	100	31.5	13
20 to 21	4	0	2	0	3	0	100	31.5	15.1
21 to 22	2	2	0	0	2	100	0	0	0

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TABLE II LIFE-TABLE ANALYSIS OF ACETABULAR COMPONENTS, WITH FAILURE DEFINED AS REVISION OR RADIOGRAPHIC LOOSENING

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98.4	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	2	1	0	57.5	3.5	96.5	95	2.8
8 to 9	54	4	0	0	54	7.4	92.6	86	4.3
9 to 10	50	1	1	0	49.5	2	98	84.5	4.7
10 to l1	48	1	1	0	47.5	2.1	97.9	83	5.0
11 to 12	46	1	4	0	44	2.3	97.7	81	5.3
12 to 13	41	2	4	0	39	5.1	94.9	77	5.9
13 to 14	35	1	4	0	33	3	97	74.5	6.5
14 to 15	30	5	3	0	28.5	17.5	82.5	61	7.1
15 to 16	22	4	6	0	19	21	79	48.5	8.0
16 to 17	12	3	0	0	12	25	75	36	8.4
17 to 18	9	1	3	0	7.5	13.3	86.7	31.5	9.5
18 to 19	5	0	1	0	4.5	0	100	31.5	12.2
19 to 20	4	0	0	0	4	0	100	31.5	13
20 to 21	4	0	2	0	3	0	100	31.5	15.1
21 to 22	2	2	0	0	2	100	0	0	0

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TABLE III LIFE-TABLE ANALYSIS OF FEMORAL COMPONENTS, WITH FAILURE DEFINED AS REVISION OR RADIOGRAPHIC LOOSENING

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98.4	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	0	2	0	57	0	100	98	1.7
7 to 8	56	0	0	0	56	0	100	98	1.7
8 to 9	56	2	0	0	56	3.6	96.4	95	2.9
9 to 10	54	0	1	0	53.5	0	100	95	2.9
10 to 11	53	1	1	0	52.5	1.9	98.1	93	3.4
11 to 12	51	0	5	0	48.5	0	100	93	3.5
12 to 13	46	1	7	0	42.5	2.4	97.6	91	4.2
13 to 14	38	0	5	0	35.5	0	100	91	4.6
14 to 15	33	2	8	0	29	6.9	93.1	85	6.2
15 to 16	23	3	4	0	21	14.3	85.7	72.5	8.3
16 to 17	16	1	0	0	16	6.25	93.75	68	9.6
17 to 18	15	0	3	0	13.5	0	100	68	10.5
18 to 19	12	0	5	0	9.5	0	100	68	12.5
19 to 20	7	0	1	0	6.5	0	100	68	15.1
20 to 21	6	0	2	0	5	0	100	68	17.2
21 to 22	4	1	1	0	3.5	28.6	71.4	48.5	18.6
22 to 23	2	0	2	0	1	0	100	48.5	34.8

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TABLE III LIFE-TABLE ANALYSIS OF FEMORAL COMPONENTS, WITH FAILURE DEFINED AS REVISION OR RADIOGRAPHIC LOOSENING

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98.4	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	0	2	0	57	0	100	98	1.7
7 to 8	56	0	0	0	56	0	100	98	1.7
8 to 9	56	2	0	0	56	3.6	96.4	95	2.9
9 to 10	54	0	1	0	53.5	0	100	95	2.9
10 to 11	53	1	1	0	52.5	1.9	98.1	93	3.4
11 to 12	51	0	5	0	48.5	0	100	93	3.5
12 to 13	46	1	7	0	42.5	2.4	97.6	91	4.2
13 to 14	38	0	5	0	35.5	0	100	91	4.6
14 to 15	33	2	8	0	29	6.9	93.1	85	6.2
15 to 16	23	3	4	0	21	14.3	85.7	72.5	8.3
16 to 17	16	1	0	0	16	6.25	93.75	68	9.6
17 to 18	15	0	3	0	13.5	0	100	68	10.5
18 to 19	12	0	5	0	9.5	0	100	68	12.5
19 to 20	7	0	1	0	6.5	0	100	68	15.1
20 to 21	6	0	2	0	5	0	100	68	17.2
21 to 22	4	1	1	0	3.5	28.6	71.4	48.5	18.6
22 to 23	2	0	2	0	1	0	100	48.5	34.8

Materials and Methods

Introduction | Materials and Methods | Results | Discussion | References

The Total Joint Registry at Brigham and Women's Hospital was used to identify patients who had had a total hip arthroplasty with cement because of juvenile rheumatoid arthritis between 1971 and 1983. A total of sixty-three such patients (102 hips) were identified. Thirty-nine patients (sixty-six hips) who were less than thirty years old at the time of the index procedure form the basis of the present study.

