Juvenile idiopathic arthritis (JIA) is recognized as a heterogenous group of disorders in which the common factor is persistent arthritis in at least 1 joint occurring before the age of 16 years. Although conservative management with nonsteroidal anti-inflammatory drugs and disease-modifying antirheumatic drugs can be effective, approximately 10% of JIA patients have end-stage degenerative changes requiring total hip arthroplasties (THAs) and total knee arthroplasties (TKAs). This article discusses the overall epidemiology, coordination of care, and medical and surgical management of JIA patients undergoing THA and TKA.
Key points
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Juvenile idiopathic arthritis (JIA) is recognized as a heterogenous group of disorders in which the common factor is persistent arthritis in at least 1 joint occurring before the age of 16 years.
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Although conservative management with nonsteroidal anti-inflammatory drugs and disease-modifying antirheumatic drugs (DMARDs) can be effective, approximately 10% of JIA patients have end-stage degenerative changes requiring total hip arthroplasties and total knee arthroplasties. Such procedures can provide significant pain relief and functional improvements.
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The surgical management of patients with JIA includes a multidisciplinary team approach, and the overall status of the patient, including other joints, must be taken into consideration.
Introduction
Juvenile idiopathic arthritis (JIA) is recognized as a heterogenous group of disorders in which the common factor is persistent arthritis in at least 1 joint occurring before the age of 16 years. It commonly occurs in children between the ages of 7 and 12 years. The incidence of JIA is approximately 6 cases per 10,000 children, and it affects an estimated 294,000 children in the United States. It is the leading cause of childhood disability, with the knee involved in approximately two-thirds of patients, and the hip in one-third of cases. However, hip joint involvement in JIA is the most significant factor affecting mobility and independence of these patients.
Approximately 10% of JIA patients will have disabling knee and hip arthritis. Total knee arthroplasty (TKA) and total hip arthroplasty (THA) in JIA patients are challenging given their young age, small abnormally shaped bones, complex deformities, and longer life span. When considering a TKA in a JIA patient, premature growth plate closures resulting in trumpet-shaped femurs and tibias, complex deformities including valgus alignment, flexion contractures, and external tibial torsion and poor bone quality must be considered ( Fig. 1 ). For the hip, JIA patients often have smaller pelvises, thinner femoral cortices, smaller femoral canals, and excessive femoral and acetabular anteversion. Regardless, TKA and THA in JIA patients can provide relief of pain and improved function if the appropriate preoperative assessment and perioperative management are enacted.
Coordination of medical care and medications
JIA patients have multiple musculoskeletal and nonmusculoskeletal manifestations that must be managed by a comprehensive medical and surgical team. Careful evaluation of all joints, including the spine, is mandatory. Assessment of cervical spine involvement is necessary to permit safe airway management, which may be challenging due to neck instability. Patients with basilar invagination, C1-2 or subaxial instability with a space available for the cord of no more than 13 mm, or myelopathy should first be evaluated by a spine surgeon. Mandibular hypoplasia is also important to identify, as it may make intubation difficult. A thorough evaluation by the patient’s rheumatologist prior to surgery is essential to evaluate for associated systemic involvement of the pericardium, respiratory system, and clotting cascade. Occasionally, evaluation by a specialist to evaluate cardiac and pulmonary status of JIA patients undergoing TKA or THA is warranted.
Perioperative management of medications used to manage inflammatory arthritis is essential, as such medications may place JIA patients at increased risk of delayed wound healing and perioperative infections. However, withholding such medications places patients at risk for a flare, thereby compromising rehabilitation. The most commonly used medications are synthetic DMARDs (such as methotrexate, hydroxychloroquine, and leflunomide), corticosteroids, and biologic agents (such as tumor necrosis factor [TNF]-blocking agents).
In regards to methotrexate, the international task force recommends that it should be continued through the perioperative period. It is also recommended that hydroxychloroquine be continued through the perioperative period given that it is not an immunosuppressant, and it may confer some protections against postoperative thromboembolism. However, corticosteroids are a potent anti-inflammatory and immunosuppressant. There are data showing that the risk of infection increases with corticosteroid dose. An increased risk of infection persists with doses of less than 5 mg/d, and the risk increases with duration of therapy. However, when more extensive surgeries such as arthroplasty are undertaken, stress dose steroids including an intraoperative supplemental dose of hydrocortisone should be given.
