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15-Year Follow-up Study of Total Knee Arthroplasty

in Patients With Rheumatoid Arthritis

Jun Ito, MD, PhD, Tomihisa Koshino, MD, PhD, Renzo Okamoto, MD, PhD, and

Tomoyuki Saito, MD, PhD

Abstract: In 25 patients with rheumatoid arthritis, 36 cases of cemented Kinematic

total knee arthroplasty were reviewed clinically and radiographically at 13 to 19

years after surgery. The mean age at the time of surgery was 51.6 8.9 years.

According to the follow-up results evaluated with the Hospital for Special Surgeryknee scoring system, 28 knees (77.7%) were classified as good or excellent. The

mean flexion angle at follow-up evaluation was 99 24 (10140). At the tibial

or femoral bonecement interfaces, a radiolucent line was seen in 10 of 36 knees

(27.8%) at follow-up evaluation. The survival rate of prostheses with revision as the

endpoint was estimated to be 93.7% at 15 years. Kinematic total knee arthroplasty

in rheumatoid arthritis patients provided a good long-term outcome. Key words:

total knee arthroplasty, kinematic prosthesis, rheumatoid arthritis, survivorship

analysis, long-term results.

2003 Elsevier Inc. All rights reserved.

Total knee arthroplasty (TKA) provides good painrelief and functional recovery in patients who have

limited walking ability with persistent knee pain

caused by chronic rheumatoid arthritis. The long-

term results of TKA for osteoarthritic and rheuma-

toid knees have been reported, and the clinical

results were satisfactory [16]. The long-term re-

sults up to 10 years for rheumatoid patients have

been reported by several authors [711], with sur-

vival rates of the prostheses of 81% to 93% [711].

Laskin [7] reported the results of use of a total

condylar knee prosthesis for rheumatoid patients

up to 10 years after surgery. These knees had anall-polyethylene tibial component and only one size

of femoral component. At 10 years, 85% of the tibialcomponents had some radiolucency on anteroposte-

rior radiographs. With revision as the endpoint, the

survival rate was 81% at 10 years after surgery. A

better survival rate was reported for patients with

rheumatoid arthritis than osteoarthritis [8,9].

The Kinematic prosthesis has a posterior cruci-

atesparing design in both the anteriorly joined

type and the posterior retention type, made from

cobalt-chromium. A metal-backed tibial prosthesis

was developed for better fixation of the prosthesis

to the bone. Further, the femoral and tibial geom-

etry was designed to obtain a greater flexion angle.Wright et al. [12] reported 90% excellent or good

medium-term (59 years) results with Kinematic

total knee arthroplasty. The long-term survival

rates from 10 to 18 years have been reported for the

Kinematic implant [3].

The purpose of the present study was to assess

the long-term results of total knee arthroplasty with

a Kinematic prosthesis with or without sacrificing

the anterior cruciate ligament in patients with

rheumatoid arthritis.

From the Department of Orthopaedic Surgery, Yokohama City Uni-versity School of Medicine, Yokohama, Japan.

Submitted September 27, 2002; accepted April 15, 2003.No benefits or funds were received in support of this study.Reprint requests: Jun Ito, MD, PhD, Department of Orthopae-

dic Surgery, Yokohama City University School of Medicine,Yokohama, Japan.

2003 Elsevier Inc. All rights reserved.0883-5403/03/1808-0007$30.00/0doi:10.1016/S0883-5403(03)00262-6

The Journal of Arthroplasty Vol. 18 No. 8 2003

984

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Materials and Methods

From 1981 to 1987, 128 cases of primary total

knee arthroplasty with a Kinematic anteriorly

joined (AJ) type or posterior cruciateretention

(PCR) were performed in 93 patients with rheuma-

toid arthritis at our University Hospital and its affil-

iated hospitals. Cement was used at the insertion of

implants. The patella was not resurfaced in any

patient at primary surgery except in 3 knees with

anterior knee pain and articular deformity in the

patellofemoral joint on radiographs.

