Anterior knee pain was present in 14 of 30 patients (47%) with an unreplaced patella and in two of 18 patients (11%) with patella resurfacing (25% of the knees: in 33% with unreplaced patellas and in 9% with resurfaced patellas (p = 0.05)). Only two of 18 painful knees (11%) (both with a metal-backed patella) had a replaced patella. Painless knees occurred in 53 of 71 knees (75%) and in 32 of 48 patients (67%). Thirty-four of 48 patients (71%) did not need any walking aids. Mild anterior knee pain was present in 17 knees and moderate pain was present in one knee.
Our previous study of 77 TKAs in 52 patients with juvenile rheumatoid arthritis seems to be the most extensive study in literature.24 The aim of the current study was to elucidate the appearance of postoperative anterior knee pain with the replaced and unreplaced patellas and the changes of the patella and patellar tendon in the same series. We evaluated the frequency of patella infera and assessed whether it had impact on anterior knee pain. However, patellar resurfacing was done only when it was considered necessary (in 30% of knees) to minimize the complication rate in this young patient group, and no matched groups were used.
The outcome of this series using the nonconstrained AGC prosthesis with a followup of 13 years was encouraging with a survival rate of 99%. Only one revision TKA was done because of instability, but no revision procedures were done for replaced patellas, and no later resurfacing was done for unreplaced patellas. Radiolucencies around the patellar component were present in 13% of knees.
Fourteen of 30 patients (47%) with an unreplaced patella and two of 18 patients (11%) with patella resurfacing had anterior knee pain. Only two of 18 painful knees (11%) (both with metal-backed components) had a replaced patella. Metal-backed components were used in 87% of replaced patellas in the current series. One significant radiolucency was encountered around the implant, but no revision procedures were done. The risk of complication has been reported to be high especially with the use of metal-backed patellar implants.3,4,9,20,29 Typically, the failure has been caused by wear, polyethylene dissociation, and metal-induced synovitis or fracture.3 It also has been shown that metal debris may play a role in the pathogenesis of late prosthesis infection.29 Schroder et a132 reported similar results with metal-backed components in their series of 51 AGC knee replacements in patients with rheumatoid arthritis. In the current study the low body mass of the patients with decreased demand in ambulation and restrictions from other weightbearing joints probably contributed to the good results.
The outcome of TKA in patients with juvenile rheumatoid arthritis was first reported in a series by Sarokhan et al30 in 1983 comprising 29 knee replacements. Four of six reoperations (18% in that series) were done because of patellofemoral pain subsequently requiring patellar resurfacing. In the study by Boublik et al,5 one reoperation was done because of failure of a metal-backed patellar component. Dalury et al10 published a followup of TKAs in patients younger than 45 years. That series comprised 103 knees, and 29% of patients had a diagnosis of juvenile rheumatoid arthritis. The patella was replaced in all patients with inflammatory joint disease. In two knees, the patellar component was revised, one for loosening and one for an acute avulsion fracture of the quadriceps insertion.
Whether to resurface the patella in knee replacement is a concern for many orthopaedic surgeons. Two studies have proved that routine resurfacing has not yielded a real benefit in patients with osteoarthritis.2,26 However, the situation is different among patients with rheumatoid arthritis and resurfacing frequently is preferred in these patients.17,34 Patients with juvenile rheumatoid arthritis differ in many aspects from other patients.1,15,24,30,35 There are strong advocates of routine resurfacing of the patella in patients with juvenile rheumatoid arthritis.15,30,33 In the current series patient contentment was higher with the replaced patella, no complications related to resurfacing occurred, and patella infera was common. Therefore, we agree with resurfacing the patella in patients with juvenile rheumatoid arthritis.
We thank Hannu Kautiainen for statistical analysis.
1. Ansell BM: Joint manifestations in children with juvenile chronic polyarthritis. Arthritis Rheum 20(Suppl):204–206, 1977.
2. Barrack RL, Bertot AJ, Wolfe MW, et al: Patellar resurfacing in total knee arthroplasty: A prospective, randomized, double-blind study with five to seven years of follow-up. J Bone Joint Surg 83A:1376–1381, 2001.
3. Bayley JC, Scott RD, Ewald FC, Holmes Jr GB: Failure of the metal-backed patellar component after total knee replacement. J Bone Joint Surg 70A:668–674, 1988.
4. Berger RA, Lyon JH, Jacobs JJ, et al: Problems with cementless total knee arthroplasty at 11 years followup. Clin Orthop 392:196–207, 2001.
5. Boublik M, Tsahakis PJ, Scott RD: Cementless total knee arthroplasty in juvenile onset rheumatoid arthritis. Clin Orthop 286:88–93, 1993.
6. Brattström H: Shape of the intercondylar groove normally and in recurrent dislocation of patella: A clinical and x-ray anatomical investigation. Acta Orthop Scand 68:1–148, 1964.
7. Brewer Jr EJ, Bass J, Baum J, et al: Current proposed revision of JRA criteria: JRA Criteria Subcommittee of the Diagnostic and Therapeutic Criteria Committee of the American Rheumatism Section of the Arthritis Foundation. Arthritis Rheum 20:195–199, 1977.