The patients were an average of 19.9 years old (range, eleven to twenty-nine years old) at the time of the index total hip arthroplasty. Sixteen patients (twenty-eight hips) were male, and twenty-three patients (thirty-eight hips) were female. Twenty-seven patients had a bilateral arthroplasty: in two of these patients the procedures had been performed during the same session of anesthesia, whereas in the other twenty-five the procedures were performed ten to fourteen days apart.

A standard posterolateral approach was used for fifty-three hips (80 per cent), and a trochanteric osteotomy was performed in the remaining thirteen (20 per cent). Custom-made or special miniature components (commonly used for patients who have congenital dislocation of the hip) were inserted into thirty-three hips (50 per cent) while standard Trapezoidal-28 (Zimmer, Warsaw, Indiana) or Aufranc-Turner (Howmedica, Rutherford, New Jersey) components were used in sixteen hips (24 per cent) and seventeen hips (26 per cent), respectively. The diameter of the prosthetic femoral head was twenty-two millimeters in thirty-three hips (50 per cent), twenty-eight or twenty-nine millimeters in eighteen (27 per cent), and thirty-two millimeters in fifteen (23 per cent). An all-polyethylene acetabular component and a non-modular femoral component were inserted with cement in each hip; so-called first-generation cementing techniques (finger-packing of the cement and no plugging of the femoral canal) were used for thirty-one hips (47 per cent), whereas pressurization of the cement and plugging of the femoral canal were used for the other thirty-five (53 per cent).

Data were gathered from the Total Joint Registry (which includes information regarding the operation as well as early and late complications) and at annual clinical visits during which the patient was interviewed and examined by a physical therapist and a physician. As Brigham and Women's Hospital is a referral institution, many patients lived out of state and were followed by their local physician; such patients were contacted and interviewed by telephone, and records and radiographs were sent to us. Patients were evaluated clinically with regard to the relief of pain and walking ability at each follow-up examination. Anteroposterior radiographs of hips with surviving implants were analyzed with regard to migration of the components relative to anatomical landmarks^9,12, the presence of radiolucent lines in the zones described by Gruen et al. and those described by DeLee and Charnley, osteolysis, femoral cortical remodeling, and heterotopic ossification (as classified according to the system described by Brooker et al.). Life-tables were constructed, according to the method described by Dobbs, to evaluate the survival of the femoral and acetabular components with revision and radiographic loosening as end points. Standard errors for the survival rates were calculated with the method of Peto et al.^18,20.

Results

Introduction | Materials and Methods | Results | Discussion | References

Follow-up Population

Six patients (eleven hips) died, with the hip prosthesis in situ, before a minimum of ten years of follow-up. The remaining thirty-three patients (fifty-five hips) were followed for at least eleven years. Over-all, twelve (18 per cent) of the sixty-six femoral components and twenty-three (35 per cent) of the sixty-six acetabular components were revised after an average of 12.8 years (range, four to twenty-one years) and 11.8 years (range, four to twenty-one years), respectively. Two revisions were performed because of a fracture of the femoral component, and all of the others were done because of aseptic loosening. After an average duration of clinical follow-up of 15.1 years (range, eleven to twenty-two years), twenty-eight surviving patients (forty-six hips) had at least one original component in situ and fifteen patients (thirty hips) had both original components in situ (Figs. 1-A and 1-B). Twenty-three of the twenty-eight patients (thirty-eight hips) were followed radiographically for an average of 14.7 years (range, eleven to twenty-two years); the remaining five patients (eight hips) in that group stated that the hip was functioning well and declined to have a radiographic examination.

Clinical Results

Preoperatively, eleven patients (twenty-one hips) were unable to walk (eight patients were confined to a wheelchair and three were bedridden), sixteen patients (twenty-six hips) used two crutches for walking outside the home, five patients (nine hips) used one cane or crutch, and seven patients (ten hips) used no assistive device. At the time of the most recent follow-up, all twenty-eight patients who had at least one original component in situ were able to walk outside the home: seven patients (ten hips) used two crutches, two patients (four hips) used one cane or crutch, and nineteen patients (thirty-two hips) used no assistive device. Only one patient had a decrease in walking ability, and this was due to an above-the-knee amputation that had been performed secondary to an infection at the site of a total knee arthroplasty.

Twenty of the twenty-eight patients (thirty-five of forty-six hips) who had at least one original component in situ were pain-free at the time of the most recent follow-up examination. The other eight patients (eleven hips) in that group had mild-to-moderate pain during activity. None of the patients in that group had severe pain that restricted activity, and all noted subjective improvement compared with the preoperative status.

