Introduction                       

Juvenile chronic arthritis was first described by George Still in 1897 to be separate from adult rheumatoid arthritis.1 The International League of Associations for Rheumatology (ILAR) has introduced the term juvenile idiopathic arthritis (JIA) to cover this heterogeneous group of conditions.2,3 JIA is defined as arthritis in one or more joints persisting for 6 weeks or more, which begins before the age of 16 and has no other known cause.2,3 The term JIA has now replaced the European term, juvenile chronic arthritis, and the American term, juvenile rheumatoid arthritis4 ILAR has classified JIA into seven subtypes. These include:

1. Systemic onset JIA

2. Oligoarticular JIA

3. Polyarthritis with negative rheumatoid factor

4. Polyarthritis with positive rheumatoid factor

5. Psoriatic arthritis

6. Enthesitis related arthritis

7. Undifferentiated arthritis

Young children 1 to 3 years old are most commonly affected, with male to female ratio of 1:2. Systemic-onset JIA is an exception with a 1:1 male to female ratio.5 Studies of the incidence of childhood arthritis using either juvenile rheumatoid arthritis or juvenile chronic arthritis classifications have documented rates of 3.5 to 13.9 per 100,000 children/yr in population-based cohorts,6-9 and a population-based study using ILAR JIA criteria suggested a rate of 15/100,000 children/yr10 (North America).

Nearly 25% of patients particularly those with early age at onset, systemic and RA positive polyarticular arthritis go on to have long-term sequelae with chronic disabling arthritis. In general, female gender, polyarticular and symmetrical joint involvement, elevated inflammatory markers and a positive rheumatoid factor are the most consistent predictors of a poor outcome. JIA demonstrates histopathological changes similar to adult onset rheumatoid arthritis with loss of articular cartilage contributing to pain and loss of movement in the joints. Hip involvement is common in systemic JIA and polyarticular JIA.

In early stages of hip disease a multi-disciplinary approach is needed which, includes an Orthopaedic surgeon, rheumatologist, physiotherapist, occupational therapist as well as a psychiatrist. Disease modifying drugs and NSAIDs are the cornerstones of therapy. Methotrexate is first choice among the disease modifying drugs. Long-term glucocorticoids must be used with caution due to risk of growth retardation and Cushing’s syndrome and its adverse effects on the hip prosthesis. The role of various immunological agents including TNF alpha antagonists is being investigated for treatment of this disease.

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The prognosis depends on the subtype of JIA. Those with disease onset under 5 years tend to have a more severe course and especially if the disease persists beyond the first five years of age. Fifteen year follow up of the Oligoarticular JIA has shown that 15% of them go on to develop polyarticular Arthritis and severe joint involvement. It is important to recognize the pauciarticular form of JIA as it is associated with a very high incidence of ocular problems.11 In the enthesitis related arthritis group up to 10% have severe limitation of mobility by the age of fifteen years and up to 33% have hip involvement. Patient’s with polyarticular group with a negative rheumatoid factor often go into remission with little erosive disease. However, the polyarticular group with a rheumatoid factor positive have a more severe course with 20% requiring total hip replacement and approximately 10% require total knee replacements. Of the children with Systemic onset JIA half of them remit without recurrence, but the remainder have severe polyarticular arthritis.

Three distinct patterns of hip involvement have been observed in patients with JIA. Patients with early involvement before the age of 11 years have dysplastic hips with large anteverted femoral heads and dysplastic acetabulum. Late onset patients usually present with severe protrusio acetabuli, while those with enthesitis related arthritis present with bony ankylosis of the hip joint. However total hip replacement remains the gold standard for treating the hip problems in JIA.

 

Total Hip Arthroplasty

 

Indications                        

Total hip arthroplasty is indicated in patients with end stage arthritis with severe pain and functional disability. It appears that patients with JIA may have relatively improved outcomes, as they may have more limited demands owing to polyarticular involvement.12 The problems of THA in patients with JIA are unique and specific to the condition. Short stature, young age, osteoporosis, polyarticular involvement, advanced contractures and abnormal bony anatomy like excessive femoral/acetabular anteversion, metaphyseal diaphyseal mismatch, narrow canals, dysplastic, fused or protrusio acetabulae make this surgery a technically demanding procedure.