8. Cameron HU, Jung YB: Patella baja complicating total knee arthroplasty: A report of two cases. J Arthroplasty 3:177–180, 1988.
9. Crites BM, Berend ME: Metal-backed patellar components: A brief report on 10-year survival. Clin Orthop 388:103–104, 2001.
10. Dalury DF, Ewald FC, Christie MJ, Scott RD: Total knee arthroplasty in a group of patients less than 45 years of age. J Arthroplasty 10:598–602, 1995.
11. Dandy DJ, Desai SS: Patellar tendon length after anterior cruciate ligament reconstruction. J Bone Joint Surg 76B:198–199, 1994.
12. Fern ED, Winson IG, Getty CJ: Anterior knee pain in rheumatoid patients after total knee replacement: Possible selection criteria for patellar resurfacing. J Bone Joint Surg 74B:745–748, 1992.
13. Freeman GH, Halton JH: Note on an exact treatment of contingency, goodness of fit and other problems of significance. Biometria 38:141–149, 1951.
14. Grelsamer RP, Bazos AN, Proctor CS: Radiographic analysis of patellar tilt. J Bone Joint Surg 75B:822–824, 1993.
15. Hyman BS, Gregg JR: Arthroplasty of the hip and knee in juvenile rheumatoid arthritis. Rheum Dis Clin North Am 17:971–983, 1991.
16. Insall J, Salvati E: Patella position in the normal knee joint. Radiology 101:101–104, 1971.
17. Kajino A, Yoshino S, Kameyama S, Kohda M, Nagashima S: Comparison of the results of bilateral total knee arthroplasty with and without patellar replacement for rheumatoid arthritis: A follow-up note. J Bone Joint Surg 79A:570–574, 1997.
18. Kolettis GT, Stern SH: Patellar resurfacing for patellofemoral arthritis. Orthop Clin North Am 23:665–673, 1992.
19. Koshino T, Ejima M, Okamoto R, Morii T: Gradual low riding of the patella during postoperative course after total knee arthroplasty in osteoarthritis and rheumatoid arthritis. J Arthroplasty 5:323–327, 1990.
20. Kraay MJ, Darr OJ, Salata MJ, Goldberg VM: Outcome of metal-backed cementless patellar components: The effect of implant design. Clin Orthop 392:239–244, 2001.
21. Kujala UM, Österman K, Kormano M, et al: Patellofemoral relationships in recurrent patellar dislocation. J Bone Joint Surg 71B:788–792, 1989.
22. Larsen A, Dale K, Eek M: Radiographic evaluation of rheumatoid arthritis and related conditions by standard reference films. Acta Radiol Diagn 18:481–491, 1977.
23. Laurin CA, Dussault R, Levesque HP: The tangential x-ray investigation of the patellofemoral joint: X-ray technique, diagnostic criteria and their interpretation. Clin Orthop 144:16–26, 1979.
24. Lybäck CO, Belt EA, Hämäläinen MM, et al: Survivorship of AGC knee replacement in juvenile chronic arthritis: 13-year follow-up of 77 knees. J Arthroplasty 15:166–170, 2000.
25. Mariani PP, Del Signore S, Perugia L: Early development of patella infera after knee fractures. Knee Surg Sports Traumatol Arthrosc 2:166–169, 1994.
26. Muller W, Wirz D: The patella in total knee replacement: Does it matter? 750 LCS total knee replacements without resurfacing of the patella. Knee Surg Sports Traumatol Arthrosc 9(Suppl):24–26, 2001.
27. Noyes FR, Wojtys EM, Marshall MT: The early diagnosis and treatment of developmental patella infera syndrome. Clin Orthop 265:241–252, 1991.
28. Okamoto R, Koshino T, Morii T: Shortening of patellar ligament and patella baja with improvement of quadriceps muscle strength after high tibial osteotomy. Bull Hosp Jt Dis 53:21–24, 1993.
29. Petrie RS, Hanssen AD, Osmon DR, Ilstrup D: Metal-backed patellar component failure in total knee arthroplasty: A possible risk for late infection. Am J Orthop 27:172–176, 1998.
30. Sarokhan AJ, Scott RD, Thomas WH, et al: Total knee arthroplasty in juvenile rheumatoid arthritis. J Bone Joint Surg 65A:1071–1080, 1983.
31. Schlenzka D, Schwesinger G: The height of the patella: An anatomical study. Eur J Radiol 11:19–21, 1990.
32. Schroder HM, Aaen K, Hansen EB, Nielsen PT, Rechnagel K: Cementless total knee arthroplasty in rheumatoid arthritis. J Arthroplasty 11:18–23, 1996.
33. Scott RD: Total hip and knee arthroplasty in juvenile rheumatoid arthritis. Clin Orthop 259:83–91, 1990.
34. Sledge CB, Walker PS: Total knee arthroplasty in rheumatoid arthritis. Clin Orthop 182:127–136, 1984.
35. Swan M: The surgery of juvenile chronic arthritis. Clin Orthop 259:70–75, 1990.
36. Weale AE, Murray DW, Newman JH, Ackroyd CE: The length of the patellar tendon after unicompartmental and total knee replacement. J Bone Joint Surg 81B:790–795, 1999.