At follow-up, 38 patients (50 knees) had died, 16

patients (27 knees) had been lost to follow-up, and3 patients (3 knees) could not be evaluated because

of other disorders (1 patient with cervical myelop-

athy and 2 with chronic renal failure). Five patients

(6 knees) were not examined, because they did not

return to the hospital. Six patients (6 knees) under-

went revision surgery. None of the patients who

died had undergone revision surgery or experi-

enced complications related to their knees while

they were alive. Therefore 36 knees in 25 patients

were available for clinical and radiographic evalua-

tion. Three patients (5 knees) who died were in-

cluded in the cases lost to follow-up, because the

year in which they died was not clear. The prosthe-

ses in these patients were not revised while they

were alive (Table 1).

The study included 35 knees in women and one

knee in a man. The mean patient age at surgery was

51.6 8.9 years (range, 32 67 years). The mean

patient height was 154.6 6.1 cm (range, 143.0

171.0 cm), and the mean weight was 49.2 7.6 kg

(range, 35 69 kg). Eleven patients had bilateral

involvement. Twenty-eight knees received inser-

tion of an anteriorly joined type of Kinematic pros-

thesis and 8 knees received a posterior cruciate

retention type of Kinematic prosthesis. Among

these knees, 2 underwent patellar resurfacing at

initial surgery, and another 3 knees underwent

additional patellar resurfacing during the follow-up

period.

Total hip arthroplasty was performed in 6 pa-tients. Total ankle arthroplasty was performed in 2

patients. Ankle fusion was performed in 1 patient.

Femoral head replacement for femoral neck frac-

ture was performed in 1 patient. Other limb surgery

was performed in 6 patients.

The patients were evaluated clinically using the

rating systems of the Hospital for Special Surgery

(HSS) [13] and the Knee Society (KS) [14]. In the

KS rating system, 2 scores are assigned: one for

pain, range of motion, and stability (knee score)

and another for walking, stair climbing, and use of

walking aids (function score).

Data were obtained from anteroposterior radio-

graphs taken with the patient standing and lateral

radiographs. Radiolucency at the bone cement in-

terface was rated in 7 zones in the anteroposterior

view of the tibial component, 5 zones in the lateral

view of the tibial component, and 7 zones in the

lateral view of the femoral component (Table 2).

Radiolucent lines were divided into 4 grades; none

(grade I), 1 mm (grade II), 12 mm (grade III),

and 2 mm (grade IV).

Table 2. Radiolucencies

ZoneGrade I

NoneGrade II1 mm

Grade III1 mm,2 mm

Grade IV2 mm Total

Lateral femoral radiolucencies1 31 1 3 1 5 (13.9%)2 33 1 2 0 3 (8.3%)3 36 0 0 0 04 36 0 0 0 05 36 0 0 0 06 36 0 0 0 07 36 0 0 0 0

Anteroposterior tibial radiolucencies1 33 0 3 0 3 (8.3%)2 34 0 2 0 2 (5.6%)3 31 0 5 0 5 (13.9%)4 31 0 5 0 5 (13.9%)5 36 0 0 0 06 36 0 0 0 07 36 0 0 0 0

Lateral tibial radiolucencies8 34 2 0 0 2 (5.6%)9 34 2 0 0 2 (5.6%)

10 36 0 0 0 011 36 0 0 0 012 36 0 0 0 0

Table 1. State of Patients at Follow-up Evaluation

Pati ents, n (%) Knees, n (%)

Evaluated 25 (26.9) 36 (28.2)Revised 6 (6.5) 6 (4.7)Inadequate* 3 (3.2) 3 (2.3)Did not return 5 (5.4) 6 (4.7)

Died 38 (40.8) 50 (39.0)Lost 16 (17.2)/3 (3.2) 27 (21.1)/5 (3.9)Total 93(100.0) 128(100.0)

*Three patients (3 knees) could not be evaluated because ofother disorders (1 patient with cervical myelopathy and 2 withchronic renal failure).

Five patients (6 knees) were not examined, because they didnot return to the hospital.

Three patients (5 knees) were included in the cases lost tofollow-up because the year when the patient died was not clear.