Radiographic Results

Follow-up radiographs were available for twenty-six (81 per cent) of the thirty-two hips in which the acetabular component had survived and thirty-five (81 per cent) of the forty-three hips in which the femoral component had survived. Two (8 per cent) of the twenty-six surviving acetabular components were not associated with radiolucency, fifteen (58 per cent) were associated with non-continuous radiolucent lines that were no more than two millimeters wide and that were confined to one or two zones, three (12 per cent) were associated with one radiolucent line that was three to seven millimeters wide and that was confined to one zone, and six (23 per cent) were determined to be loose radiographically on the basis of the presence of a progressive continuous radiolucent line and migration (Figs. 2-A and 2-B). No pelvic osteolysis was noted in the absence of loosening.

Five (14 per cent) of the thirty-five surviving femoral components were associated with radiolucent lines that were no more than two millimeters wide and that were confined to one or two zones, one (3 per cent) was associated with one radiolucent line that was three millimeters wide and that was confined to zone I⁸, and twenty-nine (83 per cent) were not associated with radiolucent lines at either the bone-cement or the cement-prosthesis interface. No femoral components were loose radiographically. Seven femoral components were associated with a region of endosteal erosion that was confined to zone I or VII⁸; this region was approximately five millimeters in diameter in four hips and was ten, twenty, or thirty millimeters in diameter in one hip each. All seven hips were found to have thinning of the cortex compared with that seen on immediate postoperative radiographs, with longitudinal subcortical regions of osteolysis of the sizes noted. Twenty-three (66 per cent) of the thirty-five femoral components were associated with resorption of the medial part of the femoral neck beneath the prosthetic collar, and thirteen (37 per cent) were associated with cortical hypertrophy in zones III, IV, and V⁸. Grade-II heterotopic ossification³ was noted in four hips and grade-III, in two.

With revision or radiographic loosening as the end point, the over-all rate of failure was 44 per cent (twenty-nine) of the sixty-six acetabular components and 18 per cent (twelve) of the sixty-six femoral components.

Revisions for Aseptic Loosening

At the time of follow-up (average duration, 16.9 years; range, twelve to twenty-two years) of the thirty-one femoral components that had been inserted with so-called first-generation cementing techniques, ten (32 per cent) had been revised for aseptic loosening. None of the thirty-five femoral components that had been inserted with a femoral plug and cement pressurization had been revised for that reason at the time of follow-up (average duration, 13.6 years; range, eleven to 17.5 years). None of the seventeen Trapezoidal-28 femoral components were revised for aseptic loosening, compared with seven of the sixteen Aufranc-Turner femoral components and three of the thirty-three custom-made or miniature femoral components.

Eleven of the fifteen acetabular components that had been used in conjunction with a thirty-two-millimeter-diameter femoral head were revised for aseptic loosening, compared with five of the eighteen acetabular components that had been used in conjunction with a twenty-eight or twenty-nine-millimeter-diameter femoral head and seven of the thirty-three acetabular components that had been used in conjunction with a twenty-two-millimeter-diameter femoral head.

Complications

One patient (two hips) died perioperatively secondary to gastrointestinal bleeding and respiratory arrest. Five other patients died before ten years of follow-up. Another patient, who had had a revision total hip arthroplasty at eight years, died eighteen years after the index total hip arthroplasty. Six of the seven deaths were unrelated to the procedure: three patients died because of sepsis related to intestinal causes; one patient, who had hemophilia, died of complications related to acquired immunodeficiency syndrome; and two patients died of unknown causes. The mortality rate in this population of patients who had juvenile rheumatoid arthritis thus was 18 per cent (seven of thirty-nine patients). The average age at the time of death was 27.6 years (range, eighteen to thirty-four years).

A review of the medical records revealed that excessive wound drainage had occurred after three total hip arthroplasties and a superficial infection had developed after one; each of these complications resolved after non-operative treatment. A partial sciatic-nerve palsy was noted after seven procedures; in each instance, the complication resolved in the immediate postoperative period. There were no deep infections.

A repeat operation (other than revision) was necessary for four patients. Two patients had removal of trochanteric hardware because of pain, one had an open reduction of an early dislocation, and one had a trochanteric advancement because of recurrent dislocation. There was a late dislocation of two additional hips, but the dislocation did not recur. The over-all rate of reoperation (including revision) was 45 per cent (thirty of sixty-six hips).

Survival Analysis

The fifteen-year survival rate for the acetabular components was 70 per cent (standard error, 7.3 per cent) with revision as the end point (Table I) and 61 per cent (standard error, 7.1 per cent) with revision or radiographic loosening as the end point (Table II). The fifteen-year survival rate for the femoral components was 85 per cent (standard error, 6.2 per cent) with revision or radiographic loosening as the end point (Table III).