 

Contraindications                     

Contraindications to THA include active ongoing local or systemic sepsis and general medical condition which makes patient high-risk for surgery. Relative contraindications include skeletally immature patients and those with low motivation levels.

 

Preoperative                   Planning                   

Preoperative planning includes thorough clinical and radiologic examination of the patient. Managing these difficult patients needs multidisciplinary approach with close coordination between the orthopedic surgeon, anesthetist, rheumatologist and physiotherapist.

Clinical evaluation must include examination of the cervical spine and temporomandibular joint. Thorough assessment to document the extent and severity of other joint involvement is mandatory. Upper extremity involvement with arthritic shoulders, elbow and wrists present a problem with postoperative rehabilitation. Presence of a plantigrade foot is a must for successful hip and knee arthroplasty and ankle and foot problems may need to be addressed prior to hip surgery. Hip examination includes assessment of fixed deformities, limb length discrepancy and range of motion. Several of these patients have fixed deformities especially fixed flexion deformity, others may have windswept hips with one hip in abduction while the other hip in adduction. Patients may sometimes have bilateral hip and knee arthritis and in these patients addressing multiple joints may be necessary. It

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Total Hip Arthroplasty in Juvenile Idiopathic Arthritis

 

is normally the norm in the presence of ipsilateral hip and knee arthritis to address the hip first for several reasons.

1. Active knee flexion and extension depends largely on free hip function.

2. Accurate knee alignment is difficult to achieve in presence of hip deformity.

3. Arthritic hips present with pain referred to knees and knee symptoms invariably improve following hip arthroplasty.

4. Severe affection and shortening in one hip may cause the opposite knee to assume flexed position; this flexion deformity of knee may improve after replacement and realignment of opposite hip.

5. Flexion deformity of the knee can be secondary to ipsilateral hip flexion deformity which will improve after hip arthroplasty.

6. It has been observed that rehabilitation of a total hip with a stiff knee proceeds more easily than rehabilitation of a total knee with a stiff hip.

7. Finally, hip rehabilitation is less painful than knee rehabilitation making it more likely that the patient will comply with next stages of the operation.

The use of disease modifying drugs and steroids at the time of surgery is still being debated. Loza et al in a systemic review of the literature have concluded that continuing low dose methotrexate during perioperative period was safe.13 Perhala et al and Murata et al have also demonstrated that it is safe to administer perioperative methotrexate and it actually reduces the incidence of perioperative flare-ups that could hamper the postoperative rehabilitation program.14,15 However, it is important to coordinate with the rheumatologist regarding disease modifying agents.

Radiologic evaluation of the patient includes imaging of the cervical spine, anteroposterior radiograph of the pelvis with both hip joints and lateral view of the involved hip joint, AP and lateral radiograph of the femur is also essential.

Preoperative templating helps in selecting the correct prosthesis. Patients with JIA tend to have very narrow femoral medullary canal with a mismatch between the proximal and distal canal diameter. The acetabulum could vary from the dysplastic type (Fig. 29.1) to the protrusio type (Fig. 29.2) or it could be a fused hip joint (Fig. 29.3).

Figure 29.1: Dysplastic hip pattern, note superolateral hip subluxation and metaphyseodiaphyseal mismatch

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Total Hip Arthroplasty

 

Figure 29.2: Pattern of hip-protrusio, note medialization of hip center of rotation

 

 

 

Figure 29.3: Isolated bilateral hip fusion due to JIA in 20-year-old female patient, note normal SI joints

 

Implant                     Selection                     

CHOICE OF FIXATION

Bone growth and remodeling can lead to loosening of the prosthesis when arthroplasty is performed in skeletally immature patients. The results of long-term survivorship of the cemented THA in JIA have been variable. Chmell et al followed up sixty six hips for fifteen years and reported a survival of 85% for the femoral component and 61% for the acetabular component with revision or radiographic loosening as the end point.16 Sochart and Porter reported survival of a hundred hip arthroplasties for 30 year old patients with JIA and rheumatoid arthritis; in their study probability of survival of both of the original components at ten and twenty-five years was 96% and 77% respectively.17 The ten and twenty-five-year survival rates for the acetabular component were 98% and 79%; the corresponding rates for the femoral component were 97% and 85%. Lehtimaki et al reported an overall survival of cemented hips in JIA 91.9% at ten years and 83.0% at 15 years; the femoral component