Long-Term Results of Kinematic Prostheses Ito et al. 985

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Survivorship analysis was performed using the

Kaplan-Meier method, and a survival life table was

created using actual methods [15]. Three endpoints

were used: (i) death, (ii) removal or revision of the

prosthesis, (iii) additional patellar resurfacing. Pa-

tients who died or were lost to follow-up evaluation

were dropped from the life tables in the second andthird analyses. Calculation of the number at risk for

each interval and the annual success rates was

performed. The survival rate was calculated by suc-

cessive multiplication of the annual success rates.

Statistical analysis was performed with paired

t-test, Wilcoxon signed rank test, Mann-Whitney U

test, and Fishers exact method for evaluation of the

preoperative and postoperative clinical knee scores.

The log-rank test was used to assess statistical sig-

nificance after stratification of the survivorship

data. Probability values less than .05 were consid-

ered significant.

Results

Clinical Evaluation

Knee scores as determined by the HSS score

improved from a preoperative mean of 38.6 8.5

points (range, 21 60 points) to 79.3 10.6 points

(range, 5798 points) at the follow-up evaluation

(P.0001, by Wilcoxon signed rank test).

Average KS knee scores improved from a mean of

45.8 13.6 points preoperatively to 88.3 11.2points at the follow-up evaluation (P.0001, by

Wilcoxon signed rank test). Function as determined

by KS score improved from a mean of 11.9 13.6

points preoperatively to 46.5 26.4 points

(P.0001 by Wilcoxon signed rank test) at the

follow-up evaluation.

Before surgery, 28 (77.8%) of the 36 knees had

moderate or severe pain on weight bearing. At the

latest follow-up evaluation, moderate or severe

pain was not noted in any knee (P.0001 by Fish-

ers exact method), and no pain was noted in 27

knees (75%). The mean KS score for pain increased

from 19.4 7.1 points preoperatively to 48.5 3.7

points at the follow-up evaluation (P.0001, by

Wilcoxon signed rank test).

The mean range of motion of the knees was

25.9 14.9 to 105.9 27.2 of flexion preop-

eratively. At the latest follow-up evaluation, the

mean range of motion was 4.3 6.9 to 98.8

24.1 of flexion. Therefore, extension of the knee

increased (P.0001, by paired t-test), and flexion

decreased after arthroplasty compared with preop-

erative values.

Flexion contracture of more than 20 was seen in

23 knees (19 patients) preoperatively and 2 knees

(2 patients) postoperatively. Flexion of less than 70

was seen in 5 knees before surgery and in 1 knee at

follow-up evaluation.

Preoperatively, none of the patients could walk

more than 5 blocks, 12 patients (18 knees) couldwalk indoors only, and 5 patients (7 knees) could

not walk. At the latest evaluation, 9 patients (14

knees) could walk more than 5 blocks. The walking

score determined by KS score increased from a

mean of 11.7 7.1 points preoperatively to 25.3

15.9 points at follow-up evaluation (P.0001 by

Wilcoxon signed rank test). Preoperatively, 18 pa-

tients (25 knees) could not climb stairs at all. At the

latest evaluation, 5 patients (7 knees) could not

climb stairs. The KS score for stairs increased from a

mean of 5.0 8.0 points preoperatively to 25.3

13.4 points at follow-up evaluation (P.0001, byWilcoxon signed rank test). Preoperatively, 6 pa-

tients (9 knees) did not use a walking aid, and 7

patients (10 knees) used a wheelchair. At the latest

evaluation, 11 patients (15 knees) did not use a

walking aid, and 3 patients (4 knees) used a wheel-

chair.

A significant difference was found in scores of the

following items by Mann-Whitney U test between

knees with resurfacing of the patella (resurfacing: 5

knees; resurfacing at initial surgery: 2 knees; addi-

tional patellar resurfacing: 3 knees) and without

(non: 31 knees) (mean function score: none, 51.024.5; resurfacing 19.0 22.5, P.0197; mean

walking score: non 27.4 16.1, resurfacing 12.0

4.5, P.0334). Preoperative function score and

walking score failed to show any statistically signif-

icant differences between the nonresurfacing and

resurfacing groups.