Discussion

Introduction | Materials and Methods | Results | Discussion | References

Total hip arthroplasty with cement provides excellent long-term improvement in function and reduction of pain for most patients^{2,4,15,17,22,24,29}. The increasing rate of aseptic loosening that we noted, especially during the second decade after the procedure, is consistent with the findings described in previous reports of total hip arthroplasties performed with cement in young patients who had juvenile rheumatoid arthritis^{2,4,15-17,22,27,29}. Lachiewicz et al., in a study of the results of sixty-two total hip arthroplasties performed with cement in such patients, reported that sixteen acetabular components (26 per cent) and five femoral components (8 per cent) were associated with a progressive radiolucent line or had migrated after an average of six years¹⁵. Cage et al. evaluated the results of twenty-two total hip arthroplasties that had been performed with cement in adolescents and young adults who had polyarthropathy and noted that six acetabular components (27 per cent) and five femoral components (23 per cent) were loose after an average duration of follow-up of eleven years. Witt et al., in a study of the results of ninety-six total hip arthroplasties that had been performed with cement in patients who had juvenile rheumatoid arthritis, reported that twenty-four hips (25 per cent) had been revised, primarily because of aseptic loosening, after a minimum duration of follow-up of five years (average, 11.5 years).

The rates of revision for aseptic loosening in the present study (15 per cent [ten] of the sixty-six femoral components and 35 per cent [twenty-three] of the sixty-six acetabular components) are comparable with those in the reports just cited. Our finding that durable long-term fixation of the acetabular component was more difficult to obtain than durable long-term fixation of the femoral component also has been reported in long-term studies of total hip arthroplasties performed with cement for other diagnoses in both young and elderly patients^{1,7,19,21,23,25}. As in those studies, we noted that cementing technique is important with regard to the achievement of durable fixation of the femoral component. Although factors related to the design of the implants may have played a role, the finding that seven of the sixteen Aufranc-Turner implants were revised because of aseptic loosening while none of the seventeen Trapezoidal-28 components were revised for that reason probably was related to the fact that the former were used earlier in the study period and therefore were fixed with so-called first-generation cementing techniques. The higher rate of failure (eleven of fifteen) associated with acetabular components that had been used in conjunction with thirty-two-millimeter-diameter femoral heads also was not unexpected given the generally small stature of patients who have juvenile rheumatoid arthritis. The osseous anatomy of such patients often necessitates the use of an acetabular component with a smaller outer diameter, thereby resulting in a thinner polyethylene articular surface for any given size of femoral head compared with that in larger patients. The greater volume of polyethylene debris that is generated when a femoral head with a larger diameter is used may result in bone resorption, and this may have contributed to the higher prevalence of aseptic loosening associated with the acetabular components that had been used in conjunction with thirty-two-millimeter-diameter femoral heads. However, no increase in periprosthetic bone loss was noted in this group of patients in the absence of loosening, and polyethylene wear was not quantified.

We did not find that patients who have juvenile rheumatoid arthritis have an advantage in terms of the durability of total hip prostheses because they make low demands on the implant, as often has been claimed for patients who have adult rheumatoid arthritis^21,25. In fact, our results suggest that the durability of cemented total hip prostheses in patients who have juvenile rheumatoid arthritis may be inferior to that in adults. In several recent studies of adults, the over-all rate of survival of the prostheses was more than 85 per cent as much as fifteen to twenty years postoperatively^1,7,13,19,23. It is likely that a number of other factors affect the durability of total hip prostheses in patients who have juvenile rheumatoid arthritis. First, such patients often have osteopenia of varying severity secondary to a multitude of factors, including the use of medication, disuse, nutritional status, and the disease itself. Second, contractures of the lower extremity and structural osseous deformities often complicate the technical performance of a total hip replacement and may alter the usual magnitude and direction of forces borne by the implant postoperatively. Third, the dynamic state of skeletal remodeling in these often immature patients, reflected in the 37 per cent prevalence of femoral cortical hypertrophy in the present study, also may interfere with the maintenance of fixation. Finally, although adolescents and young adults who have juvenile rheumatoid arthritis generally are considered to be low-demand patients, they still face the rigors of completing an education, beginning a career, and seeking a spouse, which generally are not faced by older patients and which probably increase the demands that are placed on a prosthetic hip.