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Total Hip Arthroplasty in Juvenile Idiopathic Arthritis

 

survival was 95.6% at ten years and 91.9% at 15 years and the survival of acetabulum was 95.0% and 87.8%, respectively.12 Williams and McCullough in a prospective follow up of 57 cemented hips in patients with JIA have reported the radiologic evidence of loosening was far more common than symptomatic failure; they have reported in hips with a follow-up of more than five years the loosening rate was 43.5%.18 Witt et al reported a revision rate of 25% in 96 cemented hips (McKee-Arden prosthesis in majority).19 Learmonth et al in study of sixteen cemented hips have observed radiographic loosening in 57% of their hips.20 Wroblewski et al in a follow up of 292 cemented Charnley hips for an average of fifteen years in patients with JIA or rheumatoid arthritis and younger than 50 years of age reported a survivorship of 93% (96–90) at 10 years, 87% (92–82) at 15 years, 81% (88–73) at 20 years and 74% (87–61) at 25 years.21 It has been proposed that poor quality bone and increased vascularity make it difficult to achieve the optimum conditions needed for cemented THA (Witt et al).19 Hence biologic fixation with uncemented THA is an attractive proposition in JIA although few studies are available regarding the use of cementless THA in JIA. Kumar and Swan in a mean 4.5 years follow up of 25 uncemented hip arthroplasties reported a 12% loosening of the acetabulum.22 Odent et al reported a 100% survival of the femoral component and 90.1% for the acetabular component at 13 years in 62 uncemented hips followed up for an average of six years in JIA.23

 

MODULAR IMPLANTS

Narrow medullary canals, excessive femoral anteversion and metaphyseal-diaphyseal mismatch warrant the use of modular or custom made femoral implants in these patients. Small acetabular reamers and smaller components should be available during surgery. Implants of smaller sizes similar to the ones used for the dysplastic hips are useful. Hence preoperative templating helps in organizing the appropriate implants for the surgery.

 

BEARING SURFACE

Polyethylene wear and aseptic loosening are emerging as the major causes of long-term failure following THA. As the acetabular size in these patients is very small it might be necessary to use smaller diameter heads while using metal on the conventional polyethylene articulation in order to optimize the thickness of polyethylene. This would mean that 22 mm heads may have to be used often when the cup size is 44 mm or below. When using 22 mm heads the femoral neck geometry must allow at least 2:1 head neck ratio to minimize the chances of dislocation. The use of alternate bearings which allow for larger femoral heads to be used with smaller acetabular shells like metal on metal, ceramic on ceramic and highly crosslinked polyethylene need to be investigated in these patients.

Our choice is to use cementless THA with ceramic on crosslinked polyethylene or ceramic on ceramic articulation.

 

Surgical                    Technique                    

ANESTHESIA AND ANTIBIOTIC PROPHYLAXIS

We perform the surgery usually under combined spinal and epidural anesthesia with epidural catheter for postoperative pain relief. Occasionally general anesthesia may be needed and in these patients difficult airway due to cervical spine or temporomandibular joint involvement may need to be managed using fiberoptic nasotracheal intubation. First generation cephalosporin is administered at least 30 minutes prior to the skin incision.

APPROACH

Wide surgical exposure is critical in achieving good surgical outcome and correction of deformities. Minimally invasive surgery should not be attempted. We prefer to expose the hip through standard posterior approach.

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Figure 29.4: Patient positioning can be difficult due to fixed flexion, abduction deformity or due to fused hips

 

Figure 29.5: Sciatic nerve may be closer than expected in patients with fusion, and in protrusio with external rotation deformity

 

 

PATIENT POSITIONING

The patient is positioned in the lateral position with anterior and posterior supports to maintain neutral pelvic position. Care taken to prevent the tendency for the body to tilt anteriorly as this may lead to malalignment during implant positioning. Stiff hips and knees make patient positioning in lateral position challenging (Fig. 29.4). Extreme care must be taken to prevent fractures while patient positioning. The pressure points need adequate padding to prevent nerve palsy and pressure sores.

