Investigation performed at the Department of Orthopedics, Mayo Clinic and Mayo Foundation, Rochester, Minnesota

1090 COPYRIGHT 2003 BY THE JOURNAL OF BONE AND JOINT SURGERY, INCORPORATED Total Knee Arthroplasty in Young Patients with Juvenile Rheumatoid Arthritis BY JAVAD PARVIZI, MD, FRCS, CLAUDETTE M. LAJAM, MD, ROBERT T. TROUSDALE, MD, WILLIAM J. SHAUGHNESSY, MD, AND MIGUEL E. CABANELA, MD Investigation performed at the Department of Orthopedics, Mayo Clinic and Mayo Foundation, Rochester, Minnesota Background: Juvenile rheumatoid arthritis is a disabling and destructive condition that commonly affects the knee during childhood. Total knee arthroplasty occasionally may be necessary for the treatment of end-stage disabling arthritis of the knee in young patients. There is a paucity of available data on the results of total knee arthroplasty in adolescents. We report our experience with total knee arthroplasty in patients under the age of twenty years who had juvenile rheumatoid arthritis. Materials and Methods: We reviewed the results of twenty-five consecutive total knee arthroplasties that had been performed at our institution between 1982 to 1997 in thirteen patients (mean age, seventeen years) with juvenile rheumatoid arthritis. The average duration of clinical follow-up was 10.7 years, and the average duration of radiographic follow-up was 6.5 years. Results: The mean Knee Society pain score improved markedly from 27.6 to 88.3 points, and the mean Knee Society function score improved modestly from 14.8 to 39.2 points. There was a slight improvement in the range of motion. Symptomatic and progressive radiolucent lines were noted in two knees, one of which was revised. Two knees (one patient) required exchange of the polyethylene liner at thirteen years. There were four additional reoperations, including manipulation under general anesthesia (two knees in one patient), lysis of adhesions (one knee), and extensor mechanism realignment (one knee). Conclusions: Despite a substantial number of postoperative complications, total knee arthroplasty provided excellent relief of pain and improvement in function in this group of adolescent patients with juvenile rheumatoid arthritis. Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence. Juvenile rheumatoid arthritis, a relatively common chronic childhood arthritic condition, may lead to disabling arthritis of the knee and hip in as many as 10% of affected patients 1. Therefore, an orthopaedic surgeon occasionally may encounter very young patients with end-stage disabling arthritis of the knee that necessitates total knee arthroplasty. Total knee arthroplasty is known as one of the most successful orthopaedic procedures and has been associated with outstanding long-term outcomes, even in young patients and in those with inflammatory arthropathy 2-8. The fear of early failure and need for future complex revision procedures discourages many orthopaedic surgeons from recommending joint arthroplasty for very young patients 9,10. Numerous studies have demonstrated excellent rates of survival of modern condylar-type knee prostheses 4,11,12. However, to date, the literature has provided little information about the outcome of total knee arthroplasty in very young patients. On the basis of the information in previous series 2,4,7,9,13, it is difficult to ascertain the clinical outcome of total knee arthroplasty in this subgroup of patients because combined results usually have been reported, with a much greater number of total knee arthroplasties having been performed in older patients. Scott et al. reported the outcome of forty-six total knee arthroplasties in young patients who had juvenile rheumatoid arthritis 14. That study involved the use of various prostheses, mostly of earlier designs, in a group of older patients with juvenile rheumatoid arthritis. Despite some complications, most of the patients benefited from knee arthroplasty, with improvement in function and return to nearly normal daily activities. The purpose of the present study was to evaluate the clinical and radiographic results associated with the use of a moderndesign total knee implant in patients with juvenile rheumatoid arthritis who were younger than twenty years of age.

