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Clinicalrheumatology, 1993, 12, N ° 1
Protrusio Acetabuli in Juvenile Rheumatoid Arthritis S.E. GUSIS,
J.A. MALDONADO COCCO, E.M. S.A. GAGLIARDI
RIVERO,
J.C. BABINI,
Summary Acetabular protrusion (PA) as measured by a line crossing method was studied in 73 patients with juvenile rheumatoid arthritis (JRA) and its frequency found to be 12% (9/73), presenting bilaterally in 5 cases and unilaterally in 4. All patients had some other forms of radiological damage and the presence of PA was predominantly observed in the JRA group with greater age at onset (8 vs 4.2 years; p<0.001) and lower frequency of extraarticular manifestations (22% vs 72%; p<0.01). There was no correlation with type of JRA onset, course of disease, sex, disease duration, seropositivity for rheumatoid factor, and prior steroid intake. Key words
Protrusio Acetabuli, Juvenile Rheumatoid Arthritis, Hip Arthritis.
INTRODUCTION Protrusio acetabuli (PA) is a well-recognized complication in both adult (1) and juvenile rheumatoid arthritis (2-4). It has also been described in diseases such as ankylosing spondylitis (5), osteoarthritis (6), Paget's disease (7), osteoporosis and osteomalacia (8), sickle cell anaemia (9) and Marfan's syndrome (10), as well as secondary to X-ray irradiation therapy (11) and in the idiopathic form (12), among others. Various radiological methods have been developed to evaluate PA in adult patients, including the projection of a bony mass within the pelvic cavity (13), the presence of a Wiberg Center Edge (CE) angle greater than 45 degrees (14), the presence of crossed and reversed drop (15), medial acetabular crossing of KOhler's line (16) and medial acetabular crossing of the ilioischiatic line (17). In comparison with the others this last method has proven the most reliable for the measurement of acetabular protrusion (18). In children, acetabular protrusion has been defined grossly by the projection of a bony mass within the pelvic cavity (12). Recently, following Armbuster's criterion in adults (18), we have described PA when the acetabular line crosses medially the ilioischiatic line by at least 1 mm in boys and by at least 3 mm in girls (19). It should be pointed out that reports on PA in patients with JRA have disregarded more accurate methods and are mostly limited to a description of isolated
RheumatologyDepartment, Instituto Nacionalde Rehabilitaci6n,Buenos Aires, Axgentina.
cases (3,4). Besides, its frequency and predisposing factors are still poorly known. Thus the aim of this work was to evaluate PA prevalence in JRA patients, as well as to study the relationship with clinical features of the disease. MATERIAL AND METHODS Retrospectively, 73 consecutive patients (146 hips) with JRA diagnosed according to ARA criteria, particularly as defined by Cassidy et al. (20), selected for having an anterioposterior X-ray study of the coxofemoral joint, were studied. The absence of clinical hip involvement (movement limitation and/or pain) was not a reason for exclusion. If several coxofemoral joint X-ray studies were made only the earliest was considered. Data gathered from each patient included sex, age at onset and disease duration based on the time of the first X-ray study, as well as the presence of extraarticular manifestations such as fever, subcutaneous nodules, ocular lesions, serositis, vasculitis, hepatomegalia, splenomegalia and lymphoadenopathies. Prolonged steroid intake (for over 3 months) prior to the study was also evaluated. The presence of the rheumatoid factor was likewise assayed. In each coxofemoral joint X-ray the presence or absence of osteoporosis, joint narrowing erosions, cysts, alignment alterations, subchondral sclerosis, osteophytes, periostitis, subluxation, buttressing, bone ankylosis and PA were determined. Throughout, each X-ray study was read independently by at least two of the authors. PA was considered present when the acetabular line medially overpassed the ilioischiatic line by at least 1 mm in boys and by 3 mm in girls (19) (Fig. 1). Statistical anal-
Protrusio acetabuli in JRA
2
1
Fig. I : Diagrammatic representation of acetabular protrusio. 1- acetabular line ; 2- ilioischiatic line ; shaded zone : protruded area.
Fig. 2: Mild acetabular protrusion : acetabular line medially overpasses the ilioischiatic line by 4 mm.
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S.E. Gusis, J.A. Maldonado Cocco, E.M. Rivero, et al.
Fig. 3: Severe acetabular protrusion. Acetabular line medially overpasses the ilioischiatic line by 9 ram. Table I : Frequency of protrusio acetabuli (PA) in juvenile rheumatoid
arthritis Number
PA
73 146
9(12%)* 14 (10%)
Patients Hips * Bilateral in 5, unilateral in 4.
ysis was performed by means of the chi square test with Yates' correction and the Student t test (21,22).