Standard posterolateral skin incision is used. Gluteus maximus is split in the line of its fibers, usually it is necessary to release its insertion from the femur to facilitate anterior translation and also prevent excessive stretch on the sciatic nerve. Trochanteric bursa is incised and the short external rotators are identified. In patients with protrusio and hip ankylosis in external rotation the sciatic nerve is closer than anticipated, it is safer to identify and protect the nerve in these cases (Fig. 29.5). The plane between the piriformis and gluteus minimus is developed, adhesions between gluteus minimus and the hip capsule released and an anterosuperior pin is placed to retract the abductors. Short external rotators and hip capsule are released in a single flap close to the insertion on the femur. Radial cuts are made long the line of the piriformis and posterioinferiorly to retract the flap posteriorly to expose the posterior half of the acetabulum. Superior and anterior capsule are divided under vision. It is important to do circumferential capsulotomy in these patients to correct severe deformities. No attempt must be made to dislocate the hip in hips with ankylosis and severe protrusio as this may lead to inadvertent fracture of the femur or acetabular wall. It has been observed that the highest risk of complications is intraoperative. After the acetabulum and femoral head and neck have been exposed retractors are placed along the superior and

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inferior margins of the femoral neck and the pubofemoral arch is exposed. An in situ osteotomy is made along the femoral neck taking care not to damage the acetabular walls. The osteotomy is completed and carefully separated. The femoral neck is recut as per standard templates. The acetabulum is exposed by anteriorly retracting the femur using anterior retractor. The remainder of the femoral head is removed piecemeal and retained as autograft.

 

Total Hip Arthroplasty in Juvenile Idiopathic Arthritis

 

ACETABULUM

Acetabular anatomy is abnormal in many of these owing to a combination of developmental and disease related destruction. Preoperative Judet views and CT scans may be of use in documenting the location and extent of acetabular bone defects. Three types are characteristically found depending on the disease subtype and age of onset. These include dysplastic acetabulum (Fig. 29.1), protrusio acetabuli (Fig. 29.2) and fused hip (Fig. 29.3).

 

DYSPLASTIC ACETABULUM

JIA patients with onset of disease before the age of eleven develop dysplastic changes with large femoral heads, anteverted femur and shallow acetabulum. These patients often have fixed flexion, adduction and internal rotation at the hip. It is important to excise the floor osteophyte and identify the true floor (transverse acetabular ligament) in these hips. Medial wall of the acetabulum is usually thick. The reaming is done to medialize the hip center and the acetabular size is governed by the anteroposterior diameter. Often the acetabulum is shallow (Fig. 29.6) there is a superior and posterior defect which needs either structural (Fig. 29.7) or morselized bone grafting (Figs 29.8A to C). Cementless cups often need supplemental screw fixation for initial stability. A common error is to aim for complete coverage in these cases which leads to vertical cup placement. Superior placement of the cup is not an option in these patients because of poor bone quality of the ilium and osteopenia. The aim in these cases is to position the cup within 5 mm of the true hip center.

 

PROTRUSIO ACETABULI

 

 

These cases are difficult to expose and often the hip is fixed in external rotation making the visualization of femoral neck difficult through posterior approach. There is osteophyte formation at the periphery of acetabulum with narrowing of the rim (Fig. 29.9A). Removal of the osteophytes especially posteriosuperiorly help to visualize the femoral neck. In situ

 

Figure 29.6: Dysplastic acetabulum plate like shallow

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Total Hip Arthroplasty

 

Figure 29.7: Steps of structural autograft, fixation with screws, reaming and cementless cup fixation

 

 

 

Figures 29.8A to C: Impaction grafting of the defect followed by cemented cup fixation in dysplastic hips

 

osteotomy is performed and the head removed piecemeal (Figs 29.9B and C). Medial wall grafting and cementless cup fixation is the method of choice for these cases (Figs 29.9D to F). These cases have contained defect of the medial acetabular wall with medialized center of rotation. It is necessary to lateralize the hip center in these cases. We use autograft from the femoral head when sufficient and fresh frozen allograft in case of inadequate host bone. The bone graft is placed into the defect and impacted with acetabular impactors. Rim fitting cementless cup is impacted into place after trial and fixed with 2 cancellous screws. Cemented acetabular reconstruction can also be done using mesh, impaction grafting the floor and cemented cup insertion in the true hip center.