Complications Related to Knees

Postoperative infection occurred in 3 knees

(2.3%; 3 of 128 knees) 10 days, 4 months, and 9

months after surgery. The infection resolved withintravenous infusion of antibiotics or irrigation

without revision in 2 knees. Implant was removed

in one knee. Supracondylar fracture occurred in 2

knees (1.6% or 2 of 12 knees) as a result of falls

while walking. The patients were treated without a

cast for the rest of the affected limb, because the

fractures were nondisplaced. One knee sustained a

supracondylar fracture at 13 years after surgery.

The other patient experienced a supracondylar frac-

ture at 14 years after surgery.

986 The Journal of Arthroplasty Vol. 18 No. 8 December 2003

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Additional Patella Resurfacing

Six knees (5 patients) of 128 knees underwent

additional patella resurfacing because of patel-

lofemoral pain. Of these 6 knees, 3 were evaluated

clinically.

Revision

Six knees of 6 patients underwent revision sur-

gery. One knee was revised because of infection 4

months after the initial surgery. Two knees sus-

tained breakage of the tibial metallic tray concom-

itant with aseptic loosening. They required revision

surgery at 3 years and 13 years, respectively, after

the initial surgery. Wear of the patellar dome and

loosening of the femoral component were found on

roentgenography 5 years after resurfacing of the

patella in one knee; revision surgery was performed

18 years after the initial joint arthroplasty. Oneknee had patellofemoral joint pain and synovitis

without loosening of the components 13 years after

initial joint arthroplasty. Patellar resurfacing sur-

gery was planned for this knee. At surgery, arthrot-

omy revealed that the polyethylene plate was worn

away and the tibial metal tray was scratched. There-

fore, the tibial component and the polyethylene-

inserter were replaced in addition to patellar resur-

facing. One knee underwent revision surgery at

another hospital because of loosening 10 years after

surgery.

Roentgenographic Evaluation

Knee Alignment. The overall mean alignment

was a femorotibial angle (FTA) of 170.4 7.4 as

measured on the preoperative radiograph in the

standing position. The overall mean postoperative

alignment was a femorotibial angle of 174.5 7.9

as measured on the postoperative radiograph at

follow-up evaluation. Preoperatively, 3 knees had

more than 180 of varus angulation (range, 3 to

15). Postoperatively, the alignment had been cor-

rected to a mean femorotibial angle of 169.0 5.2

(range, 166 to 175). Preoperatively, 33 knees

were in neutral or valgus alignment (mean, 10 of

valgus angulation; range, 0 to 24). Postopera-

tively, the knees had been corrected to a mean

femorotibial angle of 175.0 8.0 (range, 156 to

197).

Position of Components. At follow-up evalua-

tion, the mean position of the femoral component

() was 97.6 5.9 (range, 88107), and the

mean position of the tibial component () was

89.7 3.0 (range, 8497). The mean angle of

the femoral component () was 4.0 5.3 (range,

1022), and the mean angle of the tibial com-ponent () was 84.3 5.4 (range, 7498). Three

knees had a angle less than 0. However, these

knees developed no complications. The angles of

the 2 knees that developed supracondylar fractures

were 6 and 21, respectively. Neither of these 2

knees had a notch on the femur.

Radiolucent Lines. At the tibial or femoral

bone cement interfaces, radiolucent lines were

seen in 10 of 36 knees (27.8%) during a follow-up

period of more than 13 years. Five knees (13.9%)

had a radiolucent line associated with the femoral

component. Ten knees (27.8%) had a radiolucent

line associated with the tibial component. Five ra-

diolucent lines were seen in zones l and 3 in zone 2

at the femoral bone cement interface. In one knee,

a radiolucent line more than 2 mm thick (grade IV)

was seen at both the femoral and tibial bone

cement interfaces. We noted 3 radiolucent lines in

zone l, 2 in zone 2, 5 in zone 3, 5 in zone 5, 2 in

zone 8, and 2 in zone 9 at the tibial bone cement

interface. No knee had a radiolucent line beneath

either the femoral or tibial tray. No correlation was

noted between radiolucency and variables such as

age, body weight, type of component, and align-

ment (Table 2).