RESULTS Out of the 73 JRA patients, PA was found in 9 (12%), bilaterally in 5 and unilaterally in 4. Considering the number of hips, 14 (10%) presented PA (Table I). In the seven affected female patients extent ranged from 3 to 11 mm and in the two males patients, PA was 2 mm in both (Figs. 2 and 3). In order to determine whether there were any significant differences between patients with and without PA, clinical and serological features were compared : 64 cases had radiological hip damage without PA and 9 had radiological damage concurrently with PA.
In the group of PA patients, onset of disease was found to occur later, with an average age of 8 years, as compared to the group without PA, whose mean age at onset was 4.2 years. Extraarticular manifestations such as spiking fever, rheumatoid rash and chronic iridocyclitis were less frequent (22%) in the PA group than in the group without PA (72%). These two features, namely greater age at onset and lower frequency of extraarticular manifestations ~proved statistically significant at p<0.002 and p<0.01 level, respectively. On the other hand, there were no significant differences in the remaining parameters evaluated, such as type at onset, mode of evolution, disease course, sex, time of evolution, rheumatoid factor and presence of subcutaneous nodules (Table II). There was a similar number of patients with a sustained or progressive disease course in both groups. Besides, prior steroid intake for over 3 months was studied as regards its correlation with PA: 28 out of 64 patients without PA (43%) had received corticosteroid therapy, whereas in the PA group 4 out of 9 (44%) had had this treatment, so that the difference was not statistically significant. Radiological damage, including joint narrowing, erosions, growth disturbances, subluxation and ankylosis failed to correlate with the presence or absence of PA (Table III).
Protrusio acetabuli in Jl~4
39
Table 1I: Protrusio acembuli tPA) in juvenile rheumatoid arthritis cli;*ical and serological features
Clinical/serological parameter
Radiological damage without PA 64 pts.
Radiological damage with PA 9 pts.
Form at onset
Polyarticular Oligoarticutar Systemic
20 24 20
6 2 1
NS
Form of evolution
Polyarticular Oligoarticular Systemic
57 4 3
8 1 0
NS
Mean age at onset (in years)
4.2
8.0 p<0.001
Extraarticular manifestations :
47/64 (72%) 40/64 (62%) 20/64
2/9 p<0.01 (22%) 2/9 (22%) 1/9
(31%)
(11%)
15/64 (23%)
0
- Spiking fever - Rheumatoid rash
- Chronic Iridocyctitis
Sex (females/total)
43/64 (67%)
7/9 (78%) NS
Mean disease duration (in years} Rheumatoid factor (positive)
6.0 6/56 (11%) 8/64
5.7 NS 1/8 (13%) NS (1/9
(13%)
(0%) NS
Subcutaneous nodules
NS: not significant
Table III: Hip radiological damage in 73 juvenile rheumatoid arthriris patients with or without ptvtrusio acetabuli (PA)
Radiological damage Narrowing Erosions Growth disturbances Subluxalion Ankylosis
Patients s~ithout PA n°=64
Patients with PA n°=9
49(76%) 4l(649~) 36(56%) 52(55%) 17(27%) 4 (6%)
9(100%) 7 (77%) 5 (55%) 5 (55%) 4 (44%) 0
DISCUSSION So far, reports on acetabular protrusion in juvenile patients have been scanty in number and apparently have failed to address the severe functional damage it represents in cases of JRA.
Thus, Friedenberg (4), Shore et al. (12), Ansell and Unlu (2) and Jacqueline et al. (3) have only described individual PA cases in juveniles or mainly considered hip damage in JRA. To the best of our knowlege, there has been no thorough study on searching for PA in JRA. On the basis of the reliable measurement method we have recently developed (19), we were able to find in our series that the frequency of PA in JRA was 12% (9/73), or 10% (14/146) if the number of hips was considered. Besides, it was observed that the mean age at onset of disease was greater in the PA group of patients, who also showed a lower frequency of systemic extraarticular manifestations. Though lacking statistical significance, the polyarticular form at onset was more common in the PA group (6/9 cases or 66%) than in the group without acetabular protrusion (20/64 cases or 31%). Such a trend suggests that patients with concurrent JRA and PA are those who more closely resemble adult rheumatoid at-
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S.E. Gusis, J.A. M a l d o n a d o Cocco, E.M. Rivero, et al.
thritis. The absence of any other kind of association, even as regards steroid intake, may be explained by the fact that our service is mainly for referrals and that follow-up is as a rule lengthy. Furthermore, the retrospective availability of hip X-rays presupposes that the patient should have some clinical symptom or sign of coxofemoral involvement.