The risk of infection with anti-TNF agents is well recognized, with multiple series documenting an increased risk of infection, including surgical site infection. The infection risk is highest in the first 6 months of therapy. Given the variety of currently utilized anti-TNF medications, there are various times when they should be discontinued prior to surgery. The authors usually stop these agents at a half-life of the drug before surgery, but no more than a month before if they have a longer half-life. These drugs typically can be started after the sutures are out and the wound is healing well, typically 2 weeks after surgery.
Staging of surgical interventions
JIA patients often present with multiple joint involvement. Because upper extremity involvement has a direct impact on the ability to utilize gait aids after lower extremity surgery, these joints must be taken into consideration. If a patient is able to utilize ambulatory aids, then lower extremity surgery is preferred. This allows patients to be free from gait aids prior to total elbow arthroplasties and total shoulder arthroplasties. However, in cases in which the upper extremities are so painful or debilitating, it is reasonable to proceed with upper extremity surgery first.
In general, it is best to perform surgery on the most painful joint first. However, in JIA patients who have multiple lower extremity joints that are affected, the authors prefer to operate on the involved foot first so that the foot is free of pain and plantigrade. This will help facilitate proper rehabilitation after TKA and THA. Next, with all other factors being equal, the authors prefer to perform a THA prior to TKA. It is difficult to rehabilitate the knee if the hip is stiff and painful. Also, if there is a flexion contracture of the hip, it is difficult to maintain full extension in the knee. Replacing the hip first should also eliminate any referred pain to the knee. Of note, bilateral THAs or TKAs are performed when possible, especially in patients with flexion contractures. Rehabilitation is facilitated when both legs can be fully extended.
Overview of lower extremity joint replacements
Total Hip Arthroplasty
THA in JIA can provide relief of pain and improved function even if skeletal maturity has not yet occurred. Given their small size and weight and relatively low activity level, JIA patients are less vulnerable to wear from joint surfaces. As previously noted, there are several factors to consider prior to completing a THA in a JIA patient, including the small and abnormal anatomic structures of the femur and acetabulum, growth and remodeling of bone in young patients, osteoporosis from disuse and steroids, and soft tissue contractures ( Fig. 2 ).
THA in JIA patients can either be cemented or cementless. Primary cemented THA in JIA patients has demonstrated aseptic loosening rates of 19% to 57% at 5 to 10 years of follow-up. However, the survivorship of cementless primary THA in patients with JIA is 96% to 100% for the femoral stem and 88% to 90% for the acetabular cup at 5 to 13 years of follow-up. Daurka and colleagues reported on 52 consecutive uncemented THAs in JIA patients with a mean age of 14.4 years, and a median follow-up of 10.5 years. They found 94% survivorship of the femoral component and 62% survivorship of the acetabular component. However, there was 100% survivorship of the ceramic-on-ceramic THAs, but only 55% survivorship with metal- or ceramic-on-polyethylene. Similarly, Odent and colleagues reported on 62 uncemented THAs in 34 JIA patients after an average follow-up of 6 years. At 13 years, the survivorship was 100% for the femoral component and 90% for the acetabular component. Witt and colleagues reported on 96 cemented THAs in patients with JIA with a mean follow-up of 11.5 years and a mean age of 16.7 years. Revision was required in 25% of patients and a further 18% had radiological signs of loosening.
Both hybrid and cemented THAs have also been completed in JIA patients. Kitsoulis and colleagues reported on 20 THAs of which all acetabular cups were uncemented, and 50% of all femoral stems were uncemented. All patients experienced excellent pain relief, and there were no failures for the femoral stems at a mean 10-year follow-up. Two acetabular cups (10%) required revision because of aseptic loosening. In 50 patients between the ages of 11 and 19 years, Torchia and colleagues found 73% survival of cemented THAs at 10 years. Similarly, De Ranieri and colleagues described the outcomes of 37 primary THAs in Charnley class C JIA patients. They noted good pain relief and functional improvements, but had 12 failures. Lachiewicz and colleagues reported 100% survival in 10 patients at 4.5 years, with a mean postoperative Harris hip score of 78. On the other hand, Wroblewski and colleagues reviewed 195 Charnley low friction arthroplasties at a mean 15-year follow-up and found that 22% of acetabular components and 8% of femoral stems were loose. The results of cemented THA seem to be better in older patients. Lehtimaki and colleagues reviewed 186 cemented THAs in 116 patients with JIA. The overall survival was 91.9% at 10 years.
The authors’ current approach to THA is to utilize cementless fixation with either a metal-on-polyethylene or ceramic-on-polyethylene articulation. We frequently obtain preoperative computed tomography (CT) scans to evaluate femoral anteversion and the need for custom-fit components ( Fig. 3 ).
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