Survivorship

Survivorship was calculated using the method of

Kaplan and Meier [15]. The survival rate for all

patients by the life-table method was estimated to

be 74.3% at 10 years, 45.2% at 15 years, and

39.2% at 19 years (Fig. 1). With revision as the

endpoint, the survival rate of the prostheses was

estimated to be 98.3% at 10 years, 93.7% at 15

years, and 89.8% at 19 years (Table 3). The survival

Fig. 1. Survival curves of original data and worst-case

scenario for the life of the patients. Graph shows a 45.2%

survival rate at 15 years for original data and 35.0% in

the worst-case scenario.


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rate of the AJ type was estimated to be 96.4% at 10

years, 92.7% at 15 years, and 88.5% at 19 years.

That of the PCR type was 100.0% at 19 years. No

significant differences were seen in the survival

rates between the AJ and PCR types (Fig. 2).

With additional patellar resurfacing as the end-

point, the survival rate of a nonresurfaced patella

was 94.2% at 10 years, 92.6% at 15 years, and

92.6% at 19 years (Table 4). The survival rate of the

patella of the AJ type was estimated to be 96.4% at

10 years, 94.6% at 15 years, and 94.6% at 19 years.

That of the patella of the PCR type was 88.2% at 10

to 19 years. No significant difference was seen in

the survival rate between the AJ type and PCR type

(Fig. 3).Worst-Case Scenario. The worst-case scenario

was that all patients considered lost to follow-up

underwent revision surgery or patellar resurfacing

just after loss. In these cases, with revision as the

endpoint, the rate of prostheses survival was esti-

mated to be 80.6% at 10 years, 76.7% at 15 years,

and 72.2% at 19 years. With additional patellar

resurfacing as the endpoint, the rate of survival of

nonresurfaced patellas was estimated to be 78.8%

at 10 years, 76.0% at 15 years, and 73.5% at 19

years (Figs. 2, 3).

Discussion

In previous reports of TKA in rheumatoid pa-

tients, the clinical results were excellent or good in

77% to 81% of patients [6,7,11]. A prosthesis other

than the Kinematic implant was used in these stud-

ies. The functional status of rheumatoid patients

after TKA remained far below that of patients with

osteoarthritis treated with TKA [12]. This was be-

lieved to be caused by the polyarticular involve-

Table 3. Survivorship Analysis of Kinematic Knee Arthroplasty With Revision as Endpoint

YearsSinceSurgery

Numberat Start Revision Withdrawn

Lost toFollow-up Died

Censored(alive)

Numberat Risk

Annual FailureRate (%)

Annual SuccessRate (%)

SurvivalRate((%)

0 to 1 128 1 7 6 0 0 124.5 0.80 99.2 99.21 to 2 121 0 4 4 0 0 119 0.00 100.0 99.2

2 to 3 117 0 7 2 5 0 113.5 0.00 100.0 99.23 to 4 110 1 6 5 1 0 107 0.90 99.1 98.34 to 5 103 0 8 3 5 0 99 0.00 100.0 98.35 to 6 95 0 6 2 4 0 92 0.00 100.0 98.36 to 7 89 0 2 0 2 0 88 0.00 100.0 98.37 to 8 87 0 3 0 3 0 85.5 0.00 100.0 98.38 to 9 84 0 3 0 3 0 83.5 0.00 100.0 98.39 to 10 81 0 2 0 2 0 80 0.00 100.0 98.310 to 11 79 1 6 3 3 0 76 1.32 98.7 97.011 to 12 72 0 3 0 3 0 70.5 0.00 100.0 97.012 to 13 69 0 5 0 4 1 66.5 0.00 100.0 97.013 to 14 64 2 5 0 4 1 61.5 3.25 96.7 93.714 to 15 57 0 11 1 3 7 51.5 0.00 100.0 93.715 to 16 46 0 11 0 7 4 40.5 0.00 100.0 93.716 to 17 35 0 5 1 1 3 32.5 0.00 100.0 93.717 to 18 30 1 12 0 1 11 24 4.17 95.8 89.818 to 19 17 0 9 0 0 9 12.5 0.00 100.0 89.8

19 to 20 8 0 6 0 0 6 6 0.00 100.0 89.8

Fig. 2. Survival curve of original data and worst-case

scenario for the prostheses, with revision as the end

point. Graph shows 93.7% survival rate of the prosthesis

at 15 years for original data and 76.7% in the worst-case

scenario. The survival rate of the anteriorly joined type

was estimated to be 92.7% at 15 years. The survival rate

of the posterior cruciateretention type was estimated to

be 100.0% at 15 years.