Previous investigators have evaluated the effectiveness of more conservative alternatives to total hip arthroplasty in patients who have juvenile rheumatoid arthritis and have attempted to improve the durability of fixation in such patients with use of implants that are inserted without cement^14,17. Bipolar hemiarthroplasty is a potential conservative alternative to total hip arthroplasty in such patients, as it may allow for the preservation of often limited acetabular bone stock. However, Wilson and Scott, in a study of twenty-five patients who were managed with bipolar hemiarthroplasty because of juvenile rheumatoid arthritis, reported a 24 per cent prevalence of migration of the socket two to five years postoperatively. Bipolar hemiarthroplasty may have a role in the treatment of juvenile rheumatoid arthritis, but the results of this procedure must be compared with those of total hip arthroplasty in a long-term follow-up study of a large group of patients.

With regard to alternative strategies for fixation, Lachiewicz reported excellent radiographic and clinical results at 4.5 years in a prospective study in which ten total hip arthroplasties had been performed without cement in patients who had juvenile rheumatoid arthritis¹⁴. Longer-term studies of patients with juvenile rheumatoid arthritis who have been managed with hybrid total hip arthroplasty (one component fixed with cement and the other, without cement) or total hip arthroplasty without cement are necessary so that the efficacy of these procedures can be compared with that of total hip arthroplasty with cement. This is especially important given the fact that often there are additional, unique difficulties with regard to the insertion of a femoral component without cement in patients who have juvenile rheumatoid arthritis. Such difficulties include osteopenic bone (as mentioned previously), a mismatch between the sizes of the metaphysis and diaphysis that precludes an adequate fit, and proximal femoral torsional deformities. In such instances, consideration may be given to a custom-made implant or a modular prosthesis that allows for variations in the sizes of the metaphysis and diaphysis and for adjustment of anteversion of the femoral neck.

The mortality rate in the present study was notable; seven (18 per cent) of the thirty-nine patients died, at an average age of 27.6 years. This finding should serve to emphasize the systemic nature of the effects of juvenile rheumatoid arthritis. Operative as well as preoperative and postoperative management must be through a team approach that includes anesthesiologists, rheumatologists, and other specialists to minimize medical complications.

In summary, total hip replacement with cement provides excellent long-term reduction of pain and improvement in function for many patients who have juvenile rheumatoid arthritis. Despite its recognized benefits, however, this procedure must be undertaken with great caution. Because of the young age of these patients and the finite longevity of fixation of the implants, total hip arthroplasty should be reserved for only the most severely affected patients in whom pain and contractures cannot be relieved by other means and who may be unable to walk unless the procedure is done.

References

Introduction | Materials and Methods | Results | Discussion | References

Ballard, W. T.; Callaghan, J. J.; Sullivan, P. M.; and |and |Johnston, R. C.: The results of improved cementing techniques for total hip arthroplasty in patients less than fifty years old. A ten-year follow-up study. J. Bone and Joint Surg.,76-A: 959-964, July 1994.76-A959 1994

Bisla, R. S.; Inglis, A. E.; and |and |Ranawat, C. S.: Joint replacement surgery in patients under thirty. J. Bone and Joint Surg.,58-A: 1098-1104, Dec. 1976.58-A1098 1976

Brooker, A. F.; Bowerman, J. W.; Robinson, R. A.; and |and |Riley, L. H., Jr.: Ectopic ossification following total hip replacement. Incidence and a method of classification. J. Bone and Joint Surg.,55-A: 1629-1632, Dec. 1973.55-A1629 1973

Cage, D. J. N.; Granberry, W. M.; and |and |Tullos, H. S.: Long-term results of total arthroplasty in adolescents with debilitating polyarthropathy. Clin. Orthop.,283: 156-162, 1992.283156 1992 [PubMed]

DeLee, J. G., and |and |Charnley, J.: Radiological demarcation of cemented sockets in total hip replacement. Clin. Orthop.,121: 20-32, 1976.12120 1976 [PubMed]

Dobbs, H. S.: Survivorship of total hip replacements. J. Bone and Joint Surg.,62-B(2): 168-173, 1980.62-B(2)168 1980

Garellick, G.; Herberts, P.; Stromberg, C.; and |and |Malchau, H.: Long-term results of Charnley arthroplasty. A 12-16 year follow-up study. J. Arthroplasty,9: 333-340, 1994.9333 1994 [PubMed]

Gruen, T. A.; McNeice, G. M.; and |and |Amstutz, H. C.: "Modes of failure" of cemented stem-type femoral components. A radiographic analysis of loosening. Clin. Orthop.,141: 17-27, 1979.14117 1979 [PubMed]

Harris, W. H.; McCarthy, J. C., Jr.; and |and |O'Neill, D. A.: Femoral component loosening using contemporary techniques of femoral cement fixation. J. Bone and Joint Surg.,64-A: 1063-1067, Sept. 1982.64-A1063 1982