In summary, P A was present in 12% of our group of J R A patients, associated with a greater age of disease onset and lower freciuency of extraarticular manifestations, thus resembling hip involvement in adult rheumatoid arthritis.
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Hastings, D.E., Parker, S.M. Protrusio acetabuli in rheumatoid arthritis. Clin Orthop 1975, 143, 62-74. Ansell, B.M., Unlu, M. Hip involvement in juvenile chronic polyarthritis. Ann Rheum Dis 1970, 29, 687-688. Jacqueline, F., Bonjout, A., Canet, L. Involvement of the hips in juvenile rheumatoid arthritis. Arthritis Rheum 1961, 4, 500-513. Friedenberg, Z.B. Protrusio acetabuli in childhood. J Bone Joint Surg 1963, 45-A, 373-378. Dwosh, I.L., Resnick, D., Becker, M.A. Hip involvement in ankylosing spondylitis. Arthritis Rheum 1976, 19, 683-692. Resnick, D. Patterns of migration of the femoral head in osteoarthritis of the hip. AJR 1975, 124, 62-74. Guyer, P.B., Dewbury, K.C. The hip joint in Paget's disease (Paget's "Coxopathy"). Br J Radiol 1978, 51, 574-578. Bible, M.W., Pinals, R.S., Palmieri, G.M., Pitcock, J.A. Protrusio acetabuli in osteoporosis and osteomalacia. Clin Exp Rheumatol 1983, 1, 323-326. Martinez, S., Apple, J.S., Barber, C., Putman, C.A., Rosse W.F. Protrusio acetabuli in sickle cell anemia. Radiology 1984, 151, 43 -44. Fast, A., Otremsky, Y., Pollack, D., Floman, Y. Protrusio acetabuli in Marian's syndrome: Report of two patients. J Rheumatol 1984, 11, 549-551. Csuka, M., Brewer, B.J., Lynch, K.L., Mc Carty, D.J. Osteonecrosis, fractures and protrusio acetabuli secondary to X-irradiation therapy for prostatic carcinoma. J Rheumatol 1987, 14, 165170. Shore, A., Macauley, D., Ansell, B.M. Idiopathic protrusio acetabuli in juveniles. Rheumatol Rehabil 1981, 20, 1-10. Pomeranz, M.M. Intrapelvic protrusion of the acetabulum (Otto Pelvis). J Bone Joint Surg 1932, 14-A, 663-686.
14. Wiberg, G. Studies on dysplastic acetabulum and congenital subluxation of the hip joint with special reference to the complication of osteoarthritis. Acta Chir Scand 1939, 83 (Suppl 58), 1-35. 15. Alexander, C. The aetiology of primary protrusio acetabuli. Br J Radiol 1965, 38, 567-580. 16. Hubbard, M.J. The measurement of progression in protrusio acetabuli. AJR 1969, 106, 506-508. 17. Edelstein, G., Murphy, W. Pr0trusio acetabuli : radiographic appearance in arthritis and other conditions. Arthritis Rheum 1983, 26, 1511-1516. 18. Armbuster, Th.G., Guerra, J., Resnick, D., et al. The adult hip : an anatomic study. Part I : The bony landmarks. Radiology 1978, 128, 1-10. 19. Gusis, S.E., Babini, J.C., Garay, S.M., et al. Evaluation of the measurement methods for protrusio acetabuli in normal children. Skeletal Radiol 1990, 19, 279-382. 20. Cassidy, J.T., Levinson, J.E., Bass, J.C., et al. A study of classification criteria for a diagnosis of juvenile rheumatoid arthritis. Arthritis Rheum 1986, 29, 374-281. 21. Swinscow, T.D. The X 2 Tests in Statistics at Square One, 8th. Ed. Ed: Swinscow T.D. London British Medical Journal, 1983, 43-53. 22. Swinscow, T.D. The T Tests in Statistics at Square One, 8th. ed. Ed: Swinscow T.D. London, British Medical Journal, 1983, 3342.
Received : 26 November 1991 ; Revision-accepted : 4 June 1992 Correspondence to: Dr. Jos6 A. MALDONADO COCCO, Seccidn Reumatologia, Instituto Nacional de Rehabilitaci6n, Echeverria 955, 1428-Buenos Aires, Argentina.