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ment of rheumatoid arthritis and the steadily de-

clining functional status that can occur in the long

term [16]. In our cases, 6 patients underwent sur-

gery on other joints. Although other joints were

involved in rheumatoid arthritis, excellent or good

results in the HSS score were obtained in 77.7% of

patients in our series after a mean follow-up of 15

years. Good to excellent long-term results were

reported in 70% to 89% of patients with the Kine-

matic prosthesis [3,10,17,18]. Good or excellent

clinical results in Japanese Orthopaedic Association

(JOA) scores at 10 years were reported in 70% of

patients with rheumatoid knees treated with the

Kinematic prosthesis by Hanyu et al. [10].

Pain score and range of motion are usually out-

side the influence of other disorders. Pain relief was

well maintained in previous reports [4,6,7,11,17].

In our cases, 27 of 36 knees had no pain. FTA was

165 to 185 in these knees. Van Loon et al. [4]

reported that 48 of 52 knees (92%) had no pain or

only occasional pain. Malkani et al. [17] reported

no pain in 70% of knees. Laskin [7] reported that

knees with a low pain score had malalignment or

malpositioning of the component, especially in the

tibia. In our cases, no significant difference in FTA

was found between knees with no pain and knees

with pain.

All of our cases had synovitis preoperatively, and

synovectomy was performed at surgery. One knee

showed synovitis caused by the polyethylene wearing

postoperatively. Laskin [7] reported that synovitis re-

curred in only 3 knees over 10 years after surgery

without synovectomy in knees with rheumatoid ar-

thritis. They suggested that the immune response that

caused recurrence of synovitis could be controlled by

removing all of the articular cartilage and extensive

synovectomy was unnecessary [7].

Table 4. Survivorship Analysis for Nonresurfaced Patella, With Patellar Resurfacing as Endpoint

YearsSinceSurgery

Numberat Start Resurfacing Withdrawn Revision

Lost toFollow-up Died

Censored(alive)

Numberat Risk

AnnualFailure

Rate(%)

AnnualSuccess

Rate(%)

SurvivalRate(%)

0 to 1 125 0 7 1 6 0 0 121.5 0.00 100.0 100.0

1 to 2 118 0 3 0 3 0 0 116.5 0.00 100.0 100.02 to 3 115 0 7 0 2 5 0 111.5 0.00 100.0 100.03 to 4 108 1 7 1 5 1 0 104.5 0.96 98.5 98.54 to 5 100 2 8 0 3 5 0 96 2.08 98.0 96.55 to 6 91 0 6 0 2 4 0 88 0.00 100.0 96.56 to 7 85 0 2 0 0 2 0 84 0.00 100.0 96.57 to 8 83 2 3 0 0 3 0 81.5 2.45 97.6 94.28 to 9 78 0 3 0 0 3 0 76.5 0.00 100.0 94.29 to 10 75 0 2 0 0 2 0 74 0.00 100.0 94.210 to 11 73 0 7 1 3 3 0 69.5 0.00 100.0 94.211 to 12 66 0 3 0 0 3 0 64.5 0.00 100.0 94.212 to 13 63 1 5 0 0 4 1 60.5 1.65 98.3 92.613 to 14 57 0 7 2 0 4 1 53.5 0.00 100.0 92.614 to 15 50 0 10 0 1 3 6 44.5 0.00 100.0 92.615 to 16 40 0 10 0 0 7 3 33.5 0.00 100.0 92.616 to 17 30 0 5 0 1 1 3 25.5 0.00 100.0 92.617 to 18 25 0 12 0 0 1 11 17.5 0.00 100.0 92.6

18 to 19 13 0 7 0 0 0 7 8.5 0.00 100.0 92.619 to 20 6 0 4 0 0 0 4 3 0.00 100.0 92.6

Fig. 3. Survival curve of original data and worst-case

scenario for the nonresurfaced patella, with additional

patellar resurfacing as the endpoint. Graph shows a

92.6% survival rate at 15 years for original data and

76.0% in the worst-case scenario. The survival rate of the

anteriorly jointed type was estimated to be 94.6% at 15

years. The survival rate of the posterior cruciateretaining

type was estimated to be 88.2% at 15 years.