Isdale, I. C.: Hip disease in juvenile rheumatoid arthritis. Ann. Rheumat. Dis.,29: 603-608, 1970.29603 1970 [PubMed]

Jacqueline, F.; Boujot, A.; and |and |Canet, L.: Involvement of the hips in juvenile rheumatoid arthritis. Arthrit. and Rheumat.,4: 500-513, 1961.4500 1961

Johnston, R. C.; Fitzgerald, R. H., Jr.; Harris, W. H.; Poss, R.; Müller, M. E.; and |and |Sledge, C. B.: Clinical and radiographic evaluation of total hip replacement. A standard system of terminology for reporting results. J. Bone and Joint Surg.,72-A: 161-168, Feb. 1990.72-A161 1990

Kavanagh, B. F.; Wallrichs, S.; Dewitz, M.; Berry, D.; Currier, B.; Ilstrup, D.; and |and |Coventry, M. B.: Charnley low-friction arthroplasty of the hip. Twenty-year results with cement. J. Arthroplasty,9: 229-234, 1994.9229 1994 [PubMed]

Lachiewicz, P. F.: Porous-coated total hip arthroplasty in rheumatoid arthritis. J. Arthroplasty,9, 9-15: 1994.9-159 1994

Lachiewicz, P. F.; McCaskill, B.; Inglis, A.; Ranawat, C. S.; and |and |Rosenstein, B. D.: Total hip arthroplasty in juvenile rheumatoid arthritis. Two to eleven-year results. J. Bone and Joint Surg.,68-A: 502-508, April 1986.68-A502 1986

Learmonth, I. D.; Heywood, A. W. B.; Kaye, J.; and |and |Dall, D.: Radiological loosening after cemented hip replacement for juvenile chronic arthritis. J. Bone and Joint Surg.,71-B(2): 209-212, 1989.71-B(2)209 1989

Maric, Z., and |and |Haynes, R. J.: Total hip arthroplasty in juvenile rheumatoid arthritis. Clin. Orthop.,290: 197-199, 1993.290197 1993 [PubMed]

Murray, D. W.; Carr, A. J.; and |and |Bulstrode, C.: Survival analysis of joint replacements. J. Bone and Joint Surg.,75-B(5): 697-704, 1993.75-B(5)697 1993

Neumann, L.; Freund, K. G.; and |and |Sorenson, K. H.: Long-term results of Charnley total hip replacement. Review of 92 patients at 15 to 20 years. J. Bone and Joint Surg.,76-B(2): 245-251, 1994.76-B(2)245 1994

Peto, R.; Pike, M. C.; Armitage, P.; Breslow, N. E.; Cox, D. R.; Howard, S. V.; Mantel, N.; McPherson, K.; Peto, J.; and |and |Smith, P. G.: Design and analysis of randomized clinical trials requiring prolonged observation of each patient. II. Analysis and examples. British J. Cancer,35: 1-39, 1977.351 1977

Poss, R.; Maloney, J. P.; Ewald, F. C.; Thomas, W. H.; Batte, N. J.; Hartness, C.; and |and |Sledge, C. B.: Six- to 11-year results of total hip arthroplasty in rheumatoid arthritis. Clin. Orthop.,182: 109-116, 1984.182109 1984 [PubMed]

Ruddlesdin, C.; Ansell, B. M.; Arden, G. P.; and |and |Swann, M.: Total hip replacement in children with juvenile chronic arthritis. J. Bone and Joint Surg.,68-B(2): 218-222, 1986.68-B(2)218 1986

Schulte, K. R.; Callaghan, J. J.; Kelley, S. S.; and |and |Johnston, R. C.: The outcome of Charnley total hip arthroplasty with cement after a minimum twenty-year follow-up. The results of one surgeon. J. Bone and Joint Surg.,75-A: 961-975, July 1993.75-A961 1993

Scott, R. D.: Total hip and knee arthroplasty in juvenile rheumatoid arthritis. Clin. Orthop.,259: 83-91, 1990.25983 1990 [PubMed]

Severt, R.; Wood, R.; Cracchiolo, A., III; and |and |Amstutz, H. C.: Long-term follow-up of cemented total hip arthroplasty in rheumatoid arthritis. Clin. Orthop.,265: 137-145, 1991.265137 1991 [PubMed]

Sullivan, D. B.; Cassidy, J. T.; and |and |Petty, R. E.: Pathogenic implications of age of onset in juvenile rheumatoid arthritis. Arthrit. and Rheumat.,18: 251-255, 1975.18251 1975

Williams, W. W., and |and |McCullough, C. J.: Results of cemented total hip replacement in juvenile chronic arthritis. A radiological review. J. Bone and Joint Surg.,75-B(6): 872-874, 1993.75-B(6)872 1993