1091 Materials and Methods Demographic Data ll patients with an age of twenty years or less who had un- condylar total knee arthroplasty at our institution Adergone between 1982 to 1997 were identified. During the years of the study, 11,912 total knee arthroplasties were carried out; of these, twenty-seven were performed in fifteen patients who were less than twenty years old at the time of the operation. Two patients with a diagnosis of posttraumatic arthritis and osteonecrosis were excluded. This left twenty-five knees in thirteen patients with a diagnosis of juvenile rheumatoid arthritis. The arthritis was polyarticular in six patients, systemic in five, and oligoarticular in two. The study group included twelve female patients and one male patient who had a mean age of seventeen years (range, thirteen to nineteen years) at the time of surgery. The patients had a mean weight of 53.9 kg (range, 34 to 79 kg) and a mean height of 137 cm (range, 118 to 173 cm) (Appendix). Surgical Data The study was restricted to patients who had been managed with a condylar-type prosthesis. Twelve knees had received a cruciate-retaining prosthesis, two had received a cruciatesacrificing prosthesis, and eleven had received a cruciatesubstituting prosthesis. The prosthesis had been inserted with cement in twenty-one knees and without cement in four. All but four knees had undergone patellar resurfacing with a polyethylene component. Six knees had received an inset patellar component and fifteen received a resurfacing component. A lateral retinacular release had been performed to facilitate exposure or to enhance patellar tracking in six knees. Previous Operations Fourteen knees had had a previous operation consisting of synovectomy (seven knees), arthroscopy (four), lateral release (one), or distraction-interposition arthroplasty with use of allograft (two knees in one patient). Follow-up Clinical and radiographic data on all patients were reviewed retrospectively. Patients had been contacted on a regular basis and, in most cases, had been examined at three months, one year, two years, five years, and every five years thereafter. Institutional approval and the written consent of all patients had been obtained prior to surgery, and no patient had refused to allow collection of these data. The average duration of clinical follow-up was 10.7 years (range, four to twenty years), and the average duration of radiographic follow-up was 6.5 years (range, two to twelve years). All patients had been followed for a minimum of two years, until failure of the prosthesis, or until death. No patient had been lost to follow-up. Two patients had died of unrelated causes. Fig. 1-A Preoperative anteroposterior radiograph of the knees of a thirteenyear-old patient with juvenile rheumatoid arthritis and severe bilateral ankylosis of the knee. The patient had undergone previous distraction arthroplasty of both knees and continued to have bilateral knee stiffness. Radiographic Evaluation Serial preoperative and postoperative anteroposterior, lateral, Merchant view, and, whenever available, long-leg radiographs showing the involved joint were reviewed to assess limb alignment 15, the degree of arthritis, patellar height, component positioning, component loosening, and prosthetic wear. At our institution, standard anteroposterior radiographs are made with the x-ray beam parallel to the tibial base-plate. Definite loosening was considered to be present if there was a complete radiolucent line on any radiograph or if there was femoral or tibial subsidence of 2 mm 16. Progression was considered to be present if a radiolucent line that had not been apparent on the immediate postoperative radiograph was apparent on the final follow-up radiograph or if a radiolucent line that had been apparent on the immediate postoperative radiograph was increasingly visible on the final follow-up radiograph. A detailed analysis was also carried out to determine the tibiofemoral angle, femoral tilt, the varus-valgus angle of the tibial component (as seen on the anteroposterior radiograph), femoral flexion or extension, and tibial slope (as seen on the lateral radiograph). In addition, the position and tilt of the patella (as seen on the Merchant radiograph) were assessed. Functional Evaluation Knee scores were calculated according to the system of the Knee Society 17, which consists of a score for pain and a score

1092 for function, each with a maximum of 100 points. Knee scores were assessed before surgery, at two years, and at the time of the latest follow-up. Statistical Analysis Changes in the pain and function scores were evaluated with the Wilcoxon signed-rank test. Individual risk factors were analyzed with the Fisher exact test. Continuous risk factors were analyzed with a two-sample t test. A 95% confidence level was used for all tests. Results Functional Outcome he mean Knee Society pain score improved from 27.6 Tpoints (range, 4 to 62 points) preoperatively to 88.3 points (range, 55 to 100 points) at the time of the latest follow-up (p < 0.001). The mean Knee Society function score improved modestly from 14.8 points (range, 0 to 30 points) preoperatively to 39.2 points (range, 10 to 85 points) at the time of the latest follow-up (p < 0.01). The overall arc of flexion improved from a mean of 70 (range, 0 to 105 ) preoperatively to a mean of 81 (35 to 120 ) postoperatively (Figs. 1-A and 1-B). This difference was not significant (p = 0.10). Eight knees had a mean residual flexion contracture of 18 (range, 12 to 35 ). Walking Ability Before the knee arthroplasty, two patients had been unable to walk, five patients had been able to walk indoors only, and the remaining six patients had been able to walk limited distances outdoors. All patients who had been able to walk used walking aids before surgery. At the time of the latest follow-up, six patients (eleven knees) could walk more than six blocks, four patients (eight knees) could walk fewer than six blocks, two patients (four knees) could walk indoors only, and one patient (two knees) was confined to a wheelchair. Three of nine patients returned to school or work following arthroplasty; such information was not available for the rest of the patients. Radiographic Findings All knees had complete loss of joint space on preoperative radiographs. Some knees also had radiographic evidence of soft-tissue swelling, juxta-articular osteopenia, and angular deformity. The mean postoperative angulation was 8 of valgus (range, 2 of valgus to 25 of valgus). At the time of the latest follow-up, anteroposterior radiographs (made with the x-ray beam parallel to the tibial base-plate) and lateral radiographs demonstrated an incomplete radiolucent line around six femoral components (24%) and two tibial components (8%). A progressive complete radiolucent line, indicating a loose prosthesis, was present around one femoral component and no tibial component. Revisions and Reoperations Mechanical failure leading to component loosening occurred in two patients (two knees). One of these patients had revision of a cemented total knee implant because of polyethylene wear and aseptic loosening of the tibial and femoral components 4.5 years after the index operation. The other patient was awaiting revision for progressive loosening of an uncemented total knee implant at the time of the latest follow-up. Both of these patients were very active in employment and hobbies. A third patient had exchange of the tibial polyethylene component in both knees at another institution thirteen years postoperatively. There were four additional reoperations, mostly for stiffness. These included manipulation under general anesthesia to improve range of motion in two knees (one patient), extensor mechanism realignment in one knee, and lysis of adhesions in one knee. One patient with bilateral stiffness had undergone a previous distraction arthroplasty. The time to reoperation ranged from ten days to 4.5 years. Fig. 1-B Postoperative radiograph demonstrating the persistence of a flexion contracture. Complications At the time of the latest follow-up, two patients (two knees) without patellar resurfacing continued to have anterior knee pain. No wound-related complications were reported. Symptomatic joint stiffness due to soft-tissue contracture was present in five knees.