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The prevalence of radiolucent lines was reported

to be 20% to 60% [1719]. Uematsu et al. [18]

reported 7% on the femoral side and 20% on the

tibial side in 616 knees. In that study, 371 knees

were followed up for less than 2 years, and the

maximum follow-up period was 7 years. A higher

prevalence was reported over a longer follow-upperiod [18]. Malkani et al. [17] reported a preva-

lence of 60% at a mean of 10 years after surgery.

Approximately 60% of these patients were diag-

nosed with osteoarthritis [17]. Ewald et al. [19]

reported that 18% (22 knees) of 124 consecutive

cases with a Kinematic condylar prosthesis had

incomplete, nonprogressive radiolucent lines less

than 1 mm in width at the tibial bone cement

interface. In our cases, the prevalence was 27.8% at

13 years or more after surgery. One of the reasons

for the low prevalence may be that all patients had

rheumatoid arthritis, which impairs the patients

activity because of multiple joint destruction and isassociated with a lower body weight.

In our series of evaluated radiographs, postoper-

ative alignment was 5 of valgus, which is consid-

ered to be ideal. Whether or not malalignment of

the knee affects the clinical results or radiolucent

lines is a most important consideration, especially in

the long term. In the 3- to 4-year follow-up results

of Ewald et al. [19], the cases of malpositioning of

the tibial component such as varus positioning

showed radiolucent lines. Furthermore, the preva-

lence of radiolucent lines was significantly higher in

cases with a varus-positioned tibial componentthan in those with the ideal position. Conversely,

the presence of radiolucent lines around the femo-

ral component was not correlated with the posi-

tioning of the femoral component [19]. With an-

other prosthesis such as the total condylar

prosthesis, varus positioning of the tibial compo-

nent was associated with a high prevalence of loos-

ening of the tibial component. A properly aligned

tibial component showed the most successful re-

sults [7]. In rheumatoid knees, Laskin [7] indicated

that varus positioning of the tibial component was

significantly correlated with radiolucency at the

bone cement interface in a 10-year follow-up

study. In our cases, the correlation between radi-

olucent lines and malpositioning was not signifi-

cant. However, 1 knee with a clear zone of more

than 2 mm had malpositioning of the femoral and

tibial components. The mean body weight in our

cases was 49.2 kg, which is lighter than the mean

body weight of 70 kg in the previous report [17].

Complications after TKA other than loosening

and infection consisted of fracture of the bone

around the prosthesis [20,21], breakage of the me-

tallic tray [22], granulomatous reaction [23], skin

necrosis, deep vein thrombosis, and nerve palsy. In

our study, one knee had a supracondylar fracture

caused by minor trauma. Range of motion of the

knee was only 15 of flexion before fracture. Lim-

ited range of motion could be a risk factor for

supracondylar fracture of the knee. One knee re-quired revision surgery because of a granulomatous

reaction after additional patellar resurfacing. Break-

age of the tibial tray was seen in 2 knees, both of

which had loosening at the cementbone interface

in the tibia.

In the evaluation of the long-term results of TKA,

deaths are inevitable. Patients with rheumatoid ar-

thritis showed a marked increase in deaths resulting

from infection or sepsis and problems associated

with the rheumatoid process itself. In our study,

survivorship of all patients by the life-table method

was estimated to be only 45.2% at 15 years. Hanyu

et al. [10] reported a 56% survival rate of patientsat 10 years, with death as the endpoint. On the

other hand, the survival rate at 10 years in the

control group was 80%.