Wilson, M. G., and |and |Scott, R. D.: The bipolar socket in juvenile rheumatoid arthritis: a two- to five-year follow-up study. J. Orthop. Rheumat.,2: 133-143, 1989.2133 1989

Witt, J. D.; Swann, M.; and |and |Ansell, B. M.: Total hip replacement for juvenile chronic arthritis. J. Bone and Joint Surg.,73-B(5): 770-773, 1991.73-B(5)770 1991

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TABLE I LIFE-TABLE ANALYSIS OF ACETABULAR COMPONENTS, WITH FAILURE DEFINED AS REVISION

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	2	1	0	57.5	3.5	96.5	95	2.8
7 to 8	55	1	0	0	55	1.8	98.2	93	3.2
8 to 9	54	4	0	0	54	7.4	92.6	86	4.3
9 to 10	50	1	1	0	49.5	2	98	84.5	4.7
10 to 11	48	1	1	0	47.5	2.1	97.9	83	5.0
11 to 12	46	1	4	0	44	2.3	97.7	81	5.3
12 to 13	41	1	5	0	38.5	2.6	97.4	79	5.8
13 to 14	35	0	5	0	32.5	0	100	79	6.3
14 to 15	30	3	5	0	27.5	10.9	89.1	70	7.3
15 to 16	22	4	6	0	19	21	79	55	8.5
16 to 17	12	2	0	0	12	16.7	83.3	46	9.8
17 to 18	10	1	4	0	8	12.5	87.5	40	11.0
18 to 19	5	0	1	0	4.5	0	100	40	14.7
19 to 20	4	0	0	0	4	0	100	40	15.6
20 to 21	4	0	2	0	3	0	100	40	18.0
21 to 22	2	1	1	0	2	66.7	33.3	13.5	10.2

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TABLE I LIFE-TABLE ANALYSIS OF ACETABULAR COMPONENTS, WITH FAILURE DEFINED AS REVISION

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	2	1	0	57.5	3.5	96.5	95	2.8
7 to 8	55	1	0	0	55	1.8	98.2	93	3.2
8 to 9	54	4	0	0	54	7.4	92.6	86	4.3
9 to 10	50	1	1	0	49.5	2	98	84.5	4.7
10 to 11	48	1	1	0	47.5	2.1	97.9	83	5.0
11 to 12	46	1	4	0	44	2.3	97.7	81	5.3
12 to 13	41	1	5	0	38.5	2.6	97.4	79	5.8
13 to 14	35	0	5	0	32.5	0	100	79	6.3
14 to 15	30	3	5	0	27.5	10.9	89.1	70	7.3
15 to 16	22	4	6	0	19	21	79	55	8.5
16 to 17	12	2	0	0	12	16.7	83.3	46	9.8
17 to 18	10	1	4	0	8	12.5	87.5	40	11.0
18 to 19	5	0	1	0	4.5	0	100	40	14.7
19 to 20	4	0	0	0	4	0	100	40	15.6
20 to 21	4	0	2	0	3	0	100	40	18.0
21 to 22	2	1	1	0	2	66.7	33.3	13.5	10.2

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TABLE II LIFE-TABLE ANALYSIS OF ACETABULAR COMPONENTS, WITH FAILURE DEFINED AS REVISION OR RADIOGRAPHIC LOOSENING

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98.4	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	2	1	0	57.5	3.5	96.5	95	2.8
8 to 9	54	4	0	0	54	7.4	92.6	86	4.3
9 to 10	50	1	1	0	49.5	2	98	84.5	4.7
10 to l1	48	1	1	0	47.5	2.1	97.9	83	5.0
11 to 12	46	1	4	0	44	2.3	97.7	81	5.3
12 to 13	41	2	4	0	39	5.1	94.9	77	5.9
13 to 14	35	1	4	0	33	3	97	74.5	6.5
14 to 15	30	5	3	0	28.5	17.5	82.5	61	7.1
15 to 16	22	4	6	0	19	21	79	48.5	8.0
16 to 17	12	3	0	0	12	25	75	36	8.4
17 to 18	9	1	3	0	7.5	13.3	86.7	31.5	9.5
18 to 19	5	0	1	0	4.5	0	100	31.5	12.2
19 to 20	4	0	0	0	4	0	100	31.5	13
20 to 21	4	0	2	0	3	0	100	31.5	15.1
21 to 22	2	2	0	0	2	100	0	0	0

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TABLE II LIFE-TABLE ANALYSIS OF ACETABULAR COMPONENTS, WITH FAILURE DEFINED AS REVISION OR RADIOGRAPHIC LOOSENING