 

FUSED HIPS

The first step is to identify the pubofemoral arch and acetabular rim (Fig. 29.10A). This may be difficult in patients with fixed external rotation deformity in which cases it may be necessary to dissect anterior to the abductors, identify the neck and perform in situ osteotomy (Fig. 29.10B). Acetabular preparation in fused hips is similar to the preparation in ankylosing

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Total Hip Arthroplasty in Juvenile Idiopathic Arthritis

 

Figures 29.9A to F: Steps in acetabular reconstruction in protrusio, narrowing of acetabular rim, in situ neck osteotomy, removal of osteophytes, grafting the floor, rim fitting cementless cup fixed with screws

 

 

 

 

spondylitis. Acetabulum appears as a sheet of bone and it is often difficult to identify the accurate version and inclination (Fig. 29.10C). The posterior superior part of the femoral head is retained while reaming as this prevents vertical cup placement. The first step is to ream inferiorly, it has been our experience that the transverse acetabular ligament is usually present and helps to set the depth of reaming (Fig. 29.10D). Rest of the reaming is done to enlarge the acetabulum followed by cementless/cemented cup fixation (Fig. 29.10E).

Figures 29.10A and B: Identification of pubofemoral arch and in situ neck osteotomy for enthesitis related JIA with hip fusion

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Total Hip Arthroplasty

 

Figures 29.10C and D: Acetabular exposure after in situ osteotomy showing sheet of bone, appearance after acetabular reaming, note intact transverse acetabular ligament (arrow)

 

Figure 29.10E: After cementless cup fixation and ceramic insert insertion

 

 

FEMORAL PREPARATION

The issues on femoral side include narrow medullary canals, metaphyseal diaphyseal mismatch and excessive femoral anteversion. The medullary canal appears wide in saggital projections but is narrow on coronal views. Options for reconstruction include use of modular stems, dysplasia cementless or cemented stems and sometimes pediatric hip implants.

Positioning of the limb for reaming can be very difficult in the presence of ipsilateral stiff knee. In these situations forcible attempts to flex can lead to iatrogenic fractures. One should just internally rotate the limb very gently to expose the femoral canal and anteversion must be crosschecked by palpating the medial and lateral epicondyles. Care should be taken while reaming the canal to avoid accidental perforation. We use flexible reamers over a guide wire in patients with very narrow canals. Modular cementless stems are useful in patients with metaphyseal diaphyseal mismatch. Excessive femoral anteversion of 60-80 degree has been reported in patients with JRA.24 One should aim to achieve a combined anteversion not exceeding 45 degree at the end of operation. This can be achieved using modular stems or cemented narrow stems; rarely subtrochanteric derotation osteotomy may be needed to correct the excessive anteversion.

 

TRIAL REDUCTION

Trial reduction must be done and the extremes of hip stability must be documented. Stability testing must be done in flexion adduction and internal rotation of the hip and also in extension

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and external rotation to check posterior and anterior stability. Shuck test to assess soft tissue tension and coplanar test to document the combined anteversion is done.

Complications                      

Total Hip Arthroplasty in Juvenile Idiopathic Arthritis

 

The surgical complications inherent to any hip arthroplasty like infection, periprosthetic fracture, deep venous thrombosis, pulmonary embolism, dislocation and loosening may occur in patients with JRA.

The incidence of infection has been reported to be higher in patients with JIA ranging from 2-5% deep infection and 20% superficial wound healing problems in some series.25-27 Disease, disuse and drug induced osteopenia combined with high incidence of stiffness leads to higher incidence of intraoperative fractures in these patients. Cage et al have reported a 10% incidence of intraoperative fractures in patients with JIA.28 The use of press fit stems

and increased level of activity postoperatively may contribute to higher fracture risk.