1093 Discussion espite improvements and recent refinements in medical Dtreatment for juvenile rheumatoid arthritis, progressive joint destruction leading to severe disability may occur in some of these very young patients 18. When medical therapy fails to control the symptoms, these patients may become candidates for surgical intervention. Alternative surgical treatment, including soft-tissue release, synovectomy, and, in some cases, osteotomy, should be considered before total knee arthroplasty. The other surgical option that is available for the treatment of end-stage arthritis in these patients is arthrodesis. However, as the majority of these young patients present mainly with functional limitations, arthrodesis of the knee does not appear to be an attractive option, particularly in cases of bilateral or multiple-joint involvement. In the present series, one patient with two well-fused knee joints required total knee arthroplasty because of painful flexion and angular deformity. Total knee arthroplasty in very young patients has been carried out at some centers. An early report by Scott et al. described the outcome of forty-eight total knee arthroplasties in patients with juvenile rheumatoid arthritis 14. The mean age of the patients was not stated. Those authors found that joint arthroplasty, despite complications, successfully restored function and relieved pain in the majority of their patients. In the same study, Scott et al. also reported the results of sixty-four total hip arthroplasties. They concluded that total joint arthroplasty is a viable option for the treatment of disabling arthritis in very young patients. Torchia et al., in a recent study from our institution, reported on the outcome of sixty-three total hip arthroplasties in patients less than twenty years old 10. Those authors noted a high rate of acetabular and femoral component loosening and recommended that total hip arthroplasty should be reserved for carefully selected young patients. The present study revealed that total knee arthroplasty provided marked relief of pain as well as improvements in function and quality of life for the majority of patients. However, total knee arthroplasty did not provide a substantial improvement in range of motion and was associated with a high rate of complications. The reason for the lack of improvement in range of motion may have been related to multiple factors. First, because of the innate nature of the inflammatory disease, most if not all of the patients with juvenile rheumatoid arthritis have involvement of the periarticular soft tissues, which results in recalcitrant contractures. In addition, these patients are subjected to a long period of medical treatment before being considered as candidates for knee arthroplasty. Hence, the majority of patients have poor motion, involvement of other joints in the extremity, worsening deformities, and joint contractures at the time of presentation. The fact that improvements in range of motion may be minimal following knee arthroplasty should be discussed frankly with patients (and families) who are contemplating knee arthroplasty, to avoid dissatisfaction. There were a considerable number of complications in our series, mostly related to poor range of motion of the knee. The other problem in our series was continued anterior knee pain in two patients. The patellae in these patients had not been resurfaced at the time of knee arthroplasty. These findings are consistent with the those of Scott et al., who also noted a high (18%) prevalence of anterior knee pain in patients with nonresurfaced patellae 14. We strongly believe that patellar resurfacing should be carried out at the time of total knee arthroplasty in patients with juvenile rheumatoid arthritis. The findings of the present study differed from those of Scott et al. in some respects. Although surgical exposure was reported to have been challenging, postoperative soft-tissue breakdown and infections were not encountered in our series. Aseptic loosening occurred in two patients, one of whom required revision of all components 4.5 years after the initial arthroplasty and one of whom was awaiting revision surgery at the time of the most recent follow-up. Both of these patients were very active individuals who were able to return to full activity after the primary knee arthroplasty. Despite the high rate of complications, total knee arthroplasty provided relief of pain, reduction of deformity, and dramatic improvement in functional status and quality of life for most of the patients in this study. However, because of extensive fibrosis, soft-tissue contracture, and poor quality of bone, total knee replacement is a more technically complex and challenging procedure in these patients. The basic principles of knee arthroplasty, including adequate soft-tissue release, deformity correction, soft-tissue balancing, and maintenance of joint stability, need to be followed. Early loosening, wear, and possible deep infection are real concerns in these young, immunocompromised patients, and appropriate measures should be taken to minimize these complications. Appendix A table showing demographic, clinical, and radiographic data is available with the electronic versions of this article, on our web site at www.jbjs.org (go to the article citation and click on Supplementary Material ) and on our quarterly CD- ROM (call our subscription department, at 781-449-9780, to order the CD-ROM). Javad Parvizi, MD, FRCS Claudette M. Lajam, MD Robert T. Trousdale, MD William J. Shaughnessy, MD Miguel E. Cabanela, MD Department of Orthopedics, Mayo Clinic, 200 First Street S.W., Rochester, MN, 55905. E-mail address for M.E. Cabanela: cabanela.miguel@mayo.edu The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

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