The survivorship of the Kinematic prosthesis at

10 years was previously reported to be 90% to

98% [35,10,24]. Hanyu et al. [10] reported 93%

survivorship of the prosthesis in rheumatoid arthri-

tis patients with a PCR model or a posterior stabi-

lizer model. In their study, the number of patients

lost to follow-up is not clear. Weir et al. [24] re-

ported prosthesis survivorship of 92% at 10 years

with the Kinematic prosthesis. The majority of theirpatients had rheumatoid arthritis as well. Prosthesis

survivorship at 10 years in patients, including a

large number of cases of osteoarthritis, was reported

to be 98% by Gill [3], 96% by Malkani et al. [17],

and 97% by Scuderi et al. [25]. Patients with rheu-

matoid arthritis and osteoarthritis were equal in

number in the report by van Loon et al. [4], and the

prosthesis survivorship at 10 years was 90%. TKA

for rheumatoid arthritis and that for osteoarthritis

are not similar in terms of the activity of patients,

osteoporosis around the knee joint, disorder of

other joints, and age at surgery. Therefore, the data

of follow-up results and survival rate are not ex-

actly comparable if the prosthesis, disease popula-

tion and age at surgery are considered. The pros-

thesis survival rate in our cases was satisfactory,

being close to 94% at 15 years. Rand et al. [9]

reported that the most favorable variables for pro-

longed survival of TKA were primary arthroplasty,

a diagnosis of rheumatoid arthritis, an age of 60

years or more, and use of a resurfacing condylar

prosthesis with a metal-backed tibial component.

Our patients had 3 of these 4 favorable variables.


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Sacrifice of the anterior cruciate ligament

changes the kinematics of knee movement, and

may cause a difference in prostheses survivorship.

According to our results, the AJ group and PCR

group did not show a significant difference in pros-

thesis survival rate.

Real survivorship including patients who werelost to follow-up might be worse than that deter-

mined from the original data. This paper presents a

worst-case scenario that assumed all patients lost to

follow-up failed. Weir et al. [24] reported a worst-

case prosthesis survivorship of 89% at 10 years. In

our study, worst-case survivorship was 80.6 % at

10 years and 76.7% at 15 years, because 16 patients

were lost to follow-up. Three patients (5 knees)

without revision were included in the cases lost to

follow-up because the year in which the patient

died was not clear. Therefore, real survivorship

should be better than the worst case. However, the

number of patients lost to follow-up was not small.From this aspect, our study of survivorship has

limitation in its accuracy.

In our study, a patellar component was not in-

serted at the initial surgery except in 3 knees. In 6

knees in 5 patients, however, the patella was addi-

tionally resurfaced because of anterior knee pain.

With patellar resurfacing as the endpoint, survivor-

ship was 92.6% at 15 years. The remaining cartilage

in cases of TKA may cause persistent inflammation

of the knee. However, the majority of our patients

did not complain of knee pain, and signs of arthritis

such as synovitis and joint effusion were not notedat follow-up evaluation.

At follow-up evaluation, the patella was resur-

faced with a patellar component in 5 of 36 knees.

The function scores of these 5 knees were signifi-

cantly lower than those of the other 30 knees. Boyd

et al. [26] retrospectively evaluated knees that had

undergone TKA with or without patellar resurfac-

ing. In that report, the overall complication rate was

4% in the group that had undergone resurfacing

and 12% in the group that had not undergone

resurfacing [26]. Chronic pain was noted signifi-

cantly more frequently in inflammatory arthritis

than in degenerative osteoarthritis after surgeries

without resurfacing. According to this result, Boyd

et al. [25] recommended resurfacing of the patella

at initial TKA. Hanyu et al. [10] reported that pa-

tellar resurfacing was performed in 3 of 88 knees

that did not undergo patellar arthroplasty at initial

surgery. Currently, the patellar component is re-

placed at TKA in patients with rheumatoid arthritis.

Conversely, inadequate patellar tracking and

component position were reported to cause a high

prevalence of complications [27]. The long-term

survivorship of the patellar component and compli-

cations involving the patellofemoral joint at our

hospital will show the benefits and disadvantages of

patellar resurfacing.

Total knee arthroplasty is the only option for

joint deformity or cartilage destruction of the knee

in rheumatoid arthritis. Hemiarthroplasty and os-teotomy do not improve inflammation and the con-

tinuous destruction of residual joint cartilage of the

knee joint. Therefore, good long-term results are

expected up to 20 years after surgery in knees with

rheumatoid patients. The results of this study sug-

gest that knee function was well maintained and

the prosthesis survival rate was still acceptable dur-

ing the long-term after 13 to 19 years.

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