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98.4	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	2	1	0	57.5	3.5	96.5	95	2.8
8 to 9	54	4	0	0	54	7.4	92.6	86	4.3
9 to 10	50	1	1	0	49.5	2	98	84.5	4.7
10 to l1	48	1	1	0	47.5	2.1	97.9	83	5.0
11 to 12	46	1	4	0	44	2.3	97.7	81	5.3
12 to 13	41	2	4	0	39	5.1	94.9	77	5.9
13 to 14	35	1	4	0	33	3	97	74.5	6.5
14 to 15	30	5	3	0	28.5	17.5	82.5	61	7.1
15 to 16	22	4	6	0	19	21	79	48.5	8.0
16 to 17	12	3	0	0	12	25	75	36	8.4
17 to 18	9	1	3	0	7.5	13.3	86.7	31.5	9.5
18 to 19	5	0	1	0	4.5	0	100	31.5	12.2
19 to 20	4	0	0	0	4	0	100	31.5	13
20 to 21	4	0	2	0	3	0	100	31.5	15.1
21 to 22	2	2	0	0	2	100	0	0	0

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TABLE III LIFE-TABLE ANALYSIS OF FEMORAL COMPONENTS, WITH FAILURE DEFINED AS REVISION OR RADIOGRAPHIC LOOSENING

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98.4	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	0	2	0	57	0	100	98	1.7
7 to 8	56	0	0	0	56	0	100	98	1.7
8 to 9	56	2	0	0	56	3.6	96.4	95	2.9
9 to 10	54	0	1	0	53.5	0	100	95	2.9
10 to 11	53	1	1	0	52.5	1.9	98.1	93	3.4
11 to 12	51	0	5	0	48.5	0	100	93	3.5
12 to 13	46	1	7	0	42.5	2.4	97.6	91	4.2
13 to 14	38	0	5	0	35.5	0	100	91	4.6
14 to 15	33	2	8	0	29	6.9	93.1	85	6.2
15 to 16	23	3	4	0	21	14.3	85.7	72.5	8.3
16 to 17	16	1	0	0	16	6.25	93.75	68	9.6
17 to 18	15	0	3	0	13.5	0	100	68	10.5
18 to 19	12	0	5	0	9.5	0	100	68	12.5
19 to 20	7	0	1	0	6.5	0	100	68	15.1
20 to 21	6	0	2	0	5	0	100	68	17.2
21 to 22	4	1	1	0	3.5	28.6	71.4	48.5	18.6
22 to 23	2	0	2	0	1	0	100	48.5	34.8

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TABLE III LIFE-TABLE ANALYSIS OF FEMORAL COMPONENTS, WITH FAILURE DEFINED AS REVISION OR RADIOGRAPHIC LOOSENING

No. of Yrs. Since Op.	No. of Hips	No. of Failures	No. Withdrawn	No. Lost to Follow-up	No. At Risk	Annual Failure Rate (Per cent)	Annual Success Rate (Per cent)	Survival Rate (Per cent)	Standard Error
0 to 1	66	0	2	0	65	0	100	100	0
1 to 2	64	0	0	0	64	0	100	100	0
2 to 3	64	0	1	0	63.5	0	100	100	0
3 to 4	63	0	0	0	63	0	100	100	0
4 to 5	63	1	2	0	62	1.6	98.4	98	1.6
5 to 6	60	0	2	0	59	0	100	98	1.6
6 to 7	58	0	2	0	57	0	100	98	1.7
7 to 8	56	0	0	0	56	0	100	98	1.7
8 to 9	56	2	0	0	56	3.6	96.4	95	2.9
9 to 10	54	0	1	0	53.5	0	100	95	2.9
10 to 11	53	1	1	0	52.5	1.9	98.1	93	3.4
11 to 12	51	0	5	0	48.5	0	100	93	3.5
12 to 13	46	1	7	0	42.5	2.4	97.6	91	4.2
13 to 14	38	0	5	0	35.5	0	100	91	4.6
14 to 15	33	2	8	0	29	6.9	93.1	85	6.2
15 to 16	23	3	4	0	21	14.3	85.7	72.5	8.3
16 to 17	16	1	0	0	16	6.25	93.75	68	9.6
17 to 18	15	0	3	0	13.5	0	100	68	10.5
18 to 19	12	0	5	0	9.5	0	100	68	12.5
19 to 20	7	0	1	0	6.5	0	100	68	15.1
20 to 21	6	0	2	0	5	0	100	68	17.2
21 to 22	4	1	1	0	3.5	28.6	71.4	48.5	18.6
22 to 23	2	0	2	0	1	0	100	48.5	34.8