Aseptic loosening remains the most common cause of failure in the long-term. These patients show loosening rates similar to other patient population despite having low activity levels and low body mass inde.29,30

Conclusion                        

Total hip arthroplasty provides reliable pain relief and improved function in JIA patients with end stage hip arthritis. However, THA in this patient population is extremely complex and technically challenging. Challenges not only relate to the hip itself but also to periopertive medical management and anesthesia issues. Polyarticular involvement, joint stiffness, muscle contractures, osteopenia and abnormal bony architecture increase the complexity of the surgery. Concerns regarding longevity of implants exist in this young patient population. The choice of fixation and bearing remains unclear. There is need to evaluate the results of cementless fixation and alternate bearings in the long-term.

Illustrative                      Case                     

CASE PRESENTATION 1 (FIGS 29.11A AND B)

• A 36-year-lady presented to us with severe pain in both hips and both knees and inability to walk for the past 2 years

• The patient had been suffering from polyarthritis from the age of 10. shoulder, elbow and wrist joints were also involved.

   

   

   

  Figure 29.11A: Radiographs of the pelvis with both hips showing dysplastic hip morphology with metaphyseodiaphyseal mismatch, note left fused knee in flexion and valgus

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  Total Hip Arthroplasty

   

  Figure 29.11B: Postoperative radiograph after left THR and left TKR in one sitting, the femoral canal had to be reamed to accommodate the smallest available stem

   

  • Clinical examination revealed short stature, frail built and stiff hips and knees on both sides with fixed flexion deformity of 35 degree of both hips and fixed flexion deformity of 40 degree at both knees. No further movements were possible at any of these joints

  • She was planned for staged surgery of all four joints. In the first stage simultaneous left hip and knee arthroplasty was done. She is presently awaiting the second side surgery

  • The patient had dysplastic hip morphology with fixed adduction and flexion deformity of the left hip and fixed flexion at the knee with bony ankylosis

  • She was managed with reverse hybrid THA (cemented acetabulum, cementless femur) followed by left total knee arthroplasty using posterior stabilized prosthesis.

     

    CASE PRESENTATION 2 (FIGS 29.12A TO D)

     

     

  • A 23-year-old lady presented with history of both hip pain for the past 10 years and progressive loss of movement for the past 4 years. Since 2 years she has no movement at both hips and cannot walk.

     

    Figure 29.12A: Radiograph of pelvis with both hips showing bony ankylosis both hips with normal SI joints

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    Total Hip Arthroplasty in Juvenile Idiopathic Arthritis

     

    Figure 29.12B: Intraoperative photographs showing identification of the pubofemoral arch, in situ osteotomy, separation of the osteotomy with osteotome, acetabular preparation and identification of TAL and cementless ceramic on ceramic THA

     

     

     

    Figures 29.12C and D: (C) Postoperative radiograph after cementless right THA (D) Postoperative radiograph after the left THA

     

• She was diagnosed as having enthesitis related JIA and was offered bilateral THR

• Staged bilateral cementless THR was done using plasma cup, bicontact stem and 32 mm delta ceramic on ceramic articulation.

 

References

 

1. Still GF. On a form of arthritis in children. Med Chir Trans 1897; 80:47. Reprinted in Arch Dis Child 1941;16:156-65.

2. Petty RE, Southwood TR, Baum J, et al. Revision of the proposed classification criteria for juvenile idiopathic arthritis: Durban, 1997. J Rheumatol 1998;25:1991-4.

3. Petty RE, Southwood TR, Manners P, et al. International League of Associations for Rheumatology classification of juvenile idiopathic arthritis: Second revision, Edmonton, 2001. J Rheumatol 2004;31:390-2.

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4. Southwood TR. Classification of childhood arthritis. In: Szer IS, Kimura Y, Malleson PN, Southwood TR (Eds). Arthritis in Children and Adolescents 2006.pp.205-9.

5. Woo P. Systemic juvenile idiopathic arthritis: Diagnosis, management, and outcome. Nat Clin Pract Rheumatol 2006;2:28-34.

6. Towner SR, Michet Jr CJ, O’Fallon WM, et al. The epidemiology of juvenile arthritis in Rochester, Minnesota 1960-1979. Arthritis Rheum 1983;26:1208-13.

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7. Denardo BA, Tucker LB, Miller LC, et al. Demography of a regional pediatric rheumatology patient population. Affiliated Children’s Arthritis Centers of New England. J Rheumatol 1994;21:1553-61.

8. Malleson PN, Fung MY, Rosenberg AM. The incidence of pediatric rheumatic diseases: results from the Canadian Pediatric Rheumatology Association Disease Registry. J Rheumatol 1996; 23:1981-7.

9. Symmons DP, Jones M, Osborne J, et al. Pediatric rheumatology in the United Kingdom: Data from the British Paediatric Rheumatology Group National Diagnostic Register. J Rheumatol 1996; 23:1975-80.

10. Berntson L, Andersson Gare B, Fasth A. Incidence of juvenile idiopathic arthritis in the Nordic countries: A population based study with special reference to the validity of the ILAR and EULAR criteria. J Rheumatol 2003;30:2275-82.

11. Petty RE, Smith JR, Rosenbaum JT. Arthritis and uveitis in children: A pediatric rheumatology perspective. Am J Ophthalmol 2003;135:879-84.

12. Lehtimäki MY, Lehto MU, Kautiainen H, Savolainen HA, Hämäläinen MM. Survivorship of the Charnley total hip arthroplasty in juvenile chronic arthritis. A follow-up of 186 cases for 22 years. J Bone Joint Surg Br 1997;79(5):792-5.

13. Loza E, Martinez-Lopez JA, Carmona L. A systematic review on the optimum management of the use of methotrexate in rheumatoid arthritis patients in the perioperative period to minimize perioperative morbidity and maintain disease control. Clin Exp Rheumatol 2009;27(5):856-62.

14. Perhala RS, Wilke WS, Clough JD, Segal AM. Local infectious complications following large joint replacement in rheumatoid arthritis patients treated with methotrexate versus those not treated with methotrexate. Arthritis Rheum 1991;34(2):146-52.

15. Murata K, Yasuda T, Ito H, Yoshida M, Shimizu M, Nakamura T. Lack of increase in postoperative complications with low-dose methotrexate therapy in patients with rheumatoid arthritis undergoing elective orthopedic surgery. Mod Rheumatol 2006;16(1):14-9.

16. Chmell MJ, Scott RD, Thomas WH, Sledge CB. Total hip arthroplasty with cement for juvenile rheumatoid arthritis. Results at a minimum of ten years in patients less than thirty years old. J Bone Joint Surg Am 1997;79(1):44-52.

17. Sochart DH, Porter ML. The long-term results of Charnley low-friction arthroplasty in young patients who have congenital dislocation, degenerative osteoarthrosis, or rheumatoid arthritis. J Bone Joint Surg Am 1997;79(11):1599-1617.

18. Williams WW, McCullough CJ. Results of cemented total hip replacement in juvenile chronic arthritis. A radiological review. J Bone Joint Surg Br 1993;75(6):872-4.

19. Witt JD, Swann M, Ansell BM. Total hip replacement for juvenile chronic arthritis. J Bone joint Surg Br 1991;73B:770-3.

20. Learmonth ID, Heywood AW, Kaye J, Dall D. Radiological loosening after cemented hip replacement for juvenile chronic arthritis. J Bone Joint Surg Br 1989;71(2):209-12.

21. Wroblewski BM, Siney PD, Fleming PA. Low-friction arthroplasty of the hip using alumina ceramic and cross-linked polyethylene. A 17-year follow-up report. J Bone Joint Surg Br 2005;87(9):1220-1.

22. Kumar MN, Swann M. Uncemented total hip arthroplasty in young patients with juvenile chronic arthritis. Ann R Coll Surg Engl 1998;80(3):203-9.

23. Odent T, Journeau P, Prieur AM, Touzet P, Pouliquen JC, Glorion C. Cementless hip arthroplasty in juvenile idiopathic arthritis. J Pediatr Orthop 2005;25(4):465-70.

24. Scott RD. Total hip and knee arthroplasty in juvenile rheumatoid arthritis. Clin Orthop 1990; 259:83-91

25. McCullough CJ. Surgical management of the hip in juvenile chronic arthritis. Br J Rheumatol 1994;33(2):178-83.

26. Leussenhop CP, Higgind LD, Brause BD, et al. Multiple prosthetic infections after joint replacements; Risk factor analysis: J arthroplasty 1996;11(97):862-8.